Department Menu:
Publication Covers
 | Ultrathin Inorganic NanowiresLudovico Cademartiri and Geoffrey A OzinAdvanced Materials cover graphic illustration of a high resolution transmission electron micrograph image of ultrathin bismuth sulphide nanowires with unprecedented diameter of only 1.6 nm, a size that bridges the fuzzy regime between molecular and nanoscopic depicts the dawn of the beginning of something new and exciting in materials chemistry and nanochemistry, emerging fields that never tire of reinventing themselves. | |
 | ||
 | Noha A. Mousa, Mais J. Jebrail, Hao Yang, Mohamed Abdelgawad, Pavel Metalnikov, Jian Chen, Aaron R. Wheeler, and Robert F. Casper Detailed view of a digital microfluidics device that extracts estradiol from tiny samples of tissue. In this segment of the process, a drop of methanol containing compounds extracted from the biological sample is circulated within a pool of isooctane to remove interfering substances. The droplet is driven from electrode to electrode by an applied AC potential. See Mousa et al. for a description of device fabrication and operation, and a discussion of its application to research and diagnostics. Each electrode is 1.5 millimeters2. | |
| ||
 | Ligand-based Reactivity of a Platinum Bisdithiolene: Double Diene Addition Yields a New C2-Chiral Chelate LigandMitchell J. Kerr, Daniel J. Harrison, Alan J. Lough, and Ulrich FeklLigand-based additions to metal dithiolene complexes are both fundamentally intriguing and promising for applications. The cover illustrates an unprecedented double diene addition to Pt(S2C2(CF3)2)2, producing a chiral, chelating bisthioether ligand, relevant for potential applications in catalysis. Inorg. Chem. 2009, 48, 9043-9045. | |
| ||
 | Multiple modular microfluidic (M3) reactors for the synthesis of polymer particlesWei Li, Jesse Greener, Dan Voicu and Eugenia KumachevaLab Chip, 2009, 9, 2715 | |
| ||
 | Reversible binding of CO2Doug StephanIt can be realized with borane-phosphane frustrated Lewis pairs (FLPs). In their Communication on page 6643 ff., Stephan, Erker and coworkers describe how the greenhouse gas CO2 is captured to form both cyclic and acyclic adducts through P -- C and O -- B bond formation. The reaction is reversed and CO2 released when the temperature of the solution is raised. Theoretical analysis describes CO2 binding by FLPs as a synchronous concerted reaction. | |
| ||
 | The culmination of a rational drug discovery program of Stat3 inhibitorsSteven Fletcher, Jagdeep Singh, Xiaolei Zhang, Peibin Yue, Brent D. G. Page, Sumaiya Sharmeen, Vijay M. Shahani, Wei Zhao, Aaron D. Schimmer, James Turkson, and Patrick T. GunningThree's company: A library of analogues of the previously reported Stat3 inhibitor S3I-201 was prepared. The most active analogues, SF-1-066 (X=NCH3) and SF-1-121 (X=O), have shown impressive in vitro and whole-cell activities that possibly result from the successful occupation of a third, hydrophobic subpocket of the Stat3 SH2 domain. | |
| ||
 | Microfluidic generation of microgels from synthetic and natural polymersEthan Tumarkin and Eugenia KumachevaChem. Soc. Rev., 2009, 38, 2161 - 2168 | |
| ||
 | A MICROFLUIDIC APPROACH TO CHEMICALLY DRIVEN ASSEMBLY OF COLLOIDAL PARTICLES AT GAS-LIQUID INTERFACESJai Il Park, Zhihong Nie, Alexander Kumachev, Ahmed I. Abdelrahman, Bernard P. Binks, Howard A. Stone, Eugenia KumachevaA chemically mediated microfluidic approach to the generation of particle-coated bubbles employs rapid, controllable dissolution of CO2 bubbles in a dispersion of carboxylated particles. Local increases in the acidity of the medium in the neighborhood of the bubbles lead to a change in the surface energy of the particles and their deposition on the gas-liquid interface. | |
| ||
 | Dye-Anchored Mesoporous Antimony-Doped Tin Oxide > Electrochemiluminescence CellKun Hou, Daniel Puzzo, Michael G. Helander, Shun S. Lo, Leonardo D. Bonifacio, Wendong Wang, Zheng-Hong Lu, Gregory D. Scholes, Geoffery A. Ozin, Advanced Materials, 2009, 21, 2492-2496A long sought after target in materials research has been the synthesis of high quality, optically transparent, electrically conductive thin films that simultaneously provide large surface area and nanocrystalline mesoporosity. Geoff Ozin and co-workers report a dye-anchored transparent, well-ordered mesoporous antimony-doped tin oxide film that functions as the working electrode in an electrochemiluminescent cell, suggesting opportunities for use in a range of optoelectronic applications. | |
| ||
 | Doug Stephan The combination of Lewis acids and bases that are sterically precluded from forming Lewis acid-base adducts, termed Frustrated Lewis pairs provide a unique route to the activation of small molecules and applications in catalysis. | |
| ||
 | A.K.Y. Wong, Ulli Krull This work is directed to improving the analytical performance of surfaces that can be used to develop DNA biosensors and microarrays. The concept of immobilization of oligonucleotides to surfaces for preparation of analytical technologies based on hybridization of target sequences is well established. However, the immobilization methods that are typically used tend to provide limited selectivity when compared to that seen for the same hybridization processes in bulk solution. This fact reflects the constraints that are imposed on the selective chemistry by the presence of a surface. This manuscript reports a method of surface derivatization whereby improvement of control of the surface energetics can be achieved to tune selectivity of immobilized ensembles of oligonucleotide probes. | |
| ||
 | Hybrid microfluidics: A digital-to-channel interface for in-line sample processing and chemical separationsMohamed Abdelgawad, Michael W. L. Watson and Aaron R. WheelerMicrochannels can separate analytes faster with higher resolution, higher efficiency and with lower reagent consumption than typical column techniques. Unfortunately, an impediment in the path toward fully integrated microchannel-based labs-on-a-chip is the integration of pre-separation sample processing. Although possible in microchannels, such steps are challenging because of the difficulty in maintaining spatial control over many reagents simultaneously. In contrast, the alternative format of digital microfluidics (DMF), in which discrete droplets are manipulated on an array of electrodes, is well-suited for carrying out sequential chemical reactions. Here, we report the development of the first digital-channel hybrid microfluidic device for integrated pre-processing reactions and chemical separations. The device was demonstrated to be useful for on-chip labeling of amino acids and primary amines in cell lysate, as well as enzymatic digestion of peptide standards, followed by separation in microchannels. Given the myriad applications requiring pre-processing and chemical separations, the hybrid digital-channel format has the potential to become a powerful new tool for micro total analysis systems. | |
| ||
 | The "Metallo-Specific" Response of Proteins: A Perspective Based on the Escherichia coli Transcriptional Regulator NikRSheila C. Wang, Alistair V. Dias and Deborah B. ZambleTransition metal ions are required by all cells but an excess of metal ions beyond physiological requirements has toxic consequences. Optimal cellular concentrations of transition metals are commonly maintained by metal-responsive transcription factors that regulate genes encoding the proteins responsible for transport, sequestration and/or use of the metals. These metalloregulators must discriminate between the bioavailable metals to properly effect metal homeostasis, but how this metal selectivity is achieved is poorly understood. This perspective examines the metal-selective response of the Escherichia coli Ni(II)-responsive metalloregulator NikR. Biochemical and structural studies of E. coli NikR reveal that the mechanism of metal-selective regulation is more complex than that defined by simple metal-binding thermodynamics. Here we examine the metal-dependent allosteric changes on NikR structure that affect DNA binding and discuss the correspondence with other metalloregulators. Given what we have learned of how metal selectivity is achieved by E. coli NikR, we propose a complete scheme for the regulatory function of NikR in E. coli nickel homeostasis. | |
| ||
 | Desai-Kapral Book-blurbRashmi C. Desai is Professor Emeritus of Physics at the University of Toronto. Raymond Kapral is Professor of Chemistry at the University of Toronto.Physical systems driven out of equilibrium may spontaneously evolve to form spatial structures. The molecular constituents of some systems may self-assemble to produce complex ordered structures. This book describes how such pattern formation processes occur in nonlinear dissipative systems and how they can be modeled on mesoscopic scales. The results of experimental observations are used to introduce the diverse systems and phenomena that lead to pattern formation. The physical origins of various spatial structures are discussed, and models for their formation are constructed. In contrast to many treatments, pattern-forming processes in nonequilibrium systems, which either relax to equilibrium or are constrained to remain far from equilibrium, are treated in a coherent fashion. The book shows how near-equilibrium and far-from-equilibrium modeling concepts are often combined to describe physical systems. This inter-disciplinary book can form the basis for postgraduate courses dealing with pattern formation and self-assembly, and can also serve as a useful reference for graduate students and researchers in a number of disciplines, including condensed matter science, nonequilibrium statistical mechanics, nonlinear dynamics, chemical biophysics and materials science & engineering. | |
| ||
 | Differential Conductivity in Self-Assembled Nanodomains of a Diblock Copolymer Using Polystyrene-block-Poly (ferrocenylethylmethylsilane)James K. Li, Shan Zou, David A. Rider, Ian Manners, Gilbert C. Walker (Adv. Mater. 10/2008)The differential conductivity of the domains of a phase-segregated diblock copolymer film, polystyrene-block-poly ferrocenylethylmethylsilane (PS-b-PFEMS), is investigated using conducting-probe atomic force microscopy. Analysis of PFEMS regions show asymmetric I-V behavior, and concomitant width increase with bias indicates filling of trap states. Here, the topography is shown to correlate with the current image when scanning with an applied voltage bias. | |
| ||
 | Concepts in NanochemistryLudovico Cademartiri and Geoffrey A. Ozin, VCH-Wiley April 2009Authored by a rising star in the field and one of its pioneers, this textbook is ideal for interdisciplinary courses . bridging chemistry and physics, materials science and engineering, biology and medicine. Adopting a completely new and visionary approach, this is a unique learning tool, focusing on just six concepts crucial for understanding nanochemistry: surface, size, shape, self-assembly, defects and the interface of biology and nanochemistry. These concepts are elucidated through the analysis of six materials representing the real life application of the nanochemistry concepts. The teaching questions included provide real food for thought, thus training students to think as a researcher does and so develop problem solving skills. | |
| ||
 | Sivaraj Baktharaman, Ryan Hili, and Andrei K. Yudin* Amino aldehydes and amino ketones are central to organic chemistry and are indispensable in the synthesis of natural products and pharmaceuticals. Their utility stems from the broad scope of synthetic transformations available to both the amine and carbonyl functional groups. The utility of amino aldehydes and ketones is not without shortcomings as nitrogen protecting groups are usually needed in order to prevent undesired inter- and intramolecular self-condensation reactions. This review focuses on recent advances in this important area. | |
| ||
 | Cathy Y. Wong, Jeongho Kim, P. Sreekumari Nair, Michelle C. Nagy & Gregory D. Scholes, Relaxation in the exciton fine structure of semiconductor nanocrystals J. Phys. Chem. C Feature Article 113, 795-811 (2009). Radiationless transitions in semiconductor nanocrystals: mechanisms for concerted energy and spin relaxation. The lowest exciton band of CdSe nanocrystals is comprised of a ladder of eight closely spaced electronic 'fine structure' states. We have found that photoexcitation energy does not equilibrate among these states in the manner of dropping down the rungs of a ladder. Instead, there are particular pathways connecting various 'rungs' (fine structure states). The dynamics of transitions between them, which span four decades of timescales, were measured using an ultrafast transient grating technique that isolates dynamics that flip the sign of the exciton total angular momentum. We conclude that the fastest relaxation in the exciton fine structure occurs mainly by a sequential mechanism involving the primary bright-to-dark transitions. | |
| ||
 | Nanochemistry: A Chemical Approach to Nanomaterials2nd Editon, Authors Geoffrey A. Ozin, Andre C. Arsenault and Ludovico Cademartiri Foreword by Chad MirkinThe global success of the 1st edition of Nanochemistry, along with exceptionally rapid change in the field, has necessitated the publication of a 2nd edition after only three years. This truly major update highlights the latest breakthroughs using more than eighty new case histories, more problem sets, and more teaching principles. Nanotechnology is touted to begin a new era by bringing us materials that were not available before. This book describes the fascinating chemistry behind nanotechnology in a clear and easy to read style. Aimed at teachers, graduate students and advanced undergraduates it provides an authoritative, rigorous and hype-free guide to this burgeoning field. For those who already have some knowledge of the subject, the book remains invaluable as a reference and source of inspiration for future research or teaching. With a combined total of over forty years teaching and research experience, the authors are leaders in the fields of materials chemistry and nanochemistry. They have chosen to focus on concepts rather than formulas whilst describing all the techniques commonly used to synthesize nanomaterials. Problem sets are used to encourage students to think creatively and laterally about what they have learnt. The questions are designed to draw connections between subjects, fields and topics - of fundamental importance for anyone intending to work in such an interdisciplinary field. Suitable for those coming from a physics, biology, medicine, materials science, engineering or chemistry background, the book is ideal for whoever needs a birds-eye view of the field. The extensive bibliography allows the reader to find any level of detail behind each of the subjects. Nowhere else in the literature is it possible to find such a comprehensive and up-to-date look at the chemistry of nanotechnology. Extracts from reviews of the 1st Edition:
| |
| ||
 | Spatially Localized Photoluminescence at 1.5 Micrometers Wavelength in Direct Laser Written Optical NanostructuresSean Wong, Oliver Kiowski, Manfred Kappes, Jƶrg K. N. Lindner, Nirajan Mandal, Frank C. Peiris, Geoffrey A. Ozin, Michael Thiel, Markus Braun, Martin Wegener, Georg von Freymann. Advanced Materials, Published Online: Oct 6 2008 6:36AMA 3D direct laser writing (3D DLW) compatible photoresist, consisting of erbium-doped arsenic trisulfide (Er:As2S3) has been developed. This photoresist simultaneously possess a refractive index (n) of 2.45 and photoluminescence at 1.5 m wavelength that is also spatially localizable. This enables 3D DLW to produce high-refractive index photonic structures with spatially selective optical activity without the need for post-processing steps. | |
| ||
 | Preparation of Chiral Diamines by the Diaza-Cope RearrangementHyunwoo Kim, Soon Mog So, B. Moon Kim and Jik ChinChiral vicinal diamines are regarded as privileged structures for making drugs and catalysts. This review describes a highly efficient method for making a wide variety of chiral vicinal diamines in enantiomerically pure form by the diaza-Cope rearrangement reaction. | |
| ||
 | Synthesis of Chiral Amines Using α-Amino AldehydesRyan Hili, S. Baktharaman, Andrei K. YudinThe cover picture is an attempt to represent a cornucopia of molecules that are derived from α-amino aldehydes. One hundred years ago, Emil Fischer attempted to prepare glycinal, a prototypical .- amino aldehyde. Although glycinal resisted isolation and was found to be too unstable, it did provide a foundation for numerous synthetic studies of related molecules. Over the last century this field has flourished, proving the lasting value of these important synthetic intermediates. A. K. Yudin et al. summarize the latest trends in α- amino aldehyde synthesis and applications on p. 5201ff. The cover art was created by Mr. Ryan Hili. The authors gratefully acknowledge ongoing financial support from NSERC. | |
| ||
 | Creating Helices with amino acids Angew Chem Int Ed (2008)Hyunwoo Kim, Soon Mog So, Cindy Pai-Hui Yen, Elisangela Vinhato, Alan J. Lough, Jong-In Hong, Hae-Jo Kim, and Jik Chin, Angew. Chem. Int. Ed. 2008, 47, 8657-8660A spiral staircase follows the many helical structures in nature (DNA, protein etc.). Amino acids that form alpha-helical proteins in biology can also be used to generate small helical structures with 2,2.-dihydroxybenzophenone. Signaling groups can be attached to allow the receptor to sense amino acid enantiopurity. | |
| ||
 | Heterolytic Dihydrogen Activation by a Frustrated Carbene-Borane Lewis Pair / Hydrogen and Amine Activation by a Frustrated Lewis Pair of a Bulky N-Heterocyclic Carbene and B(C6F5)3 (Angew. Chem. Int. Ed. 39/2008) (p 7369)Dirk Holschumacher, Thomas Bannenberg, Cristian G. Hrib, Peter G. Jones, Matthias Tamm, Preston A. Chase, Douglas W. StephanForcing a square peg into a round hole: tBu2ImC: and B(C6F5)3 form a frustrated Lewis pair (FLP),allowing the synergistic activation of H2. On page 7428 ff.,M. Tamm et al. describe how the irreversible formation of an abnormal carbene-borane adduct eliminates mismatching between acid and base so that this system can circumvent frustration at the expense of activity. In addition, D. W. Stephan and P. A. Chase demonstrate on page 7433 ff. that this FLP combination not only effects heterolytic cleavage of H2, but also of amine N-H bonds. | |
| ||
 | Photonic Ink and Elastic Ink Lab-to-MarketOzin, Z. Anorg. Allg. Chem., 2008, 634, 1871-2100A notable trend these days amongst academics, especially in the fields of information technology, biotechnology and nanotechnology, is the increasing tendency to transfer the fruits of their research into the marketplace. Nowhere is this more apparent than in the globally burgeoning and highly competitive area of nanotechnology. Particularly interesting is the large number of spin-off companies now emerging from universities all racing to develop, manufacture and commercialize nanotechnology based on the potential of a cornucopia of new nanomaterials in diverse areas from electronics to photonics, biometrics to cancer therapy. In this paper I will present a personal account of some of our recent research in the area of photonic crystals that has evolved over the last ten years from a laboratory curiosity to two new nanotechnology platforms, affectionately called P-Ink and Elast-Ink. These nanotechnology platforms are both founded on active color tuning of opals, a capability that provides electrical and mechanical access to materials with any visible color you want, including the invisible ultraviolet and near infrared wavelength range. P-Ink is made of a metallopolymer opal gel that reversibly swells and shrinks with application and removal of a voltage. Elast-Ink is made of an elastomeric opal that undergoes reversible dimensional changes on applying and removing a mechanical force. P-Ink and Elast-Ink actively tuned opals show considerable promise for the development of new generation of full color displays, biometric security and anti-counterfeiting systems. | |
| ||
 | Quantum dots as donors in fluorescence resonance energy transfer for the bioanalysis of nucleic acids, proteins, and other biological moleculesUlli KrullQuantum dots (QDs) have a number of unique optical properties that are advantageous in the development of bioanalyses based on fluorescence resonance energy transfer (FRET). Researchers have used QDs as energy donors in FRET schemes for the analysis of nucleic acids, proteins, proteases, haptens, and other small molecules. Superior brightness, resistance to photobleaching, greater optimization of FRET efficiency, and/or simplified multiplexing are possible with QD donors. | |
| ||
 | Stoichiometric and Catalytic Activation of P-H and P-P bondsSharonna Greenberg and Douglas W. Stephan, Chem. Soc. Rev., 2008, 37, 1482The abilities of transition metal species to activate P-H and P-P bonds are emerging. Such investigations provide novel M-P species, as well as stoichiometric and catalytic routes to P(III) compounds. The application of organometallic approaches and methodologies to phosphorus chemistry is providing emerging, stoichiometric and catalytic routes to phosphorus compounds and materials. This tutorial review surveys recent advances, with a focus on the activation of P-H and P-P bonds. The isolation of novel M-P species provides insight, while stoichiometric and catalytic reactivity expands the arsenal of synthetic strategies leading to P(III) compounds. | |
| ||
 | Molecular Approaches towards the Inhibition of the Signal Transducer and Activator of Transcription 3 (Stat3) ProteinChemMedChem, 2008, 3, 1159-1168. Steven Fletcher, James Turkson and Patrick T. GunningStat3 inhibition represents an exciting new approach to the treatment of cancer. The advances in the direct molecular inhibition of Stat3 are highlighted through discussion of the various inhibitors currently under investigation, including peptide sequences, peptidomimetics, small molecules and platinum-based agents. | |
| ||
 | Large-Scale Synthesis of Ultrathin Bi2S3 Necklace NanowiresAngew. Chem. Int. Ed. 2008, 20, 3652, Ludovico Cademartiri, Reihaneh Malakooti, Paul G. O'Brien, Andrea Migliori, Srebri Petrov, Nazir P. Kherani, Geoffrey A. OzinUltrathin necklaces of Bi2S3 nanowires can be synthesized in solution on a gram scale and using cheap and non-air-sensitive reagents. Despite their small size, these nanostructures show quantum confinement effects never before observed in Bi2S3 at room temperature and a semiconductivity which bodes well for their use in flexible electronics devices. | |
| ||
 | Controlling the Optical Properties of Inorganic NanoparticlesGregory D. Scholes, Adv. Funct. Mater. (2008) 18, 1157 - 1172The size tunability and close relationship of inorganic nanoparticles to bulk semiconductors have inspired intense study of these materials. Applications, such as diodes and lasers, can take advantage of the light-emitting properties of nanoscale systems, as pictured on the cover. A growing and important area of application for these materials is renewable energy. A challenge for researchers is to elucidate how to design and control the desirable optical properties of nanoparticles by manipulating electronic structure using chemical design. | |
| ||
 | Development of Analytical Methods for Multiplex Bio-assay with Inductively Coupled Plasma Mass SpectrometryO.I. Ornatsky , R. Kinach , D.R. Bandura , X. Lou , S.D. Tanner , V.I. Baranov , M. Nitz and M.A. Winnik, Journal of Analytical Atomic Spectrometry , 2008, 23, 463-469Advances in the development of highly multiplexed bio-analytical assays with inductively coupled plasma mass spectrometry (ICP-MS) detection are discussed. Use of novel reagents specifically designed for immunological methods utilizing elemental analysis is presented. The major steps of method development, including selection of elements for tags, validation of tagged reagents, and examples of multiplexed assays, are considered in detail. The paper further describes experimental protocols for elemental tagging of antibodies, immunostaining of live and fixed human leukemia cells, and preparation of samples for ICP-MS analysis. Quantitative analysis of surface antigens on model cell lines using a cocktail of seven lanthanide labeled antibodies demonstrated high specificity and concordance with conventional immunophenotyping. | |
| ||
 | Visualization of Stacking Faults and their Formation in Colloidal Photonic Crystal Films (Adv. Mater. 6/2008)Van Vekris, Vlad Kitaev, Doug Perovic, Stewart. Aitchison and Geff OzinA colloidal crystal with fundamental photonic stopband in the near-infrared and higher-frequency photonic bands in the visible was designed to yield impressive sensitivity to stacking fault formation. Diagnostic patterns of brilliant colors emerge, providing a powerful spectroscopic tool to elucidate the origin, nature, and control of stacking faults. | |
| ||
 | Ultra-thin Sb2S3 NanowiresR. Malakooti, L. Cademartiri, A. Migliori, G. A. OzinA simple synthetic route is described which allows the reproducible synthesis of ultra-thin Sb2S3 nanowires with a diameter below 2 nm and micron lengths. The colloidal nature of such nanowires and their unparalleled small diameters makes them amenable to solution processing and deposition on flexible substrates. The interest in high performance metal chalcogenide nanothermoelectric materials with reduced dimensionality motivates this work and further encourages the exploration of synthetic routes to enable the next generation of practical thermoelectric nanostructures for possible use in solid-state refrigeration and power generating systems. | |
| ||
 | Metal-Free Catalytic HydrogenationPreston A. Chase, Gregory C. Welch, Titel Jurca, and Douglas W. Stephan*Off the beaten path aptly describes a main-group alternative for catalyzing hydrogenation reactions using H2. Whereas the main road is based on transition metals, D.W. Stephan and co-workers offer a new path in their Communication on page 8050 ff. with metal-free phosphonium borates, which effect the reduction of sterically hindered imines and aziridines under relatively mild conditions. The cover picture illustrates this alternative but parallel route with the bicycle and pedestrian paths of the "Promenade" in Muenster, Germany. | |
| ||
 | Nanorod Heterostructures Showing Photoinduced Charge SeparationSandeep Kumar, Marcus Jones, Shun S. Lo, Gregory D. Scholes, Small (2007) 3(9), 1633-1639.Size- and shape-dependent property modifications of semiconductor nanocrystals have been a subject of intense interest because of their potential for future engineering devices. The bandgap and related optical-property tuning of these materials are mainly governed by the nature of their band edges. In addition, fusing one type of nanocrystal over another enables further control of material properties that are dependent on the relative alignments of their energy levels. On a molecular scale, the synthesis of supramolecular compounds has inspired advances in theories for photoinduced charge transfer. Heterostructured nanocrystals potentially provide a nanoscale analog of such systems. A method for preparing heterostructured nanocrystals of complex morphologies showing photoinduced charge separation is presented. It is shown that the energy and lifetime of the charge-transfer photoluminescence band can be tuned by changing the relative alignment of band edges in CdSe/CdTe heterostructure nanorods. The long-lived charge transfer states in these type II semiconductors may make them attractive for photovoltaic applications. | |
| ||
 | Low-lying exciton states determine the photophysics of semiconducting single wall carbon nanotubesGregory D. Scholes, Sergei Tretiak, Timothy J. McDonald, Wyatt K. Metzger, Chaiwat Engtrakul, Garry Rumbles and Michael J. Heben (contribution from NREL, UofT, and LANL)Single wall carbon nanotubes are extraordinary carbon-compounds that can be up to millimeters in length. It is concluded that the interplay of multiple exciton states--rather than only one as is well known for molecules--determines fluorescence emission. On the basis of a combination of experiment and theory, it is concluded that a kinetic model that captures the nonradiative relaxation among four low-lying exciton states is essential to interpret the photophysics of single wall carbon nanotubes. | |
| ||
 | Novel Hydrido-Ruthenium(II) Complexes of Histidine Derivatives and Their Application in the Hydrogenation of KetonesChristine Sui-Seng, Alen Hadzovic, Alan J. Lough, and Robert H. Morris, Dalton Transactions , 2007, 2536The complexes RuHCl((R)-binap)(L-NH2) with L-NH2 = (S)-histidine-Me-ester (1), histamine (3), (S)-histidinol (4) or 1-Me-(S)-histidine-Me-ester (5), and RuHCl((S)-binap)(L-NH2) with L-NH2 = (S)-histidine-Me-ester (2) have been prepared in 60–81% overall yields in a one-pot, three-step procedure from the precursor RuCl2(PPh3)3. Their octahedral structures with hydride trans to chloride were deduced from their NMR spectra and confirmed by the results of a single crystal X-ray diffraction study for complex 3. Under H2 and in the presence of KOtBu, complexes 1–5 in 2-propanol form moderately active catalyst precursors for the asymmetric hydrogenation of acetophenone to 1-phenylethanol. Complex 5 is more active and enantioselective than complexes 1–4, allowing complete conversion to 1-phenylethanol in 46% e.e. (R) in 72 h at 20 ?C under 1 MPa of H2 with substrate : catalyst : base = 2000 : 1 : 30. Complex 5, when activated, also catalyzes the hydrogenation of trans-4-phenyl-3-buten-2-one to exclusively the allyl alcohol 4-phenyl-3-buten-2-ol under 2.7 MPa of H2 at 50 ?C in 2-propanol. This selectivity for C=O versus C=C hydrogenation is consistent with a mechanism involving the outer sphere transfer of hydride and proton to the polar bond. Further extensions to complexes with peptides with N-terminal histidine groups appear feasible on the basis of the current work. | |
| ||
![Properties of the Polyhydride Anions [WH<SUB>5</SUB>(PMe<SUB>2</SUB>Ph)<SUB>3</SUB>]<SUP>-</SUP> and [ReH<SUB>4</SUB>(PMePh<SUB>2</SUB>)<SUB>3</SUB>]<SUP>-</SUP> and Periodic Trends in the Acidity of Polyhydride Complexes](/_shared/images/covers/thumbs/thumb_cover_june2007.jpg) | Properties of the Polyhydride Anions [WH5(PMe2Ph)3]- and [ReH4(PMePh2)3]- and Periodic Trends in the Acidity of Polyhydride ComplexesJustin G. Hinman, Alan J. Lough, and Robert H. MorrisThe new anionic complexes [K(18-crown-6)][WH5(PMe2Ph)3], [K(1,10-diaza-18-crown-6)][WH5(PMe2Ph)3], [K(2,2,2-crypt)][ReH4(PMePh2)3], and [K(1,10-diaza-18-crown-6)][ReH4(PMePh2)3] were prepared by reaction of KH/crown or KH/crypt with the appropriate neutral polyhydride WH6(PMe2Ph)3 or ReH5(PMePh2)3. The rate of deprotonation of the rhenium hydride in THF is much greater for the reaction involving crypt compared with that of crown. The structure of [ReH4(PMePh2)3]- is distorted pentagonal bipyramidal as determined by an X-ray diffraction study of the crypt salt. No hydridic-protonic M-H···HN bonding is detected between the hydrides of the anionic hydrides and the amino hydrogens of the cations [K(1,10-diaza-18-crown-6)]+ suggesting that stronger M-H···K interactions are present. Acid dissociation constants Ka of polyhydride complexes in THF, approximately corrected for ion pairing, are determined by NMR in order to better understand the periodic trends of metal hydrides. The pK  THF of (WH6(PMe2Ph)3/[WH5(PMe2Ph)3]-) is 42 ± 4 according to the equilibrium set up by reacting WH6(PMe2Ph)3 with [K(2,2,2-crypt)][ReH6(PCy3)2]. The pKTHF for ReH5(PMePh2)3 can be estimated as greater than the pKαTHF of 38 for HNPh2 and less than the pKαTHF of 41 for ReH7(PCy3)2. Reaction of the phosphazene base P4-tBu with ReH7(PCy3)2 gave an equilibrium with [HP4-tBu]+[ReH6(PCy3)2]- whereas reaction with WH6(PMe2Ph)3 gave an equilibrium with [HP4-tBu]+[WH5(PMe2Ph)3]-. From these and a related equilibrium, the pKTHF of [HP4-tBu]+ is found to be 40 ± 4. In general, neutral complexes MHx(PR3)n (M = W, Re, Ru, Os, Ir; n = 3, 2) studied to date have pKαTHFvalues from 30 to 44 on going from phenyl-substituted to alkyl-substituted phosphine ligands whereas MHx(PR3)n+(M = Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt; n = 4, 3), including diphosphine ligands ((PR3)2 = PR2-PR2), have values from 12 to 23. From the equilibrium established from the reaction of [HP2-tBu][BPh4] and [K(2,2,2-crypt)][OP(OEt)2NPh], [HP2-tBu]+ was calculated to have a pKTHF of 30 ± 4. The equilibrium constant for the similar deprotonation reaction with [K(18-crown-6)][{ReH2(PMePh2)2}2(α-H)3] confirmed this value.
| |
| ||
 | Perfluorinated acids in arctic snow: New evidence for atmospheric formationYoung, Cora J.; Furdui, Vasile I.; Franklin, James; Koerner, Roy M.; Muir, Derek C.G.; Mabury, Scott A. "Perfluorinated acids in Arctic snow: New evidence for atmospheric formation". Environmental Science and Technology 2007, 41, 3455-3461Perfluorinated acids (PFAs) are ubiquitously found in water and biota, including remote regions such as the High Arctic. Under environmental conditions, PFAs exist mainly as anions and are not expected to be subject to long-range atmospheric transport in the gas phase. Fluorinated telomer alcohols (FTOHs) are volatile and can be atmospherically oxidized to form perfluorocarboxylic acids. Analogously, fluorosulfamido alcohols can be oxidized to form perfluorooctane sulfonate (PFOS). High Arctic ice caps experience contamination solely from atmospheric sources. By examining concentrations of PFAs in ice cap samples, it is possible to determine atmospheric fluxes to the Arctic. Ice samples were collected from high Arctic ice caps in the spring of 2005 and 2006. Samples were concentrated using solid phase extraction and analyzed by LC-MS-MS. PFAs were observed in all samples, dating from 1996 to 2005. Concentrations were in the low-mid pg L-1 range and exhibited seasonality, with maximum concentrations in the spring-summer. The presence of perfluorodecanoic acid and perfluoroundecanoic acid on the ice cap was indicative of atmospheric oxidation as a source. Ratios of PFAs to sodium concentrations were highly variable, signifying PFA concentrations on the ice cap were unrelated to marine chemistry. Fluxes of the PFAs were estimated to the area north of 65°N for the 2005 season, which ranged from 114 to 587 kg year-1 for perfluorooctanoic acid (PFOA), 73 to 860 kg year-1 for perfluorononanoic acid (PFNA), 16 to 84 kg year-1 for PFDA, 26 to 62 kg year-1 for PFUnA and 18 to 48 kg year-1 for PFOS. The PFOA and PFNA fluxes agreed with FTOH modelling estimations. A decrease in PFOS concentrations through time was observed, suggesting a fast response to changes in production. These data suggest that atmospheric oxidation of volatile precursors is a primary source of PFAs to the Arctic. | |
| ||
 | Materials Chemistry for Low-k MaterialsHatton, B.D., Landskron, K., Hunks, W.J., Bennett, M.R., Shukaris, D., Perovic, D.D., Ozin, G.A., 2006, Materials Chemistry for Low-k Materials, Materials Today 9 , 22-31 ( front cover ).The microelectronics industry is constantly trying to reinvent itself, to find new technological solutions to keep pace with the trend of increasing device densities in ultra-large-scale integrated (ULSI) circuits. Integral in this development has been the replacement of the conventional Al/SiO 2 metal and dielectric materials in multilevel interconnect structures. Higher-conductivity Cu has now successfully replaced Al interconnects, but there is still an urgent need for new low dielectric constant (low-k) materials, as an interlayer dielectric. This paper critically appraises low-k materials under development as interlayer dielectrics (ILD) materials. It delineates how recent developments in materials chemistry, particularly the recent introduction of a new class of materials called periodic mesoporous organosilicas (PMOs), invented in our laboratory may provide novel solutions to the low-k challenge. | |
| ||
 | Suppression of aqueous surface hydrolysis by monolayers of short chain organic amphiphilesDaniel Clifford, Thorsten Bartels-Rausch and D.J. Donaldson Phys. Chem. Chem. Phys. , 2007 , 9 , 1362-1369Aqueous aerosols and other water surfaces in the environment may be coated with organic films, which can give rise to significant effects on gas-solution transport and surface reactivity. We have used a surface active fluorescent pH probe to examine the hydrolysis of nitric acid and ammonia at both the uncoated and the organic-coated air-water interface. For uncoated samples, a transient change in pH is observed at the interface upon introduction of acid or base vapour, followed by a relaxation to a final pH which is different than the initial value, and equal to the final bulk pH. Solutions having monolayer and sub-monolayer films of 1-octanol do not display the transient, but do show the same long-time change in pH. The degree of suppression of the surface pH transient depends directly on the amount of octanol present at the surface, however when monolayers of butanol and of uncompressed stearic acid are present at the surface there is little difference seen from the clean interface. We propose that the surface component of the hydrolysis reaction depends directly on the concentration of available water at the interface. In the upper half of the figure, the time dependence of surface pH is shown after gas phase nitric acid is introduced above a bare interface (in blue) and one having a monolayer of 1-octanol at the surface (red). Beside these traces are photos of the fluorescence observed with higher (top) and lower (bottom) values of the surface pH. The lower portion of the figure shows a cartoon depicting the inhibition of surface hydrolysis by an organic monolayer. | |
| ||
 | Properties of Single Organic Molecules on Crystal SurfacesJohn PolanyiWithin nanoscience, an emerging discipline is the study of the physics and chemistry of single molecules. Molecules may be considered as the ultimate building blocks, and are therefore interesting for the development of molecular devices and for surface functionalization. Thus, it is interesting to study their properties when adsorbed on a suitable substrate such as a solid or crystal surface, and also for their potential applications in nano- or molecular-electronics and nansensing. Investigations have been made possible by the advent of high resolution surface imaging and characterization techniques, commonly referred to as Scanning Probe Microscopes. This book focuses on the fascinating properties of the single molecules, and the difference between single molecules and ensembles of molecules is emphasized. As the first book intended for graduate courses in the field, after each chapter, students should be able to answer the question: What physical or chemical properties do you learn from a single molecule in this particular context? Contributed by experts across the disciplines, the book provides useful reference material for specialized practitioners in surface science, nanoscience and nanoelectronics. | |
| ||
 | Polymer nanostructured material for the recording of biometric featuresHung H. Pham, Ilya Gourevich, James E. N. Jonkman and Eugenia KumachevaThe cover shows three spatially overlapping biometric features recorded in the same location of the nanostructured polymer material and selectively accessed under particular, well-defined conditions. We conceptualized, designed, synthesized and fabricated a polymer multiphase nanostructured material that was used as a medium for the recording of biometric features. The material was produced from polymer multilayer particles containing three fluorescent dyes with largely non-overlapping absorption and emission spectra. Recording was conducted by selective photobleaching of the dyes localized in the different phases of the film. We demonstrate two distinct approaches to the recording of biometric features in the polymer material. In the first strategy, we encrypted in the polymer films full colour photographs with different shades of grey. In the second approach, we recorded three spatially overlapping biometric features in the same location of the material with no spectral overlap between them. Each feature was accessed by irradiating the material at a specific well-defined wavelength. The reported material can be used as a medium for the recording of biometric features of holders of identification documents. | |
| ||
 | Imprinting and locking chiral memory for stereoselective catalysisJik Chin, Yong S. Chong, Rhiana Bobb, Lisa Studnicki and Jong-In HongThe image shows a right handed double helix used to imprint and then padlock a chiral Möbius strip. This is much like using an amino acid to imprint our diamine based metal complex and then lock the chirality by acylation. A metal complex that is made with an achiral ligand is imprinted with a chiral amino acid. The metal complex retains the chiral memory even when the amino acid is displaced with an achiral amine. This chiral memory can be covalently locked by acylation. The imprinted and locked metal complex can be used as a stereoselective catalyst for ring opening of epoxides. It can also be used as a stereoselective receptor for amino acids and amines. | |
| ||
 | How energy funnels from the phycoerythrin antenna complex to Photosystem I and Photosystem II in cryptophyte Rhodomonas CS24 cellsChantal D. van der Weij-De Wit, Alexander B. Doust, Ivo H. M. van Stokkum, Jan P. Dekker, Krystyna E. Wilk, Paul M. G. Curmi, Gregory D. Scholes, and Rienk van GrondellePhotosynthetic organisms capture incident light in vast arrays of light-harvesting proteins. These antenna proteins then shuttle the absorbed solar energy, through a series of steps often involving ~200 molecules, to the core of photosystems I and II. It is there that solar energy conversion takes place, concomitant with the evolution of an important biproduct: oxygen. Ultimately ATP--Nature's energy currency--is created. The initial steps of this chain of events occur with remarkable efficiency (>95% quantum yield) and on a heirarchy of time- and length-scales; femtoseconds to nanoseconds, Angstroms to several nanometers. We report an investigation of the ultrafast excitation energy migration dynamics in intact (living) cells of the photosynthetic cryptophyte Rhodomonas CS24. This red organism lives in marine environments off the coast of Sydney, Australia. Our work shows that the antenna proteins function more effectively in the organism than in isolation. We expose the dynamics of this complex machinery, thus providing functional picture of the nanoscale organization of the photosynthetic apparatus. | |
| ||
 | Coherent Control of Retinal Isomerization in BacteriorhodopsinV.I. Prokhorenko, A.M. Nagy, S.A. Waschuk, L.S. Brown, R.R. Birge, R.J.D. Miller, Coherent Control of Retinal Isomerization in Bacteriorhodopsin, Science 2006, 313, 1257-1261Do we live in a Quantum World? Quantum mechanics dictates that all matter has an inherent wave property. On a molecular scale, this property can lead to destructive and constructive interferences that have a pronounced effect on transmission probabilities along reaction coordinates, particularly the photo-induced isomerization of retinal molecule in rhodopsins. In bacteriorhodopsin, random fluctuations among the enormous number of degrees of freedom of protein might be expected to cancel any quantum interference effects. However, the proteins are highly evolved structures and the question arises whether the phases of the underlying matter waves could play a role or even be manipulated in directing biological processes. To answer this question, Valentyn I. Prokhorenko et al. (research team of Prof. R.J. Dwayne Miller) has performed an experimental test of possibility to manipulate the isomerization quantum yield of the retinal in bacteriorhodopsin, a key molecule in light capture and vision, at very weak excitation level (relevant to natural biological conditions) using coherent control approach. By manipulating the shape of the light pulse that jump-starts retinal's transformation, the UofT researchers were able to enhance or suppress the retinal isomerization yield by 20% in either direction and found the effect to depend on the phase of the light field or timing of the various excited nuclear motions. The latter effect is consistent with constructive and destructive wave interference effects along the reaction coordinate defined by the protein structure. This experimental observation illustrates that the wave properties of matter can play a role in biological processes to the point that they can even be manipulated. | |
| ||
 | Curling Colloidal Photonic CrystalsEvangellos Vekris, Geoffrey A. Ozin, Vladimir V. KitaevThe cover features a schematic illustration (right) and three representative electron microscopy images (left) of photonic-crystal strips with controlled curvature. The curvature is induced by infiltration of polymer opal with alkoxide precursors to attain a nanoscale overlayer that experiences controllable shrinkage upon hydrolysis. Both continuity and high structural order are perfectly preserved throughout precursor infiltration and polymer microsphere removal. | |
| ||
 | Laser-Induced Spatial Symmetry Breaking in Quantum and Classical MechanicsIgnacio Franco and Paul BrumerPhase-controllable transport in laser-irradiated spatially symmetric systems is shown to arise both quantum mechanically and classically from a common field-driven interference mechanism. Specifically, the quantum-to-classical transition for symmetry breaking in a quartic oscillator driven by a field and its second harmonic is studied. For this, a double perturbation theory in the oscillator anharmonicity and external field strength, that admits a smooth classical limit, is carried out in the Heisenberg picture. The interferences responsible for the symmetry breaking are shown to survive in the classical limit and are the origins of classical control. Differences between reflection symmetry that plays a key role in the analysis, and parity that does not, are discussed. | |
| ||
 | KetenesThomas T. TidwellMy book is Ketenes 2nd ed, published by Wiley, Hoboken, New Jersey, 2006. Wiley published the first edition in 1995, but were then on Park Avenue in New York City, so they have moved a step down. The book has 656 pages and 3,300 references. The first book on the subject was "Die Ketene", by Hermann Staudinger (the founder of this field, and the discoverer of the first ketene in 1905), published in 1912. I organized a Symposium for the Ketene Centennial as part of Pacifichem in Honolulu in Dec, 2005, and wrote a history of the discovery published in Angewandte Chemie Int. Ed. 2005, 44, 5778-5785. | |
| ||
 | From colour fingerprinting to the control of photoluminescence in elastic photonic crystalsANDRÉ C. ARSENAULT, TIMOTHY J. CLARK, GEORG VON FREYMANN, LUDOVICO CADEMARTIRI, RICCARDO SAPIENZA, JACOPO BERTOLOTTI, EVANGELLOS VEKRIS, SEAN WONG, VLADIMIR KITAEV, IAN MANNERS, R. Z. WANG, SAJEEV JOHN, DIEDERIK WIERSMA and GEOFFREY A. OZINIn photonic crystals (PCs), strong scattering and destructive wave interference lead to a modification of the photon density of states in particular energy regions and along certain crystallographic directions1, 2. The consequences of this range from suppression and enhancement of luminescence3-7 to narrow-band bright reflections useful for colour sensors8, 9, displays10 and tuneable filters11-14. Here we demonstrate large-area films of porous elastomeric photonic crystals (EPCs) that are compressively?decompressively cycled to reversibly shift the position of the photonic band structure over a large wavelength range. Owing to their low compressive threshold, such porous EPCs can be used for imaging that is pressure and time sensitive, for example, to obtain colour fingerprints with high accuracy. Furthermore, by incorporating luminescent PbS quantum dots in the EPCs, the photonic stop-gap can be tuned through the near-infrared (NIR) quantum dot photoluminescence (PL) peak. Thereby we demonstrate a tuneable modification of photonic characteristics, including the suppression and enhancement in emission and dynamic modification of luminescence lifetimes. | |
| ||
 | Conformational chemistry of surface-attached calmodulin detected by acoustic shear wave propagationXiaomeng Wang, Jonathan S. Ellis, Emma-Louise Lyle, Priyanka Sundaram and Michael ThompsonA thickness shear-mode acoustic wave device, operated in a flow-through format, was used to detect the binding of ions or peptides to surface-attached calmodulin. On-line surface attachment of the protein was achieved by immobilisation of the biotinylated molecule via a neutravidinbiotin linkage onto the surface of the gold electrode of the detector. The interaction between calmodulin, and calcium and magnesium ions induced an increase in resonant frequency and a decrease in motional resistance, which were reversible on washing with buffer. Interestingly, the changes in resonant frequency and motional resistance induced by the binding were opposite to the normal operation of the detector. The response was interpreted as a decrease in surface coupling (partial slip at the liquid/solid interface) instigated by exposure of hydrophobic domains on the protein, and an increase in the thickness, and hence effective wavelength, of the acoustic device, corresponding to an increase in the length of calmodulin by 1.5 . This result is consistent with the literature value of 4 . In addition, the interaction of the protein with peptide together with calcium ions was detected successfully, despite the relatively low molecular mass of the 2-kDa peptide. These results confirm the potential of acoustic wave physics for the detection of changes in the conformational chemistry of monolayer of biochemical macromolecules at the solid/liquid interface. | |
| ||
 | Formation of C7F15COOH (PFOA) and other Perfluorocarboxylic acids (PFCAs) during the Atmospheric Oxidation of 8:2 Fluorotelomer Alcohol (n-C8F17CH2CH2OH)T. J. Wallington, M. D. Hurley, J. Xia, D. J. Wuebbles, S. Sillman, A. Ito, J. E. Penner, D. A. Ellis4, J. Martin, S. A. Mabury, O. J. Nielsen, M. P. Sulbaek Andersen Ford, University of Michigan, Illinois, Copenhagen, and TorontoCalculations using a 3-D global atmospheric chemistry model (IMPACT) indicate that n-C8F17CH2CH2OH (widely used in industrial and consumer products) degrades in the atmosphere to give perfluorooctanoic acid (PFOA) and other perfluorocarboxylic acids (PFCAs). PFOA is persistent, bioaccumulative, and potentially toxic. Molar yields of PFOA depend on location and season, are in the range 1-10%, and are of the correct order of magnitude to explain the observed levels in Arctic fauna. Fluorotelomer alcohols such as n -C8F17CH2CH2OH appear to be a significant global source of persistent bioaccumulative perfluorocarboxylic acid pollution. This is the first modeling study of the atmospheric chemistry of a fluorotelomer alcohol. | |
| ||
 | Redox Tunable Defects in Colloidal Photonic CrystalsFriederike Fleischhaker, Andre C. Arsenault, Zhuo Wang, Vladimir Kitaev, Frank C. Peiris, Georg von Freymann, Ian Manners, Rudolf Zentel and Geoffrey A. Ozin, Advanced Materials 2005 (20), 2455.Redox Tunable Defects in Colloidal Photonic Crystals Friederike Fleischhaker, Andre C. Arsenault, Zhuo Wang, Vladimir Kitaev, Frank C. Peiris, Georg von Freymann, Ian Manners, Rudolf Zentel and Geoffrey A. Ozin, Advanced Materials 2005 (20), 2455. Reversible tuning of an intragap transmitting state induced by redox cycling is accomplished using a redox-active polyferrocenylsilane polyelectrolyte multilayer planar defect embedded in a colloidal photonic crystal (CPC). The wavelength position of the defect state can be changed by changing the oxidation state of the ferrocene moieties in the polymer backbone. This could find applications in electrochemically tunable microcavities, and - if light emitters are incorporated - electrochemically tunable CPC-based laser sources. | |
| ||
 | Analyzing the 3D Structure of Human Carbonic Anhydrase II and Its Mutants Using Deep View and the Protein Data BankNoam J. Ship and Deborah B. ZambleA lab was designed to teach biological chemistry students to critically analyze the 3D structure of a protein. The enzyme studied was human carbonic anhydrase (II) and students also examined mutants and protein bound to a variety of ligands, metals, and inhibitors. The coordinate files for each protein are downloaded by the students from the Protein Data Bank. The structure is viewed and manipulated with the public-domain molecular-viewing software Deep View. Students learn how to interpret Ramachandran plots, study familial homology, make virtual mutations, compare structures, analyze structural details, and produce stunning 3D images. The lab runs on personal computers with Internet access and requires minimal to no supervision. This lab can be used as an independent project or as part of a more comprehensive set of experiments, and it can be adapted to the study of other biomolecules. | |
| ||
 | Aziridines and Epoxides in Organic SynthesisYudin, A. K.Aziridines and epoxides are among the most widely used intermediates in organic synthesis, acting as precursors to complex molecules due to the strain incorporated in their skeletons. Besides their importance as reactive intermediates, many biologically active compounds also contain these three-membered rings. Filling a gap in the literature, this clearly structured book presents the much-needed information in a compact and concise way. | |
| ||
 | Nanochemistry: A Chemical Approach to NanomaterialsG Ozin, A Arsenault; University of Toronto, CanadaFrom the author of the highly cited paper "Nanochemistry: Synthesis in Diminishing Dimensions" Advanced Materials 1992, 4, 612-649, comes the first teaching textbook on the subject entitled "Nanochemistry: A Chemical Approach to Nanomaterials". The textbook is published by The Royal Society of Chemistry and is co-authored by Geoffrey A. Ozin and Andre Arsenault, Materials Chemistry Research Group, Department of Chemistry, University of Toronto. It is scheduled to appear in July 2005. Details of the book can be found on the following web sites:
This is the first textbook for teaching Nanochemistry and adopts an interdisciplinary and comprehensive approach to the subject. It presents a basic chemical strategy for making nanomaterials and describes some of the principles of materials self-assembly over "all" scales. It demonstrates how nanometer and micrometer scale building blocks, with a wide range of shapes, compositions and surface functionalities, can be coerced through chemistry to organize spontaneously into unprecedented structures, which can serve as tailored functional materials. Suggestions of new ways to tackle research problems in Nanoscience and speculations on how to think about assembling the future of Nanotechnology are given. Designed for teaching the underpinnings of Nanoscience through the eye of the materials chemist and crosscutting the traditional boundaries of chemistry and physics, materials science and engineering, biology and medicine, this twelve-chapter book will appeal to graduate and advanced undergraduate students. It has however been written so that it can be easily be adapted for introducing the principles of Nanochemistry to undergraduates in their freshman to higher years. It is well illustrated with graphical representations of the synthesis, structure and form of nanomaterials, and contains problem sets as well as other pedagogical features such as further reading, case studies and a comprehensive bibliography. It also presents a blueprint of experiments for NanoLab, an undergraduate laboratory that gives a hands-on experience to the student wishing to appreciate the practical side of Nanochemistry, as described in each chapter of the book. The Contents of the book follows the order: Preface - In the Beginning there was Nano; Nanochemistry Basics; Chemical Patterning and Lithography; Layer-By-Layer Self-Assembly; Nanocontact Printing and Writing; Nanorod, Nanotube, Nanowire Self-Assembly; Nanocluster Self-Assembly; Microspheres - Colours from the Beaker; Microporous and Mesoporous Materials; Self-Assembling Block Copolymers; Biomaterials and Bioinspiration; Self-Assembly of Large Building Blocks; Nano and Beyond; Nanochemistry and Nanolabs; Appendices, Subject Index. | |
| ||
 | Microfluidics: From Dynamic Lattices to Periodic Arrays of Polymer DisksMinseok Seo, Zhihong Nie, Shengqing Xu, Patrick C. Lewis, and Eugenia KumachevaIllustration by Eugenia Kumacheva. We used a microfluidic flow-focusing device to generate highly monodisperse discoid droplets of oil or monomer liquid. The droplets were assembled into two-dimensional gliding lattices with a high degree of order and symmetry by coupling of flow and confinement. Following increase in total volume of droplets produced per unit time, the lattices underwent a transition from a close-packed array of circular disks to the array of hexagonal disks. In situ photopolymerization of the monomer droplets produced highly periodic arrays of solidified polymer disks. For more information see "Microfluidics: From Dynamic Lattices to Periodic Arrays of Polymer Disks" by Minseok Seo, Zhihong Nie, Shengqing Xu, Patrick C. Lewis, and Eugenia Kumacheva, on pages 4773-4775 of this issue. Copyright 2005 American Chemical Society. | |
| ||
 | Photon echo studies of biexcitons and coherences in colloidal CdSe quantum dotsAnne E. Colonna, Xiujuan Yang, and Gregory D. Scholes*Lash-Miller Chemical Laboratories, University of Toronto, 80 St. George St., Toronto, Ontario, M5S 3H6, Canada phys. stat. sol. (b) 242, No. 5, 990Š1000 (2005) Nonlinear optical properties of colloidal quantum dots are studied to elucidate the significance and nature of many-body effects. Two-pulse photon echo studies of nanocrystalline CdSe quantum dots are reported for samples dispersed in a poly(butylmethacrylate) film (4.4 K). Oscillations are observed in the experimental data that are attributed to 1S3/2 1Se -> 2S3/2 1Se biexciton cohererences. Signals are simulated using a phenomenological model based on the many-body description of the dynamics (the average polarization model). It is found that the electronic coherences and the nonlinear response originating from biexciton source terms are important, but their manifestation in the photon echo signals is strongly influenced by the interplay between homogeneous and inhomogeneous line broadening. | |
| ||
 | Colloidal Crystal Capillary Columns - Towards Optical ChromatographyU. Kamp, V. Kitaev, G. von Freymann, G. A. Ozin, S. A. Mabury Advanced Materials 2005(4), 438 Published Online: 5 Jan 2005 DOI: 10.1002/adma.200400020ABSTRACT: The cover illustration, designed by Ludovico Cademartiri, is an artistic rendering of novel micro- and nanobore chromatographic columns. The three-dimensional periodic arrangement of the building blocks, solid spheres or air-spheres, constituting the chromatographic stationary phase allows wavelength-selective interaction of electromagnetic radiation with the stationary phase. The photonic stop-band responsible for the structural color of the column is monitored spectroscopically and shifts of its wavelength, generated by minute refractive index changes within a mobile phase (here represented by alkane homologues), can be immediately detected at any point along and around the column due to the exceptional structural uniformity. | |
| ||
 | Evolution of Nanocrystallinity in Periodic Mesoporous Anatase Thin FilmsSung Yeun Choi, Marc Mamak, Scott Speakman, Naveen Chopra, Geoffrey A. Ozin Small 2005(2), 226Herein we report the first kinetic study of the intrachannel wall phasetransition of amorphous titania to nanocrystalline anatase for periodic mesoporous titania thin films, monitored by time-resolved in situ hightemperature X-ray diffraction. Structural transformations associated with the phase transition are further probed by high-resolution scanning electron microscopy and transmission electron microscopy. The model found to be most consistent with the kinetic data involves 1D diffusioncontrolled growth of nanocrystalline anatase within the spatial confines of the channel walls of the mesostructure. The observation of anisotropic, rod-shaped anatase nanocrystals preferentially aligned along the channel axis implies that the framework of the liquid-crystal-templated mesostructure guides the crystal growth. | |
| ||
 | An Atomic-Level View of Melting Using Femtosecond Electron DiffractionBradley J. Siwick, Jason R. Dwyer, Robert E. Jordan, R. J. Dwayne MillerWe used 600-femtosecond electron pulses to study the structural evolution of aluminum as it underwent an ultrafast laserinduced solid-liquid phase transition. Real-time observations showed the loss of long-range order that was present in the crystalline phase and the emergence of the liquid structure where only short-range atomic correlations were present; this transition occurred in 3.5picoseconds for thin-film aluminum with an excitation fluence of 70 millijoules per square centimeter. The sensitivity and time resolution were sufficient to capture the time-dependent pair correlation function as the system evolved from the solid to the liquid state. These observations provide an atomic-level description of the melting process, in which the dynamics are best understood as a thermal phase transition under strongly driven conditions. | |
| ||
 | Synthetic self-propelled nanorotorsSebastien Fournier-Bidoz, Andre C. Arsenault, Ian Manners* and Geoffrey A. Ozin*Self-powered completely synthetic nanorotors have been prepared from barcoded gold–nickel nanorods having the gold end anchored to the surface of a silicon wafer; constant velocity circular movements are observed when hydrogen peroxide fuel is catalytically decomposed to oxygen at the unattached nickel end of the nanorod. | |
| ||