Showing papers in "Israel Journal of Chemistry in 2012"
TL;DR: The history of indigo dye and its deriv- ative Tyrian purple, from their roles in the ancient world to recent research showing the semiconducting properties of indigoids is described in this article.
Abstract: We describe the history of indigo dye and its deriv- ative Tyrian purple, from their roles in the ancient world to recent research showing the semiconducting properties of indigoids. Indigoids are natural dyes that have been pro- duced for centuries, and indigo is currently the most pro- duced dye worldwide. Herein we review the history of these materials, their chemistry and physical properties, and their semiconducting characteristics in the solid state. Due to hy- drogen bonding and p-stacking, indigo and Tyrian purple form highly-ordered crystalline thin films. Such films have been used to fabricate high-performance organic field-effect transistors with ambipolar charge transport, as well as com- plementary-like circuits. Mobility values were found to be in the range of 10 � 2 -0.4 cm 2 /Vs. With performance on par with the best available organic semiconductors, indigoids dem- onstrate the potential of sustainable electronics based on biodegradable and biocompatible materials.
130 citations
TL;DR: In this paper, the basic structure-reactivity correlation for initiators and catalyst complexes and the radical nature of reactive intermediates of ATRP are discussed. And the effect of variable amounts of catalysts on molecular weight distribution and morphology of nanostructured block copolymers are presented.
Abstract: Atom transfer radical polymerization (ATRP) is currently one of the most often used synthetic polymerization methods to prepare well-defined polymers with complex architecture. This review covers some fundamentals of copper-based ATRP, presents basic structure–reactivity correlation for initiators and catalyst complexes and discusses the radical nature of reactive intermediates. New ATRP initiating processes with ppm amounts of copper catalysts and various reducing agents are described together with recent electrochemically controlled ATRP and polymerization in aqueous homogeneous and dispersed media. Examples of polymers with precisely controlled architecture are presented together with the effect of variable amounts of catalysts on molecular weight distribution and morphology of nanostructured block copolymers. Some current and forthcoming applications of polymers made by ATRP are presented.
128 citations
TL;DR: This review focuses on recent research efforts to understand and control the photocatalytic processes mediated by colloidal II-VI nanocrystalline materials, such as cadmium and zinc chalcogenides, and highlights how nanocrystal properties govern the rates and efficiencies of charge-transfer processes relevant to photocatalysis.
Abstract: The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This review focuses on recent research efforts to understand and control the photocatalytic processes mediated by colloidal II-VI nanocrystalline materials, such as cadmium and zinc chalcogenides. First, we highlight how nanocrystal properties govern the rates and efficiencies of charge-transfer processes relevant to photocatalysis. We then describe the use of nanocrystal catalyst heterostructures for fuel-forming reactions, most commonly H2 generation. Finally, we review the use of nanocrystal photocatalysis as a synthetic tool for metal–semiconductor nano-heterostructures.
120 citations
TL;DR: In this paper, the basic phenomenon of molecular alignment induced by a single pulse, continue with selective alignment of close molecular species and unidirectional molecular rotation induced by two time-delayed pulses, and lead up to novel schemes for manipulating the spatial distributions of molecular samples through rotationally controlled scattering off inhomogeneous fields and surfaces.
Abstract: Spectroscopy aims at extracting information about matter through its interaction with light. However, when performed on gas and liquid phases as well as solid phases lacking long-range order, the extracted spectroscopic features are in fact averaged over the molecular isotropic angular distributions. The reason is that light–matter processes depend on the angle between the transitional molecular dipole and the polarization of the light interacting with it. This understanding gave birth to the constantly expanding field of “laser-induced molecular alignment”. In this paper, we attempt to guide the readers through our involvement (both experimental and theoretical) in this field in the last few years. We start with the basic phenomenon of molecular alignment induced by a single pulse, continue with selective alignment of close molecular species and unidirectional molecular rotation induced by two time-delayed pulses, and lead up to novel schemes for manipulating the spatial distributions of molecular samples through rotationally controlled scattering off inhomogeneous fields and surfaces.
98 citations
TL;DR: The similarities and differences between the application of PDT for the treatment of microbial infections and for cancer lesions are discussed and the structure-function relationships of optimal anticancer and antimicrobial photosensitizers are outlined.
Abstract: Photodynamic therapy (PDT) was discovered over one hundred years ago when it was observed that certain dyes could kill microorganisms when exposed to light in the presence of oxygen. Since those early days, PDT has mainly been developed as a cancer therapy and as a way to destroy proliferating blood vessels. However, recently it has become apparent that PDT may also be used as an effective antimicrobial modality and a potential treatment for localized infections. This review discusses the similarities and differences between the application of PDT for the treatment of microbial infections and for cancer lesions. Type I and type II photodynamic processes are described, and the structure-function relationships of optimal anticancer and antimicrobial photosensitizers are outlined. The different targeting strategies, intracellular photosensitizer localization, and pharmacokinetic properties of photosensitizers required for these two different PDT applications are compared and contrasted. Finally, the ability of PDT to stimulate an adaptive or innate immune response against pathogens and tumors is also covered.
89 citations
TL;DR: In this article, a review of recent advances and challenges in the field of thermotropic cubic phases of the bicontinuous type (Cubbi) formed by low molecular mass molecules is presented.
Abstract: This review article focuses on recent advances and challenges in the field of thermotropic cubic phases of the bicontinuous type (Cubbi) formed by low molecular mass molecules. In the Cubbi phases, the constituent molecules self-organize into 3D network structures, although local molecular diffusional motions are preserved to some extent. This review illustrates which types of molecules form such structures, and summarizes the latest developments in structural characterization. Moreover, their phase behaviors, and analogies and differences in comparison with other related systems such as lyotropic liquid crystals and block copolymers are discussed. Finally, potential applications utilizing the dynamically ordered 3D network structures are presented.
85 citations
TL;DR: In this article, the polaron-pair and triplet-triplet pair mechanisms that are responsible for the magnetic field effects in organic semi-conductor systems are described, and the effect of the hyperfine interaction, both isotropic and anisotropic, and different g-factors of the two po- larons composing the pair are analyzed.
Abstract: In this contribution we review recent advances of the organic magnetic field effects, namely magneto-conduc- tance and magneto-electroluminescence, in both experiment and theory. We describe a number of processes, including the polaron-pair and triplet-triplet pair mechanisms that are responsible for the magnetic field effects in organic semi- conductor systems. For the polaron pair mechanism, we review in detail the effect of the hyperfine interaction, both isotropic and anisotropic; different g-factors of the two po- larons composing the pair; and the spin orbit interaction. The effect of the triplet-triplet annihilation process is also analyzed. Experimental examples for each case treated theo- retically are given.
68 citations
TL;DR: In this article, a review summarizes recent work on side-chain metallocene-containing polymers prepared by controlled and living polymerizations, which include living anionic polymerization (LAP), ring-opening metathesis polymerization, and controlled radical polymerization.
Abstract: This review summarizes recent work on side-chain metallocene-containing polymers prepared by controlled and living polymerizations, which include living anionic polymerization (LAP), ring-opening metathesis polymerization (ROMP) and controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). The majority of efforts in the field are focused on side-chain ferrocene-containing polymers, while cobaltocenium-containing polymers have recently started to draw attention. Future direction on the development of other metallocene-containing polymers is discussed.
63 citations
TL;DR: In this article, the recent progress of emerging new materials of inorganic nanosheet liquid crystals is reviewed with a focus on the behaviors of each system, alignment by external field, and theoretical aspects.
Abstract: Inorganic layered crystals such as clay minerals, layered niobates, and graphite are exfoliated in solvents to form colloidal dispersions of extremely thin inorganic nanosheets. Recently, the liquid crystal phases of these “nanosheet colloids” have been rediscovered and are attracting interest as new types of inorganic liquid crystals. The huge anisotropy of the mesogenic nanosheets compared to other liquid crystal systems is an important feature of the nanosheet liquid crystals for fundamental studies in the fields of colloid science and soft matter physics. In addition, the rich functionalities intrinsic to inorganic materials open a variety of applications such as smart colloids and composite materials with structural regularity. In this article, the recent progress of the emerging new materials of inorganic nanosheet liquid crystals is reviewed with a focus on the behaviors of each system, alignment by external field, and theoretical aspects.
61 citations
TL;DR: In this article, localized surface plasmon resonances (LSPRs) in doped semiconductor quantum dots (QDs) have been studied and the authors describe the key properties of QD LSPRs.
Abstract: We review the discovery of localized surface plasmon resonances (LSPRs) in doped semiconductor quantum dots (QDs), an advance that has extended nanoplasmonics to materials beyond the classic gamut of noble metals. The initial demonstrations of near-infrared LSPRs in QDs of heavily self-doped copper chalcogenides and conducting metal oxides are setting the broad stage for this new field. We describe the key properties of QD LSPRs. Although the essential physics of plasmon resonances are similar to that in metal nanoparticles, the attributes of QD LSPRs represent a paradigm shift from metal nanoplasmonics. Carrier doping of quantum dots allows access to tunable LSPRs in the wide frequency range from the THz to the near-infrared. Such composition or carrier density tunability is unique to semiconductor quantum dots and not achievable in metal nanoparticles. Most strikingly, semiconductor quantum dots allow plasmon resonances to be dynamically tuned or switched by active control of carriers. Semiconducting quantum dots thus represent the ideal building blocks for active plasmonics. A number of potential applications are discussed, including the use of plasmonic quantum dots as ultrasmall labels for biomedicine and electrochromic materials, the utility of LSPRs for probing nanoscale charge dynamics in semiconductors, and the exploitation of strong coupling between photons and excitons. Further advances in this field necessitate efforts toward generalizing plasmonic phenomena to a wider range of semiconductors, developing strategies for achieving controlled levels of doping and stabilizing them, investigating the spectroscopy of these systems on a fundamental level, and exploring their integration into optoelectronic devices.
60 citations
TL;DR: The basic concepts of microsegregation and a fundamental understanding of the formation of positionally ordered LC phases based on micro- and nanophases, interaction parameters and interfaces are discussed in this paper.
Abstract: This review is focused on the basic concepts of microsegregation and a fundamental understanding of the formation of positionally ordered LC phases based on micro- and nanophases, interaction parameters and interfaces. Selected examples were chosen from the actual literature to illustrate the concepts. Microsegregation is the basis of classical LC phases and cybotaxis, and most importantly, it paves the way to a huge number of new LC phases. Beside the distinct modes of micellar packing motifs and liquid quasicrystals formed by self-assembly of dendritic molecules, attention is also focused on the specific effects of rigid anisometric units and polyphilicity. Honeycomb LC phases, vesicular LC phases and mesophases with 3D-lattices lead to enhanced complexity of LC self-assembly.
TL;DR: Ionic discotic liquid crystals have been extensively studied in the literature as discussed by the authors, focusing on the mesomorphism of ionic liquid crystals and its dependence on structural changes, which is also the focus of most reported studies.
Abstract: Ionic discotic liquid crystals are salts of discotic liquid crystals that may display lyotropic and thermotropic mesomorphism. Columnar structures of π-π stacking ionic discotic liquid crystals function not only as anisotropic organic semiconductors, similar to their neutral analogues, but they may also efficiently conduct ions. This combination of electronic and ionic conduction is only one of several unique properties that these materials may display, but their systematic investigation has been limited because of their often complex synthesis, purification, and characterization. However, a comprehensive account of existing reports on ionic discotic liquid crystals is not straightforward, despite their relatively small number, because publications are scattered across different areas of research, such as liquid crystals, ionic liquids, and ionic self-assembly. This review intends to provide a concise but comprehensive overview of the published work on ionic discotic liquid crystals and related compounds and is expected to stimulate further exploration. Highlighted in this review is the mesomorphism of ionic discotic liquid crystals and its dependence on structural changes, which is also the focus of most reported studies. Particular attention was given to the dependence of mesomorphism on the location and types of the charged groups as these are parameters unique to these compounds. Also described are electronic, optical, and other properties of these materials if reported.
TL;DR: This review discusses the synthesis and use of paracyclophane-based phosphines and aims to give an insight into their success and failures to encourage the design of new planar chiral phosphines for use in transition metal-mediated catalysis and organocatalysis.
Abstract: [2.2]Paracyclophane offers an exciting framework for the synthesis of planar chiral phosphines. Its rigid structure and unusual electronic properties have led to the development of a range of mono- and di-phosphines including the commercially available ligand, PhanePhos. This review discusses the synthesis and use of [2.2]paracyclophane-based phosphines and aims to give an insight into their success and failures. It is hoped that this review will encourage the design of new planar chiral phosphines for use in transition metal-mediated catalysis and organocatalysis.
TL;DR: In this article, a review article on the photorefractive properties of carbazole-based materials is presented, where a new class of discotic, calamitic and banana-shaped liquid crystalline materials are discussed.
Abstract: Liquid crystals are commonplace in technological devices, such as watch and computer displays and temperature and pressure monitors. Such materials are central to our technological lifestyles. Classically, liquid crystalline materials are based on a structural motif which could be classed as rod-like (e.g. biphenyl derivatives) and in more recent times as disc-like (e.g. triphenylene derivatives). The rod-like materials are very attractive in terms of their chemical stability and their response to electric fields, both of which are a prerequisite for display devices, whereas disc-like materials show promise as one-dimensional conducting materials. Increasing scientific and technological requirements mean that new materials are continually sought to surpass the liquid crystalline materials which are presently known. Carbazole derivatives are well-known interesting natural products. Several methods have been developed and reported in the literature for the synthesis of carbazole derivatives. There are several review articles published on the photorefractive properties of carbazole-based materials. Chemical modification of the carbazole moiety to create a new class of discotic, calamitic and banana-shaped liquid crystalline materials, which will have novel and enhanced photorefractive properties over the amorphous carbazole derivatives, will be discussed in this mini review.
TL;DR: In this paper, the evolution of chiral MOF catalysts from simple Lewis acid and Lewis base catalysts that afford limited selectivity to more recent advancements that exhibit high stereo-and regioselectivities is discussed.
Abstract: This review documents the evolution of chiral MOF catalysts from simple Lewis acid and Lewis base catalysts that afford limited selectivity to more recent advancements that exhibit high stereo- and regioselectivities. MOF-based catalysts provide unprecedented opportunities for interrogating structure-activity relationships at high structural precision and for controlling catalytic activity by using external stimuli. The most notable disadvantage of MOF-based catalysts has been the inherent instability of the materials. This hurdle, which effectively limits the reaction scope of MOF catalysts, is slowly being overcome by the advent of new binding moieties and secondary building units.
TL;DR: A review of the progress in this field can be found in this article, where a number of strategies based on combinatorial screening and high-throughput experimentation have been introduced for the design and optimization of new ligands and catalytic systems.
Abstract: The design of novel chiral ligands is at the core of asymmetric catalysis. The catalytic characteristics of a transition metal catalyst such as activity, selectivity and stability can be fine-tuned by optimization of the steric and electronic properties of the coordinating ligands. In asymmetric transformations, catalyst optimization still relies to a large extent on trial-and-error and educated guesses. New strategies based on combinatorial screening and high-throughput experimentation have been introduced for the design and optimization of new ligands and catalytic systems. Supramolecular bidentate ligands that form by self-assembly of building blocks are particularly suited for this combinatorial approach as the potential number of catalysts grows exponentially with the number of building blocks synthesized. Catalytic systems based on supramolecular interactions have proven to be highly advantageous in creating large ligand libraries for high-throughput screening, which allows optimization of activity and selectivity for a variety of reactions. In this review we describe the progress in this field.
TL;DR: A survey of olefination reactions that have been used in the synthesis of cyclophanes is presented in this paper, which covers the Ramberg-Backlund reaction, the Wittig and related reactions, the McMurry reaction, ring-closing metathesis (alkenes, alkynes and ene-ynes), aldol condensations and Siegrist reactions, as well as miscellaneous reactions.
Abstract: A survey of olefination reactions that have been used in the synthesis of cyclophanes is presented. This covers the Ramberg–Backlund reaction, the Wittig and related reactions, the McMurry and related reactions, ring-closing metathesis (alkenes, alkynes and ene-ynes), aldol condensations and Siegrist reactions, as well as miscellaneous reactions. The McMurry reaction and ring-closing metathesis have enjoyed the greatest popularity in recent years, but they are typically used for complementary purposes. In virtually all cases, the McMurry reaction is used to install a two-carbon (1,2-ethenylene) bridge, whereas ring-closing metathesis is used to construct bridges that are at least four-membered, but usually considerably longer. Some well-known olefinations have seen little or no use in the field of cyclophane chemistry.
TL;DR: In this article, four contemporary density functionals of meta-GGA, hybrid-GA, meta-GA-hybrid, and double hybrid type connected with two versions of our recent dispersion correction (DFT-D3) are tested for the description of the geometric and electronic structures of typical cyclophanes.
Abstract: Four contemporary density functionals of meta-GGA, hybrid-GGA, meta-GGA-hybrid, and double-hybrid type connected with two versions of our recent dispersion correction (DFT-D3) are tested for the description of the geometric and electronic structures of typical cyclophanes. Strain energies (SE) as well as aromatic interaction energies (AIE) are considered. The systems [2.2]para- and [2.2]metacyclophane, [2.2.2.2.2.2]cyclophane, [2.2]paracyclonaphthane, [2.2](9,10)anthracenophane, and [2.2](1,4)anthracenophane are investigated. Computed structures are compared to experimental X-ray data. For the three smallest cyclophanes, accurate CCSD(T)/CBS reference SE and AIE values are computed to assess the accuracy of the DFT methods. It is found that medium-range dispersion (correlation) effects are important for all cyclophanes. Dispersion corrections in the Becke–Johnson damping (BJ) variant of the DFT-D3 method provide the most accurate results. The best density functionals yield relative (strain) energies accurate to within about 5–10 %. Inter-ring distances can be computed very accurately with errors less than about 0.003 A while, for example, uncorrected B3LYP yields large average errors of almost 0.1 A for this property. The PW6B95-D3(BJ) and TPSS-D3(BJ) general purpose quantum chemical methods overall perform best and can be recommended also for studies of cyclophanes. The strain energies are partitioned to chemically meaningful components and the effect of the crystal environment is discussed.
TL;DR: Asymmetric autocatalysis with amplification of enantiomeric excess is found in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde using pyrimidyl alkanol as an asymmetric auto-catalyst as mentioned in this paper.
Abstract: Asymmetric autocatalysis with amplification of enantiomeric excess is found in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde using pyrimidyl alkanol as an asymmetric autocatalyst. Asymmetric autocatalysis has been employed as a method for clarifying the origin of homochirality. Circularly polarized light, inorganic chiral crystals and statistical fluctuation of enantiomeric imbalance act as chiral initiators in asymmetric autocatalysis to afford highly enantioenriched products. We have investigated asymmetric autocatalysis using chiral crystals formed from achiral and racemic compounds as an origin of chirality. Absolute control of the crystal chirality of cytosine was achieved by the removal of crystal water. Enantioselective carbon-carbon bond formation at the enantiotopic crystal face of aldehydes was established using diisopropylzinc vapor. In addition, asymmetric autocatalysis triggered by chiral compounds arising from H, C and O isotope substitution has been achieved.
TL;DR: Asymmetric counteranion-directed catalysis (ACDC) holds special promise for long-standing challenges from all areas of catalysis, where matched cases can be designed and a new way of thinking during method development is represented.
Abstract: Asymmetric counteranion-directed catalysis (ACDC) is a powerful new concept, which can potentially be used to achieve enantioselectivity in any type of reaction proceeding through positively charged intermediates. It has already been applied in different areas of catalysis, such as organocatalysis, transition-metal catalysis, and Lewis acid catalysis. Due to its complementarity with traditional approaches to achieve enantioselection, ACDC holds special promise for long-standing challenges from all areas of catalysis, where matched cases can be designed. ACDC also represents a new way of thinking during method development, which could be of help to chemists from a variety of research areas.
TL;DR: In this article, a review summarizes the major design and synthetic strategies for tuning paracyclophane-containing small molecules by introducing various moieties featuring (hetero)aromatic rings directly connected to each other.
Abstract: In the search for molecules for organic photonics and electronics, several strategies have been used to modulate physical and chemical properties of [2.2]paracyclophane derivatives by sequential functionalization of their three-dimensional cores. This review summarizes the major design and synthetic strategies for tuning paracyclophane-containing small molecules by introducing various moieties featuring (hetero)aromatic rings directly connected to each other, as well as alternating (hetero)aryl and ethylene or ethynylene units. Several examples are presented that elucidate the structural, optical, and electronic consequences of incorporating these fragments in the aromatic decks, particularly relating to applications in organic optoelectronics.
TL;DR: In this paper, a bird's-eye view on discotic liquid crystals and their potential applications is provided, including design principles, synthesis, modification of physical properties and potential applications.
Abstract: This review article provides a bird’s-eye view on discotic liquid crystals and their potential applications. Design principles, synthesis, modification of physical properties and potential applications of some common discotic liquid crystals have been briefly summarized.
TL;DR: In this article, a review about the development of blue host OLED materials based on molecules designed and derived from the core structure of anthracene and their application as bipolar charge-carrier transport materials in OLEDs is presented.
Abstract: The phenomenon of organic electroluminescence (EL) was first discovered from studies on anthracene crystals in the 1960s. Since then, its derivatives have been studied extensively in applications such as organic light-emitting diodes (OLEDs) and organic thin-film transistors because of their excellent EL, transport, and good electrochemical properties. A blue fluorescence emitter based on anthracene is also important in constructing hybrid tandem white OLEDs for lighting applications. This article provides a review about the development of blue host OLED materials based on molecules designed and derived from the core structure of anthracene and their application as bipolar charge-carrier transport materials in OLEDs. The recent development of efficient, stable, blue-doped p-i-n OLEDs with simplified device architecture based on the single common host 2-methyl-9,10-di(2-napthyl)anthracene, with its stable thin-film morphology, large band gap energy, high fluorescence quantum yield, and ambipolar charge-carrier transport properties, is also highlighted.
TL;DR: A review of the recent progress in understanding of blinking and potential applications in bioimaging using inorganic fluorescent tags can be found in this article, where several distinct mechanisms and is mediated by surface charge trapping.
Abstract: Luminescence intermittency, also termed ‘blinking’, refers to spontaneous changes in the brightness of a luminescent fluorophore under continuous optical excitation. Blinking was first observed in colloidal semiconductor nanocrystals over fifteen years ago, shortly after synthetic protocols became advanced enough to produce brightly luminescent nanocrystals. The underlying physical mechanism was initially associated with long-lived photo-induced charging of the nanocrystals. In recent years, however, significant evidence has accumulated to point at a more complex physical picture of the process, which involves several distinct mechanisms and is mediated by surface charge trapping. In parallel, efforts to synthesize highly luminescent semiconductor nanocrystals that do not exhibit blinking have recently borne fruit. We review the recent progress in understanding of blinking and potential applications in bioimaging using inorganic fluorescent tags.
TL;DR: In this paper, the authors discuss the dependence of the dynamics of the energy transfer and charge transfer processes in Mn-doped II-VI semiconductor nanocrystals on the structure of the host nanocrystal, spatial distribution of the dopant ions, and charge carrier-trapping molecules near the surface of the nanocystals.
Abstract: Doping semiconductor nanocrystals with transition metal ions introduces new optical, electronic, and magnetic properties to the host semiconductor nanocrystals. The energy transfer and charge transfer between exciton and dopant ions are the key photophysical processes responsible for the unique properties of doped semiconductor nanocrystals, which are distinct from their undoped counterparts. Since the energy transfer and charge transfer processes between exciton and dopant ions compete with the usual relaxation pathways of the exciton, competition among different dynamic processes ultimately determines the photophysical properties of doped nanocrystals. In this review, we discuss the dependence of the dynamics of the energy transfer and charge transfer processes in Mn-doped II-VI semiconductor nanocrystals on the structure of the host nanocrystal, spatial distribution of the dopant ions within the nanocrystal, and charge carrier-trapping molecules near the surface of the nanocrystals.
TL;DR: In this paper, the preparation of optically pure alcohols, axially chiral allenes, and amine derivatives by using enzymes and transition-metal catalysts through dynamic kinetic resolution (DKR) is reviewed.
Abstract: The preparation of optically pure alcohols, axially chiral allenes, and amine derivatives by using enzymes and transition-metal catalysts through dynamic kinetic resolution (DKR) is reviewed. After a general introduction into enzymatic kinetic resolutions and racemizations catalyzed by transition-metal complexes, selected examples of DKRs are presented, from early work to more recent outstanding contributions, and also applications of this approach.
TL;DR: In this article, a review highlights microwave heating being applied during reversible addition-fragmentation chain transfer (RAFT) polymerization and demonstrates that the high polymerization rates observed do not necessarily lead to significant end group loss from termination.
Abstract: Advances in controlled radical polymerization (CRP) have facilitated access to well-defined polymers with controlled molecular weight, topology, and functionality. However, despite the benefits afforded by many CRP techniques, control over these key polymer attributes often comes at the expense of polymerization rate. One method proposed for accelerating chemical synthesis is microwave heating. This review highlights recent examples of microwave heating being applied during reversible addition-fragmentation chain transfer (RAFT) polymerization. In addition to successfully leading to homopolymers from a variety of monomers, block copolymers have also been prepared by microwave-assisted RAFT, which suggests that the high polymerization rates observed do not necessarily lead to significant end group loss from termination. Despite significant debate regarding the origin of rate enhancement observed during microwave-assisted reactions, the reports included herein provide insight into mechanisms by which well-defined functional polymers can be prepared in an accelerated fashion.
TL;DR: In this article, the authors examine how molecular topology and interactions influence phase formation and report on material design, showing that the topology of a material can influence the phase formation process.
Abstract: It is often a question that is asked: “How can you predict from the molecular architecture of a material the structure of the condensed phases it forms, and what properties would you expect the phase to exhibit?” For liquid crystals, knowing how to design materials for particular applications requires precision molecular engineering. In this article we examine how molecular topology and interactions influence phase formation and report on material design.
TL;DR: In this paper, a review of surface-initiated radical polymerization initiated from ordered mesoporous silicas (OMSs) surfaces is presented, and the synthesis of polymer brushes in mesopores through the combination of ATRP or other polymerizations and the "click" chemistry is also outlined.
Abstract: Recent advances in the synthesis of well-defined high-surface-area mesoporous silica/polymer composites via surface-initiated polymerization (“grafting from” method) and via attachment of preformed polymer chains (“grafting to” method) to surfaces of ordered mesoporous silicas (OMSs) are reviewed in the context of related research areas. Prior work on polymerizations in nanoscale confinements of OMSs is outlined and surface-initiated polymerization in disordered mesoporous silicas is briefly discussed. Early work on the surface-initiated radical polymerization initiated from OMS surface is reviewed and recent work involving OMS supports with large mesopores is discussed to illustrate the ability to form well-defined polymer brushes in nanopores using atom transfer radical polymerization (ATRP). The synthesis of polymer brushes in mesopores through the combination of ATRP or other polymerizations and the “click” chemistry is also outlined.
TL;DR: Irradiance-dependence on PIT efficacy was a function of the conjugation chemistry, providing an additional variable for optimization of PIT outcome, and 1 cycle of chemotherapy significantly reduced tumor burden, comparable to multiple chemotherapy cycles.
Abstract: Significant toxicities from multiple cycles of chemotherapy often cause delays or early termination of treatment, leading to poor outcomes in ovarian cancer patients. Complementary modalities that potentiate the efficacy of traditional agents with fewer cycles and less toxicity are needed. Photodynamic therapy is a mechanistically-distinct modality that synergizes with chemo and biologic agents. A combination regimen with a clinically relevant chemotherapy cocktail (cisplatin + paclitaxel) and anti-EGFR targeted photoimmunotherapy (PIT) is evaluated in a murine model for ovarian carcinomatosis. Mice received either 1 or 2 chemotherapy cycles followed by PIT with a chlorine6-Erbitux photoimmunoconjugate and 25 J/cm2 light. PIT + 1 cycle of chemotherapy significantly reduced tumor burden, comparable to multiple chemotherapy cycles. Relative to 1 cycle of chemotherapy, the addition of PIT did not cause significant mouse weight loss, whereas 2 cycles of chemotherapy led to a significant reduction in weight. Irradiance-dependence on PIT efficacy was a function of the conjugation chemistry, providing an additional variable for optimization of PIT outcome.