Self-Assembly of Semiconductor Quantum Dots using Organic Templates

Colloidal semiconductor nanocrystals, known as quantum dots (QDs), are regarded as brightly photoluminescent nanomaterials possessing outstanding photophysical properties, such as high photodurability and tunable absorption and emission wavelengths. Therefore, QDs have great potential for a wide range of applications, such as in photoluminescent materials, biosensors and photovoltaic devices. Since the development of synthetic methods for accessing high-quality QDs with uniform morphology and size, various types of QDs have been designed and synthesized, and their photophysical properties dispersed in solutions and at the single QD level have been reported in detail. In contrast to dispersed QDs, the photophysical properties of assembled QDs have not been revealed, although the structures of the self-assemblies are closely related to the device performance of the solid-state QDs. Therefore, creating and controlling the self-assembly of QDs into well-defined nanostructures is crucial but remains challenging. In this Minireview, we discuss the notable examples of assembled QDs such as dimers, trimers and extended QD assemblies achieved using organic templates. This Minireview should facilitate future advancements in materials science related to the assembled QDs.     

A Drying‐Free,Water‐Based Process for Fabricating Mixed‐Matrix Membranes with Outstanding Pervaporation Performance

Despite much progress in the development of mixed matrix membranes (MMMs) for many advanced applications, the synthesis of MMMs without particle agglomeration or phase separation at high nanofiller loadings is still challenging. In this work, we synthesized nanoporous zeolitic imidazole framework (ZIF‐8) nanoparticles with a particle size of 60 nm and a pore size of 0.34 nm in water and directly added them into an aqueous solution of the organic polymer poly(vinyl alcohol) (PVA) without an intermediate drying process. This approach led to a high‐quality PVA/ZIF‐8 MMM with enhanced performance in ethanol dehydration by pervaporation. The permeability of this MMM is three times higher than that of pristine PVA, and the separation factor is nearly nine times larger than that of pristine PVA. The significantly improved separation performance was attributed to the increase in the fractional free volume in the membranes.     

Crystal Structures and Phase Sequences of Metallocenium Salts with Fluorinated Anions: Effects of Molecular Size and Symmetry on Phase Transitions to Ionic Plastic Crystals

Sandwich compounds often exhibit various phase transitions, including those to plastic phases. To elucidate the general features of the phase transitions in metallocenium salts, the thermal properties and crystal structures of [Fe(C₅Me₅)₂]X ([ 1 ]X), [Co(C₅Me₅)₂]X ([ 2 ]X), and [Fe(C₅Me₄H)₂]X ([ 3 ]X) have been investigated, where the counter anions (X) are Tf₂N (=(CF₃SO₂)₂N^?), OTf (=CF₃SO₃^?), PF₆, and BF₄. The Tf₂N salts commonly undergo phase transitions from an ordered phase at low temperatures to an anion‐disordered phase, followed by a plastic phase and finally melt at high temperatures. All these salts exhibit a phase transition to a plastic phase, and the transition temperature generally decreases with decreasing cation size and increasing anion size. The crystal structures of these salts comprise an alternating arrangement of cations and anions. About half of these salts exhibit phase transitions at low temperatures, which are mostly correlated with the order–disorder of the anion.     

Solid-phase synthesis of benzazoles,quinazolines, and quinazolinones using an alkoxyamine linker

An alkoxyamine linker was applied for the solid-phase synthesis of benzazoles, quinazolines, and quinazolinones. Aromatic aldehydes were anchored by aldoxime linkage. After some reactions on a solid support, the products were cleaved with paraformaldehyde under the acidic conditions to afford the corresponding aldehydes, which were subsequently subjected to oxidative coupling with 2-substituted anilines under air atmosphere to give the desired compounds.     

Advanced optimization method for spherical aberration and focus offset for optical disc drive

We developed an optimization method for spherical aberration and focus offset for an optical disc drive using an elliptical approximation. This method measures the small number of points that are located at specific positions. Furthermore, it approximates a characteristic distribution to an ellipse and calculates the center of the ellipse as the optimal point. The effectiveness of this method is experimentally confirmed using Blu-ray discs with three types of protective layer of various thicknesses.     

Controlled radical polymerization of anthracene‐containing methacrylate copolymers for stimuli‐responsive materials

Novel reversible networks utilizing photodimerization of crosslinkable anthracene groups and thermal dissociation were investigated. Reversible addition‐fragmentation chain transfer polymerization yielded well‐defined copolymers with 9‐anthrylmethyl methacrylate (AMMA) and other alkyl methacrylates such as methyl methacrylate (MMA) and 2‐ethylhexyl methacrylate (EHMA) having different AMMA compositions. Well‐controlled block copolymerization of AMMA and alkyl methacrylates was also successfully accomplished using a trithiocarbonate‐terminated poly(alkyl methacrylate) macro‐chain transfer agent. The anthracene‐containing copolymers showed reversibility via crosslinking based on photodimerization with ultraviolet irradiation and subsequent thermal dissociation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2302–2311     

Preparation of poly(ether ketone)s derived from 2,5‐furandicarboxylic acid via nucleophilic aromatic substitution polymerization

From the viewpoint of the suppression of the petroleum consumption, aromatic poly(ether ketone)s (PEKs) were prepared by the nucleophilic aromatic substitution polymerization of 2,5‐bis(4‐fluorobenzoyl)furan (BFBF) synthesized from biomass and aromatic bisphenols. The model reaction of BFBF and p‐methoxyphenol revealed that BFBF possessed enough reactivity for the nucleophilic aromatic substitution reactions. The polymerizations of BFBF and aromatic bisphenols afforded high molecular weight polymers with good yields in N‐methylpyrrolidone and diphenyl sulfone for several hours. The longer polymerization time brought about the formation of insoluble parts in any solvents and reduction of molecular weight. The obtained PEKs were thermoplastics and exhibited good thermal stability, mechanical properties, and chemical resistance comparable to common high‐performance polymers. The thermal properties were tunable with the structure of bisphenols. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3094–3101     

Synthesis and chiroptical properties of phenanthrene-fused N2O-type BODIPYs

A series of phenanthrene-fused N₂O-type boron-dipyrrin complexes (BODIPYs) with various substituents were synthesized. The synthesized BODIPYs show light absorption and emission in the red to near-infrared region due to their extended π-system. Furthermore, the first optical resolution of the N₂O-type BODIPY was achieved using the phenyl-substituted complex. The separated enantiomers are stable to racemization at room temperature, and exhibited a Cotton effect in the deep-red region.