Organic vapor triggered repeatable on-off crystalline-state luminescence switching

A nonporous crystalline solid consisting of an organoarsenic platinum(II) complex, i.e., a mononuclear diiodoplatinum(II) complex trans-PtI(2)(cis-DHDAtBu)(2) (1) with cis-1,4-dihydro-1,4-dimethyl-2,3,5,6-tetrakis(tert-butoxycarbonyl)-1,4-diarsinine (cis-DHDAtBu), shows on-off solid-state luminescence switching through reversible solvent vapor uptake and escape. The on-off switching of solid-state luminescence was achieved without changing the structure or electronic state of the organoarsenic platinum(II) complex.     

Palladium-catalyzed asymmetric synthesis of silicon-stereogenic dibenzosiloles via enantioselective C-H bond functionalization

A Pd-catalyzed asymmetric synthesis of Si-stereogenic dibenzosiloles is developed through enantioselective C-H bond functionalization of prochiral 2-(arylsilyl)aryl triflates. High chemo- and enantioselectivities are achieved by employing a Josiphos-type ligand under mild conditions.     

One‐Step Borylation of 1,3‐Diaryloxybenzenes Towards Efficient Materials for Organic Light‐Emitting Diodes

The development of a one‐step borylation of 1,3‐diaryloxybenzenes, yielding novel boron‐containing polycyclic aromatic compounds, is reported. The resulting boron‐containing compounds possess high singlet‐triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. Using these compounds as a host material, we successfully prepared phosphorescent organic light‐emitting diodes exhibiting high efficiency and adequate lifetimes. Moreover, using the present one‐step borylation, we succeeded in the synthesis of an efficient, thermally activated delayed fluorescence emitter and boron‐fused benzo[6]helicene.     

Measurements of Liquid-Phase Adsorption under High Pressure

Adsorption equilibria at about 1000 atm were measured for aqueous solutions of aromatic compounds. No significant difference between the isotherms at atmospheric pressure and at 1000 atm was found for nitrobenzene and ethylbenzene on activated carbon fiber. The decrease in the amount adsorbed due to the solubility increase with pressure and the increase in the amount adsorbed caused by compression of the adsorbed phase were considered to cancel each other. On the other hand, pressure had a marked effect on the adsorption of L-phenylalanine on a macroreticular adsorbent, resulting in a 1.5 to 2 times larger amount adsorbed at 1500 atm. The pressure effect was greater with larger amounts adsorbed. This implies that the molar volume of the adsorbed state is smaller than those of the pure state and dissolved state, and varies with the amount adsorbed.     

Interpretation of structure formation during the sol-gel transition of a resorcinol-formaldehyde solution by population balance

Growth of colloidal particles formed during the sol-gel transition of a resorcinol-formaldehyde (RF) solution was simulated based on the population balance equation by using the discrete-sectional model (DSM). During the early stage of the sol-gel transition, the transient change of sizes of colloidal particles estimated by this method agreed well with the previous experimental observation by dynamic light scattering (DLS), which confirmed the influence of the catalyst concentration of a starting RF solution on the growth rate of the particles. From the size distribution of colloidal particles predicted at the gelation time, the surface area of a RF hydrogel after the completion of the sol-gel transition was estimated, which coincided with the BET surface area of a RF aerogel because the porous structure of a hydrogel was maintained and few micropores were formed during supercritical drying.     

Formation of Supramolecular Nanostructures through in Situ Self-Assembly and Post-Assembly Modification of a Biocatalytically Constructed Dipeptide Hydrazide**

Aqueous self-assembly of short peptides has attracted growing attention for the construction of supramolecular materials for various bioapplications. Herein, we describe how the thermolysin-assisted biocatalytic construction of a dipeptide hydrazide from an N-protected amino acid and an amino acid hydrazide leads to the formation of thermally stable supramolecular hydrogels. In addition, we demonstrate the post-assembly modification of the supramolecular architectures constructed in situ tethering hydrazide groups as a chemical handle by means of fluorescence imaging.     

Rhodium‐Catalyzed Stitching Polymerization of 1,5‐Hexadiynes and Related Oligoalkynes

A new mode of polymerization, rhodium‐catalyzed stitching polymerization, has been developed for the synthesis of π‐conjugated polymers with bridged repeating units from nonconjugated 1,5‐hexadiynes containing both terminal and internal alkyne moieties as monomers. The polymerization proceeded smoothly with a high degree of stitching efficiency under mild conditions, and 1,5,9‐decatriyne and 1,5,9,13‐tetradecatetrayne monomers could also be employed. The present polymerization strategy would be particularly beneficial for the synthesis of polymers consisting of a repeating unit that is difficult to prepare as a stable monomer because it does not require the use of a preformed bridged π‐conjugated monomer.     

Microwave oven synthesis of esters promoted by imidazole

Using imidazole as promotion agent, primary, secondary and phenolic alcohol compounds were esterified with aliphatic and aromatic carboxylic acid anhydrides. Heating a ternary mixture of alcohol, anhydride and imidazole in an unmodified microwave oven produced esters in low to high yields, depending on the steric bulk of the alcohol.     

Notes on braidzel surfaces for links

As a generalization of pretzel surfaces, L. Rudolph has introduced a notion of braidzel surfaces in his study of the quasipositivity for pretzel surfaces. In this paper, we show that any oriented link has a braidzel surface. We also introduce a new geometric numerical invariant of links with respect to their braidzel surface and study relationships among them and other ``genus' for links.