Dithienoazepine-Based Near-Infrared Dyes: Janus-Faced Effects of a Thiophene-Fused Structure on Antiaromatic Azepines.

We here disclose that the incorporation of thiophene rings into a seven-membered 8π azepine in a fused fashion produces a useful antiaromatic core for near-infrared (NIR) dyes. In contrast to dibenzazepine derivatives with bent structures, dithieno-fused derivatives with electron-accepting groups adopt flat conformations in the ground state. The dithieno-fused derivatives exhibited broad absorption spectra that cover the visible region as well as sharp emission bands in the NIR region, which are considerably red-shifted relative to those of the dibenzo-fused congeners. Theoretical study revealed two contradictory effects of the less-aromatic thiophene-fused structure, i.e., the enhancement of the antiaromaticity of the adjacent azepine ring and the relief of the antiaromaticity through the contribution of a quinoidal resonance form. The combination of the dithienoazepine core with cationic electron-accepting groups produced a NIR fluorescent dye with an emission at 878 nm in solution.

Wettability evaluation of hydrophilic-hydrophobic nanohybrid silica thin films using picoliter water droplets.

Water wettabilities of hydrophilic-hydrophobic nanohybrid silica thin films were investigated by contact angles of extremely small size water droplets (8 pL-1 nL) and using an antifog analyzer. The nanohybrid silica was prepared via our unique sol-gel process based on tetramethoxysilane (TMOS) and metyltrimethoxysilane (MTMS) with a hydroxyacetone catalyst, in which hydrophilic portion was generated from hydrolysis of microporous silica prepared from TMOS and hydrophobic portion was directly prepared from MTMS. The sizes of these domains were controlled by the growth time of the microporous precursor polymers in solution. The hydrophilic and hydrophobic domains in the nanohybrid surface were visualized and confirmed by a lateral-mode friction force microscopy using the cantilever modified with self-assembled monolayers of mercaptohexadecanol. Using a small size of water droplets (< 100 pL), the contact angles for the nanohybrid silica films were lower than those for the wholly hydrophilic silica. The small size of the water droplet has a characteristic effect on the lower contact angle on the nanohybrid silica. The contact angles using the small size 70 pL of the water droplet on the nanohybrid silica films at [MTMS]/[TMOS] ratios from 0.25 to 0.75 were lower than those using the conventional size 2 microL. The dependence of the [MTMS]/[TMOS] ratio in the preparation on the antifog parameter was similar to that on the contact angle using the small size 70 pL of the water droplet. The use of the small water droplet for the contact angle measurement was suitable for the evaluation of the antifog films.

A trinuclear chromium(iii) chlorocarbyne.

Reduction of CCl4 by CrCl2 in THF afforded a trinuclear chromium(iii) carbyne [CrCl(thf)2]3(µ3-CCl)(µ-Cl)3. The chlorocarbyne complex reacted with aldehydes to afford chloroallylic alcohols and terminal alkynes. The mechanistic study proposed two competitive pathways via an α-chlorovinyl intermediate.

Regioselective Sequential Silylation and Borylation of Aromatic Aldimines as a Strategy for Programming Synthesis of Multifunctionalized Benzene Derivatives.

Regioselective difunctionalization of two different C-H bonds in one pot using a three-component coupling reaction is described. The reaction order is important for controlling the reactivity and regioselectivity, and the first silylation promotes the second borylation. The introduced formyl, silyl, and boryl functional groups could be independently converted to other functional groups, and the substitution pattern for the resulting benzenes is difficult to access by conventional methods.