Amorphous Solid Simulation and Trial Fabrication of the Organic Field-Effect Transistor of Tetrathienonaphthalenes Prepared by Using Microflow Photochemical Reactions: A Theoretical Calculation-Inspired Investigation

Toward Accurate Prediction of Ion Mobility in Organic Semiconductors by Atomistic Simulation

A multiscale scheme (MLMS: Multi-Level Multi-Scale) to predict the ion mobility (μ) of amorphous organic semiconductors is proposed, which was successfully applied to the hole mobility predictions of 14 organic systems. An inverse relationship between μ and reorganization energy is observed due to local polaronic distortions. Another moderate inverse correlation between μ and distribution of site energy change exists, representing the effects of geometric flexibility. The former and the latter represent the intramolecular and intermolecular geometric effects, respectively. In addition, a linear correlation between transfer coupling and μ is observed, showing the importance of orbital overlaps between monomers. Especially, the highest hole mobility of C6-2TTN is due to its large transfer coupling. On the other hand, another high hole mobility of CBP turned out to come from the high first neighbor density (ρ_FND) of its first self-solvation, emphasizing the proper description of amorphous structural configurations with a sufficiently large number of monomers. In general, systems with either unusually high transfer coupling or high first neighbor density can potentially have high μ regardless of geometric effects. Especially, the newly suggested design parameter, ρ_FND, is pointing to a new direction as opposed to the traditional π-conjugation strategy.

A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes

Trimethylsilyldiazomethane (TMS-CHN₂) reacts readily with hetaryl thioketones to give sterically crowded 2-trimethylsilyl-4,4,5,5-tetrahetaryl-1,3-dithiolanes with complete regioselectivity at −75 °C as well as at rt. Thiofluorenone, a relatively stable and highly reactive aryl thioketone, yields upon treatment with TMS-CHN₂ at −60 °C the corresponding 1,3,4-thiadiazoline. This unstable cycloadduct undergoes decomposition at ca. −45 °C and the silylated thiocarbonyl S-methanide generated thereby is trapped with complete regioselectivity by aryl or hetaryl thioketones forming also sterically crowded 2-trimethylsilyl-1,3-dithiolanes. The obtained 1,3-dithiolanes, by treatment with an equimolar amount of TBAF in a one-pot procedure, are converted in high yields into hetaryl/aryl-substituted ethenes or dibenzofulvenes, respectively, via a cycloreversion reaction of the intermediate 1,3-dithiolane carbanion. The presented protocol offers a new, highly efficient approach to tetrasubstituted ethenes and dibenzofulvenes bearing aryl and/or hetaryl substituents.

Aggregation-induced emission: mechanistic study of the clusteroluminescence of tetrathienylethene

In this work we have investigated the aggregation-induced emission (AIE) behaviour of 1,1,2,2-tetra(thiophen-2-yl)ethene (tetrathienylethene, TTE). The semi-locked and fully-locked derivatives (sl-TTE and fl-TTE) have been synthesized to better understand the mechanism behind the solid state photoluminescence of TTE. TTE is a typical AIEgen and its luminescence can be explained through the mechanistic understanding of the restriction of intramolecular motions (RIM). The emissive behaviour of TTE in the THF/water aggregates and crystal state have also been studied, revealing a remarkable red-shift of 35 nm. A similar red-shift emission of 37 nm from the THF/water aggregates to the crystal state is also observed for (E)-1,2-di(thiophen-2-yl)ethene (trans-dithienylethene, DTE). Crystal analysis has revealed that the emission red-shifts are ascribable to the presence of strong sulfur-sulfur (S···S) intra- and intermolecular interactions that are as close as 3.669 Å for TTE and 3.679 Å for DTE. These heteroatom interactions could help explain the photoluminescence of non-conventional luminophores as well as the luminescence of non-conjugated biomacromolecules.