Enhancement of coloring under ultraviolet irradiation in photochromic diarylbenzenes

Fast T-Type Photochromic Crystals of Diarylbenzene

“…Under such a background, we have developed 1,2-diaryl­benzene (DAB) as a novel family of fast T-type photochromic molecules by only introducing a tetrafluorobenzene ring to the ethene bridge of diarylethene (DAE), which is a P-type photochromic molecule and has excellent properties such as high durability, high sensitivity, rapid response, and reactivity in the crystalline state. − As the photochromic reaction of DAB is based on the 6π-electron photocyclization and thermal cycloreversion reactions, the photochromic reactivity in the crystalline state can be expected as well as DAE if the molecules are fixed in the photoreactive antiparallel conformation in the ground state and the distance between reactive carbons is shorter than 4.0 Å (Figure S1). However, unfortunately, DABs 1a – 3a that we have synthesized so far exhibited no photochromism in the crystalline phase because they crystallized into a nonphotoreactive parallel conformation or an antiparallel conformation with the reactive carbon distance longer than 4.0 Å (Figure S2).…”

Broadening the Horizon of the Bell–Evans–Polanyi Principle towards Optically Triggered Structure Planarization

“…These lead to the conclusion that a decrease in the reaction barrier should increase the reaction exothermicity. While the B‐E‐P principle has been applied to a number of reactions involving bond rearrangement, [9–14] the fundamental issue of whether the reaction parameters, e.g., transition‐state structure and reactive frequency, meet the criteria is often overlooked.…”

“…where E 0 is the intercept, and a is avalue characteristic of the transition state along the reaction coordinate,w hich should be in the range of 0 a < 1. These lead to the conclusion that adecrease in the reaction barrier should increase the reaction exothermicity.While the B-E-P principle has been applied to anumber of reactions involving bond rearrangement, [9][10][11][12][13][14] the fundamental issue of whether the reaction parameters,e .g., transition-state structure and reactive frequency, meet the criteria is often overlooked. In yet another instance,u pon excitation, changes in the electron density distribution are induced, where structure relaxation becomes au biquitous phenomenon.…”

Rational design of photochromic diarylbenzene with both high photoreactivity and fast thermal back reactivity

“…Quantum chemical calculations of open-ring isomers (Open), closed-ring isomers (Closed), and transition states (TS) were performed by the same procedures reported previously using Gaussian16 Rev.C.01 program package. [30][31][32] Single crystal X-ray crystallographic analysis was carried out using a Rigaku AFC/Mercury CCD diffractometer with MoK radiation ( = 0.71073 Å) monochromated by graphite. The crystal structures were solved by a direct method using SIR92 and refined by the full matrix least-squares method on F 2 with anisotropic displacement parameters for nonhydrogen atoms using SHELXL-2014.…”