Influence of periodic heteroatom substitution in the aryl rings on optical properties and thermal stability of diarylethene derivatives

Abstract

Photochromic diarylethene derivatives are one of the most promising candidates for various applications in optoelectronic devices. The heteroatom substitution of the aryl groups of diarylethene derivatives could greatly influence their optical properties and thermal stability. For example, the diarylethene derivatives with two thiophene rings (Dithienylethenes) have longer absorption wavelength, better fatigue resistance, sensitivity and thermal bistability than those with two furan rings. To further understand the influence of the heteroatom substitution in aryl rings, a series of diarylethene derivatives with different heteroatoms in IV (C, Si, Ge), V (N, P, As), and VI groups (O, S, Se) of Periodic Table were theoretically explored with DFT/TD-DFT functionals. According to the predicted results, the substituent effects of increasing atomic weights could influence the optical properties, the relative energies, the thermal bistability of the open isomer and the closed isomers. The maximum optical absorptions of the closed isomers and the open isomers could be finely tuned by these heteroatom groups in visible region of 395∼522 nm and in ultraviolet region of 300∼341 nm, respectively. The diarylethene with Se substituent diarylethene was predicted to have the best thermal bistability of all the nine substitutions and also have comparable photochomic properties than widely-used S diarylethene (Dithienylethenes). As 6π-electron system is indispensable part for nearly all known diarylethene derivates, the study probably provides a useful guideline for the future design of novel Se substituent diarylethene compounds with tunable photochromic properties and improved thermal bistability.