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Theoretical Study on Photoisomerization Mechanisms of Diphenyl‐Substituted N,C‐Chelate Organoboron Compounds
Author(s) -
Du XinYi,
Li QuanSong
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202002529
Subject(s) - organoboron compounds , photoisomerization , photochromism , boron , chemistry , photochemistry , conical intersection , reactivity (psychology) , chelation , excited state , isomerization , computational chemistry , organic chemistry , molecule , atomic physics , physics , medicine , alternative medicine , pathology , catalysis
N,C‐chelate organoboron compounds are widely employed as photoresponsive and optoelectronic materials due to their efficient photochromic reactivity. It was found in experiments that two diphenyl‐substituted organoboron compounds, namely B(ppy)Ph 2 (ppy=2‐phenylpyridyl) and B(iba)Ph 2 (iba= N ‐isopropylbenzylideneamine), show distinct photochemical reactivity. B(ppy)Ph 2 is inert on irradiation, whereas B(iba)Ph 2 undergoes photoinduced transformations, yielding BN‐cyclohepta‐1,3,5‐triene via a borirane intermediate. In this work, the complete active space self‐consistent field and its second‐order perturbation (CASPT2//CASSCF) methods were used to investigate the photoinduced reaction mechanisms of B(ppy)Ph 2 and B(iba)Ph 2 . The calculations showed that the two compounds isomerize to borirane in the same way by passing a transition state in the S 1 state and a conical intersection between the S 1 and S 0 states. The energy barriers in the S 1 state of 0.54 and 0.26 eV for B(ppy)Ph 2 and B(iba)Ph 2 , respectively, were explained by analyzing the charge distributions of minima in S 0 and S 1 states. The results provide helpful insights into the excited‐state dynamics of organoboron compounds, which could assist in rational design of boron‐based photoresponsive materials.