Mono-Heteroatom Substitution for Harnessing Excited-State Structural Planarization of Dihydrodibenzo[a,c]phenazines
Journal
Chemistry - A European Journal
Journal Volume
25
Journal Issue
72
Pages
16755-16764
Date Issued
2019
Author(s)
Abstract
With the aim of generalizing the structure–properties relationship of bending heterocyclic molecules that undergo prominent photoinduced structural planarization (PISP), a series of new dihydrodibenzo[ac]phenazine derivatives in which one nitrogen atom is replaced by oxygen (PNO), sulfur (PNS), selenium (PNSe), or dimethylmethanediyl (PNC) was strategically designed and synthesized. Compounds PNO, PNS, and PNSe have significantly nonplanar geometries in the ground state, which undergo PISP to give a planarlike conformer and hence a large emission Stokes shift. A combination of femtosecond early relaxation dynamics and computational approaches established an R*→I* (intermediate)→P* sequential kinetic pattern for PNS and PNSe, whereas PNO undergoes R*→P* one-step kinetics. The polarization ability of the substituted heteroatoms, which is in the order O
Subjects
fluorescence; heterocycles; photoinduced planarization; sensors; substituent effects
SDGs
Other Subjects
Excited states; Fluorescence; Ground state; Sensors; Synthesis (chemical); Computational approach; Heteroatom substitution; Heterocycles; Heterocyclic molecules; Lone pair electrons; Planarization; Relaxation dynamics; Substituent effect; Selenium compounds
Type
journal article