Premium
Fluorescent Crystals of Zwitterionic Imidazolium Pyridinolates: A Rational Design for Solid‐State Emission Based on the Twisting Control of Proemissive N ‐Aryl Imidazolium Platforms
Author(s) -
Komiya Naruyoshi,
Yoshida Atsushi,
Zhang Di,
Inoue Ryo,
Kawamorita Soichiro,
Naota Takeshi
Publication year - 2017
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201700943
Subject(s) - chemistry , thermochromism , fluorescence , aryl , quenching (fluorescence) , pyridine , photochemistry , ring (chemistry) , crystallography , crystal (programming language) , blueshift , stokes shift , emission spectrum , photoluminescence , spectral line , organic chemistry , materials science , optics , optoelectronics , alkyl , physics , computer science , programming language , astronomy
The synthesis and structural variations in solid‐state emission of zwitterionic imidazolium pyridinolates are described. N ‐Alkylimidazolium 2‐pyridin‐3‐olate 1 exhibits intense blue emission at ambient temperature ( Φ 298 K = 0.44, λ max = 424 nm) in the crystalline state, while phenolate 2 , another pyridinolate analogue bearing the nitrogen atom at a different position on the pyridine ring 3 , and N ‐phenylimidazolium ring 4 are less emissive ( Φ 298 K = 0.05, 0.05, and 0.04) under the same measurement conditions. Temperature‐dependent emission spectra indicate that crystal 1 exhibits high heat‐resistance properties towards emission decay and redshifting thermochromism upon increasing temperature, both of which are in contrast with the heat quenching and blueshift properties of phenolate analogue crystal 2 under the same measurement conditions. XRD analysis and DFT calculations revealed that the effect of the 2‐pyridinolate functionality on the specific efficiency and thermochromism in the crystalline‐state fluorescence of imidazolium arenolates arises from specific restriction of molecular rotation and the resultant molecular constraints in the crystals.