Crystallization‐Induced Emission Enhancement and Amplified Spontaneous Emission from a CF3‐Containing Excited‐State Intramolecular‐Proton‐Transfer Molecule. Issue 18 (24th July 2017)

• Record Type: Journal Article
• Authors: Park, Sanghyuk; Kwon, Ji Eon; Park, Sun‐Young; Kwon, Oh‐Hoon; Kim, Joon Ki; Yoon, Seong‐Jun; Chung, Jong Won; Whang, Dong Ryeol; Park, Sang Kyu; Lee, Dong Ki; Jang, Du‐Jeon; Gierschner, Johannes; Park, Soo Young
• Is Part Of: Advanced optical materials. Volume 5:Issue 18(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-07-24
• Subjects: amplified spontaneous emission -- crystallization‐induced emission enhancement -- excited‐state intramolecular proton transfer -- fluorescence -- solid‐state emitter; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.201700353
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract : In this work, a simple but effective molecular design strategy is developed for the generation of intense blue emission in the solid state including single crystals through the multiple secondary intermolecular interactions such as CF…HC hydrogen bonding. The synthesized novel imidazole‐based excited‐state intramolecular proton transfer (ESIPT) molecule, 2‐(1‐(3, 5‐bis(trifluoromethyl)phenyl)‐4, 5‐diphenyl‐1H‐imidazol‐2‐yl)phenol (HPI‐CF3 ), shows significantly enhanced blue fluorescence in single crystal (ΦF = 0.67) compared to faint emission in solution (ΦF < 0.05). It is considered that tight but slipped stacking structure of HPI‐CF3 molecules in the single crystal not only effectively suppresses the nonradiative decay pathways such as twist intramolecular charge transfer but also induces highly allowed transition character. Taking advantage of the crystallization‐induced emission enhancement characteristics and four‐level ESIPT photocycle process of HPI‐CF3, an efficient amplified spontaneous emission at 475 nm with a threshold of 13.1 mJ cm −2 is observed from the single crystal by picosecond laser optical pumping. Abstract : The unique stacking structure in a single crystal leads to significantly enhanced blue fluorescence (ΦF = 0.67) and efficient amplified spontaneous emission from an imidazole‐based excited‐state intramolecular‐proton‐transfer molecule. Full photophysical studies and theoretical calculations reveal that simple substitution of two CF3 groups into the molecule effectively suppresses nonradiative decay pathways as well as induces highly allowed transition character.