Difluoromethoxyl bridged substituted 2-cyano-pyrrole based pure organic luminescent liquid crystals towards white light emitting single-molecule

• Published in: Liquid crystals Vol. 50; no. 11-12; pp. 1699 - 1708
• Main Authors: Luo, Shunyin, Yang, Guoliang, Zhang, Mei, Lu, Liping, Mo, Xiaofeng, Irfan, Majeed, Zeng, Zhuo
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 26.09.2023; Taylor & Francis Ltd
• Subjects: Bromine; Chemical synthesis; Crystals; difluoromethoxy bridge; Excitation; Light emission; Liquid crystals; Luminescent Liquid Crystals (LLCs); multicolour luminescence; Room temperature; single-molecule white light emission; substituted 2-cyano-pyrrole; Substitutes; White light
• ISSN: 0267-8292; 1366-5855
• DOI: 10.1080/02678292.2023.2203123

A series of new luminescent liquid crystals (LLCs) comprised of difluoromethoxy and substituted 2-cyano-pyrrole (CN-Py) bridge with the molecular rigid core were synthesised. Their emission colours could be adjusted facilely and reversibly in a non-invasive manner by simply changing the excitation wavelength at room temperature. A simple and practical approach has been developed to avoid the use of hazardous and highly toxic elemental bromine to achieve a green and environmentally friendly synthesis pathway for difluoromethoxy-bridged liquid crystals. Notably, excitation-dependent multicolour luminescence has been realised in a single molecule of 5CC-CF 2 O-2Br-CN based on pure organic difluoromethoxy bridged liquid crystal, whose emission colours changes from yellow to blue with a blue shift of excitation wavelength. Interestingly, the CIE coordinates (0.29,0.33) of 5CC-CF 2 O-2Br-CN is very close to the white light coordinates (0.33, 0.33) under excitation at a wavelength of 335 nm. Therefore, 5CC-CF 2 O-2Br-CN can be a candidate of promising white light emitting luminescent liquid crystal. This protocol offers efficient access to single-molecule liquid crystal material with white light emission.