Acceptor-regulated luminescence in carbazole-based charge transfer complexes. Issue 31 (9th July 2021)

• Record Type: Journal Article
• Authors: Wang, Si-Si; Li, Kechang; Ma, Xiaohui; Xue, Pengchong
• Is Part Of: CrystEngComm. Volume 23:Issue 31(2021)
• Page Start: 5314
• Page End: 5320
• Publication Date: 2021-07-09
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/d1ce00656h
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : A dicarbazole derivative and two acceptors could formed 1D mixed stacking columns in their charge transfer co-crystals. Moreover, the LUMO energy levels of the acceptors determine the fluorescence colors of the co-crystals. Abstract : A dicarbazole derivative (CC4C) was synthesized and used as an electron donor to construct charge-transfer co-crystals with 1, 4-dicyanotetrafluorobenzene (DCTFB) and 1, 2, 4, 5-tetracyanobenzene (TCNB) to investigate the effect of electron acceptors on the molecular stacking and photoluminescence behaviors of crystals. The results suggested that face-to-face and T-shaped dimers were present in the rodlike crystals of CC4C, and DCTFB and TCNB formed co-crystals with CC4C. The two co-crystals possessed the same crystal system and space group, and molecules formed 1D columns, in which donors and acceptors stacked in a mixed –D–A–D–A– fashion with a strong π–π overlap because of their short distances. However, the weak interactions between the columns in the two co-crystals were different. Additional H⋯F hydrogen bonds existed in the co-crystals of CC4C and DCTFB besides CN⋯H hydrogen interactions in the co-crystals of CC4C and TCNB because of the four fluorine atoms in DCTFB. More importantly, the acceptors might regulate the fluorescence properties of the co-crystals. The block co-crystals with DCTFB are yellowish and emitted strong blue-green fluorescence, and the red co-crystals with TCNB have orange-red emission under UV light. Quantum chemical calculations implied that the energy level of the lowest unoccupied molecular orbitals of the acceptors determined the transition energies and a lower lowest unoccupied molecular orbital will induce a longer emission wavelength.