A series of luminescent Cu() complexes based on the diphosphine ligand and diimine ligand: weak intermolecular interactions, terahertz spectroscopy and photoproperties

• Published in: CrystEngComm 2021-12, Vol.23 (47), p.8323-8333
• Main Authors: Li, Zi-Xi, Kuang, Xiao-Nan, Wang, Guo, Zhu, Ning, Sun, Zhen-Zhou, Han, Hong-Liang, Yang, Yu-Ping, Li, Zhong-Feng, Xin, Xiu-Lan, Jin, Qiong-Hua, Ren, Zhi-Gang
• Format: Article
• Language: English
• Subjects: Absorption spectroscopy; Ambient temperature; Charge transfer; Chemical analysis; Coordination compounds; Crystal structure; Crystallography; Crystals; Density functional theory; Diimide; Fluorescence; Infrared analysis; Ligands; Luminescence; NMR; Nuclear magnetic resonance; Optical properties; Photoluminescence; Single crystals; Spectrum analysis; Time domain analysis
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/d1ce01132d

Five novel mononuclear [Cu(Bphen)(bdppmapy)]X complexes showing photoluminescence were synthesized. The same diphosphine ligand and diimine ligand and different Cu( i ) salts were used in the one-pot synthesis of complexes 1-5 . These complexes are listed as follows: [Cu(Bphen)(bdppmapy)]CF 3 SO 3 ( 1 ), [Cu(Bphen)(bdppmapy)]BF 4 ·0.268CH 3 OH ( 2 ), [Cu(Bphen)(bdppmapy)]ClO 4 ( 3 ), [Cu(Bphen)(bdppmapy)]I·CH 3 OH ( 4 ) and [Cu(Bphen)(bdppmapy)]Br·2CH 3 OH ( 5 ) (Bphen = 4,7-diphenyl-1,10-phenanthroline, bdppmapy = N , N -bis((diphenylphosphino)methyl)-2-pyridinamine). IR, NMR, elemental analysis, single-crystal X-ray diffraction analysis, UV-vis, fluorescence spectroscopy and terahertz time-domain absorption spectroscopy (THz-TDS) were used to characterize 1-5 . Their crystal structures have been elucidated by X-ray crystallography and their photophysical properties have been investigated in detail. These five complexes have a similar coordination center, while their space stacked structures are different, from a 0D dimeric structure to a 3D supramolecular structure. Photophysical studies and density functional theory calculations (DFT) show that the luminescence properties of these five complexes are mainly ascribed to metal-to-ligand charge transfer (MLCT). Among these five complexes, 1 emits luminescence with the highest quantum yield of 36.96% and a lifetime of 11.90 μs at ambient temperature. Different counter-anions lead to the distinction of QYs, maybe due to the influence of weak forces. Terahertz time-domain absorption spectroscopy was used to characterize these ligands and complexes in the range of 0.2-2.4 THz. Counter-ions can regulate the luminescence of complexes by changing the weak intermolecular interactions, which can be observed by THz spectroscopy.