The unusual thermochromic NIR luminescence of Cu(I) clusters: tuned by Cu-Cu interactions and packing modes

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 41; no. 31; pp. 9411 - 9416
• Main Authors: Shan, Xiao-Chen, Jiang, Fei-Long, Yuan, Da-Qiang, Wu, Ming-Yan, Zhang, Shu-Quan, Hong, Mao-Chun
• Format: Journal Article
• Language: English
• Published: England 21.08.2012
• Subjects: Arrays; Bands; Clusters; Coordination Complexes - chemistry; Copper; Copper - chemistry; Crystallography, X-Ray; Emission; Ligands; Luminescence; Powder Diffraction; Pyridines; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Thermogravimetry; Three dimensional; X-Ray Diffraction
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt30909b

Two hexanuclear Cu(I) clusters [Cu(I)(3)(4-ptt)(3)](2)·3DMF·3H(2)O (1) and [Cu(I)(4-ptt)](6)·8DMF·7H(2)O (2) (4-Hptt = 5-(pyridin-4-yl)-1H-1,2,4-triazole-3-thiol, DMF = N,N-dimethylformamide), were synthesized and characterized. Compounds 1 and 2 with similar coordination environments are isomers, but their detailed structures are different due to the reaction temperature tuning effect. Both 1 and 2 extend from monomers to 3D supramolecules with the help of hydrogen bonding between the triazole and pyridine from the 4-ptt ligands. The Cu(6)S(6) units of 1 pack in a polydirectional array, while the Cu(6)S(6) units in 2 extend in one direction and link the planes of adjacent ligands to enhance the delocalization of π electrons. Their varied Cu-Cu interactions and individual packing modes cause differences in luminescent and thermostable behaviors. Compound 1 exhibits an unusually long wavelength at about 900 nm and a higher thermal stability; while the emission of 2 splits into two bands (high-energy and low-energy emission bands) as the temperature decreases. Therefore, the emissions of 1 originate from a (3)CC transition, and those of 2 are from a mixture of (3)CC and MLCT.