Crystal Structures and Luminescence Behaviour of d10 Metal-Organic Complexes with Multipyridine Ligands

Six d(10) metal-organic complexes with multipyridine ligands, [Cd(terpy)(2)](NO3)(2)center dot 2H(2)O (1), [Cd(terpy)(NO3)(2)(H2O)] (2), [Hg(terpy)I-2] (3), [Zn(tpt)(NO3)(H2O)(2)]NO3 (4), [Zn-2(tpt)(2)(4,4'-bipy)(4H(2)O)](NO3)(4)center dot 4H(2)O (5), [Zn(tpt)(OAc)(2)]center dot 5H(2)O (6) (terpy = 2,2':6',2'-terpyridine, tpt = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, 4,4'-bipy = 4,4'-bipyridine) were synthesized and structurally characterized. The abundant hydrogen-bonding interactions extend complex 2 into ladder-like 1D chains, discrete molecules of 4 into a 2D layer structure, complex 5 into a 2D hydrogen-bonded network through linking the hydrogen-bonded ribbons with hexagonal and four-sided rings, and complex 6 into a 3D hydrogen-bonded network through combining water helical chains. Fluorescence analyses of 1-6 in the solid state are investigated at both room temperature and 10 K. The emission spectra of 1-2 show a large red shift, which is ascribed to ligand-to-ligand charge transfer combined with ligand-to-metal charge transfer, whereas emissions of 4-6 all originate from intraligand pi-pi* transitions. In organic solvents, 1-6 behave very differently and their emission spectra exhibit various luminescences, with an obvious blue shift indicating strong solvent effects. The X-ray diffraction and thermal gravimetric analyses for complexes 1-6 are also reported.