Crystal structures and fluorescent properties of the first 2d and 3d cadmium(II) pyromellitate coordination polymers

Abstract

Two novel cadmium polymeric complexes, [Cd2(btec)·6H2O] n (1), and [Cd2(btec)] n (2) (H4btec = 1,2,4,5-benzenetetracarboxylic acid), were obtained by assembly of Cd(NO3)2·4H2O and Cd(OH)2 with H4btec at different pH values and characterized by elemental analysis, IR spectra, X-ray single-crystal diffraction, TGA and fluorescent spectra. Complex 1 crystallizes in the triclinic system with space group , a = 5.595(1), b = 7.770(2), c = 9.685(2) Å, α = 111.93(2), β = 101.78(2), γ = 98.28(2)° and complex 2 crystallizes in the monoclinic system with space group C2/m, a = 6.588(2), b = 18.038(5), c = 4.728(2) Å, β = 116.49(1)°. Complex 1 contains a novel step-like 2D layered network and complex 2 possesses a 3D pillared-layered structure. These two complexes exhibit strong fluorescent emission bands at 363.5 and 486.5 nm (λex = 215 nm) for complex 1, 386.5 nm (λex = 335 nm) for complex 2 in the solid state at room temperature.