Synthesis, Structure and Luminescent Property of a 3D Layered-Pillared Cd(II) Metal-Organic Framework Derived from Mixed Rigid and Flexible Ligands

A new 3D Cd(II) metal-organic framework of [Cd-2(HIDC)(2)(bibp)(1.5)](n) (1) was synthesized hydrothermally by the reaction of imidazole-4,5-dicarboxylic acid (H2IDC) and 4,4 '-bis(imidazol-1-ylmethyl)biphenyl (bibp) with Cd(NO3)(2)center dot 4H(2)O. Single-crystal X-ray diffraction analysis reveals that this compound crystallizes in triclinic, space group Pi with a = 9.6610(3), b = 15.5866(5), c = 16.0228(6) A, alpha = 110.662(3), beta = 101.521(3), gamma = 107.115(3), V = 2029.46(15) A(3), Z = 2, D-c = 1.644 g cm(-3), mu = 1.113 mm(-1), F(000) = 1002, the final R-1 = 0.0468 and wR(2) = 0.0962 for 8932 observed reflections with I > 2 sigma(I). In 1, the alternately interconnection of Cd(II) ions by mu(2)-HIDC2- and mu(3)-HIDC2- anions resulted in the formation of 1D [Cd-2(mu(2)-HIDC)(mu(3)-HIDC)](infinity) with the right- and left-helical chains, which were further linked by the oxygen atoms derived from one of the carboxylate groups of mu(3)-HIDC2- anions, generating the 1D double helical chain structure of [Cd-4(mu(2)-HIDC)(2)(mu(3)-HIDC)(2)](infinity) along a axis. These adjacent 1D double chains are further linked by cis-mu(2)-bibp ligands to form a 2D network structure of [Cd-4(mu(2)-HIDC)(2)(mu(3)-HIDC)(2)(cis-mu(2)-bibp)(2)](n), which are further pillared by trans-mu(2)-bibp ligands to generate a 3D layered-pillared metal-organic framework architecture of [Cd-4(mu(2)-HIDC)(2)(mu(3)-HIDC)(2)(cis-mu(2)-bibp)(2)(trans-mu(2)-bibp)](n). Furthermore, the thermal stability and luminescent property of 1 have also been investigated. Graphic abstract A 3D Cd(II) layered-pillared metal-organic framework was synthesized hydrothermally. This new compound displays high thermal stability and intense fluorescent emission. [GRAPHICS] .