The [Cd(BDAC)2(H2O)2]H2O units are further bridged by O—H O, N—H O, C—H O hydrogen bonds, — stacking and C—O interactions, generating a three-dimensional supramolecular structure. <...> In addition, luminescence measurements reveal that complex 1 exhibits strong fluorescent emission in the solid state at room temperature. <...> INTRODUCTION Considerable interest has been devoted to the development of the design, synthesis, and characterization of metal organic framework materials with luminescent properties because of their potential applications in chemical sensors, photochemistry, and electroluminescent display [ 1—3]. <...> In particular, the coordination complexes of cadmium(II) are being studied [ 4—6]. <...> Among them, all kinds of imidazole and their derivatives have been extensively used in the synthesis of a metal organic framework (MOF) because of their diversified coordination modes and flexibility [10—13 ]. <...> However, relatively less attention has been paid to a new imidazole derivative ligand: (1H-[ 2,2]biimidazoly-1-yl)-acetic acid. <...> EXPERIMENTAL The HBDAC ligand was synthesized following the published procedure [ 14 ]. <...> The IR spectra were obtained within the 400—4000 cm–1 as KBr disks on a VECTOR 22 spectrometer. <...> Elemental analysis was performed on a Perkin Elmer 240C elemental analyzer. <...> An emission spectrum was recorded on a Hitachi F-4500 fluorescence spectrophotometer, using a 5 nm slit width and excitation at room temperature for the solid samples. <...> All non-hydrogen atoms were located in difference Fourier maps and refined anisotropically. <...> All H atoms were refined isotropically, with the isotropic vibration parameters related to the non-H atom to which they are bonded. <...> Crystal data collection and refinement parameters are given in Table 1. <...> RESULTS AND DISCUSSION Single crystal X-ray diffraction revealed that complex 1 crystallized in the monoclinic space group P21/c with an asymmetric unit consisting of a cadmium atom on the crystallographic inversion center, one singly deprotonated HBDAC ligand, one aqua ligand, and a half-occupied crystallization water molecule. <...> As shown in Fig. 1, the cadmium atom Cd1 possesses a distorted {CdN4O2} octahedron, with the equatorial positions taken by chelating nitrogen atoms from two different <...>