Solvent-regulated assembly of two new Cd(II) coordination polymers based on 3-(1H-benzimidazol-2-yl) propanoic acid

Two new cadmium(II) coordination polymers, namely, {[Cd5Cl2(HBIP)4(BIP)2]·4DMF}n (1) and [Cd3(HBIP)2(BIP)2]n (2), were synthesized from the solvothermal reactions of CdCl2·2.5H2O with 3-(1H-benzimidazol-2-yl) propanoic acid (H2BIP) under different solvent atmospheres. Both the complexes were characterized via elemental analysis, infrared spectra, powder X-ray diffraction, thermogravimetric analysis, and single-crystal X-ray diffraction analysis. Complex 1 exhibits a distinct (4,4) network constructed from the linkage of the N atoms of the μ3-BIP2 − ligands and the infinite pentanuclear secondary building units. Complex 2 presents an interesting one­dimensional structure with helical character, composed of four helical chains weaving together in two reverse orientations. Furthermore, the solvent may play a subtle and important role in the assembly procedure. Thermogravimetric analyses show that 2 is stable up to 400 °C. The study of luminescence properties reveals that these complexes exhibit intense, large red-shift emissions in the visible region at room temperature.