Syntheses, Crystal Structure, and Properties of Two New Coordination Polymers from a Triphenylamino-Based Ligand

Two new coordination polymers, namely, {[CdCl₂(BIPAB)₂]·H₂O}_n (I) (BIPAB = 4-(bis(4-(1H-imidazol-1-yl)phenyl)amino)benzonitrile) and {[NiCl₂(HBIPABA)₂]·2H₂O}_n (II) (HBIPABA = 4-(bis(4-(1H-imidazol-1-yl)phenyl)amino)benzoic acid), have been successfully synthesized by using a triphenylamino-based ligand BIPAB, as original reactant and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, TG, and luminescence. X-ray single crystal diffraction analysis (CCDC nos. 2283736 and 2283737 for I and II, respectively) shows that both compounds I and II crystallize in monoclinic crystal system with space groups are P2/c and P2₁, respectively. All of them exhibit one-dimensional (1D) ribbon coordination chain formula as [MCl₂(L)₂]_n. However, the 1D chains were packing into different three-dimensional (3D) supramolecular frameworks mainly due to the uncoordinated additional functional groups on the ligand. For compound I, the 1D chains cross arrange to form a 3D supermolecule framework, in which the nitrile grouping showed as guest molecule to be accommodated by Cd₂L₂ ring on adjacent 1D chains; for compound II, the 1D chains were connected by the hydrogen bonds between in situ formed carboxyl groups to formed a two-dimensional (2D) hydrogen bonding network, and the 2D networks were further interpenetrated to forms a 3D supermolecule framework. Compounds I and II showed a thermal stability up to 380 and 280°C, respectively. Moreover, compound I exhibits an intense blue emission centered at 490 nm upon excitation at 370 nm.