| Abstrakt: |
Several 0D, 1D, and 3D metal–organic hybrid frameworks of ZnIIhave been synthesized by using the asymmetric ligand 6-(1H-benzoimidazol-2-yl)pyridinecarboxylic acid (HL) with control of the temperature and solvent in a solvothermal synthesis technique. In DMF, the structure at room temperature confirms that the resulting compound Zn(L)2·2(H2O) (1) is the 0D mononuclear structure, above ∼80 °C, C–N bond cleavage of partial DMF molecules induces the formation of the 1D chain-like compound {[Zn(L)(HCOO)]·2(H2O)}n(2), but on warming up to 120 and 160 °C, due to the decomposition of a large number of DMF molecules, the same reaction, respectively, gives two 3D metal–organic coordination polymers with 3D channels reported previously {[Zn(HCOO)3]−·[H2N(CH3)2]+}n(3) and [Zn(HCOO)2]n(4), in which the 3D channels of 3contain guest [H2N(CH3)2]+motifs, while at high temperature the 3D channels of 4are an open stable system without any guest molecules. Replacing DMF in the above reaction by ethanol or acetonitrile, only 0D compound 1is obtained in the range from room temperature to 160 °C. However, the same reaction in DMSO provides a 1D wave-like compound {[Zn(L)(DMSO)]·(ClO4)·H2O}n(5), in which the solvent DMSO molecule coordinates to the central metal ZnIIion. Furthermore, in three new complexes 1, 2and 5, through ππ stacking and hydrogen bonding interactions, 3D supramolecular networks are assembled. It is worth noting that the existence of the twelve-membered cyclic water–perchlorate dimers [(ClO4)(H2O)]22−with chair-conformation in the solid state of 5not only increases the stability of the supramolecular structure, but also results in a stronger fluorescence signal compared with ligand HL, 1and 2. [ABSTRACT FROM AUTHOR] |
