| Popis: |
Solvothermal and classical synthesis with an identical recipe involving 4H-1,2,4-triazol-4-yl acetic acid (HL1) and CdCl2 afforded two-dimensional (2D) (1)l and one-dimensional (2) coordination polymers, respectively. Hexagonal plate-like crystals of [Cd-2(L1)(2)Cl-2] (1), which crystallize in the chiral orthorhombic space group (P2(1)2(1)2(1)), were obtained in high yield. The 1,2,4-triazole-4-yl acetate (Li? ligand, which has a significant kink in the spacer, leads to the formation of a Cd-II complex displaying a 2D single-stranded helical array. The pitch height of the helix is equal to the length of the crystallographic a axis (7.579 angstrom) which comprises two cadmium atoms and two ligands. Solid-state emission of 1 shows a strong emission band around 465 nm with photoexcitation at 290 nm. Mercury porosimetry measurements reveal pore size distribution with a diameter of 80, 10, and 1 mu m. BET shows no preference for N-2(g) but a low H-2(g) adsorption of 4 cm(3)/g. Complex 1, which is constituted by a "soft" nonaromatic network that begins to collapse around 170 C, was subjected to controlled pyrolysis to produce CdO with morphology and phase selectivity. Texture of the thus obtained pure cubic phase of CdO (beta-form) was further tuned with the regulation of the annealing temperature. Crystals of rectangular blocks of [Cd(HL1L1)Cl]center dot 2H(2)O (2), which were formed in small quantity, feature a centrosymmetric, monoclinic space group (P2(1)/c). Their crystal structure reveals a one-dimensional linear chain where Cd atoms are connected by a triple bridge made up of one mu-chloride and two mu-N1,N2-1,2,4-triazole HL1 and L1. The coordination polymer charge is balanced by both chloride and the carboxylate group of L1. |
