名称:
Water dimers connect [Cu(cda)(py)3] (cda=pyridine-4-hydroxy-2,6-dicarboxylate, py=pyridine) complex units to left- and right-handed helices that form a tubular coordination polymer through supramolecular bonding
摘要:
The reaction between pyridine-4-hydroxy-2,6-dicarboxylic acid (cdaH(2)) and Cu(NO3)(2) center dot 3H(2)O afford products that depend on the reaction conditions applied. In presence of excess of aqueous pyridine (1:2 v/v), equimolar amounts of the reactants form {[Cu(cda) (py)(3)](2) center dot 5H(2)O} (1). In this complex, dimeric water clusters are H-bonded to carboxylate 0 atoms forming both left- and right-handed helices. These helices are further H-bonded to form a tubular coordination polymer. It crystallizes in the monoclinic space group P2(1)/a with a = 14.235(5), b = 23.097(4), c = 15.542(6) angstrom, beta = 114.392(5)degrees, V= 4654(2) angstrom(3), Z = 4, R-1 = 0.0422, wR(2) = 0.0992, S = 0.899. When pyridine is used in place of aqueous pyridine, a new coordination polymer, {Cu(cda)(py)}(n)(2) is formed that crystallizes in the monoclinic space group P2(1)/c with a = 12.391(5), b = 12.770(5), c = 7.135(5) angstrom, beta = 95.155(5)degrees, V= 1124(1)angstrom(3), Z = 4, R-1 = 0.0415, wR(2) = 0.0882, S = 1.190. The structure of 2 consists of carboxylate-bridged [Cu(cda)(py)] units extending as a zigzag infinite chain where each metal ion shows square-pyramidal geometry. Variable temperature magnetic susceptibility measurements in the temperature range, 2-300 K for 2 is also reported. (c) 2007 Published by Elsevier B.V.