Molecular interactions of zinc(II) cyclams toward maleate and fumarate anions

Two new zinc(II) complexes of the composition {[Zn(L)(maleate)] · H2O}n (1) and [Zn(L)(H2O)2](fumarate) · 4H2O (2) (L = cyclam, 1,4,8,11-tetraazacyclotetradecane) have been prepared and structurally characterized by a combination of analytical, spectroscopic, thermogravimetric, and crystallographic methods. The carboxylate groups of the maleate ligand in 1 show a coordination tendency toward zinc(II) cyclams resulting in the formation of a 1D coordination polymer. However, the carboxylate groups of the isomeric fumarate anion in 2 do not interact with zinc(II) cyclam. The identification of strong interactions between carboxylate groups and zinc(II) ions in 1 may provide better knowledge for the improved design of receptor-targeted zinc(II) cyclams in anti-HIV agents.