Building thiol and metal-thiolate functions into coordination nets: Clues from a simple molecule

The simple and easy-to-prepare bifunctional molecule 2,5-dimercapto-1,4-benzenedicarboxylic acid (H4DMBD) interacts with the increasingly harder metal ions of Cu+, Pb2+ and Eu3+ to form the coordination networks Of Cu-6(DMBD)(3)(en)(4)(Hen)(6), (1), Pb-2(DMBD)(en)(2) (2) and Eu-2(H2DMBD)(3)(DEF)(4) (3), where the carboxyl and thiol groups bind with distinct preference to the hard and soft metal ions, respectively. Notably, 1 features uncoordinated carboxylate groups and Cu-3 cluster units integrated via the thiolate groups into an extended network with significant interaction between the metal centers and the organic molecules; 2 features a 2D coordination net based On the mercapto and carboxylic groups all bonded to the Pb2+ ions; 3 features free-standing thiol groups inside the channels of a metal-carboxylate-based network. This study illustrates the rich solid state structural features and potential functions offered by the carboxyl-thiol combination. (C) 2009 Elsevier Inc. All rights reserved.