resumo
In an effort to understand the role of non-covalent interactions in binding of biologically and commercially important non-coordinating anions like I-, ClO4- and IO4-, four new mixed ligand Co(III) complex salts; [Co(phen)(2)Hbiim]Cl-2 center dot 10H(2)O (1), [Co(phen)(2)Hbiim]I-2 center dot 3H(2)O (2), [Co(phen)(2)Hbiim](ClO4)(2) (3) and [Co(phen)(2)Hbiim] (IO4)(2)center dot 0.5H(2)O (4) (where phen = 1,10-phenanthroline, Hbiim = 2,2'-biimidazole; monoanionic) have been synthesized. Elemental analyses, spectroscopic studies (IR, UV-Vis, H-1 and C-13 NMR), solubility product, conductance measurements were performed to characterize the complex salts. Single crystal X-ray structure determination revealed that complex salt 2 crystallizes in the triclinic crystal system (P (1) over bar) while 3 and 4 crystallize in monoclinic crystal system with space group P2(1)/c. In complex salts 3 and 4, the complex cations are arranged in the 2D sheets stabilized by N-H center dot center dot center dot N and C-H center dot center dot center dot pi interactions. The anionic moieties are arranged like pillars in between these sheets which are stabilizing the three-dimensional architecture by C-H-pen/Hbiim(delta+)center dot center dot center dot O-anion(delta-) second sphere interactions besides electrostatic forces of attraction. The structural studies suggest that the non-covalent interactions like C-H center dot center dot center dot O, C-H center dot center dot center dot pi, pi-pi stacking interactions cohesively play a decisive role in binding of biologically and commercially important anions (I-, ClO4- and IO4-) by [Co(phen)(2)Hbiim](2+) in aqueous medium. (C) 2011 Elsevier B. V. All rights reserved.
palavras-chave
2ND SPHERE COORDINATION; X-RAY-STRUCTURE; PI INTERACTIONS; TRANSITION-METAL; RECOGNITION; RECEPTORS; PERCHLORATE; RINGS; WATER; IONS
categoria
Chemistry
autores
Sharma, RP; Singh, A; Brandao, P; Felix, V; Venugopalan, P
nossos autores
Paula Cristina Ferreira da Silva Brandão
Investigador Auxiliar
Vítor Félix
Professor Associado com Agregaçãoagradecimentos
The authors gratefully acknowledges the financial support of CSIR vide Grant No. 09/135/0594/2010/EMR-I.