Discrete and Polymeric, Mono- and Dinuclear Silver Complexes of a Macrocyclic Tetraoxime Ligand with Ag^I–Ag^I Interactions

Author： Tashiro Shohei Tanihira Jun-ichiro Yamada Mihoko Shionoya Mitsuhiko

Publisher： MDPI

E-ISSN： 1424-8220|13|5|5671-5685

ISSN： 1424-8220

Source： Sensors, Vol.13, Iss.5, 2013-05, pp. : 5671-5685

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Abstract

Macrocyclic compounds that can bind cationic species efficiently and selectively with their cyclic cavities have great potential as excellent chemosensors for metal ions. Recently, we have developed a tetraoxime-type tetraazamacrocyclic ligand 1 formed through a facile one-pot cyclization reaction. Aiming to explore and bring out the potential of the tetraoxime macrocycle 1 as a chelating sensor, we report herein the preparation of several kinds of silver complexes of 1 and their unique coordination structures determined by single-crystal X-ray diffraction analyses. As a result, the formation of two kinds of discrete structures, monomeric complexes [Ag(1)X] (X = counter anions) and a dimeric complex [Ag₂(1)₂]X₂, and two kinds of polymeric structures from a mononuclear complex, [Ag(1)]_nX_n, and from a dinuclear complex, [Ag₂(1)X₂]_n, was demonstrated. In the resulting complexes, the structurally flexible macrocyclic ligand 1 was found to provide several different coordination modes. Notably, in some silver complexes of 1, Ag^I–Ag^I interactions were observed with different Ag^I–Ag^I distances which depend on the kind of counter anions and the chemical composition.