The concentration controlled 1D and 2D supramolecular isomers of lanthanide with 2,2′-bipyridyl-3,3′-dicarboxylate and phenanthroline

The reactions of 2,2'-bipyridyl-3,3'-dicarboxylic acid (H(2)bpdc) and 1,10-phenanthroline (phen) with lanthanide (III) salts in different concentrations under hydrothermal conditions formed two series of supramolecular isomers of 1D zigzag chains of [Ln(bpdc)(1.5)(phen)(H2O)](n)center dot 3nH(2)O (1Ln center dot 3H(2)O), and 2D frameworks of [Ln(bpdc)(1.5)(phen)(H2O)](n) (2Ln), (Ln = Ho, Er, Tm, and Yb). At lower concentrations, the supramolecular isomers of 1Ln were formed, in which each isomer has a dinuclear centrosymmetric dimeric unit of [Ln(2)(phen)(2)(H2O)(2)(mu(2)-bpdc)(2)](2+), and the dimeric units are alternately connected by mu(2)-bpdc(2) to form a 1D zigzag chain of 1Ln. At higher concentrations, the supramolecular isomers of 2Ln were formed. All the compounds of 2Ln are isomorphous, in which two mu(3)-bpdc(2) bridge two [Ln(phen)(H2O)](3+) units to yield a 1D double-chains of [Ln(2)(phen)(2)(H2O)(2)(bpdc)(2)](n)(2n+), and [Ln(2)(phen)(2)(H2O)(2)(bpdc)(2)](n)(2n+) chains are further connected by mu(4)-bpdc(2) to form a 2D network of [Ln(bpdc)(1.5)(phen)(H2O)](n). The 2D sheets are combined through the intersheet pi-pi interactions between the adjacent phen molecules to form a 3D structure of 2Ln. The compounds of Er(III), and Yb(III) exhibit corresponding characteristic photoluminescence in the near-infrared (NIR) region, in which 1Ln and 2Ln show obviously different emission intensity due to their different structures. (C) 2009 Elsevier B. V. All rights reserved.