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

Abstract 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)(H 2 O)] n ·3 n H 2 O ( 1Ln ·3H 2 O), and 2D frameworks of [Ln(bpdc) 1.5 (phen)(H 2 O)] 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 (H 2 O) 2 (μ 2 -bpdc) 2 ] 2+ , and the dimeric units are alternately connected by μ 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 2 Ln are isomorphous, in which two μ 3 -bpdc 2− bridge two [Ln(phen)(H 2 O)] 3+ units to yield a 1D double-chains of [Ln 2 (phen) 2 (H 2 O) 2 (bpdc) 2 ] n 2 n + , and [Ln 2 (phen) 2 (H 2 O) 2 (bpdc) 2 ] n 2 n + chains are further connected by μ 4 -bpdc 2− to form a 2D network of [Ln(bpdc) 1.5 (phen)(H 2 O)] n . The 2D sheets are combined through the intersheet π – π 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.