Indium(III)-2,5-pyridine dicarboxylate complexes with mononuclear, 1D chain, 2D layer and 3D chiral frameworks

Five indium(III) compounds with 2,5-pyridine dicarboxylate ligands: {[4,4′-Hbipy] [In(Hpdc)(H₂O)Cl₃]·2H₂O}_n (1), {[4,4′-H₂bipy]₄[In₂(pdc)₇(H₂O)]·7H₂O}_n (2), {[4,4′-H₂bipy]₃ [In₂(pdc)₆(H₂O)]·6H₂O}_n (3), {[In₂(pdc)₂(bpno)(H₂O)₂Cl₂]·2H₂O}_n (4) and [In₂(pdc)₂(2,2′-bipy)Cl₂]_n (5), (H₂pdc = 2,5-pyridine-dicarboxylic acid, 4,4′-bipy = 4,4′-bipyridine, bpno = 4,4′-bipyridine N,N-dioxide, 2,2′-bipy = 2,2′-bipyridine) were hydrothermally or solvothermally synthesized and their structures were determined by X-ray single-crystal diffraction. Compounds 1 and 2 are both mononuclear structures, which are assembled into 3-D supramolecular structures by various hydrogen bonding; compound 3 consists of two types of infinite 1-D indium(III)-carboxylate chains; compound 4 is a 2-D wave-like plane structure formed by bpno linked indium(III)-carboxylate chains. An unprecedented 3-D chiral framework of compound 5 with three kinds of helices along [010] direction is observed, considering that the construction of a chiral structure by rigid achiral ligands is rare. A topological analysis using TOPOS4.0 indicates that compound 5 is a unique and novel example of self-penetrated (4,8)-connected binodal lattice with a {3².6⁴}{3⁴.4⁴.5⁸.6⁹.7².8} Schläfli symbol. The above-mentioned compounds were also characterized by X-ray powder diffraction (XRD), thermal gravity analysis (TGA) and photoluminescent studies.