Construction of functional coordination polymers derived from designed flexible bis(4-carboxybenzyl)amine

Abstract

Four coordination polymers (CPs), [Zn₂(H₂BCA)₂(o-bimb)₂(H₂O)₂]_n (1), {[Pb(H₂BCA)(p-bib)_0.5]·H₂O}_n (2), {[Cd₂(H₂BCA)₂(p-bib)₂]·(H₂O)₃}_n (3) and {[Zn(H₂BCA)(m-bib)]·H₂O}_n (4), have been derived from the designed flexible bis(4-carboxybenzyl)amine (H₂BCA) with bis(imidazole) linkers (p-bib = 1,1′-benzene-1,4-diylbis(1H-imidazole), m-bib = 1,3-bis(1-imidazoly)benzene, and o-bimb = 1,2-bis(imidazol-1-ylmethyl) benzene). X-ray single crystal diffraction analyses reveal that complex 1 is a 3D supramolecular structure composed of 2D 3-connected hcb layers via hydrogen contacts. Complex 2 exhibits a 3D 2-nodal (4,5)-connected {4⁴.6²}{4⁴.6⁶}-tcs net. Complex 3 shows a novel 2-nodal 3D (4,5,5)-connected net with the point symbol {4.6⁶.8³}₂{4².6².8²}. Complex 4 displays a 3D 3-fold interpenetrating 3-connected {10³} ThSi2 net. Structural comparison reveals that the central ions as well as the auxiliary ligand play critical roles in determining the coordination modes of H₂BCA and the final structures. In addition, the luminescence measurements of two zinc-containing compounds (1 and 4) have been discussed and show excellent selectivity and sensitivity in detecting acetone molecules and Cr₂O₇²⁻/CrO₄²⁻ anions in aqueous solution.