A pseudo-honeycomb coordination net formed with 5-sulfoisophthalic acid

The first coordination polymer of a sulfoisophthalic acid isomer is reported. The ligand, 5-sulfoisophthalic acid, L, can be regarded as similar to the much-studied 1,3,5-benzenetricarboxylic acid (BTC) but where a sulfonate group has replaced one of the carboxyl groups on the benzene core. The complex, {[Cu-1.5(L)(py)(5)](py)(H2O)(6.76)}(infinity), 1, adopts a pseudo-honeycomb structure with channels occupied by guest solvent molecules. The framework is a pseudo-honeycomb, in contrast to the BTC analogue, owing to the sulfonate lone electron pairs being directed out of the plane of the isophthalic acid moiety. The ruffled stucture of the layers precludes extensive pi interactions between adjacent lamellae. However, amongst several disordered guests, one guest pyridine molecule is fixed by both face-to-face and edge-to-face non-covalent interactions.