A new copper(II) supramolecular coordination polymer and a dinuclear compound with multifunctional 2-amino-5-sulfobenzoic acid and flexible N-donor ligands: synthesis, structure and characterization.

Multifunctional 2-amino-5-sulfobenzoic acid (Hafsb) can exhibit a variety of roles during the construction of supramolecular coordination polymers. The pendant carboxylic acid, sulfonic acid and amino groups could not only play a role in directing bonding but could also have the potential to act as hydrogen-bond donors and acceptors, resulting in extended high-dimensional supramolecular networks. Two new Cu coordination compounds, namely catena-poly[[[diaquacopper(II)]-μ-1,6-bis(1H-1,2,4-triazol-1-yl)hexane-κN:N] bis(3-amino-4-carboxybenzenesulfonate) dihydrate], {Cu(CHN)(HO)·2HO} or {Cu(bth)(HO)·2HO}, (1), and bis(μ-2-amino-5-sulfonatobenzoato-κO:O)bis{μ-1,2-bis[(1H-imidazol-1-yl)methyl]benzene-κN:N}bis[aquacopper(II)] trihydrate, [Cu(CHNOS)(CHN)(HO)]·3HO or [Cu(afsb)(obix)(HO)]·3HO, (2), have been obtained through the assembly between Hafsb and the Cu ion in the presence of the flexible N-donor ligands 1,6-bis(1H-1,2,4-triazol-1-yl)hexane (bth) and 1,2-bis[(1H-1,2,4-triazol-1-yl)methyl]benzene (obix), respectively. Compound (1) consists of a cationic coordination polymeric chain and 3-amino-4-carboxybenzenesulfonate (Hafsb) anions. Compound (2) exhibits an asymmetric dinuclear structure. There are hydrogen-bonded networks within the lattices of (1) and (2). Interestingly, both (1) and (2) exhibit reversible dehydration-rehydration behaviour.