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 (H 2 afsb) 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 II coordination compounds, namely catena -poly[[[diaquacopper(II)]-μ-1,6-bis(1 H -1,2,4-triazol-1-yl)hexane-κ 2 N 4 : N 4′ ] bis(3-amino-4-carboxybenzenesulfonate) dihydrate], {[Cu(C 10 H 16 N 6 ) 2 (H 2 O) 2 ](C 7 H 6 NO 5 S) 2 ·2H 2 O} n or {[Cu(bth) 2 (H 2 O) 2 ](Hafsb) 2 ·2H 2 O} n , (1), and bis(μ-2-amino-5-sulfonatobenzoato-κ 2 O 1 : O 1′ )bis{μ-1,2-bis[(1 H -imidazol-1-yl)methyl]benzene-κ 2 N 3 : N 3′ }bis[aquacopper(II)] trihydrate, [Cu 2 (C 7 H 5 NO 5 S) 2 (C 14 H 14 N 4 ) 2 (H 2 O) 2 ]·3H 2 O or [Cu 2 (afsb) 2 (obix) 2 (H 2 O) 2 ]·3H 2 O, (2), have been obtained through the assembly between H 2 afsb and the Cu II ion in the presence of the flexible N-donor ligands 1,6-bis(1 H -1,2,4-triazol-1-yl)hexane (bth) and 1,2-bis[(1 H -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.