pH- and metal-dependent structural diversity from mononuclear to two-dimensional polymers based on a flexible tricarboxylate ligand

Six complexes based on a flexible tripodal ligand H3TTTA (2,2′,2″-[1,3,5-triazine-2,4,6-triyltris(thio)]tris-acetic acid) have been hydrothermally synthesized and structurally characterized. X-ray single-crystal diffractions reveal that they have rich structural chemistry: mononuclear, [Zn(HTTTA)(2,2′-bpy)(H2O)3]n (1); dimeric metallamacrocycle, [Zn(HTTTA)(2,2′-bipy)(H2O)]n (2) and [Cd(HTTTA)(2,2′-bipy)(H2O)·H2O]n (3); two-dimensional networks with binodal (3,6)-connected CdI2 topology based on linear trinuclear M3(μ2–CO2)4(μ2–CO2)2 SBUs (Secondary Building Units), [M3(TTTA)2(2,2′-bipy)2(H2O)m·nH2O]n (M=Zn·4, m=0, n=4; Cd·5 and Mn·6, m=2; n=2). The value of pH and the metal ions has large influences on the resulting structures. The flexible tricarboxylic acid exhibits four coordination modes from monodentate to μ6-bridge. Fluorescence and magnetic properties of the complexes have also been investigated in details.