In situ synthesis, crystal structures, topology and photoluminescent properties of poly[di-μ-aqua-di­aqua­[μ3-4-(1H-tetra­zol-1-id-5-yl)benzoato-κ4O:O,O′:O′′]barium(II)] and poly[μ-aqua-di­aqua­[μ3-4-(1H-tetra­zol-1-id-5-yl)benzoato-κ4O:O,O′:O′]strontium(II)]

Two alkaline-earth coordination compounds, [Ba(C8H4N4O2)(H2O)4]n, (I), and [Sr(C8H4N4O2)(H2O)3]n, (II), from the one-pot hydrolysis transformation of benzoyl chloride and the in situ self-assembled [2 + 3] cyclo­addition of nitrile are presented. These coordination compounds are prepared by reacting 4-cyano­benzoyl chloride with divalent alkaline-earth salts (BaCl2 and SrCl2) in aqueous solution under hydro­thermal conditions. The mononuclear coordination compounds (I) and (II) show the same mode of coordination of the organic ligands. The cohesion of the crystalline structures is provided by hydrogen bonds and π-stacking inter­actions, thus forming three-dimensional supra­molecular networks. The two compounds have a three-dimensional (3,6)-connected topology, and the structural differences between them is in the number of water mol­ecules around the alkaline earth metals. Having the same emission frequencies, the compounds exhibit photoluminescence properties with a downward absorption value from (I) to (II).