Being the conjugate base of a strong acid (sulfuric acid), sulfate is not basic. It is more commonly a counterion in coordination chemistry. Tuttons salts, with the formula MM(SO)(HO) (M' = K, etc.; M = Fe, etc.), illustrate the ability of water to outcompete sulfate as a ligand for M. Similarly alums, such as chrome alum ([K(HO)][Cr(HO)][SO]), features  with noncoordinated sulfate. In a related vein, some sulfato complexes confirmed by X-ray crystallography, convert to simple aquo complexes when dissolved in water.  Copper(II) sulfate  examplifies this behavior, sulfate is bonded to copper in the crystal but dissociates upon dissolution.