Coordination ability of alkali metal or alkaline earth metal ions with aromatic dicarboxylate, sulfonate, or disulfonate ions in acetonitrile

► The coordination ability of alkali metal and alkaline earth metal ions has been examined. ► The formation of [C6H5CO2Ca]+ in acetonitrile is evidenced by ESI-MS. ► The successively formed species are proposed to be CaL22 −, CaL0, and Ca2L2 +. ► The Li+ ion causes the non-charged species as well as re-dissolution of charged species. ► The “reverse” coordination constants have been successfully evaluated.