Potent, highly selective Ca2+ ionophore. Effective mobile ion carrier for Ca2+, highly specific for divalent cations (Ca > Mg >> Sr = Ba). Useful for studies of Ca2+ transport across biological membranes and increasing intracellular Ca2+ concentrations. Complexes with Ca2+ between pH 7 and 9.5. Absorption max. (280 nm, MeOH): 18600 M-1cm-1.