Influence of Metal Cations and Coordination Modes on Luminescent Group 1 and 2 Metal Sulfonate Complexes Constructed from 4,4′‐Dihydroxybiphenyl‐3,3′‐disulfonic Acid

Abstract

The reactions of 4,4′-dihydroxybiphenyl-3,3′-disulfonic acid (H4L) with group 1 and 2 metal salts in aqueous solution lead to six metal sulfonate complexes, [K2(H2L)]n (1), {[Cs2(H2L)(H2O)]n·nH2O} (2), 2[Mg(H2O)6]2+·2(H2L)2–·2H2O (3), {[Ca(H2L)(H2O)2]n·4nH2O} (4), {[Sr(H2L)(H2O)4]n·3nH2O} (5), and {[Ba(H2L)(H2O)]n·nH2O} (6), which have been characterized by elemental analysis, IR spectroscopy, thermogravimetry (TG), photoluminescence (PL) spectroscopy, powder XRD, and single-crystal XRD. Complexes 1, 2, and 6 exhibit 3D pillared-layered networks formed by M–O–S layers bridged by the biphenyl rings of H2L2– dianions. The [Mg(H2O)6]2+ cations and sulfonate groups in 3 are held together by second-sphere interactions to generate layer motifs. Complex 4 presents a layer structure formed by Ca–O chains bridged by the biphenyl rings of H2L2– dianions. Complex 5 has a 3D interdigitating architecture (2D + 2D 3D), in which the 44 hydrogen-bonding layer is constructed from linear chains. Meanwhile, the recrystallization of H4L from aqueous solution affords the supramolecular complex 2(H3O+)·(H2L)2–·3H2O (S1), which exhibits a 3D pillared-layered network. The solid-state luminescence properties demonstrate that 1–6 exhibit violet emission at room temperature and can sensitize EuIII and TbIII ions to exhibit their characteristic emissions.