Cooperative effects of metal cations and coordination modes on luminescent s-block metal–organic complexes constructed from V-shaped 4,4′-sulfonyldiphenol

Abstract

The self-assembly of 4,4′-sulfonyldiphenol (H₂sdp) with s-block metal salts in an aqueous or mixed H₂O/alcohol solution gives rise to the formation of 13 new complexes, namely, [Li(Hsdp)(H₂O)]_n (1), [Na(Hsdp)(H₂O)]_n (2), [K(Hsdp)(H₂sdp)(H₂O)]_n (3), [Cs(Hsdp)(solvent)(H₂O)]_n [solvent = EtOH (4) and i-PrOH (5)], [Mg(H₂O)₆]·2(Hsdp)·(H₂sdp)·4H₂O (6), [Ca(Hsdp)₂(H₂O)₄] (7), [AE₂(Hsdp)₄(H₂sdp)₄] [AE = Sr (8) and Ba (9)], [Mg(sdp)(H₂O)]_n (10), [Ca(sdp)]_n (11), [Sr(sdp)(H₂O)₂]_n (12), and [Ba₂(sdp)₂(MeOH)₂(H₂O)]_n (13), which have been characterized by elemental analysis, IR spectroscopy, TGA, PL, and powder and single-crystal X-ray diffraction. The smaller Li(I) and Na(I) cations in complexes 1 and 2 tend to induce the formation of chain and layer structures, whereas the larger K(I) and Cs(I) cations in complexes 3, 4 and 5 tend to induce the formation of a 3-D hybrid network. Complexes 6–9 and 10–13 also exhibit an increase in dimensionality in the sequence from Mg(II) to Ba(II) cations. From a reaction at room temperature, mononuclear (6 and 7) and dinuclear (8 and 9) motifs are observed. In contrast, from a hydrothermal reaction, layer (10 and 12) and 3-D hybrid (11 and 13) networks are formed with less coordination of water molecules and more intricate coordination modes of sdp²⁻ dianions. The structural evolution is mainly determined by the effective coordination numbers (ECNs) and radii of the metal cations, as well as the coordination modes of the ligands. As a result of hydrogen bonding, these 13 complexes possess various types of network, i.e., porous networks with rhombic or hexagonal channels, organic–inorganic hybrid networks, and ABAB packing networks. The solid-state luminescence properties demonstrate that all these complexes exhibit violet and blue emissions in the range of 375–429 nm at room temperature.