Temperature dependent structure formation and photoluminescence studies of a series of magnesium-based coordination networks

A series of three magnesium trimesate coordination networks was synthesized from identical reaction mixtures by varying synthetic temperature. Mg(HBTC)(DMF)2·[(CH3)2NH] (1; BTC = trimesate; space group P63/m, a = 16.596(4) Å, c = 14.351(8) Å) crystallizes at 65 °C, Mg3(BTC)(HCOO)3(DMF)3 (2; space group P¯3, a = 13.928(2) Å, c = 8.025(6) Å) crystallizes at 100 °C, and Mg3(BTC)2(DMF)4 (3; space group P21/c, a = 17.490(4) Å, b = 11.940(2) Å, c = 18.460(4) Å, β = 116.87(3)°) crystallizes at a temperature of 180 °C. Each network contains metal-coordinated solvent DMF molecules, but thermodynamics and solvent hydrolysis play major roles in structure formation. Compounds 1 and 2 are two-dimensional networks which incorporate hydrolysis byproducts. Compound 3 is a three-dimensional network and shows no inclusion of byproducts. The series follows the trend of increased network connectivity resulting from increased temperature. Each of the networks show a weak photoluminescence response, suggesting that coordinated solvent molecules and interlayer species play a role in quenching photoluminescence.

A series of magnesium trimesate coordination networks was synthesized using temperature as the synthetic variable. Both solvent and thermodynamic effects are observed in the formation of the networks. Each of the networks show a weak photoluminescence response, suggesting that solvent coordination plays a role in quenching fluorescence.Figure optionsDownload as PowerPoint slideHighlights
► Synthesis of a series magnesium networks linked by trimesate ligand.
► Temperature used as synthetic variable to yield different topologies.
► Weak fluorescence of networks suggests quenching by coordinated solvent.