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.