Electrosynthesis of coordination polymers containing magnesium(II) and benzene 1,3,5-tricarboxylate: the influence of solvents and electrolytes toward the dimensionality

Abstract

The synthesis of coordination polymers (CPs) and metal-organic frameworks (MOFs) through electrochemical method has become an interesting preference due to ease of handling, time and cost-efficient, and abundant results with high crystallinity. In this research one- and two-dimensions of CPs containing magnesium (II) and benzene 1,3,5-tricarboxylic acid (H3BTC) were successfully electro-synthesized at 15 V for 1.5 h. Reaction parameters such as solvents and electrolytes were variated and produced white crystalline materials. X-Ray diffractogram revealed that the use of 0.1 M tetrabutyl ammonium tetra-fluoroborate (TBATFB) as an electrolyte in both ethanol and ethanol: water (1:1, mol/mol) lead to the formation of 2-dimensional CP [Mg2 (BTC)(OH)(H2O)4] 2H2O (NICS-5) (NICS: National Institute of Chemistry Slovenia) . The use of 0.1 M tributyl methyl ammonium methyl sulfate (MTBS) in both ethanol and ethanol: water (1: 1) indicates conformity with the simulated pattern of [Mg3 (BTC)2(H2O)12] (NICS-4) which has a one-dimensional structure. The formation of these two compounds is further confirmed by FTIR analysis. Nitrogen sorption isotherm indicates the both compounds are non-porous materials. Compound NICS-5 synthesized in ethanol: water (1: 1) has a BET surface area of 44.243 m2/g with a total pore volume of 0.16 cc/g and an average pore diameter of 16.81Å, larger than the compound NICS-5 synthesized only in ethanol. SEM image shows that compound NICS-5 has a bigger average crystallite size than compound NICS-4. Compound NICS-5 and NICS-4 are thermally stable up to 490°C and 455°C, respectively, according to thermogravimetric measurement.