Synthesis and characterization of some new copper based metal-organic frameworks

Metal-organic frameworks (MOFs) have been attracting increasing interest of the scientific world not only for their interesting and fascinating crystal structures, but also because of diversity of their application areas. Herein we aimed to obtain copper based new MOFs using pyrazole-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid or pyridine-3,5-dicarboxylic acid and as a result, six different copper complexes were prepared. Only {[CuII][CuII(pydc)(H2O)]·1.5MeCN·H2O}n (5) and {[Cu(MeCN)4]· 2[CuII]·2[CuII2(pydc)2(H2O)1.5(OH)0.5]·MeCN·4AcOH·8H2O}n (6) are porous frameworks which contain pyridine-3,5-dicarboxylato linker. Synthesized compounds were characterized by means of elemental analysis, fourier transform infrared (FTIR) spectroscopy, thermo gravimetric analysis (TG/DTA), X-ray diffraction (single crystal and/or powder), and low temperature (77 K) nitrogen gas adsorption/desorption measurements for porous compounds. Additionally, magnetic susceptibilities of the compounds were measured and spin magnetic moments were calculated. 5 and 6 converted to 5a and 6a under vacuum at 110 °C. Brauner-Emmett-Teller (BET) spesific surface area is 498 and 515 m2/g for 5a and 6a, respectively. According to the photoluminescence measurements, the prepared MOFs have cluster-based emissions. Though 5a keep its luminescece properties when adsorb both toluene and 2-nitrotoluene, 6a shows luminescence when adsorbed 2-nitrotoluene. This ''on–off" luminescence property of 6a is independent of the concentration of 2-nitrotoluene.