Concomitant Metal Organic Frameworks of Cobalt(II) and 3‑(4-Pyridyl)benzoate: Optimized Synthetic Conditions of Solvatochromic and Thermochromic Systems

Two coordination networks, {[Co­(34pba)2]·DMF}n (1 and 2), where
34pba is 3-(4-pyridyl)­benzoate, were prepared by solvothermal methods. 1 is a three-dimensional metal organic framework formed by
linking [Co2(34pba)8] clusters in a bcu net. 2 consists of single [Co­(34pba)4] units
in a tetragonal plane net of sql topology. The thermal
conditions leading to their selective synthesis were established:
120 °C for 1 and 75 °C for 2.
Their structures were solved and their thermal behavior was investigated.
Further experiments established the activation energy for the desorption
of the DMF molecules entrapped in their framework: 76(6)–106(16)
kJ mol–1 for 1 and 49(3)–58(3)
kJ mol–1 for 2. For 1,
sorption experiments were carried out to demonstrate the ability of
the coordination network to absorb different solvents, and the framework
solvatochromic response was also ascertained.