title: Aza-heterocyclic ligand assisted assembly of new cobalt MOFs with pcu and graphite related structures.
abstract: A hydrothermal reaction of a mixture of cobalt salt, 5-nitro isophthalic acid and triazole (compound I), 3-aminotriazole (3-AT) (compound II) and 3,5-diaminotriazole (compound III) at 220 °C for a day resulted in the isolation of three different, but related, compounds containing cobalt clusters. The three-dimensional compounds have Co(5) (compound-I) and Co(4) (compound-II and compound-III) clusters connected through the carboxylate and triazolate forming structures with pcu net (compound-I and compound-II) and a graphite-related net (compound-III). The water molecules (coordinated and lattice) can be readily re-adsorbed by the structure of compound-I, whereas the removal of the water molecule leads to a collapse of the structures of compound-II and compound-III. The TGA studies suggest the possibility of an intermediate structure for compound-1, which was investigated using in situ single crystal to single crystal (SCSC) transformations. The identification of an intermediate structure during the dehydration/hydration cycle in compound-I is important and provides important pointers about the dynamics of the water molecules in these compounds. Compound-I was also investigated in detail using a variety of spectroscopic techniques such as IR, UV-Vis spectroscopy etc. Magnetic studies on the synthesized compounds indicate anti-ferromagnetic behavior.
authors.affiliation: Framework solids Laboratory, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Debajit
authors.initials: D
authors.lastname: Sarma
authors.forename: Vishwas
authors.initials: V
authors.lastname: Srivastava
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Natarajan