metalorganic frameworks as precursor for metal oxide nanostructures part i: mof-derived copper oxide embedded in carbon matrix

Three isostructural metal-organic framework materials (mofs) formulated as m[(hbtc)(h2o)]ˑh2o(m = cu for 1, zn for 2 and ca for 3) constructed with 1, 3, 5-benzenetricarboxylate (btc) were synthesized under hydro/solvothermal conditions. the three compounds were characterized on the basis of infrared and uv-vis spectroscopy and the structure of 3 elucidated with the help of single-crystal x-ray crystallography. the uv-vis spectrum of 1 exhibited a unique band at 511 nm. in the region 520 – 534 nm, the band splits into two moderately intense peaks at 527 and 531 nm. these absorption peaks along with other bands at 629 and 638 nm were assigned to d-d transitions of the copper (ii) ion with distorted square planar geometry. the infrared spectra of the three compounds revealed that the ligand, btc anion coordinated in a chelating and / or bridging mode to the metal center. the presence of absorption bands at 1699 cm^-1 in 1 and 2, (1681 cm^-1 in 3) can be attributed to protonated hbtc for 1-3. single-crystal x-ray crystallographic studies of compound 3 revealed well-ordered structure with btc ligand linking the individual chains to form a network structure. on heating cu(hbtc)(h2o)ˑh2o up to 400oc, a copper-oxide embedded in carbon matrix was obtained with uniform particles of 10 -100 nm size