Preparation, characterization, and photoluminescent and semiconductive properties of an iron compound

One iron compound {[Fe(bipy)3]2(SO3)(OH)4}·14H2O (1) (bipy = 2,2'-bipyridine) has been obtained from a hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. Compound 1 is characterized by an isolated (0D) structure and the iron center is coordinated by six nitrogen atoms of three bipy molecules to yield an octahedron. Photoluminescence investigation shows that compound 1 displays an emission in the green region. Time-dependent density functional theory (TDDFT) calculation reveals that the photoluminescent emission can be assigned to the ligand-to-metal charge transfer (LMCT) (from the HOMO of the bipy to the LUMO of the iron). Solid-state diffuse reflectance spectra discover that compound 1 features a narrow optical band gap of 1.82 eV, indicating that it is a potential narrow band gap semiconductor.