Crystal structure, vibrational and optical properties of a new self-organized material containing iodide anions of bismuth(III), [C6H4(NH3)2]2Bi2I10·4H2O

Bismuth-iodide type zero-dimensional (0-D) organic/inorganic hybrid compound [C6H4(NH3)2]2Bi2I10·4H2O was synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P21/n, with a = 11.483(5), b = 12.896(5), c = 14.974(5) Å, β = 112.437°(5) and Z = 4; and consists of a p-phenylenediammonium dications, water molecules of crystallization in addition to the anion, which is built up of edge-sharing bioctahedra. The crystal packing is governed by I⋯I electrostatic interactions and ionic N–H⋯I hydrogen bonds forming a self-assembled multiple zero-dimensional structure. Raman and infrared spectra of the title compound were recorded in the 0–170 and 400–4000 cm−1 frequency regions, respectively. An assignment of the observed vibration modes is reported. Optical transmission measurements on thin films of [C6H4(NH3)2]2Bi2I10·4H2O revealed two absorption bands at 2.84 and 2.4 eV. Photoluminescence measurements showed a strong emission line at 2.13 eV associated with radiative recombinations of excitons confined within the bioctahedra Bi 2 I 10 4 - .