Crystal structure, photoluminescent properties, and DFT calculation of a new polymorph hybrid based on perchlorate salts

The hybrid compound with the formula (C7H7N2)ClO4 is synthesized at room temperature by the slow evaporation method from an aqueous solution. It crystallizes in the monoclinic symmetry, space group P21/c, with the following parameters: a = 19.71(2)?, b = 9.138(9) ?, c = 10.073(10) ?, beta= 104.15(3)degrees, and Z = 8. However, the supramolecular crystal structure was built from perchlorate anions (ClO4)- and organic benzimidazolium cations (C7H7N2)+ connected with hydrogen bonds only to form a zero-dimensional network. The infrared (FTIR) and Raman spectra confirm the existence of vibrational modes that correspond to the organic and inorganic entities. The Hirshfeld analysis results show that the crystal packing was stabilized mainly by HMIDLINE HORIZONTAL ELLIPSISO/OMIDLINE HORIZONTAL ELLIPSISH (50.8%). Furthermore, the thermal behavior studied by thermogravimetric (TGA) and differential scanning calorimetry (DSC) appears to have good stability up to 200 degrees C. Finally, optical properties were investigated by UV-Vis absorption and photoluminescence spectroscopy along with TDDFT theoretical calculations. This new compound exhibits lower cut-off energy and emission properties, with a band gap energy of 4.47 eV.