Synthesis, crystal structure, Hirshfeld surface, optical and dielectrics properties of N-(3-aminopropyl)-1,3 diaminopropanium dichromate: (C6H20N3)2[Cr2O7]3

Abstract A new organic–inorganic material, (C 6 H 20 N 3 ) 2 [Cr 2 O 7 ] 3 has been synthesized by the solvent evaporation method and characterized by single crystal X-ray diffraction, infrared absorption, optical absorption, thermal analysis and dielectric studies. The crystal structure consists of two N-(3-aminopropyl)-1,3 diaminopropanium cations and three dichromate anions linked together by N⋯H⋯O hydrogen bonds. 3-D Hirshfeld surface analysis and 2-D fingerprint plots indicate that the packing is dominated by H⋯O/O⋯H, H⋯H, O⋯O and Cr⋯H contacts. In this study, we found that this ionic compound exhibits a triclinic P-1 orthorhombic P222 structural phase transition at about ( T 1  = 345 K) as characterized by X-ray diffraction powder, analysis and DSC. The optical absorption measurements on a (C 6 H 20 N 3 ) 2 [Cr 2 O 7 ] 3 pellet revealed two absorption bands at 3.46 and 4.68 eV. A dielectric study as a function of temperature and frequency of dichromate sample revealed a relaxation behavior at about 345 K.