Crystal structure, energy band and optical properties of benzoic acid —2-amino-4,6-dimethylpyrimidine (1:1) co-crystals

Co-crystals formed between benzoic acid and 4,6-dimethyl-2-aminopyrimidine in 1:1 molar ratio (C6H9N3C7H6O2) have been prepared and studied. According to single crystal XRD analysis, the structure is monoclinic, P21/c, a = 6.7019(9) Å, b = 7.647(1) Å, c = 25.285(3) Å, β = 91.36(2)°, V = 1295.4(3) Å3, Z = 4. The asymmetric unit contains 2-amino-4,6-dimethylpyrimidine and benzoic acid molecules linked to each other by two hydrogen bonds [O1-H1N1, HN = 1.819 Å; N3-H3AO2, HO = 2.157 Å]. Calculations of band structure, density of states, absorption and reflectivity spectra have been performed in the frame of density functional theory using the CASTEP code, and the corresponding experimental optical properties have been investigated. The theoretical results indicate that (C6H9N3C7H6O2) single crystal is a wide band-gap semiconductor with the theoretical direct band gap 3.0271 eV. The title co-crystal may become promising host for fluorescence-emitting; it can absorb ultraviolet radiation.