Crystal growth, optoelectronic and biological properties of acetamidinium compounds: experimental and computational approaches

New molecular crystals, namely acetamidinium picrate (AP), and acetamidinium p-toluene sulphonate (APTS) have been synthesised and grown as single crystals. Crystal structure of AP and APTS were determined as C2/c and P21/c, respectively. They were characterised by spectral methods like UV-Vis, PL, FT-IR, FT-Raman and NMR. The SHG efficiency of the crystals was investigated by the Kurtz–Perry powder method. Experimentally, antioxidant activities and DNA binding abilities were analysed. Molecular docking studies clearly suggested that the synthesised compound shows binding affinity to the minor groove and establishes hydrogen bonding. The molecular geometries of the entitled compounds are computationally simulated and compared with their respective experimental crystal structures. Quantum chemically, total density of states (TDOS) and partial density of states (PDOS) have been estimated to explain the contributions of individual molecular fragments to the bonding properties of AP and APTS molecules. Additionally, quantum chemical calculations are also used to explore the optical and third-order nonlinear optical (NLO) polarizability of synthesized compounds. The calculated third-order NLO polarizability amplitudes are found to be 13.19 × 10–36 and 27.14 × 10–36 esu, for AP and APST, respectively, which are about four and nine times greater than p-NA (a prototype NLO molecule). The molecular orbitals and ground state electrostatic potentials are drawn to explain the charge distributions over the molecular surfaces of entitled molecules. The current study puts the entitled molecules under the spotlight of scientific interest not only in optical fields but also for biological applications, which may evoke the interest of the scientific community in the respected fields.