Crystal structures, Hirshfeld surface analysis, antimicrobial activity, and optical properties based on DFT calculations of two new organic-inorganic hybrids: [nClBzPy]2[MnCl4] (n = 2, 4)

In this paper, two new organic-inorganic hybrids, 2-chlorobenzylpyridinium tetrachloromanganate(II) [2ClBzPy]2[MnCl4](1) and 4-chlorobenzylpyridinium tetrachloromanganate(II) [4ClBzPy]2[MnCl4](2) were synthesized. Single-crystal X-ray diffraction analyses showed that both quaternary ammonium salts produced belonged to the monoclinic crystal system and crystallized in the C2/c and P21 space groups, respectively. Hirshfeld surface analysis, dnorm, and two-dimensional fingerprint plots were investigated to validate the contributions of the different intermolecular contacts within the supramolecular structures. The emission wavelengths were 516 nm (1) and 515 nm (2), showing excellent green luminescence performance. The geometric structure is theoretically simulated through DFT calculation, and the theoretical values are then compared with the experimental results. The intermolecular energies, the energy gaps between the HOMO and LUMO orbitals, and the first hyperpolarizabilities were obtained on the basis of DFT calculations. The first hyperpolarizabilities (βtot) of two quaternary ammonium salts are 578.01 × 10−30 and 18.31 × 10−30, which are 843.8 and 26.7 times higher than the reference crystal KDP, respectively. This demonstrated that quaternary ammonium salts 1 and 2 had good nonlinear optical properties and were excellent materials for NLO applications. In addition, the results of bacteriostatic experiments showed that both complexes had good bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).