Single crystal, Hirshfeld surface and theoretical analysis of methyl 4-hydroxybenzoate, a common cosmetic, drug and food preservative—Experiment versus theory

Abstract

Methyl 4-hydroxybenzoate, commonly known as methyl paraben, is an anti-microbial agent used in cosmetics and personal-care products, and as a food preservative. In this study, the single crystal X-ray structure of methyl 4-hydroxybenzoate was determined at 120 K. The crystal structure comprises three methyl 4-hydroxybenzoate molecules condensed to a 3D framework via extensive intermolecular hydrogen bonding. Hirshfeld surface analysis was performed to determine the intermolecular interactions and the crystal packing. In addition, computational calculations of methyl 4-hydroxybenzoate were obtained using the Gaussian 09W program, and by quantum mechanical methods, Hartree Fock (HF) and Density Functional Theory (DFT) with the 6-311G(d,p) basis set. The experimental FT-IR spectrum strongly correlated with the computed vibrational spectra (R 2 = 0.995). The energies of the frontier orbitals, HOMO and LUMO, were used to calculate the chemical quantum parameters. The lower band gap value (ΔE) indicates the molecular determinants underlying the known pharmaceutical activity of the molecule.

Practical and Computational Studies of Bivalence Metal Complexes of Sulfaclozine and Biological Studies

“…Frontier molecular orbital, FMO, studies provide the electronic characteristics of molecular systems and the reactivity of the compounds ( Abdel-Kader et al, 2019 ; Sharfalddina et al, 2020a ). Thus, the map of HOMO and LUMO energies of the studied ligand and its complexes in the ground state was extracted and is presented in Figure 6 .…”

“…The GaussView molecular visualization program ( Dennington et al, 2016 ) was used to visualize the input files and extract the HOMO–LUMO energies. The reactivity descriptors: chemical potential (μ), global hardness (η), chemical softness (S), and electrophilicity (ω), were calculated using the following formulas ( Sharfalddina et al, 2020a ): …”

Synthesis and theoretical calculations of metal-antibiotic chelation with thiamphenicol:in vitroDNA and HSA binding, molecular docking, and cytotoxicity studies

“…HOMO and LUMO energies were obtained and used to calculate essential quantum parameters using the following equations: energy gap (E gap = E LUMO À E HOMO ), absolute electronegativities (w = ÀE HOMO + E LUMO /2), absolute hardness (Z = E LUMO À E HOMO /2), chemical potentials (m = Àw), global softness (S = 1/2Z), and global electrophilicity (o = p 2 /2Z). 12,13 MEP maps were projected by applying the B3LYP/LANL2DZ level within DFT.…”

“…Studying the molecular orbital compositions and energy levels of a molecule is a practical approach to describe the electronic characteristics of molecular systems. 13 Frontier molecular orbital (FMO) maps were generated via the HOMO and LUMO for the studied ligand and its complexes in the ground state and are presented in Fig. 6.…”

Synthesis, Spectroscopic Characterization and Biological Studies of Mn(II), Cu(II), Ni(II), Co(II) and Zn(II) Complexes with New Schiff Base of 2-((Pyrazine-2-ylimino)methyl)phenol

“…The obtained vibrational frequencies have indicted the optimized geometry corresponds to valid energy minimum and is scaled by 0.966 and 0.961 factors for 6-31G and LAND base site, respectively. The obtain HOMO and LUMO energies were used to calculate the essential quantum parameters by the following equation: energy gap (Egap = ELUMO − EHOMO), absolute electronegativities (χ = −EHOMO + ELUMO/2), absolute hardness (ɳ = ELUMO − EHOMO/2), chemical potentials (μ = −χ), global softness (S = 1/2ɳ), global electrophilicity (ω = π2/2ɳ) [15].…”