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This study reports the nonlinear optical (NLO) properties of the exohedral adsorption of N-(4-methoxybenzylidene) isonicotinohydrazone (INH) onto B12N12 and Al12N12 nanocages. All ground state computations were performed using the density functional theory (DFT) method at the B3LYP-D3/6-311G(d,p) level of theory in the gaseous phase. Excited state computations were achieved via the time-dependent density functional theory (TD-DFT) at the CAM-B3LYP/6-311G(d,p) level of theory. Molecular electrostatic potential (MEP) analysis of INH reveals the presence of three preferential interaction sites: the O-atom of carbonyl (site 1), the N-atom of pyridine (site 2), and the N-atom of the azomethine group (site 3). The highest interaction energy values for the adsorption of INH onto the B12N12 and Al12N12 were −43.560 and −52.724 kcal·mol−1, respectively, indicating a chemisorption process. The computed Gibbs free energy change (ΔGad) and adsorption enthalpy change (ΔHad) values for all complexes studied are negative, indicating that the adsorption process is spontaneous and exothermic. Quantum theory of atoms in molecules (QTAIM) analysis reveals that the adsorbate-adsorbent interactions are partially covalent, which agrees with the reduced density gradient (RDG) analysis. Exohedral adsorption on the nanocages reduces the band gap, which ranges between 2.851 eV and 6.748 eV, according to density of state (DOS) diagrams. Furthermore, the first and second hyperpolarizabilities (βtot and γtot) were also determined. The outcomes show that adsorption improves these values over INH, and the complexes could be useful materials in optoelectronics and the development of more responsive NLO devices.

Cell wall disturbance is an important step in the downstream process of improving the efficiency of lipid extraction from microalgae. Surfactants have been proven to be efficient alternatives to organic solvents in the extraction process. In this study, an effective approach involving deep eutectic solvent (DES) (choline chloride and carboxylic acids) treatment supplemented with surfactants has been developed to disrupt the cell walls of microalgae and increase the extraction of lipids suitable for biodiesel production. A combination of polar and non-polar solvents (ethyl acetate and n-butanol) was used for the lipid extraction process. Microalgae biomass pretreated with choline chloride malonic acid supplemented with the surfactant hexadecyl trimethylammonium chloride (HTAC) showed the best results, improving lipid extraction by 12.365%. Further elucidation of the detailed mechanism behind the cell disruption of the microalga wall by DES was achieved using density functional theory (DFT) methods. The DFT calculations revealed that hydrogen bonds between the chloride ion of the DES and hydrogen bond donor (HBD) molecules are key factors dominating the destruction of the cell wall structure of Chlorella pyrenoidosa. The optimization of lipid extraction was performed through a single-factor experiment, which included the effects of different variables (time, temperature, dosage of surfactant, and ratio of n-butanol to ethyl acetate). An extraction period of 60 min at 80 °C with a surfactant concentration of 0.5% at a 1:2 ratio of n-butanol to ethyl acetate was found to produce the maximum lipid yield (16.97%). Transesterification reactions were used to obtain fatty acid methyl esters from the optimized extracted lipids. Thus, it was determined that C16:0 (20.04%), C18:2 (29.95%), and C18:3 (21.21%) were the most prevalent fatty acids. The potential for producing biodiesel from C. pyrenoidosa was validated by the high yields of C18 fatty acid methyl esters, and the properties of biodiesel are within the European and US standards.

The sensitivity of pure and doped X12N12 (X = B and Al) fullerene-like nano-cages (FLNs) toward the anti-cancer drug temozolomide (TMZ) is probed herein at DFT/M06-2X-D3/6-311G(d,p) theoretical level in both gas phase and water. A noticeable affinity of the FLNs toward TMZ was observed along with the negative gas-phase adsorption energies −1.37 and −2.09 eV for the most stable configurations of pure B12N12 and Al12N12 pristines, respectively. Considerable charge transfer from TMZ to the FLNs was also revealed via NBO analysis and the Hirshfeld atomic charges, making the dipole moment vector of the molecular complexes to be oriented from the nano-cages to the TMZ moiety. Furthermore, a percentage decrease in the HOMO-LUMO energy gap (ΔEg) of 38.09 and 17.72% was obtained for the B12N12 and Al12N12 nano-cages, respectively. The percentage change in ΔEg was found to be reduced upon doping and solvation of the FLNs. Finally, a recovery time in vacuum ultraviolet light of 1.06 s is found for the complex with pure B12N12, which in addition to the above-mentioned parameters make this boron nitride cage the best sensor for TMZ, among the FLNs considered in the present work.

We examined the structure-reaction enthalpies-antioxidant activity relationship of the molecule library built around juglone and its derivatives at B3LYP/6-31+G(d,p) level. Three major antioxidant mechanisms (hydrogen atom transfer (HAT), single electron transfer-proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET)) have been investigated in five solvents and in the gas phase. The delocalization of the unpaired electrons in the radicals or cation radicals has been explored by the natural bond orbital analysis and the interpretation of spin density maps. The results obtained have proven that the HAT mechanism is the thermodynamically preferred mechanism in the gas phase. But, in the solution phase, the SPLET mechanism has been shown to be more predominant than HAT. The reactivity order of compounds towards selected reactive oxygen species has also been studied.

The chelating ability of juglone and two of its derivatives towards Fe2+ ion and the antioxidant activity (AOA) of the resulting chelates and complexes (in the presence of H2O and CH3OH as ligands) in gas phase is reported via bond dissociation enthalpy, ionization potential, proton dissociation enthalpy, proton affinity, and electron transfer enthalpy. The DFT/B3LYP level of theory associated with the 6-31+G(d,p) and 6-31G(d) Pople-style basis sets on the atoms of the ligands and the central Fe(II), respectively, was used. Negative chelation free energies obtained revealed that juglone derivatives possessing the O-H substituent (L2) have the greatest ability to chelate Fe2+ ion. Apart from 1B, thermodynamic descriptors of the AOA showed that the direct hydrogen atom transfer is the preferred mechanism of the studied molecules. NBO analysis showed that the Fe-ligand bonds are all formed through metal to ligand charge transfer. QTAIM studies revealed that among all the Fe-ligand bonds, the O1-Fe bond of 1A is purely covalent. The aforementioned results show that the ligands can be used to fight against Fe(II) toxicity, thus preserving human health, and fight against the deterioration of industrial products. In addition, most of the complexes studied have shown a better AOA than their corresponding ligands.

Herein, the response surface methodology (RSM) has been used to study simultaneously the effects of carbonization temperature, residence time and moisture content on the activated hydrochar preparation-based vegetable-tanned leather shavings (VTS) using hydrothermal carbonization method (HTC). Owing to the desirability chosen, three responses were analysed, namely: the hydrochar yield, iodine and methylene blue numbers. The analysis of experimental results revealed that the hydrochar yield was decreased with increase in carbonization temperature which led to micropores formation inside the hydrochar network. The optimal preparation conditions retained were: 83.10%, 390.44 mg g−1 and 259.63 mg g−1 for the hydrochar yield, iodine and methylene blue number respectively. The hydrochar micrograph showed the presence of external pores, whereas the FTIR analysis recorded the presence of acidic functional groups found on hydrochar surface. The findings revealed that the VTS is a good precursor for the hydrochar preparation useful in the removal of organic and inorganic pollutants in aqueous media.