Solvent and spin state effects on molecular structure, IR spectra, binding energies and quantum chemical reactivity indices of deferiprone–ferric complex: DFT study

Density functional theory studies on properties of cluster ConMoS (n=1 ~ 5): interatomic interactions, electronic properties, frontier orbitals

CONTEXT

To comprehend the microscopic property alterations within the ConMoS cluster (n=1-5), this study investigates its internal interactions, electronic characteristics, and orbital correlations employing density functional theory. Structural optimization and theoretical analysis of the cluster are conducted using the Gaussian09 software package, considering various spin multiplicities and employing the B3LYP/def2tzvp quantum chemical method as the computational standard. The outcomes reveal the optimization of the cluster, resulting in 21 stable configurations while continually acquiring energy from the external environment. Analysis of the interaction region indicator functions, the independent gradient model based on Hirshfeld partition, the localized orbital indicator functions, and the electron localization function reveals a trend toward chemical bonding interactions within the interatomic interaction regions. Moreover, the interatomic forces exhibit a high likelihood of engaging in covalent bonding interactions. Both Co and Mo atoms display greater electron delocalization, facilitating the exchange of electrons with the external environment. The paper discuss electron space range, hardness and softness, polarizability, dipole moment, Mulliken population analysis, density of states, HOMO-LUMO diagram, and UV-Vis spectra. Configuration 5a exhibits the broadest electron delocalization and the highest reactivity. It maintains structural stability in external conditions and displays the most polarized molecules. Metal atoms in this cluster exhibit superior mobility compared to non-metal atoms. We elucidate the electron density aggregation region within the cluster. Configuration 1a demonstrates the highest correlation with molar absorption coefficient for its peak. Analyzing the HOMO and LUMO orbital delocalization index and center-of-mass distances revealed that the front orbits of configuration 5a exhibited a broad distribution in space and the minimum center-of-mass distance.

METHODS

This study presents a theoretical investigation of Co-Mo-S clusters employing density functional theory (DFT). DFT is a prevalent method for exploring the electronic structure and characteristics of atoms, molecules, and solids. The paper examines cluster attributes encompassing interatomic interactions, electronic properties, and frontier orbitals. Gaussian09 software is employed for optimizing cluster structures, while the analysis is augmented using Multiwfn wave function analysis software. By harnessing these theoretical and computational tools, it aims to delve deeper into cluster properties, yielding valuable insights.

Theoretical and experimental study of the diastereoisomers (2S) and (2R)-naringenin-6-C-β-D-glucopyranoside obtained from Clitoria guianensis

In this work the diastereoisomers (2S) and (2R)-naringenin-6-C-β-D-glucopyroside, isolated for the first time from Clitoria guianensis, were studied using the density functional theory. The frontier molecular orbitals and structural properties showed that the diastereoisomers exhibit the same energy gap 166.61 kcal mol^-1 and structural properties different, where in the S diastereoisomer, the bond length between the chiral carbon and the phenolic group is greater (difference of 0.0126 Å). The HPLC data showed that the retention time of the S-diastereoisomer (16.7 min) is shorter than that of R, suggesting that the S compound is more polar than R. The HPLC results corroborates with the molecular electrostatic potential which showed that in the S configuration, the electronegative density was more intense overall, particularly in the glucose molecule. The reactivity indices showed that the diastereoisomers are good electrophiles and reactive species. Finally, the absolute configuration of the diastereoisomers were determined using electronic circular dichroism (ECD) spectroscopy and the theoretical spectra were similar to the experimental. METHODS : All calculations of Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) were performed using the program Gaussian 09 and the structures of the diastereoisomers were generated and analyzed using the GaussView program. The optimization and vibrational frequency calculations were performed using the functional CAM-B3LYP and 6-311 +  + G(2d,2p) basis set. Conformational searches were performed for R configuration, by molecular mechanics using the MM + , MMFF, and OPLS05 force fields; the entire molecular mechanics simulation was performed using the Maestro/MacroModel software. The calculations for the simulations of the ECD spectra were performed for the eight lowest energy conformers obtained in the geometric optimization step, and the TDDFT at the CAM-B3LYP/6-311 +  + G(2d,2p) theory level used. The effects of methanol and chloroform were calculated using the SMD implicit solvent model.

Density Functional Theory-Assisted Synthesis of Self-Curing Epoxy-Acrylic Resin

A density functional theory-assisted synthesis of self-curing epoxy–acrylic resin (EMPA) is described. The calculated quantum chemistry reaction index of the reacting monomer in the basic state, i.e., the radical reaction index (F_k⁰), is used as a guide to optimize the synthesis conditions. The reliability of the F_k⁰-assisted synthesis method is confirmed after evaluating the physical appearance, mechanical properties after curing, and thermal stability of the obtained EMPA. The special functional groups of the resin are characterized by Fourier transform infrared spectroscopy to prove the rationality of the reaction mechanism. The cross-sectional morphology characteristics of the cured resin are observed by field-emission scanning electron microscopy. The results show that the closer the molar ratio of monomers in the reaction to the ratio of F_k⁰ of the reacting monomers, the better the polymerization performance.

A DFT study on the metal ion selectivity of deferiprone complexes

In this work, systematic density functional theory (DFT) calculations were performed to study the interactions of various metal ions (Al³⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) and the clinically useful chelating agent called deferiprone (DFP) at the M05-2X/6-31G(d) level of theory. The thermodynamic parameters of metal-deferiprone complexes were determined in water. Based on the obtained data, the theoretical binding energy trend is as follows: Al³⁺ > Fe³⁺ > Cu²⁺ > Ni²⁺ > Co²⁺ > Zn²⁺, confirming that [Al(DFP)₃] has the most interaction energy. Moreover, Natural bond orbital analysis was employed to determine and analyze the natural charges on different atoms and charge transfer between the metal ions and ligands (oxygen atoms) as well as the interaction energy (E(2)) values. The calculated value of ƩE(2) (donor-acceptor interaction energy) for [Al(DFP)₃] complex is higher than other complexes, which is according to energy analysis. To confirm the type of effective interactions and bonding properties in the water, the quantum theory of atoms in molecules (QTAIM) analysis was applied. QTAIM analysis confirmed that the strongest M - O bond is found in the [Al(DFP)₃] complex. The calculated topological properties at the bond critical points, such as the ratio of the kinetic energy density to the potential energy density, -G(r)/V(r), electronic energy density, H(r), confirm that M - O bonds in the Al-deferiprone complex are non-covalent, while in other complexes, they are electrostatic and partially covalent.

Metal chelating ability and antioxidant properties of Curcumin-metal complexes - A DFT approach

Curcumin, a well-documented phytochemical compound used to treat various diseases because of its more tolerability in the human body and has no side effects. The present study describes the metal chelating ability of Curcumin for Mn²⁺, Fe²⁺ and Zn²⁺ metal ions and their antioxidant properties using density functional theory in both gas and DMSO solvent phases. Results reveal that the carbonyl group at diketo moiety is destabilized due to the metal ion coordination. The interaction energies reveal that CurEN-Zn²⁺ are the most stable rather than the CurEN-Mn²⁺ and CurEN-Fe²⁺ complexes. The AIM analysis confirms that the interaction between the metal ions and Curcumin are to be electrostatic dominant. The HOMO-LUMO orbital analysis shows that the charge transfer interaction is dominant for CurEN-Mn²⁺ and CurEN-Fe²⁺ complexes. The DMSO solvent interactions decrease the stability of the CurEN-M²⁺ cation complexes. The antioxidant mechanism is more reactive for metal complexes than the isolated Curcumin. Since Curcumin possess both metal chelating and antioxidant properties, it can be used in chelation therapy for the cure of Alzheimer's disease.

Computational study on favipiravir adsorption onto undoped- and silicon-decorated C60 fullerenes

Adsorption and interaction mechanisms of fullerene-based complex systems for possible drug delivery vehicles have been at the center of increasing attention. In the scope of this work, the interaction mechanism between an important antiviral drug favipiravir and silicon-doped/undoped C60 fullerenes have been investigated using density functional theory (DFT). Calculations were carried out in both gas phase and water media to see the possible solvent effects. The effect of adsorption of the favipiravir on the SiC59 fullerene system and the nature of interaction were examined by analyzing the band shifts in the carbonyl stretching vibrations and natural bond orbital (NBO) properties of the examined complexes. Some important structural and electronic properties were reported and discussed as well. It was observed that doping the C60 fullerene nanocages with silicon atom enhanced the adsorption mechanism and calculations performed in water media gave rise to more stable complexes for silicon-doped systems compared to the results obtained for the gas phase. Results and parameters found in the present search reveal further insights into the drug delivery systems.