Photophysical properties of four-membered BN3 heterocyclic compounds: theoretical insights

Structures, bonding aspects and spectroscopic parameters of morin, myricetin, and quercetin with copper/zinc complexes: DFT and TDDFT exploration

CONTEXT

In the present work, DFT/TDDFT techniques is used to analyze structure, bonding, reactivity and electronic transitions of quercetin, morin, myricetin with their metal (Cu and Zn) complexes. In order to comprehend metal complexes and ligands reactivity patterns, we calculated energy gaps between frontier molecular orbitals. Global reactivity characteristics, such as ionization potential, electronegativity (χ), hardness (η), softness (S), electrophilicity index (ω) electron affinity, and chemical potential (μ), were computed based on the FMO energies. Molecular electrostatic potential (MEP) maps were used to identify nucleophilic and electrophilic sites in complexes. Within the examined complexes, TDDFT and NBO analysis shed light on bonding, electronic transitions and stabilizing interactions. Ligands morin, myricetin, and quercetin exhibited higher HOMO-LUMO gap than their corresponding metal complexes, suggesting electron transfer may be faster in the metal complexes. The metal complexes displayed more negative electrostatic potentials. The absorption spectra of the ligands ranged from 258 to 360 nm, whereas their complexes exhibited a broader range from 252 to 1035 nm. These spectra provided important insights into charge transfer and electronic transitions, enhancing our knowledge of electronic and bonding characteristics of such compounds.

METHODS

G16 software is used to optimize all species. B3LYP functional was employed in combination with LanL2DZ basis set for Cu and Zn, and 6-311G(d,p) basis set for other atoms (C, H and O). Natural bond orbital examination was conducted in order to investigate interactions between the filled orbitals of one unit and empty orbitals of other unit. ORCA software was utilized to compute spectral features, incorporating ZORA method to account for relativistic effects. TDDFT studies is carried out using B3LYP functional to calculate excitation energies.

Design, characterization and implementation of cost-effective sodium alginate/water hyacinth microspheres for remediation of lead and cadmium from wastewater

The aquatic plant water hyacinth was dried then cross-linked with sodium alginate to produce ionic cross-linked microspheres. The mechanism of controlling cadmium (Cd) and lead (Pb) in wastewater was tested by DFT at B3LYP level using LANL2DZ basis set. Modeling results indicated that the hydrated metals could interact with sodium alginate (SA)/water hyacinth (WH) microspheres through hydrogen bonding. Adsorption energies showed comparable results while total dipole moment and HOMO/LUMO band gap energy showed slight selectivity towards the remediation of Pb. FTIR spectra of cross-linked microspheres indicated that WH is forming a composite with SA to change its structure into a microsphere to remove Cd and Pb from water. Raman mapping revealed that the active sites along the surface of the microspheres enable for possible adsorption of metals through its surface. This finding is supported by molecular electrostatic potential and optical confocal microscopy. Atomic absorption spectroscopy results confirmed that the microspheres are more selective for Pb than Cd. It could be concluded that WH cross-linked with SA showed the potential to remove heavy metals through its unique active surface as confirmed by both molecular modeling and experimental findings.

DFT and TDDFT exploration on electronic transitions and bonding aspect of DPA and PTDC ligated transition metal complexes

CONTEXT

In this study, we have investigated the structure, reactivity, bonding, and electronic transitions of DPA and PDTC along with their Ni-Zn complexes using DFT/TD-DFT methods. The energy gap between the frontier orbitals was computed to understand the reactivity pattern of the ligands and metal complexes. From the energies of FMO's, the global reactivity descriptors such as electron affinity, ionization potential, hardness (η), softness (S), chemical potential (μ), electronegativity (χ), and electrophilicity index (ω) have been calculated. The complexes show a strong NLO properties due to easily polarization as indicated by the narrow HOMO-LUMO gap. The polarizability and hyperpolarizabilities of the complexes indicate that they are good candidates for NLO materials. Molecular electrostatic potential (MEP) maps identified electrophilic and nucleophilic sites on the surfaces of the complexes. TDDFT and NBO analyses provided insights into electronic transitions, bonding, and stabilizing interactions within the studied complexes. DPA and PDTC exhibited larger HOMO-LUMO gaps and more negative electrostatic potentials compared to their metal complexes suggesting the higher reactivity. Ligands (DPA and PDTC) had absorption spectra in the range of 250 nm to 285 nm while their complexes spanned 250 nm to 870 nm. These bands offer valuable information on electronic transitions, charge transfer and optical behavior. This work enhances our understanding of the electronic structure and optical properties of these complexes.

METHODS

Gaussian16 program was used for the optimization of all the compounds. B3LYP functional in combination with basis sets, such as LanL2DZ for Zn, Ni and Cu while 6-311G** for other atoms like C, H, O, N, and S was used. Natural bond orbital (NBO) analysis is carried out to find out how the filled orbital of one sub-system interacts with the empty orbital of another sub-system. The ORCA software is used for computing spectral features along with the zeroth order regular approximation method (ZORA) to observe its relativistic effects. TD-DFT study is carried out to calculate the excitation energy by using B3LYP functional.