Experimental and DFT studies on the vibrational and electronic spectra of 2-(1H-Imidazo [4,5-ƒ][1,10]phenanthrolin-2-yl)phenol

Highly efficient poly(6-acryloylamino-N-hydroxyhexanamide) resin for adsorption of heavy metal ions

Heavy metal wastewater pollution has become an ecological challenge worldwide. This study reports the development of a novel poly (6-acryloylamino-N-hydroxyhexanamide) (PAHHA) resin for effective adsorption of heavy metal ions, including Cu²⁺, Pb²⁺ and Ni²⁺. The chelating resin was synthesized by the grafting reaction between 6-amino-N-hydroxyhexanamide and polyacrylic resin, thus containing the hydroxamate and acylamino groups. The batch adsorption experiments revealed that the PAHHA resin exhibited an excellent adsorption performance for Cu²⁺, Pb²⁺ and Ni²⁺. The maximum adsorption capacities of Cu²⁺, Pb²⁺ and Ni²⁺ were determined to be 238.59, 232.48 and 115.77 mg·g^-1, respectively. Based on the adsorption kinetics, the pseudo-second-order kinetic model was noted to fit well for all metal ions. The metal ion concentration as a function of the equilibrium adsorption capacity fitted well with the Langmuir isotherm, thus indicating the single layer adsorption process. The adsorption mechanism was investigated by using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS) and adsorption isotherms. It was revealed that the PAHHA resin possessed multiple active sites, including -CONHOH, -CONH- and -COOH, which could strongly adsorb the metal ions. Specifically, the -CONHOH group displayed a high affinity by forming a stable five-membered ring with heavy metal ions. Overall, the developed resin exhibits advantages such as simple synthesis, inexpensive raw material and good recyclability, along with high adsorption ability, thus providing a new approach for efficiently treating wastewater contaminated with heavy metal ions.

Probing the hydrophobic mechanism of N-[(3-hydroxyamino)-propoxy]-N-octyl dithiocarbamate toward bastnaesite flotation by in situ AFM, FTIR and XPS

HYPOTHESIS

Both hydroxamate and dithiocarbamate groups exhibit a unique bonding characteristic toward rare earth ions. A hydroxamic acid surfactant containing a dithiocarbamate group should possess a specific affinity to hydrophobize bastnaesite [(Ce, La)CO₃F] flotation.

EXPERIMENTS

N-[(3-hydroxyamino)-propoxy]-N-octyl dithiocarbamate (OAHD) was synthesized, and its flotation mechanism toward bastnaesite was investigated by in situ AFM, FTIR, XPS, micro-flotation and contact angle.

FINDINGS

In situ AFM clearly observed that OAHD aggregated on bastnaesite surface, which improved the contact angle and surface hydrophobicity of bastnaesite. FTIR spectra and XPS recommended that OAHD's dithiocarbamate and hydroxamate groups co-anchored on bastnaesite surface through strong chemisorption, which strengthened the bonding affinity of bastnaesite toward OAHD. UV spectra showed that both dithiocarbamate and hydroxamate groups exhibited weak affinity toward Ca²⁺ ions, which benefited OAHD's selective flotation separation of bastnaesite from calcite. The co-adsorption and special hydrophobic structure improved OAHD's flotation performance. As a result, OAHD returned higher flotation selectivity for bastnaesite than OHA (n-octyl hydroxamic acid) which chemisorbed on bastnaesite surface only through the hydroxamate group and used the heptyl as hydrophobic group.

Kamlet-Taft and Catalán solvatochromism of some π-expanded phenanthrimidazole derivatives - DFT analysis

Some π-expanded phenanthrimidazole derivatives have been synthesised and characterised by different spectral techniques. Kamlet-Taft and Catalán solvatochromism of synthesised phenanthrimidazole derivatives have been analysed. Non-linear optical (NLO) and natural bond orbital (NBO) analysis have been made by ab initio method to show intramolecular interactions. The energies of the HOMO and LUMO levels, the molecular electrostatic potential (MEP) energy surface, NBO studies have exploited the existence of intramolecular charge transfer (ICT) within the molecule.

Vibrational spectroscopy investigation using M06-2X and B3LYP methods analysis on the structure of 2-Trifluoromethyl-10H-benzo[4,5]-imidazo[1,2-a]pyrimidin-4-one

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized bioactive agent namely, 2-Trifluoromethyl-10H-benzo[4,5]-imidazo[1,2-a]pyrimidin-4-one (TIP) have been investigated. The experimental FT-IR (4000-400 cm(-1)) and Laser-Raman spectra (4000-100 cm(-1)) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and the optimized geometric parameters (bond lengths and bond angles) have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

Computational studies on the anastrozole and letrozole, effective chemotherapy drugs against breast cancer

In this paper, computational studies were carried out on anastrozole and letrozole, chemotherapy drugs used against breast cancer. Optimization and frequency calculations were performed at B3LYP/6-31G (d) basis set and vibrational frequencies were assignment. Single point calculations were performed at DFT method with a hybrid functional B3LYP/6-311G (d, p) basis set. Theoretical NMR data were obtained at DFT method with a hybrid functional B3LYP/6-311G++ (2d, p) with GIAO (Gauge-Independent Atomic Orbital). IEF-PCM method was used as solvation model. NBO calculations were performed by the same basis set and calculation method with single point calculation. Global and localized reactivity parameters; fukui indices (f) chemical hardness (η), softness (S), chemical potential (μ), electronegativity (χ) and electrophilicity index (ω) were calculated. All computational parameters were compared with the experimental results obtained from the literature.