Mixed ligand copper(II) chelates derived from an O, N, S- donor tridentate thiosemicarbazone: Synthesis, spectral aspects, FMO, and NBO analysis

An efficient coumarin-based thiosemicarbazone probe for ratiometric fluorescent sensing of Zn2+ and application in live cell imaging

Selective recognition of Zn2+ in biological and environmental samples is a challenge. An N, N-diethyl substituted coumarin thiosemicarbazone was designed as a fluorogenic sensor, HADICIT, [(E)-2-(1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)ethylidene)-N-isopropylhy drazine-1-carbothioamide] for the detection of Zn2+ to address the issue. The compound was characterized using FTIR, 1H NMR, 13C NMR, and mass spectrometry methods. The fluorogenic probe produces a selectively enhanced red-shift emission response in solution upon the addition of Zn2+ compared to other competing metal ions. The optical and fluorescence titration experiments suggest a 2:1 binding ratio of HADICIT to Zn2+, with an association constant of 3.33 × 106 M-1. The limit of detection (LoD) of HADICIT is found to be 86 nM, which is much below the WHO recommended standards in environment samples. Frontier molecular orbital calculations suggest intra-ligand charge transfer (ILCT) transitions. Cell imaging on HEK 293 cells using HADICIT indicates that the probe can detect Zn2+ ions in live cells.

Curating Benzothiophene Experimental Absorption and Emission Spectra to Design Fluorescent Organic Polymer Chemical Space: A Machine Learning Quest

In this study, an approach to design new fluorescent organic polymers based on benzodithiophene (BDT) chromophores are presented by utilizing machine learning (ML) techniques. For this, the BDT chromophores, from the literature, along with their corresponding λe. by using Rapid Discovery Kit (RDKit), their molecular descriptors are designed to employ ML models for predicting their λmax and λe properties. Among the evaluated models, Linear Regression, Random Forest and Decision Tree models demonstrate the best performance, achieving R² values between 0.96 and 0.98. Their analysis of SHapley Additive exPlanations (SHAP) values reveals that the Labute Accessible Surface Area (ASA) and the number of Rotatable Bonds can be the most influential features to impact their performance. Leveraging these insights, their 5,000 new polymers are designed with their predicted λe extending up to 987 nm. Their highest Synthetic Accessibility Likelihood Index (SALI) scores for the top 1,000 polymers reaches up to 3.21 to indicate their accessibility for synthesis. This work not only advances the understanding of BDT -based materials but can also provide a framework for designing of new fluorescent polymers.

Machine Learning Assisted Bithiophene Based Donor Acceptor Selection to Design New Fluoresent Dyes for Photovoltaic Applications

This study investigates the electronic properties and photovoltaic (PV) performance of newly designed bithiophene-based dyes, focusing on their light harvesting efficiency (LHE), open-circuit voltage (Voc), fill factor (FF), and short-circuit current density (Jsc).These new dyes are designed with the help of machine learning (ML) to design best donor acceptor designs. For this, we collect 2567 differenr electron donor groups and calculated their bandgap with the help of Random Forest (RF) Regression method. Their maximum absorption (λmax) values are redshifted with their 367-501 nm range having TA1 with higher value. Their LHE values range from 52 to 89%, with TA3 demonstrating the highest efficiency. Their Voc values varies significantly, with TA2 achieving the highest at 1.584 V, while TA5 and TA6 exhibit lowest values. Their FF)from 25.9 for TA4 to 59.3 for TA3, highlighting the superior charge extraction capabilities. Their Jsc values further reflect their performance potential, with TA1 leading at 39.43 mA/cm², while TA4 and TA6 show significantly lower values of 3.28 and 4.40 mA/cm², respectively. Overall, the findings suggest that the bithiophene-based dyes, particularly TA2 and TA3, possess promising characteristics for enhancing the efficiency of solar cells.

Molecular Engineering for UV-Vis to NIR Absorption/Emission Bands of Pyrazine-based A-π-D- π-A Switches to Design TiO2 Tuned Dyes: DFT Insights

This study investigates the tuning of the UV-Vis/NIR absorption bands of pyrazine-based A-D-A switches for designing efficient UV retardancy over TiO2 surfaces. The electronic properties and optical characteristics of seven dyes (DP1-DP7) were analyzed using computational methods. The results indicate that the dyes possessed distinct UV-Vis/NIR absorption properties. Their absorption wavelengths ranged from 389 to 477 nm, with corresponding energies ranging from 2.59 to 3.19 eV. The major contributions to the absorption were found to be the HOMO-LUMO transitions, varying from 86 to 96%. The dyes exhibited different donor (D) and acceptor (A) groups, influencing their electronic properties and absorption characteristics. The tunable electronic and optical properties of these dyes make them promising candidates for applications requiring UV protection for TiO2-based materials. The results contribute to understand the structure-property relationships in the design of UV-Vis/NIR absorbers and provide a foundation for further experimental investigations in the field of UV retardancy.

Structure-based screening of sp2 hybridized small donor bridges as donor: acceptor switches for optical and photovoltaic applications: DFT way

CONTEXT

This research aims to investigate the potential of pyrazine-based small donor moieties as donor-acceptor switches for optical and photovoltaic applications. The designed organic dyes have a high light harvesting efficiency (LHE) and can potentially generate significant electrical energy.

METHODS

The study focuses on understanding the structural and electronic properties of these dyes through the analysis of dihedral angles, bond lengths, and energies of frontier molecular orbitals The UV-Vis spectroscopy parameters of the designed organic dyes revealed their absorption characteristics, including transition energies, wavelengths (λmax), and oscillator strengths (f). The photovoltaic properties of the developed organic dyes show a range of values: a range of 0.95-0.99 for LHE and a range of 1.77-33.02 W for maximum power output (Pmax) with the highest value for dye DDP5. For their stabilization energies, their natural bond orbitals had values ranging from 0.56 to 128.48 kcal/mol, their E(j)E(i) values from 0.22 to 1.29 a.u, and their Fi,j values from 0.024 to 0.213 kcal/mol. Out of all dyes, the DDP5 produced highest push-pull effect and can be good choice for further studies. The design of these novel organic materials for effective and economical solar energy conversion will be aided by evaluating the potential of 5,10-diphenyl-5,10-dihydrophenazine as a donor moiety and determining the structure-property correlations controlling the photovoltaic performance of the compounds.

An atomistic scale simulation study of structural properties in the silk-fibrohexamerin complex

The use of Bombyx mori silk fibroin in composite materials has been extensively explored in many studies, owing to its remarkable mechanical properties. Recently, the N-glycan-engineered P25 protein was utilized to improve the mechanical properties of silk. However, the mechanism by which N-glycan-engineered P25 protein enhances the mechanical properties of silk remains unclear. This study analyzed the interaction between the P25 protein and silkworm silk using quantum mechanics/molecular mechanics multiscale simulations and discovered stronger hydrogen bonding between the amorphous domain and the P25 protein. The results confirmed that glycoengineering of the mannose molecule in N-glycan in orders of three, five, and seven increased the hydrogen bonding of the amorphous structures. However, P25 has fewer binding interactions with the crystalline domain. Silk amino acids and mannose molecules were analyzed using QM simulations, and hydroxyl and charged amino acids in the amorphous domains were found to have relatively higher reactivity with mannose molecules in N-glycans than basic and aliphatic amino acids in the crystalline domain. This study demonstrates how the N-glycan-engineered P25 protein can improve the mechanical properties of silk fibroin and identifies a key factor for N-glycan-engineered proteins.

Role of Imidazole and Chelate Ring Size in Copper Oxidation Catalysts: An Experimental and Theoretical Study

In this work, the structural, solution, electrochemical, and catalytic properties of the complexes with ligands derived from imidazole and pyridines were studied. A comparative study of five bioinspired copper catalysts with or without coordinated imidazole and with different chelate ring sizes is presented. Catalytic efficiency on the oxidation of 3,5-di-tert-butylcatechol (DTBC) and ortho-aminophenol (OAP) in a MeOH/H2O medium was assessed by means of the Michaelis-Menten model. Catalysts comprising imidazole-containing ligands and/or a six-membered chelate ring proved to be more efficient in both oxidation reactions. Determination of stability constants and electrochemical parameters of the copper complexes supported the explanation of the catalytic behavior. A catalytic cycle similar for both reactions has been proposed. The results of density functional theory (DFT) free energy calculations for all five complexes and both catalytic reactions agree with the experimental results.

Design, synthesis and characterization of novel Ni(II) and Cu(II) complexes as antivirus drug candidates against SARS-CoV-2 and HIV virus

This paper describes the structure-based design, synthesis and anti-virus effect of two new coordination complexes, a Ni(II) complex [Ni(L)2] (1) and a Cu(II) complex [Cu(L)2] (2) of (E)-N-phenyl-2-(thiophen-2-ylmethylene) hydrazine-1-carbothioamide(HL). The synthesized ligand was coordinated to metal ions through the bidentate-N, S donor atoms. The newly synthesized complexes were characterized by various spectroscopic and physiochemical methods, powdered XRD analysis and also X-ray crystallography study. Ni(II) complex [Ni(L)2](1) crystallize in orthorhombic crystal system with the space group Pbca with four molecules in the unit cell (a = 9.857(3) Å, b = 7.749(2) Å, c = 32.292(10) Å, α = 90°, β = 90°, γ = 90°, Z= 4) and reveals a distorted square planar geometry. A Hirshfeld surface and 2D fingerprint plot has been explored in the crystal structure of Ni(II) complex [Ni(L)2] (1). Energy framework computational analysia has also been explored. DFT based calculations have been performed on the Schiff base and its metal complexes to study the structure-property relationship. Furthermore, the molecular docking studies of the ligand and its metal complexes with SARS-CoV-2 virus (PDB ID: 7BZ5) and HIV-1 virus (PDB ID: 6MQA) are also investigated. The molecular docking calculations of the Ni(II) complex [Ni(L)2] (1) and a Cu(II) complex [Cu(L)2] (2) with SARS-CoV-2 virus revealed that the binding affinities at inhibition binding site of receptor protein are 9.7 kcal/mol and -9.3 kcal/mol, respectively. The molecular docking results showed that the binding affinities of Ni(II) complex (1) and Cu(II) complex (2) against SARS-CoV-2 virus were found comparatively higher than the HIV-1 virus (-8.5 kcal/mol and -8.2 kcal/mol, respectively). As potential drug candidates, Swiss-ADME predictions analyses are also studied and the results are compared with Chloroquine (CQ) and Hydroxychloroquine (HCQ) as anti-SARS-CoV-2 drugs.

Exploration of Pull-Push Effect for Novel Photovoltaic Dyes with A-π-D Design: A DFT/TD-DFT Investigation

The π-rich versus π-poor units in 4,6-di(thiophen-2-yl)pyrimidine (DTB) alternating the π-backbone of solar cells dyes have been extended with a push-pull technique to lower their HOMO-LUMO energy gap and to increase Intramolecular Charge Transfer (ICT). Density functional theory was used to optimize the ground state molecular geometries of newly designed dyes (DTB1-DTB6). Time Dependent DFT (TD-DFT) was used to simulate the Uv-vis spectral values at the maximum absorbance values ranging between 481-535 nm. These values were red shifted from DTB value of experimental (333 nm) and theoretical (346 nm). however, their computed absorbance and fluorescence spectra revealed a bathochromic shift of them upon an increasing the solvent polarity. Different DFT functionals such as (B3LYP, CAM-B3LYP, B97XD, and APFD) were employed to choose their proper use Uv-visible analysis to reveal an unexpected coherence at the B3LYP level with experimental values. As a result, the B3LYP with most diffused basis sets of 6-31G + (d,p) were used for further calculations. The parameters of Global Chemical reactivities revealed that all the dyes had a softer nature with their softness value range of 0.27-0.41. their Ionization Potentials (IP) ranged between 6.21-8.10 eV to comply that the new dyes had good electron donating potentials. With a good electron injection potential of -1.47-1.74 eV, aluminum can be the best electrode, while Au is excellent towards a hole injection operation which had the potential range of 1.79-3.68 eV. For Natural Bond Orbital (NBO) assessment, (N14)LP → (F16-F28)π* with stabilization energy of 42.55 kcal/mol was noted for DTB4. Their Second order hyperpolarizability [Formula: see text] values as their Nonlinear Optical (NLO) response ranged between 59.16-232.11 debye-angstrom^-1 which were almost 6 times higher than the reference DTB (8.47D). The NLO attributes has also shown that a dyes with its small bandgap was related with higher hyperpolarizability values. Because of the decreased reorganization frequencies, newly discovered derivatives with electron transfer qualities might be comparable to or equivalent to those of commonly used electron transmission materials.

Calcium sulfide-organosilicon complex for sustained release of H2S in strongly acidic wastewater: Synthesis, mechanism and efficiency

Sulfide precipitation is an efficient method to remove Cu(II) and As(III) from strongly acidic wastewater, but the instantaneous release of H₂S from traditional sulfuration reagents causes serious H₂S pollution. Moreover, the obtained precipitates are mixtures of CuS and As₂S₃, leading to difficulties in resource recovery. In this study, a calcium sulfide-organosilicon complex (CaS-OSCS), in which CaS was coated into a matrix of {[O_1.5Si(CH₂)₃NH]CS}_n (OSCS) via the coordination bonding, was developed. OSCS, as a matrix of CaS-OSCS, can ensure the sustained and stable release of H₂S under strongly acidic conditions owing to its low swelling (1.75% swelling ratio) and excellent acid resistance. The release longevity of H₂S from CaS-OSCS extended from 5 min up to 50 min compared with that from CaS because the hydrophobic OSCS prevented solution diffusing to the pores of CaS-OSCS and thus slowed down the hydrolysis of CaS in pores. 99% of Cu(II)/As(III) was precipitated without H₂S escape, and the dosage of sulfuration reagents was reduced by 30%. In addition, CaS-OSCS improved the selective separation of copper from wastewater, and a separation factor between Cu(II) and As(III) reached 2376. This study provides a potential approach for the elimination of H₂S pollution and selective recovery of copper.

Electrochemical investigations and theoretical studies of biocompatible niacin-modified carbon paste electrode interface for electrochemical sensing of folic acid

The modified electrode–analyte interaction is critical in establishing the sensing mechanism and in developing an electrochemical sensor. Here, the niacin-modified carbon paste electrode (NC/CPE) was fabricated for electrochemical sensing applications. The two stable structures of the niacin were optimized and confirmed by the absence of negative vibrational frequency, at B3LYP and B3LYP-GD3BJ level and 6–311 g** basis set. The physical and quantum chemical quantities were used to explain the molecular stability and electronic structure-related properties of the niacin. The natural bond orbital (NBO) analysis was performed to disclose the donor–acceptor interactions that were a critical role in explaining the modifier–analyte interaction. The fabricated NC/CPE was used for the determination of folic acid (FA) in physiological pH by cyclic voltammetry (CV) method. The limit of detection (LOD) for FA at NC/CPE was calculated to be 0.09 µM in the linear concentration range of 5.0 µM to 45.0 µM (0.2 M PBS, pH 7.4) by CV technique. The analytical applicability of the NC/CPE was evaluated in real samples, such as fruit juice and pharmaceutical sample, and the obtained results were acceptable. The HOMO and LUMO densities are used to identify the nucleophilic and electrophilic regions of niacin. The use of density functional theory-based quantum chemical simulations to understand the sensory performance of the modifier has laid a new foundation for fabricating electrochemical sensing platforms.

Zeolite/Cellulose Acetate (ZCA) in Blend Fiber for Adsorption of Erythromycin Residue From Pharmaceutical Wastewater: Experimental and Theoretical Study

The expanding amount of remaining drug substances in wastewater adversely affects both the climate and human well-being. In the current investigation, we developed new cellulose acetic acid derivation/zeolite fiber as an effective technique to eliminate erythromycin (ERY) from wastewater. The number of interchangeable sites in the adsorbent structures and the ratio of ERY to the three adsorbents were identified as the main reasons for the reduction in adsorption as the initial ERY concentrations increased. Additionally, for all adsorbents, the pseudo–second-order modeling showed better fitting for the adsorption than the pseudo–first-order modeling. However, the findings obtained in the pseudo–first-order model were still enough for explaining the sorption kinetics of ERY, showing that the surface displayed all chemisorption and physi-sorption adsorption processes by both adsorbents. The R² for the second order was very close to 1 for the three adsorbents in the case of pseudo–second-order. The adsorption capacity reached 17.76 mg/g. The three adsorbents showed negative values of ΔH, and these values were −6,200, −8,500, and −9600 kJ/mol for zeolite, CA, and ZCA, respectively, and this shows that the adsorption is exothermic. The desorption analysis shows no substantial loss of adsorption site after three trials, indicating higher stability and resilience of the three adsorbents, indicating a strong repeatability of their possible use in adsorption without contaminating the environment. In addition, the chemical attitude and possible donor–acceptor interactions of ERY were assessed by the quantum chemical parameters (QCPs) and NBO analysis performed, at the HF/6-311G** calculations.

Novel Ag(I)-NHC complex: synthesis, in vitro cytotoxic activity, molecular docking, and quantum chemical studies

The importance of organometallic complexes in cancer biology has attracted attention in recent years. In this paper, we look for the in vitro cytotoxic capability of novel benzimidazole-based N-heterocyclic carbene (NHC) precursor (1) and its Ag(I)-NHC complex (2). For this purpose, these novel Ag(I)-NHC complex (2) was characterized by spectroscopic techniques (¹H, ¹³C{¹H} nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FT-IR)). Then, in vitro cytotoxic activities of NHC precursor (1) and Ag(I)-NHC complex (2) were investigated against MCF-7, MDA-MB-231 human breast, DU-145 prostate cancer cells, and L-929 healthy cells using MTT assay for 24, 48, and 72 h incubation times. Ag(I)-NHC complex (2) showed promising in vitro cytotoxic activity against all cell lines for three incubation times, with IC₅₀ values lower than 5 µM. It was also determined that (NHC) precursor (1) were lower in vitro cytotoxic activity than Ag(I)-NHC complex (2) against all cell lines. Selectivity indexes (SI_s) of Ag(I)-NHC complex (2) against cancer cells were found higher than 2 for 24 and 48 h incubation time. Besides, the electronic structure and spectroscopic data of the newly synthesized precursor and its Ag-complex have been supported by density functional theory (DFT) calculations and molecular docking analysis. After, the anticancer activity of these compounds has been discussed considering the results of the frontier molecular orbital analysis. We hope that the obtained results from the experiments and computational tools will bring a new perspective to cancer research in terms of supported by quantum chemical calculations.