Electronic Absorption Studies Research Articles

Unraveling the Solvation Behavior of Levocetirizine Dihydrochloride: Insights from Volumetric, Acoustic, Viscometric, and Electronic Absorption Studies in Aqueous l-Proline and l-Valine Solutions

Unraveling the Solvation Behavior of Levocetirizine Dihydrochloride: Insights from Volumetric, Acoustic, Viscometric, and Electronic Absorption Studies in Aqueous <scp>l</scp>-Proline and <scp>l</scp>-Valine Solutions

Urocanic acid as a novel scaffold for next-gen nature-inspired sunscreens: II. Time-resolved spectroscopy under solution conditions.

In recent years the use of synthetic UV filters in commercial skincare formulations has come under considerable scrutiny. Urocanic acid is a naturally occurring UV filter that could serve as a scaffold for developing next-generation biomimetic UV filters. We have carried out time-resolved electronic and vibrational absorption studies on urocanic acid and modified variants in various solvents on timescales spanning eighteen orders of magnitude; from femtoseconds to hours. In combination with quantum chemical calculations these provide vital insight into the photochemical and photophysical properties of urocanic acid and how these are tuned by substitutions and solvents. Moreover, they solve the hitherto conundrum of the wavelength dependence of the photochemistry of trans-urocanic acid in an aqueous environment. Crucially, these studies - together with the accompanying article that reports high-resolution laser spectroscopic studies performed under isolated gas-phase conditions (https://doi.org/10.1039/D4CP02087A) open novel avenues for a rational design of urocanic acid-based UV filters.

One-pot domino synthesis of 1,2,4-triazolo [3,4-b][1,3,4] 6-amino thiadiazines and their CT-DNA binding study

A facile one-pot three component domino protocol has been successfully developed for the combinatorial synthesis of novel Schiff bases of 3-(2-(6-amino-7H- [1,2,4]-triazolo[3,4-b] [1,3,4]thiadiazin-3-yl)hydrazineylidene)indolin-2-ones 4, 5. This protocol utilizes readily available starting materials, leads to produce high yields (79–92 %).This domino reaction involves the formation of three new bonds (two CN and one C–S bond) and one heterocyclic ring in a single step. Notably, this reaction shows several remarkable features, such as short reaction time, eliminating the requirement for extensive workup and column chromatographic purification. In addition to this, the reaction demonstrates good scalability, producing satisfactory yields even on a gram -scale. Further, all the compounds were screened for their electronic absorption and fluorescence emission spectral studies by using CT-DNA. Compounds 5l, 5m, 5r, 5o, 5s have shown greater binding affinity with CT-DNA. In fluorescence emission spectra 5l, 5o, 5s demonstrate good quenching constant values with CT-DNA. And also, molecular docking studies were carried out for all the synthesized compounds.

Exploring the pH-Responsive Interaction of β-Blocker Drug Propranolol with Biomimetic Micellar Media: Fluorescence and Electronic Absorption Studies.

Interaction of neutral and charged lipophilic beta-blocker drug, propranolol (PPL) with biomimicking nanocavities formed by micelles bearing same and opposite charges namely, cationic cetyltrimethylammonium bromide (CTAB), a surface-active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (HDMIC) and anionic sodium dodecyl sulphate (SDS) have been investigated using fluorescence and absorption spectroscopic techniques. Binding of PPL to SDS at pH < pKa is characterised by biphasic interactions with decrease in fluorescence intensity at lower concentrations and subsequent increase post micellization. All the surfactants show significant interactions with the neutral drug molecule at pH > pKa, which is evident from the strongest binding constant ( ) values at pH 10.4. Results of quenching studies indicate that the location of drug molecule is determined by its charge, which is influenced by both pH and charge on micelle surface. For PPL-CTAB and PPL-HDMIC systems, quenching was strongest at pH 10.4, moderate at pH 7.4 and was absent at pH 3.5. However, the PPL-SDS system displayed similar values at all pH conditions, suggesting that the probe is at the same position regardless of pH. Non-covalent interactions, which play crucial role in biological systems, are similarly the primary driving force governing the interaction between PPL and surfactant micelles.

Disruption of zinc (II) binding and dimeric protein structure of the XIAP-RING domain by copper (I) ions.

Modulation of metalloprotein structure and function via metal ion substitution may constitute a molecular basis for metal ion toxicity and/or metal-mediated functional control. The X-linked Inhibitor of Apoptosis Protein (XIAP) is a metalloprotein that requires zinc for proper structure and function. In addition to its role as a modulator of apoptosis, XIAP has been implicated in copper homeostasis. Given the similar coordination preferences of copper and zinc, investigation of XIAP structure and function upon interaction with copper is relevant. The Really Interesting New Gene (RING) domain of XIAP is representative of a class of zinc finger proteins that utilize a bi-nuclear zinc-binding motif to maintain proper structure and ubiquitin ligase function. Herein, we report the characterization of copper (I) binding to the Zn2-RING domain of XIAP. Electronic absorption studies that monitor copper-thiolate interactions demonstrate that the RING domain of XIAP binds 5-6 Cu(I) ions and that copper is thermodynamically preferred relative to zinc. Repetition of the experiments in the presence of the Zn(II)-specific dye Mag-Fura2 shows that Cu(I) addition results in Zn(II) ejection from the protein, even in the presence of glutathione. Loss of dimeric structure of the RING domain, which is a requirement for its ubiquitin ligase activity, upon copper substitution at the zinc-binding sites, was readily observed via size exclusion chromatography. These results provide a molecular basis for the modulation of RING function by copper and add to the growing body of literature that describe the impact of Cu(I) on zinc metalloprotein structure and function.

Electronic Absorption, Emission Spectral, and Electrochemical Studies of [Cu(OBTTAP)] Linked (bpy)2RuII, (phen)2RuII, and (PPh3)CpRuII Complexes

Electronic Absorption, Emission Spectral, and Electrochemical Studies of [Cu(OBTTAP)] Linked (bpy)2RuII, (phen)2RuII, and (PPh3)CpRuII Complexes

Synthesis, Spectral Interpretation, and Biological Efficiency of Azo Colorants Derived from Sulfadiazine Moiety

The simple, economic, and conventional diazo-coupling method was developed for the synthesis of five different scaffolds of sulfadiazine incorporated azo dyes in acidic medium at chilled condition. The structural aspects of the prepared azo dyes were confirmed by various physical and spectroscopic techniques such as elemental analysis, electronic absorption studies, infrared, nuclear magnetic resonance (1H and 13C), and mass spectrometry. The electronic absorption study indicates that all the prepared azo dyes possess excellent coloring properties and it is supported by its molar absorptivity values. Further, these azo colorants were examined for different biological studies such as antimicrobial assay, radical scavenging, antituberculosis, anti-inflammatory, and DNA cleavage studies. From the results, all the studied azo dyes showed provoked and proficient biological efficacy against the tested assays.

Electronic properties and optical absorption study of Arsene with PtSe2 type-II heterostructure: based on the first-principles calculation

Electronic properties and optical absorption study of Arsene with PtSe2 type-II heterostructure: based on the first-principles calculation

DFT calculations on three 2,3‐dihydrobenzofuran linked chalcones: Structural, HOMO‐LUMO and spectroscopic (UV‐Vis and IR) interpretation

AbstractThree chalcones with a 2,3‐dihydrobenzofuran linkage were analyzed by applying the density functional theory (DFT) and B3LYP approach with the 6‐311G(d,p) basis set in this report. Spectroscopic and theoretical analyses were used to examine the structures of these three chalcones. The chalcone molecules' HOMO‐LUMO energy was determined. Chemical reactivity parameters and molecular electrostatic surface potential (MESP) plots were obtained to gain useful insight into the distribution of charge density. The HOMO–LUMO gap of all three chalcones were calculated and discussed. The (E)‐3‐(2,3‐dihydrobenzofuran‐5‐yl)‐1‐phenylprop‐2‐en‐1‐one (DBPP) is discussed in detailed for the theoretical and experimental correlation. The captodative phenomenon appears to be the most polar molecule, with a dipole moment of 8.53 Debye. The decreased bandgap indicates that charge transfer occurs within the DBNPP molecule. When the solvent polarity is changed to DCM and DMSO from the gas phase, there is an event of a hyperchromic shift. The C19 carbon atom has the highest negative atomic charge while C21 is the carbon with the largest positive charge. From the MESP plots, we can conclude that the most electropositive region is located over the hydrogen atoms of the five‐membered ring, and the electronegative region is located over the oxygen atoms. Time‐dependent density functional theory (TD‐DFT) using B3LYP functional with 6‐311G(d,p) as basis set were used for the electronic absorption study in gas phase, dichloromethane and dimethyl sulfoxide. The UV‐Vis absorption peaks and fundamental vibrational wavenumbers were calculated and a good agreement between observed and theoretical results has been achieved.

Evaluation of a trinuclear heteroleptic bis-cyclometalated iridium(III) complex as a photoredox catalyst for visible light-mediated hydrothiolation reactions

A trinuclear bis-cyclometalated iridium(III) polypyridyl complex was synthesised and evaluated as a photoredox catalyst for visible light- mediated thiol-ene coupling reactions. Electronic absorption and emission studies revealed that the complex shows a blue-shifted emission spectrum, with a wavelength at 578 nm, relative to the canonical iridium complex, [Ir(ppy)3] (598 nm). The emissions are attributed to the transition from the triplet MLCT excited state (3MLCT) to the ground state. Cyclic voltammetry studies demonstrated that this complex is a promising candidate for the photoredox catalysed reactions, with the trinuclear iridium complex increasing the oxidation potential without sacrificing the reduction ability. The iridium(III) complex was evaluated as a photoredox catalyst in the model hydrothiolation coupling reaction and benchmarked against a trinuclear ruthenium congener. Reactions conducted with the trinuclear iridium polypyridyl complex resulted in the highest NMR yields.

Synthesis, structural investigations, XRD, DFT, anticancer and molecular docking study of a series of thiazole based Schiff base metal complexes

A novel Schiff base (SB) ligand, abbreviated as HDMPM, resulted from the condensation of 2-amino-4-phenyl-5-methyl thiazole and 4-(diethylamino)salicyaldehyde, and its metal complexes with [Co(II), Cu(II), Ni(II), and Zn(II)] ions in high yield were formed. The physico-chemical techniques such as elemental analysis, molar conductance, IR, 1H and 13C NMR, mass spectroscopy, and electronic absorption studies were utilized to characterize the synthesized compounds. The studied compounds were examined for their possible anticancer activity against a number of human cancerous cell lines, including A549 lung carcinoma, HepG2 liver cancer, HCT116 colorectal cancer, and MCF-7 breast cancer cell lines, with doxorubicin serving as the standard. The study revealed that Zn(II) complex showed significant activity to inhibit growth of HepG2, MCF7, A549, and HCT116 cell lines by a factor of 88, 70, 75, and 70, respectively, when compared to untreated. In addition, the reported compounds were optimized by employing Gaussian16 program package with B3LYP functional incorporating dispersion with two different basis sets (LanL2DZ and 6–31G(d,p)). Moreover, Autodock Vina software was used to assess the biological effectiveness of the studied compounds against SARS-CoV-2 Omicron variant (PDB ID: 7T9K).

Selective Recognition and Reversible “Turn-Off” Fluorescence Sensing of Acetate (CH3COO−) Anion at Ppb Level Using a Simple Quinizarin Fluorescent Dye

A simple and cost-effective optical sensing system based on quinizarin fluorescent dye (QZ) for the selective and reversible sensing of CH3COO− anions is reported. The anion binding affinity of QZ towards different anions was monitored using electronic absorption and fluorescence emission titration studies in DMSO. The UV-visible absorption spectrum of QZ showed a decrease in the intensity of the characteristic absorption peaks at λ = 280, 323, and 475 nm, while a new peak appeared at λ = 586 nm after the addition of CH3COO− anions. Similarly, the initial strong emission intensity of QZ was attenuated following titration with CH3COO− anions. Notably, similar titration using other anions, such as F−, Cl−, I−, NO3−, NO2−, and H2PO4-, caused no observable changes in both absorption and emission spectra. The selective sensing of CH3COO− anions was also reflected by a sharp visual color change from bright green to faint green under room light. Further, the binding was found to be reversible, and this makes QZ a potential optical and colorimetric sensor for selective, reversible, and ppb-level detection of CH3COO− anions in a DMSO medium.

The enthralling effect of packing on the light emission of pyridazinone based luminophore: Crystallographic, electronic absorption and computational studies

The present study unfolds the synthesis and characterization of a new butylidine linked hetero dimer of pyridazinone (PNP). The crystal structure analysis of PNP reveals that it exhibited infinite 1D linear chains connected through C-H∙∙∙O interaction and interlayer connectivity was supported by the unconventional orthogonal dipolar interaction via nitro-aromatic (ONO2···π(C)Ar). These interactions are also described using DFT calculations and are potentially studied. Here we discuss the influence of crystal structure on the photophysical properties of a new solid state emitter containing brick layer packing. Furthermore, we conducted detailed exploration of the intermolecular interactions that maintain the crystal packing of the structure by employing the Hirshfeld surface analysis and its corresponding two-dimensional fingerprint plots revealing that the C-H∙∙∙O interaction mainly stabilized the crystal structure. Time-dependent density functional theory (TDDFT) studies and observed nitro aromatic interactions (ONO2∙∙∙(C)Ar) in the crystal helped to explain the electronic behaviour of PNP. The validity of the computations is supported by a good agreement between the estimated and experimental values of the excitation energy transfer. Furthermore, we conducted detailed research on the Hirshfeld surface analysis and the intermolecular interactions that stabilize the crystal packing using their corresponding two-dimensional fingerprint plot. Some standard thermodynamical parameters such as specific heat, entropy and free energy have also been computed. In addition to this, the variation of specific heat with temperature has been explored.

Newly Synthesized Benzothiazole Derived Ligand and its Co(III) and Ru(III) Complexes as Biological Potent Molecules: Chemical Preparation, Structure, Antimicrobial, in vitro and in vivo Cytotoxicity Studies

Herein we describe the synthesis of 2-((E)-(2-(benzo[d]thiazol-2-yl)phenylimino)methyl)-5-methoxyphenol imine base (BMM) and its metal complexes such as [Co(BMM)2] C1, [Co(BMM)(ph)] C2, [Ru(BMM)2] C3 and [Ru(BMM)(ph)] C4. The ligand and its complexes were characterized by spectroscopic, TGA, Powder X-ray diffraction (XRD), and elemental analysis. The coordination number and geometry were confirmed by various experimental data. The Co(III) and Ru(III) complexes are assigned to be having octahedral geometry. Further, the experimental results revealed that complex C2 and C4 emerged as moderate DNA binding intercalators compared to standard intercalators and prominent nuclease activity compared with C1 and C3 complexes. The extent of interaction and intercalation mode was confirmed by monitoring electronic absorption studies, fluorescence quenching probe, and viscosity measurement. Furthermore, the complexes C1-C4 were investigated for their in vitro cytotoxic studies against a panel of human cancer cell lines, viz., A549, NIH3T3, MCF-7, and EAC. Also, the cell adhesion and migration behavior were carried out after administering the complex C2 and C4 to respective cancer cell lines. In mice, the toxicities and tolerabilities of the complex C2 and C4 were also investigated through in vivo studies. The resultant complexes were screened for their microbial inhibition studies through the good diffusion method. All the complexes display moderate microbial inhibition properties compared to their uncoordinated analog.

Experimental and theoretical studies of azo derivatives in terms of different donors, acceptors and position isomerism: Synthesis, characterization and a combined electronic absorption, electrochemical and DFT study

Eight azo derivatives with two donor groups- diphenylamine and N,N-dimethylphenyl, and four acceptor groups - 3-nitrophenyl, 4-nitrophenyl, 4-phenylcarboxylic acid, and 3-phenylcarboxylic acid, were synthesized and characterized using 1H-NMR and HRMS spectroscopies. Both experimental and computational vibrational spectroscopic analyses of the derivatives have been performed. Solvatochromism in different solvent polarities has been studied, both computationally and experimentally. We have also performed electrochemical studies on the chosen dyes. From cyclic voltammetry and UV-Visible absorption spectra, the HOMO and LUMO energies of the dyes were calculated, and compared with computational results, which are found to be in fair agreement. Protonation studies of the dyes showed that the neutral and the protonated forms of the dyes absorb differently in solvents of differing polarities. This anomaly in different solvents could be explained with the help of differential pulse voltammetry experiments. Our studies show that the HOMO energy levels of the molecules are shifted upward in energy in nonpolar DCM solvent which reduces the bandgap and is responsible for the bathochromic shift in absorption. Thermal stability investigations showed that all the dyes are very well stable at least until 220 °C.

2-Methylimidazolium pyridine-2,5-dicarboxylato zinc(II) dihydrate: Synthesis, characterization, DNA interaction, anti-microbial, anti-oxidant and anti-breast cancer studies

2-Methylimidazolium pyridine-2,5-dicarboxylato zinc(II) dihydrate crystal (1) is synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), single crystal X-ray diffraction analysis (SCXRD), thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), powder X-ray diffraction analysis (PXRD), proton nuclear magnetic resonance (1H NMR) studies, electronic absorption studies (UV-VIS) and DNA interaction studies. 1 was then explored for anti-microbial, anti-oxidant and anti-cancer activity. The SCXRD studies show that the compound crystallizes in the triclinic system and exhibits a distorted octahedral geometry with methyl imidazole ion as the cation. An exothermic decomposition at 400 °C implies high temperature stability in TG-DTA. PXRD confirms the phase purity of the sample. 1H NMR and UV-VIS results show that the solution structure of 1 is in agreement with SCXRD data. DNA interactions evaluated by agarose gel electrophoresis method substantiate the intercalative mode of binding. Anti-oxidant analysis shows that it exhibits good scavenging ability against DPPH and NO radicals. Anti-microbial activity suggests that 1 has better activity against Escherichia coli than Staphylococcus aureus. Further, the potential anti-cancer activities of complex indicate that the compound has good activity with a half-maximal inhibition concentration (IC50) value of 21.3 against MCF-7 human breast cancer cell line, suggesting that it may act as an anti-breast cancer drug.

Solvent-Dependent Spectral Properties in Diverse Solvents, Light Harvesting and Antiviral Properties of Mono-Azo Dye (Direct Yellow-27): A Combined Experimental and Theoretical Study

In this paper, we have discussed for the first time a detailed electronic absorption study of the mono-azo dye Direct Yellow 27 [C[Formula: see text]H[Formula: see text]N4Na2O9S3] (DY-27) with five different homogeneous media by applying experimental and theoretical techniques along with some new characteristics of DY-27 in the field of solar cells as well as antiviral activities. A clear absorption band in the UV-visible region was observed, although the absorption maxima lie in the visible region. The electronic absorption transitions observed in our study were fully spin and symmetry allowed transitions with [Formula: see text]–[Formula: see text] character. Time-dependent density functional theory (TD-DFT) analysis has been done for understanding the electronic and the charge transfer performance. Moreover, the impacts of polar protic and polar aprotic solvents in the structural variation of DY-27 have been reported here. Further, applications of the dye in the field of solar cell, as well as antiviral activity, were performed using molecular modeling approaches. The dye exhibited a D–[Formula: see text]–A–A structure with a high light-harvesting efficiency (LHE) and good injection efficiency acts as an effective dye sensitized solar cell (DSSC). Molecular docking studies of the dye DY-27 performed with M-protease of the different corona viruses, MERS, SARS-CoV-1 and SARS-CoV-2 indicated comparable binding energies with the controlled inhibitors and best interactions are observed for the SARS-CoV-1.

Microwave prompted solvent-free synthesis of new series of heterocyclic tagged 7-arylidene indanone hybrids and their computational, antifungal, antioxidant, and cytotoxicity study

In this study, we report the expeditious synthesis of ten new antifungal and antioxidant agents containing heterocyclic linked 7-arylidene indanone moiety. The solvent-free microwave technique, ample substrate scope, superfast synthesis, and very simple operation are noteworthy features of this protocol. Antifungal activities of the newly synthesized compounds were evaluated against four fungal strains namely Rhizophus oryzae, Mucor mucido, Aspergillus niger, and Candida albicans. Most of the compounds were shown strong inhibition of the investigated fungal agents. In vitro, antioxidant potential against DPPH and OH radicals affirmed that the synthesized compounds are good to excellent radicals scavenging agents. The cytotoxicity data of the synthesized compounds towards HL-60 cells uncovered that the synthesized compounds display very low to negligible cytotoxicity. The structural and quantum chemical parameters of the synthesized compounds were explored by employing density functional theory (DFT) at B3LYP functional using 6-311G(d,p) basis set. The compound 3a is discussed in detail for the theoretical and experimental correlation. Time-dependent density functional theory (TD-DFT) at CAM-B3LYP functional with 6-311G(d,p) basis set was used for the electronic absorption study in the gas phase and indichloromethane and benzene solvents. The UV–Visible absorption peaks and fundamental vibrational wavenumbers were computed and a good agreement between observed and theoretical results has been achieved. From the DFT and antifungal activity correlation, it has been found that the 7-heteroarylidene indanones with more stabilized LUMO energy levels display good antifungal potential.

Synthesis, solvatochromism and electric dipole moment study of coumarin-fused quinoline: experimental and quantum chemical computational investigations

A new coumarin-fused quinoline push–pull fluorescent probe was designed, synthesized and characterized using $$^{\mathrm {1}}$$ H NMR, $$^{\mathrm {13}}$$ C NMR and mass spectrometry analysis. Electronic absorption and fluorescence studies of the synthesized probe were investigated in wide range of solvents of varying polarities, and the data were used to study its solvatochromic properties. The ground and excited state dipole moments of fluorescent probe were obtained from Bakhshiev’s and Bilot–Kawasaki’s equations by means of the solvatochromic shift method. The high value of dipole moment for the excited state over ground-state value was attributed to more polar excited state of molecule. Also, emission peak undergoes a bathochromic shift with an increase in the polarity of the solvent, confirming $${\varvec{\pi }} \rightarrow {\varvec{\pi }}{} \mathbf * $$ transition. The ground-state and excited-state dipole moments were calculated and compared using DFT calculations. Both experimental and computational studies revealed that excited-state dipole moment values are higher than corresponding ground-state value of studied compound. A new coumarin-fused quinoline push–pull fluorescent probe was designed, synthesized and characterized. The ground-state and excited-state dipole moments were calculated and compared using DFT calculations.

Synthesis, antibacterial and computational studies of Halo Chalcone hybrids from 1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)ethan-1-one

In an endeavor to develop antibacterial agents, a series of six 1,4-benzodioxan-6-yl substituted chalcone derivatives were synthesized by the base-catalyzed Claisen-Schmidt reaction of the 1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethan-1-one with fluoro and chloro substituted aromatic aldehydes. The synthesized products were characterized by FT-IR, 1H NMR, and 13C NMR spectroscopic techniques. The density functional theory (DFT) calculations were performed using the B3LYP functional with the 6-31G(d,p) basis set for the optimization of molecular geometries and frequency calculations. The CAM-B3LYP functional with a 6-31G(d,p) basis set was used in time-dependent density functional theory (TD-DFT) calculations for the electronic absorption studies. Optimized geometries, frontier molecular orbitals, and global reactivity descriptors' specifications were computed and addressed. The simulated electronic absorption spectra were recorded in the gas phase and dichloromethane (DCM) solvent. The electronic configurations, oscillator strengths, and excited state energies were also discussed. The theoretical UV–Vis and IR vibrational analyses were equated with the experimental findings for the assignment of absorption bands. The synthesized chalcones were evaluated for in vitro antibacterial activities against two Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram negative bacteria (Escherichiacoli and Proteus vulgaris). The DFT simulations were correlated with the antibacterial findings and it was discovered that they were highly helpful in the designing antibacterial agents and to establish the structure–activity relationship. Theoretical calculations are in good correlation with the in vitro antibacterial results.