Simulated UV Vis Spectra Research Articles

Synergistic charge-transfer dynamics of novel pyridoquinazolindone-containing triphenylamine-based push-pull chromophores: from structural optimization to performance metrics in photovoltaic solar cells and static, dynamic, solvent-dependent nonlinear optical response applications.

Modern technological breakthroughs depend on nonlinear optical (NLO) and photovoltaic (PV) materials, essential for creating advanced photonic devices and efficient solar cells. Herein, the NLO, PV, electrical, and photophysical characteristics of proposed chromophores (WLK-1-WLK-6) designed from pyridoquinazolindone-containing triphenylamine have been systematically altered by the addition of different spacers categorized as K1, K2, K3, K4, K5, and K6 (named as i-series). This fine-tuning was accomplished using TD-DFT, DFT computations, and the Scharber model. The impact of spectrum of medium polarity, ranging from the least polar to the most polar, including water (ε = 78.36), methanol (ε = 32.61), DMSO (ε = 46.83), tetrahydrofuran (ε = 7.43), benzene (ε = 2.27) and chloroform (ε = 4.71), is explored in detail utilizing the IEFPCM model on NLO and PV properties. Moreover, the response of different analyses like DOS, NCI, NBO, FMO, dipole moments (µ), and hyperpolarizability (β) in both gas, polar and non-polar solvents was analyzed. Our structure-property relationship studies revealed that adding extra spacer groups, particularly those containing thiophene spacers, considerably impacted the lowering of the energy gap (3.853-4.190 eV). The simulated UV-Vis spectra illustrate significant π → π* transitions and lower n → π* transitions, primarily in the near-infrared (IR) range of 558.613 to 429.844 nm. Push-pull chromophores showed extraordinary frequency-dependent NLO properties, SHG β(-2ω, ω, ω), and EOPE β(-ω, ω, 0) effect computed at laser frequencies of 1064 and 532 nm. Among the proposed compounds, WLK-6 with the K6 spacer demonstrated a smaller energy gap (3.853 eV), resulting in a maximum optical absorption peak at λ max = 558.613 nm and the maximum hyperpolarizability in benzene (9.00 × 104 a.u.), methanol (1.22 × 105 a.u.), THF (1.12 × 105 a.u.), DMSO (1.23 × 105 a.u.), and water (1.23 × 105 a.u.). Our study found that WLK-6, WLK-5, and WLK-1 compounds also had good photovoltaic (PV) capabilities, reaching a power conversion efficiency (PCE) of around 5% and an injection efficiency (ΔG inject) of 0.191. In addition to these analyses, we performed topologic studies, such as TDM, ELF, NCI, MEP, LOL, and electron-hole overlap plots to better understand both intra and intermolecular interactions. Based on these results, it is clear that modifying longer π-linker groups in A-D-π-A conjugated systems benefits the optoelectronic characteristics and NLO responses for organic PV devices.

Combined experimental and theoretical studies of diorganotin(IV) complexes of 1,2,4-triazole based Schiff base: Synthesis, spectroscopic investigation, DFT calculation, antifungal activity

Two novel diorganotin(IV) compounds of Schiff base (HL) with a general formula of R2Sn(L)Cl (where R equals n-Bu(1) or Ph (2)) have been formed and structurally identified. The identification was made through examination of various properties including elemental analysis, FT-IR, multinuclear NMR, 2D-HMQC, ESI-MS, and UV–vis analysis. The proposed structure for these organotin(IV) derivatives is a distorted tetrahedron surrounding tin, with the Schiff base ligand acting as a monoanionic monodentate by coordinating through the Ohydroxyl group. The density functional theory (DFT) calculation was accomplished at the B3LYP/6-31G(d,p)/Def2- SVP(Sn) level. The MEP map was used to recognize the reactive sites on the molecules, and atomic charges were determined at specific atoms. The global reactivity descriptors and the Frontier MO's were calculated using conceptual-DFT to understand the behavior of the structure and reactivity. We compared the experimental and simulated vibrational frequencies and found a strong correlation. A time-dependent DFT method utilizing the IEFPCM model was employed to determine the simulated UV–vis spectrum. Both of the analyzed complexes were tested for their ability to inhibit fungal growth in vitro against selected fungal strains. The significant antifungal effect of complexes could be observed against all strains.

In-Situ-Grown Cu Dendrites Plasmonically Enhance Electrocatalytic Hydrogen Evolution on Facet-Engineered Cu2 O.

Herein, facet-engineered Cu2 O nanostructures are synthesized by wet chemical methods for electrocatalytic HER, and it is found that the octahedral Cu2 O nanostructures with exposed crystal planes of (111) (O-Cu2 O) has the best hydrogen evolution performance. Operando Raman spectroscopy and ex-situ characterization techniques showed that Cu2 O is reduced during HER, in which Cu dendrites are grown on the surface of the Cu2 O nanostructures, resulting in the better HER performance of O-Cu2 O after HER (O-Cu2 O-A) compared with that of the as-prepared O-Cu2 O. Under illumination, the onset potential of O-Cu2 O-A is ca. 52 mV positive than that of O-Cu2 O, which is induced by the plasmon-activated electrochemical system consisting of Cu2 O and the in-situ generated Cu dendrites. Incident photon-to-current efficiency (IPCE) measurements and the simulated UV-Vis spectrum demonstrate the hot electron injection (HEI) from Cu dendrites to Cu2 O. Ab initio nonadiabatic molecular dynamics (NAMD) simulations revealed the transfer of photogenerated electrons (27 fs) from Cu dendrites to Cu2 O nanostructures is faster than electron relaxation (170 fs), enhancing its surface plasmons activity, and the HEI of Cu dendrites increases the charge density of Cu2 O. These make the energy level of the catalyst be closer to that of H+ /H2 , evidenced by the plasmon-enhanced HER electrocatalytic activity.

Exploration of the Atomic Pathway of Seed-Mediated Growth from Icosahedral [Au25(SR)18]− to Bi-Icosahedral Au38(SR)24 and Au44(SR)26 Clusters Based on the 2e– Hopping Mechanism

Size growth is ubiquitous in the gold nanocluster synthesis. However, the atomic-level mechanism of seed-mediated growth of gold clusters remains mysterious. In this study, the seed-mediated growth pathway from the icosahedral [Au25(SR)18]- cluster to the bi-icosahedral Au38(SR)24 and Au44(SR)26 clusters is studied based on the two-electron (2e-) hopping mechanism. First, atomic structures of three key intermediate clusters, [Au29(SR)20]-, [Au33(SR)22]-, and Au41(SR)25, are predicted based on the 2e--unit decomposition strategy. The theoretically simulated UV-Vis spectra based on the predicted structure model of [Au29(SR)20]- and [Au33(SR)22]- matched well with the experimental curves reported previously. Based on the predicted intermediate cluster structures, the size growth pathway from the eight-electron (8e-) [Au25(SR)18]- cluster to 14-electron (14e-) Au38(SR)24 and 18-electron (18e-) Au44(SR)26 clusters is determined. In the step of formation of bi-icosahedral Au38(SR)24 from icosahedral [Au25(SR)18]-, two Au4 units are first formed. The third 2e- hopping step results in formation of an icosahedron unit. The present studies offered new insights into the formation and size conversion mechanism of ligand-protected gold nanoclusters containing icosahedral cores.

Electron density, charge transfer, solvent effect and molecular spectroscopic studies on 2,2-Dimethyl-N-pyridin-4-yl-propionamide – A potential antioxidant

Quantum-level theoretical studies employing density functional theory and spectral methods such as Fourier Transform-Raman, Fourier Transform-Infrared, and Ultraviolet–Visible have been conducted on the chemical 2,2-Dimethyl-N-pyridine-4-yl-propionamide (2DNP4YP). Density functional theory computes the equilibrium geometry, numerous molecular components, atom bonding, and vibrational frequencies. The 2DNP4YP has undergone topological analyses using the Quantum Theory of Atoms in Molecules (QTAIM) to determine the inter and intramolecular charge transfer as well as calculated the Natural Bond Orbital study. By the Time Dependent-Density Functional Theory (TD-DFT) technique with several solvents and a simulated UV–Vis spectrum, the absorption of maximum wavelengths is found. The biological activity of the 2DNP4YP is explained by all other significant electronic factors utilizing the Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbitals energy values from the Density Functional Theory style. The Non-Linear Optical (NLO) properties of 2DNP4YP were investigated by changing the keyword in the same basis set. Molecular Electrostatic Potential (MEP) and Fukui function studies are used to identify the reactive regions around the molecule.

How to Characterize 4–90 nm Size Gold Nanospheres with Experimental and Simulated UV–Vis and a Single SEM Image

It is crucial nowadays to predict in a fast and simple manner physical-chemical behaviors like, the size-dependent optical properties of gold nanospheres (Au NSs). The idea behind this experiment is trying to replace (as much as possible) robust and expensive microscopy techniques with UV–vis spectrophotometry and friendly simulations. Students chemically synthesized ∼4 and ∼15 nm diameter NSs and grew larger ones to ∼32, ∼50, and ∼70 nm diameter using the previously obtained ∼15 nm as seeds. They characterized them via UV–vis spectroscopy to ultimately compare the spectra with user-friendly software including MiePlot, nanoHUB.org, and the Amendola algorithm (Wolfram Mathematica). For Au NSs ≤25 nm diam., the experimental UV–vis spectra fitted very well with the Amendola algorithm to determine the size. For Au NSs >25 nm diam., the experiment exhibited larger Au NSs than expected as noticed by the systematic red shift of the plasmon band with respect to the simulated one. A SEM image confirmed larger Au NSs; therefore, students were challenged to determine the source of discrepancy between experimental and simulated UV–vis spectra, which was later attributed to the aging of the Au NSs seeds. This experiment demonstrates an easy way to accurately determine the nanoparticle size while exploring and solving potential issues that students may face during the chemical synthesis and simulations.

Calculation of excited states of monolayer TPPA-COF based on first principles.

Two-dimensional covalent organic frameworks (COFs) have always been a hot topic in condensed matter physics. Herein, the first 100 excited states of the TPPA-COF are calculated to investigate the optical absorption properties of the materials in the interval. The stable molecular structure of monolayer TPPA-COF is obtained by first-principles calculation, which can be regarded as a hexagon with an aperture size of 18.25 Å. By means of the band structure and density of state analysis, it is found that the monolayer band gap width of the TPPA-COF is 1.52 eV. All excited states of the TPPA-COF exhibit obvious pi → pi* (delocalized π to anti π) local excitation characteristics through analysing the spatial distribution of the electron-hole pairs of the 10 excited states with the highest oscillator strength among the first 100 excited states. In addition, the simulated UV-vis spectra show that the maximum absorption intensity of the TPPA-COF is about 357 684 mol-1 cm-1, indicating that the TPPA-COF is a potential light-absorbing material.

Synthesis, Electronic Structure, UV–Vis, Wave Function, and Molecular Docking Studies of Schiff Base (Z)-N-(Thiazol-2-yl)-4-((Thiophene-2-ylmethylene)Amino)Benzenesulfonamide

The (Z)-N-(thiazol-2-yl)-4-((thiophene-2-ylmethylene)amino)benzenesulfonamide (TH2TH) were synthesized. The geometry was optimized by density functional theory (DFT) method. The titled compound week interaction and main binding areas confirmed by topological analysis. The simulated UV–Vis spectrum was calculated by TD-DFT method using IEFPCM solvation model. The HOMO-LUMO, molecular electrostatic potential, and nonlinear optical properties were carried out in the DFT method using gas phase. The pharmacological properties and toxicity were carried out using Swiss-ADME online tools, this result shows titled compound good drug-likeness properties. The molecular docking done using autodock software, against 5LOF protein.

Performance Enhancement of Dye-Sensitized Solar Cells: Solvation Model

A solubility model for Merocyanine-540 dye together with the interface's electron transfer kinetics of MC-540/TiO2 has been investigated (Merocyanine 540-based dye has been used effectively in dye-sensitized solar cells). The highest absorption peaks were recorded at 489 nm and 493 nm in Water and Ethanol solvent, versus the vacuum phase which yielded 495 nm (associated with a modest electron injection-free energy value (ΔGinj) of -2.34 eV for both Water and Ethanol solvents). The time-dependent density functional theory (TD-DFT) method approach has been applied in this simulation. Additionally, the electronic structure and simulated UV-Vis spectra of the dye in different solvents have been determined, and the alignment with the solar spectrum has been discussed to a certain extent. The energy level diagrams and electron density of the primary molecular orbitals are shown, and the major issues that have an impact on our new interface's performance are examined. It is concluded that the proposed Solvation Model (SM) can improve the performance of Dye-Sensitized Solar Cells.

Quantum mechanical/molecular mechanical approach for the simulation of UV–Vis absorption spectra of π-conjugated oligomers

It is crucial to understand the light absorption features and electronic structures of conjugated organic materials for their optoelectronic applications. However, neither reliable interpretations of reported ultraviolet–visible (UV–vis) absorption spectra nor correct predictions of new organic materials have been made because of the absence of proper calculation methods. To date, excited-state quantum chemical calculations, such as configuration interaction singles (CIS) and time-dependent density functional theory (TDDFT), have provided such information by overlooking the facts that many conformational isomers of conjugated organic molecules can exist at a given temperature and the resulting distributions of backbone structure can modulate π-conjugated electronic structures. In this study, we introduced a computational method combining the quantum mechanical/molecular mechanical molecular dynamics simulation (QM/MM MD) and the excited-state electronic structure calculation to include various conformers distributed due to the finite temperature and present a near-perfect simulation of experimentally obtained UV–vis absorption spectra. The simulated UV–vis spectrum of 3,6-bis(5-(benzofuran-2-yl)thiophen-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione [DPP(TBFu)2], a π-conjugated organic material for organic photovoltaic cells (OPV), shows excellent agreement with its experimental spectrum, and each absorption band is assigned to the different conformers with characteristic excitation energies. We believe that our new method provides an improved interpretation of the electronic structures as well as the conformational variations of π-conjugated organic materials under ambient environments.

Simulation of electronic and optical properties of polyene-diphenylaniline-sensitizers for perovskite n-ZnTiO3 towards efficient dye sensitized solar cells

Four polyene-diphenylaniline dyes (D5, D7, D9 and D11) are simulated here, for the first time, as sensitizers for nano-ZnTiO3-based dye-sensitized solar cells (DSSCs). First-principles calculations method has been used to describe dye-semiconductor surface interactions. Bonding between the ZnTiO3 nanoparticle, considered as (ZnTiO3)8 cluster, is studied using density-functional theory (DFT) and time-dependent (TD-DFT). Dye parameters have been used in analyzing electron-transfer processes from dye excited molecules into semiconductor. Electronic structures and simulated UV–Vis spectra of four dyes (isolated and ZnTiO3-bound forms) are described together with energy level diagrams and electrochemical parameters. Results are compared with earlier experimental results and used to discuss parameters that affect DSSC performance. The excited D11 (with −2.0173 eV level) has highest electron injection rate toward the ZnTiO3 conduction band. D9 (with −0.5369 eV level) is regenerated, by I−/I3−redox couple, more efficiently than D5, D7 and D11 dyes, with minimal charge-recombination rates. Moreover, D9 displays highest peak absorption, in both free form (at 544 nm) and adsorbed form (at 563 nm). D5 and D9 exhibit high Light Harvesting Efficiency values 0.7752 and 0.8416, respectively, between dye LUMO and ZnTiO3 conduction-band, compared to D7 (0.4921) and D11 (0.5441). D9 exhibits highest open-circuit potential (VOC, 0.88 eV) while D5, D7 and D11 have 0.79, 0.47 and 0.29 eV, respectively. The D9@ZnTiO3 interface shows highest stability with largest adsorption energy (−47.16 eV, −4550.62 kJ/mol) among different systems. Results indicate that D9@ZnTiO3-based DSSCs should exhibit highest power conversion efficiency (PCE) among the series.

Guiding synthetic targets of anodically coloring electrochromes through density functional theory.

Electrochromic devices offer many technological applications, including flexible displays, dimmable mirrors, and energy-efficient windows. Additionally, adsorbing electrochromic molecular assemblies onto mesoporous metal-oxide surfaces facilitates commercial and manufacturing potential (i.e., screen-printing and/or roll-to-roll processing). These systems also demonstrate synthetic versatility, thus making a wide array of colors accessible. In this work, using Time-Dependent Density Functional Theory (TD-DFT), we investigated ten different bi-aryl type molecules of 3,4-ethylendioxythiophene (EDOT) conjugated to various phenyl derivatives as potential anodically coloring electrochromes (ACEs). The non-substituted phenylene, hexylthiol-EDOT-phenyl-phosphonic acid, PA1, was synthesized and characterized as a means of model validity. PA1 absorbs in the UV region in its neutral state and upon oxidation absorbs within the visible, hence showcasing its potential as an ACE chromophore. The properties of PA1 inspired the designs of the other nine structural derivatives where the number and position of methoxy groups on the phenylene were varied. Using our DFT treatment, we assessed the impact of these modifications on the electronic structures, geometries, and excited-state properties. In particular, we examined stabilization intermolecular interactions (S-O and O-H) as they aid in molecule planarization, thus facilitating charge transport properties in devices. Additionally, destabilizing O-O forces were observed, thereby making some chromophores less desirable. A detailed excited state analysis was performed, which linked the simulated UV-Vis spectra to the dominant excited state transitions and their corresponding molecular orbitals. Based on these results, the nine chromophores were ranked ergo providing an ordered list of synthetic targets.

Excited-State Properties of Defected Halide Perovskite Quantum Dots: Insights from Computation.

CsPbBr3 quantum dots (QDs) have been recently suggested for their application as bright green light-emitting diodes (LEDs); however, their optical properties are yet to be fully understood and characterized. In this work, we utilize time-dependent density functional theory to analyze the ground and excited states of the CsPbBr3 clusters in the presence of various low formation energy vacancy defects. Our study finds that the QD perovskites retain their defect tolerance with limited perturbance to the simulated UV-vis spectra. The exception to this general trend is that Br vacancies must be avoided, as they cause molecular orbital localization, resulting in trap states and lower LED performance. Blinking will likely still plague CsPbBr3 QDs, given that the charged defects critically perturb the spectra via red-shifting and lower absorbance. Our study provides insight into the tunability of CsPbBr3 QDs optical properties by understanding the nature of the electronic excitations and guiding improved development for high-performance LEDs.

Sequestering Ability of a Synthetic Chelating Agent towards Copper(II) and Iron(III): A Detailed Theoretical and Experimental Analysis.

In the continuous effort to identify selective chelators towards bioavailable and toxic metal ions, the potential selectivity of a novel N,O chelating ligand, recently synthesized and claimed to be able to bind to Cu(II) ions forming stable complexes while leaving unaltered the level of essential metal ions, was scrutinized using a combined theoretical and experimental approach. A multistep synthetic procedure was used to synthesize the ligand, whose chelating properties along with the stability of the complexes formed binding Cu(II) and, for comparison, Fe(III) ions were evaluated using potentiometric measurements and UV-Vis spectroscopy. DFT analysis allowed to disclose the structural characteristics of the formed complexes. In the plethora of all the possible structures, a selection of the most reliable ones was achieved by means of a stringent comparison between experimental and simulated UV-Vis spectra. The outcomes of the present investigation demonstrate that the Cu(II) sequestering ability of the ligand is smaller than that towards Fe(III). The strategy used here should allow to check the propensity of ligands in selectively binding metal ions.

Existence of α‐mangostin conformers and effects of aprotic and protic solvents on their equilibria, UV–Vis spectra, and chemical descriptors: Density functional theory and time‐dependent density functional theory study

AbstractThe physicochemical, thermodynamic, spectroscopic, and electronic properties of α‐mangostin dye (1,3,6‐trihydroxy‐7‐methoxy‐2,8‐bis(3‐methyl‐2‐buten‐1‐yl)‐9H‐xanthen‐9‐one) were investigated. Five conformers of the α‐mangostin dye were obtained using three different polarizable continuum model (PCM)/density functional theory (DFT) methods: wB97XD/6‐31+G(d,p), M06‐2X/6‐31+G(d,p), and B3LYP/6‐31+G(d,p). The species distribution of the five conformers in acetonitrile, water, and the gas phase was derived from the Gibbs free energy changes of their interconversion equilibria. Three dominant conformers (Conformers 2, 3, and 4) were found as coexisting species in solvents. Chemical descriptors of the three dominant conformers of the α‐mangostin in acetonitrile and water were obtained. Simulated UV–Vis spectra of the existing conformers and their mixtures in acetonitrile and water derived from the PCM/TD‐DFT calculations were in good agreement with experimental results. Because the three dominant conformers of α‐mangostin absorb light in the UV region, the application of α‐mangostin dye for UV protection is suggested. The performance of the three dominant α‐mangostin conformers in dye sensitized solar cells was also investigated.

Spectrophotometric-chemometrics study of the effect of solvent composition and temperature on the spectral shape and shift of copper and nickel phthalocyanines in different aqueous-nonaqueous mixed solvents.

Phthalocyanines (Pcs) are green-blue colored aromatic macrocyclic compounds used extensively in the dyeing industry. The assembly phenomenon for dye molecules is directly traceable by most of the spectroscopic methods. In this investigation, the monomer-dimer equilibria of copper and nickel phthalocyanines tetra sulfonic acid tetrasodium salts (CuPcTS, NiPcTS) have been investigated by spectrophotometric and chemometrics methods in binary mixtures of H2O-DMSO and H2O-CH3CN. The dimerization constants, (KD), enthalpies and entropies of CuPcTS and NiPcTS have been calculated by studying the UV-Vis spectra at different concentrations of dyes (10-6 to 10-4molL) and in the temperature range 298-343 K and in some samples up to 353 K by multivariate curve resolution (mcr) methods. By increasing the temperature, the value ofKD decreases. The inverse temperature dependence of KD(van't Hoff equation) was used for determination of ΔH0 and ΔS0and following that ΔG0of the dimerization reactions. As a result, upon aggregation, an increase in the intensity of the new shoulder at (~600 nm) and the Q-band at (662-670 nm) and concomitant decrease of the dimer band at (630-624 nm) are observed for all of the samples in different solvents composition. Therefore, the H-dimer type of these pigments was notable, in studied binary solvents. The effect of the solvent composition, concentration dye, and temperature on the spectral responses, the exciton parameters and concentration distribution diagrams of the two pigments were studied and discussed. The density functional theory (DFT) calculations were done in the aqueous and gas phase that they were included the HOMO-LUMO energies and the simulated UV-Vis spectrum. These calculations were beneficial for studying the UV-Vis spectrum of it in the aqueous phase for checking experimental data.

Luminescence spectral analysis for Eu(III), and the dinuclear (Zn(II), Cu(II)) complexes with organic ligands by quantum chemical methods

We are very interested in elucidating the theoretical reason why the luminescence of Eu(III)-organo-ligand complexes is enhanced in the presence of Zn(II)-Schiff base complexes, or quenched in the addition of Cu(II) ones. The reason for luminescence enhanced and quenching spectra is deduced from the dynamic (time-dependent) and static (time-independent) standpoints. In the dynamic behavior, we describe that such luminescence spectra depend upon the lifetimes of electron populations at the excited state for their metal-complexes by considering experimental investigations of Eu(III), Zn(II), Cu(II), and dinuclear Eu(III)-(Zn(II), or Cu(II)) complexes with organo-ligands. We also consider the chemical rate equations to form the dinuclear metal complexes, and derive the new equation for the ratio of quantum yields to estimate lifetimes of the Zn(II)- and Cu(II)-saltn complexes. From the static viewpoint, electronic states of septet Eu(III) (as an electron donor), singlet Zn(II) {(or doublet Cu(II)) as an electron acceptor}, and the dinucleus septet Eu(III)⋅Zn(II) (or octet Eu(III)⋅Cu(II)) complexes with organo-ligands are calculated by using DFT and TD-DFT methods. We discuss that the simulated UV–Vis spectra in the range of 450–700 nm reflect to the enhanced Eu(III)⋅Zn(II) and quenching Eu(III)⋅Cu(II) peaks with the experimental ones.

Theoretical and experimental study of torsional potentials, molecular structure (monomer and dimer), vibrational analysis and molecular characteristics of some dimethyl bipyridines

This study deals with the determination of torsional potentials, molecular geometry in monomer and dimer form and vibrational assignments of 4,4′-dimethyl-2,2′-bipyridine (4DB); 5,5′-dimethyl-2,2′-bipyridine (5DB); and 6,6′-dimethyl-2,2′-bipyridine (6DB) using quantum chemical calculations carried out by density functional theory (DFT) employing B3LYP functional in conjunction with 6–311++G(d,p) basis set. Existence of inter-molecular hydrogen bonds was predicted. Fourier Transform infrared (FTIR) and Fourier Transform Raman (FT-Raman) spectra were recorded and vibrational analysis of the molecules was made using potential energy distribution (PED) and eigen vectors obtained in the computations. Observed and calculated frequencies agreed with an rms error 9.20, 8.21, and 8.33 cm−1 for 4DB, 5DB, and 6DB, respectively. 1H and 13C NMR spectra were simulated using time-dependent DFT (TD-DFT); compared with the recorded experimental spectra of the samples in Chloroform-d (CDCl3) solvent and observed that the chemical shifts agree well with their theoretical counterparts. Electronic transitions were analyzed using experimental and simulated UV–Vis spectra of the three molecules. Molecular characteristics like HOMO-LUMO; thermodynamic parameters; and molecular electrostatic surface potential (MESP) quantified with natural charges obtained by NBO analysis are also investigated.

Combined experimental and theoretical studies on the diorganotin(IV) complexes of sparfloxacin: Synthesis, spectroscopic and DFT studies, and biological activity

New diorganotin(IV) derivatives of sparfloxacin having general formula R2SnCl(L), (where L = monoanion of sparfloxacin (HL) and R = n-Bu (1)/Ph (2)) have been synthesized and structurally characterized by elemental analysis, IR, NMR (1H, 13C, 119Sn), HMQC, ESI-MS, UV–Vis and emission spectroscopy. These investigations suggest that, in these 1:1 monomeric derivatives the sparfloxacin ligand acts as monoanionic bidentate coordinating through the Ocarboxylate and Opyridone, and the polyhedron around tin is intermediate between pseudotetrahedral and cis-trigonal bipyramidal. The proposed structures have been validated by density functional theory (DFT) based electronic structure calculations at B3LYP/6-31G(d,p)/Def2-SVP(Sn) level of theory through the calculation of the atomic charges at the selected atoms, molecular electrostatic potential (MEP) map to assign sites on the surface of the molecules, the selected conceptual-DFT based global reactivity descriptors to obtain an insight into the structure and reactivity behaviour, and the frontier molecular orbital analysis to analyze the nature of frontier orbitals. A comparative analysis of the experimental vibrational frequencies and simulated harmonic frequencies indicates good correlation between them. The simulated UV–Vis spectrum was obtained with time dependent-DFT method in gas phase and in the solvent field with IEFPCM model. The simulated 1H and 13C NMR spectra were obtained by gauge-independent atomic orbital (GIAO) method and the results were in good agreement to the experimental results. The complexes were screened for their in vitro antibacterial activity against two Gram-positive and five Gram-negative bacterial strains. Both the complexes exhibited promising antibacterial activity against all the chosen strains (MIC: 0.062–0.125 μg ml−1).

Computational study of quinacridone on silver and gold clusters: Applications to organic light emitting diodes and nonlinear optical devices

Interaction of quinacridone (QA) on silver and gold clusters has been investigated using computational methods. This interaction induces variations in the structural parameters of QA, which are confirmed by the electrostatic potential plot and the vibrational analysis. The red shift in the simulated UV–Vis spectra confirms the process of adsorption on metal clusters, which is mainly due to the electrostatic interaction between the metals and QA. Reduction in the hole reorganization energy along with the increment in hyperpolarizability points to a possible use of QA adsorbed on silver cluster as an effective material in organic light emitting diodes (OLED) and nonlinear optical (NLO) devices.