Visible Absorption Maxima Research Articles

Synthesis, characterization, and anti-cancer activity of chalcone derivatives as-potent anaplastic lymphoma kinase inhibitors

Chalcone derivatives (7a–k) have been synthesized and characterized by 1H-NMR, 13C-NMR, mass, and elemental analysis. The synthesized compounds 7a, 7d, and 7g have been examined and it is confirmed that the most promising cytotoxicity and also cell morphology analysis exhibited good apoptotic activity against lung cancer A549 cell. The free energy binding of compound 7d exhibits − 8.96 kcal/mol with five hydrogen bonding Asn1254, Arg1253, Asp1249, and Gly1123 amino acids of ALK receptors. The LUMO of the electron density present in α, β-double bond and influence the anticancer activity. The Mulliken atomic charges and MEPs are scrutinizing the ligand interaction with the amino acid binding of ALK receptors. UV-visible and photoluminescence spectra showed that the properties of chalcone derivatives have a significant effect on the visible absorption and emission maxima (531–535 nm) red shift in the emission spectra which also systematically investigated electrochemical in various solvents with increasing solvent polarity.

Molecular structure, spectroscopic, quantum chemical, topological, molecular docking and antimicrobial activity of 3-(4-Chlorophenyl)-5-[4-propan-2-yl) phenyl-4, 5-dihydro-1H-pyrazol-1-yl] (pyridin-4-yl) methanone

The conjugated experimental and theoretical vibrational study of 3-(4-Chlorophenyl)-5-[4-propane -2-yl) phenyl-4, 5-dihydro-1H-pyrazole-1-yl] (pyridine -4-yl) methanone (CPPPM) molecule has been extend out and they have been dully compared with standard values in arrangement to exhibit the constancy of the results. Results of DFT analysis move out using B3LYP functional with 6-311++G (d, p) and 6-311G (d, p) basis sets, respectively. The experimental geometrical parameters were compared with theoretical data. The fundamental modes of vibrations were attributing by PED, the computed and experimental values uphold each other. The HOMO-LUMO energy allotment was computed which demonstrate the charge carry over within the molecule. Molecular Electrostatic Potential (MEP) was mapped. The UV-Vis data of the molecule were used to study the visible absorption maxima (λmax) by Time- Dependent DFT. Topological parameters at bond critical points (BCPs) have been evaluated by Quantum theory of atoms in molecules (QTAIM), Electron Localization Function (ELF) and reduced density gradient of the title molecule was investigated by the interaction of molecule . The natural bonds orbital (NBO) analysis was executed to know the transpose of electrons within the molecule and the stability, charge delocalization of the entitle molecule were deliberate. CPPPM has been picking for its antimicrobial activity and found to demonstrate antibacterial and antifungal effects. Docking simulation has been achieved.

Quantum Chemical Computations, Molecular Docking, Experimental and DFT Calculation of 4-Amino-3-Phenylbutanoic Acid

In this examination, we report a combined experimental and theoretical study on molecular structure and vibrational spectra of 4-amino-3-phenylbutanoic acid. Vibrational spectra were analyzed on the basis of potential energy distribution (PED) of each vibrational mode, which provides quantitative as well as qualitative interpretation of IR and Raman spectra. The theoretical UV-visible range of the compound are utilized to examine the visible absorption maxima (λmax). HOMO-LUMO energy gap and other related atomic properties are additionally determined. The non-linear optical properties such as dipole moment (µ), polarizability (αtot) and molecular first order hyperpolarizability (β) of the 4-amino-3-phenylbutanoic acid compound are computed with B3LYP/6-311++G(d,p) level of theory. In addition a molecular docking study has supported the anticonvulsant activity of the 4-amino-3-phenylbutanoic acid molecule.

Effect of Alkyl Substituents on DPP‐based Small Molecules for Organic Solar Cells

Two diketopyrrolopyrrole (DPP)‐based π‐conjugated small molecules, DPP4T and α‐DPP4T, were synthesized to investigate the effect of alkyl end groups on the physical properties of the molecules. The flexible alkyl end groups resulted in lower phase‐transition temperatures and enhanced solubility of α‐DPP4T. The UV–vis absorption maxima (λmax) of films of both small molecules were blue‐shifted compared with those of solutions of the molecules. More importantly, a relatively larger shift in λmax between the solution and film states and an enhanced shoulder peak in the longer‐wavelength region were observed in the spectra of the α‐DPP4T film, indicating relatively greater intermolecular packing of α‐DPP4T molecules. The enhanced device performance (in particular, a higher short‐circuit current density and better external quantum efficiency profile) of the α‐DPP4T‐based device was explained by the improved film morphology and stronger intermolecular interactions of α‐DPP4T. After device optimization, a power conversion efficiency of 2.42% was achieved using α‐DPP4T.

Cocos nucifera Leaf Extract Mediated Green Synthesis of Silver Nanoparticles for Enhanced Antibacterial Activity

Antibiotic resistance is currently a global human health concern and insists on the importance of the production of new, alternative and most effective antibiotics. Nano-sized trace metals such as silver nanoparticles (AgNPs) is a potential material with antibacterial properties and hence the synthesis of this material is of considerable interest to the scientific community mainly for antimicrobial applications. In this work, we have successfully green synthesized the AgNPs using Cocos nucifera leaf aqueous extract as the natural reducing and stabilizing agent, and aqueous silver nitrate (AgNO3) solution as a precursor by a newly developed technique. The material was characterized by ultraviolet–visible (UV–Vis) spectrophotometry, X-ray diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM) analyses; and subsequently, evaluated their potential candidacy as antibacterial agents against some common human pathogens by the standard disc diffusion method. The synthesized AgNPs were identified by XRD analysis as a cubic crystal system with an average crystallite size of 14.2 nm. The aqueous colloidal suspension of AgNPs shows a UV–Vis absorption maxima of 380 nm indicating its formation. FT-IR analysis identified the C–N, –OH and N–H as the major and probable functional groups in the leaf extract responsible for the production of stable AgNPs. The results of antibacterial studies of the material showed the considerable zones of inhibition against both Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, and Citrobacter freundii) bacteria ranging from 10 to 20 mm with less inhibition for the former than the latter. The maximum (20 mm) and minimum (10 mm) inhibition zone was shown by C. freundii and Bacillus subtilis, respectively and P. aeruginosa shows the second-highest zone of inhibition (19 mm). The antibacterial performance of the material implies that the C. nucifera leaf extract mediated green synthesized AgNPs can be regarded as a potential candidate for antimicrobial application appreciably.

Synthesis of tin(IV) complexes of chlorophyll-a derivatives with two halides as axial ligands and their optical properties in solution

Methyl pyropheophorbides prepared from naturally occurring chlorophyll-a were reacted with tin(II) dihalide in aerated solvents to give their tin(IV) complexes with two halides as the axial ligands. The tin(II)-insertion into the central position and the successive air-oxidation of tin(II) to tin(IV) proceeded cleanly for the 3-ethyl-, vinyl-, acetyl-, and formyl-chlorins. Their visible absorption and fluorescence emission maxima in dichloromethane were shifted to longer wavelengths in the order of F < Cl < Br as the axial ligand and CH2CH3 < CH = CH2 < COCH3 < CHO as the 3-substituent. The heavy atom effect was observed for their fluorescence emission quantum yields and lifetimes, which were suppressed in the order of H2 (free base) > SnF2 > SnCl2 > SnBr2 at the central position.

Web-ARM: A Web-Based Interface for the Automatic Construction of QM/MM Models of Rhodopsins.

This article introduces Web-ARM, a specialized tool, online available, designed to build quantum mechanical/molecular mechanical models of rhodopsins, a widely spread family of light-responsive proteins. Web-ARM allows the rapidly building of models of rhodopsins with a documented quality and the prediction of trends in UV-vis absorption maximum wavelengths, based on their excitation energies computed at the CASPT2//CASSCF/Amber level of theory. Web-ARM builds upon the recently reported, python-based a-ARM protocol [J. Chem. Theory Comput., 2019, 15, 3134-3152] and, as such, necessitates only a crystallographic structure or a comparative model in PDB format and a very basic knowledge of the studied rhodopsin system. The user-friendly web interface uses such input to generate congruous, gas-phase models of rhodopsins and, if requested, their mutants. We present two possible applications of Web-ARM, which showcase how the interface can be employed to assist both research and educational activities in fields at the interface between chemistry and biology. The first application shows how, through Web-ARM, research projects (e.g., rhodopsin and rhodopsin mutant screening) can be carried out in significantly less time with respect to using the required computational photochemistry tools via a command line. The second application documents the use of Web-ARM in a real-life educational/training activity, through a hands-on experience illustrating the concepts of rhodopsin color tuning.

Atomistic Insight into the Role of Threonine 127 in the Functional Mechanism of Channelrhodopsin-2

Channelrhodopsins (ChRs) belong to the unique class of light-gated ion channels. The structure of channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2) has been resolved, but the mechanistic link between light-induced isomerization of the chromophore retinal and channel gating remains elusive. Replacements of residues C128 and D156 (DC gate) resulted in drastic effects in channel closure. T127 is localized close to the retinal Schiff base and links the DC gate to the Schiff base. The homologous residue in bacteriorhodopsin (T89) has been shown to be crucial for the visible absorption maximum and dark–light adaptation, suggesting an interaction with the retinylidene chromophore, but the replacement had little effect on photocycle kinetics and proton pumping activity. Here, we show that the T127A and T127S variants of CrChR2 leave the visible absorption maximum unaffected. We inferred from hybrid quantum mechanics/molecular mechanics (QM/MM) calculations and resonance Raman spectroscopy that the hydroxylic side chain of T127 is hydrogen-bonded to E123 and the latter is hydrogen-bonded to the retinal Schiff base. The C=N–H vibration of the Schiff base in the T127A variant was 1674 cm−1, the highest among all rhodopsins reported to date. We also found heterogeneity in the Schiff base ground state vibrational properties due to different rotamer conformations of E123. The photoreaction of T127A is characterized by a long-lived P2380 state during which the Schiff base is deprotonated. The conservative replacement of T127S hardly affected the photocycle kinetics. Thus, we inferred that the hydroxyl group at position 127 is part of the proton transfer pathway from D156 to the Schiff base during rise of the P3530 intermediate. This finding provides molecular reasons for the evolutionary conservation of the chemically homologous residues threonine, serine, and cysteine at this position in all channelrhodopsins known so far.

Conformational Stability Effect of Polymeric Iron Chelators.

SummaryThe design and synthesis of metal chelators with extraordinary metal affinities is a basic and challenging scientific problem of both fundamental and practical importance. Here, we demonstrate a “conformational stability effect” that can significantly enhance the metal affinity of ligands after conjugation to polymer chains with the ability to spontaneously adopt a specific conformation as an optimal “soft” scaffold to ensure maximum thermodynamic stability of the metal complexes. Using iron chelators as models, we show that simple conjugation of small molecule catechol ligands to a polyallylamine chain resulted in more than 8–9 orders of magnitude enhancement of the iron-binding affinity, which is comparable to that of enterobactin, the strongest iron chelator ever known. This study demonstrates that flexible polymer chelators may realize the highest possible metal affinities of the conjugated ligands owing to their ability to achieve an optimal conformation, which could advance the identification of strong metal chelators.

Double connector to TiO2 surface in small molecule triphenyl amine dyes for DSSC applications

Two novel dyes 3a and 3b named triphenylamine groups containing donor–acceptor structural units have been explored to be used in dye sensitized solar cells as organic sensitizers. The absorption bands of the dyes were extended up to ~ 550 nm with visible absorption maxima at 408–430 nm and optical band gaps of 2.44–2.47 eV. Compared to the methoxyphenyl-substituted dye, the introduction of triisopropylphenyl group instead of that increased fluorescence quantum yields and exhibited red-shift emission in chloroform. We have investigated the photovoltaic properties of DSSCs based on these metal free organic dyes. It has been found that the power conversion efficiency of DSSCs sensitized with methoxyphenyl based triphenylamine dye is higher than that for sensitized with triisopropylphenyl derivative.

Solvatochromic analysis and DFT computational study of N-(hexyl)-N-(5-(3-hydroxynaphthyl-2-yl)-1,3,4-oxadiazol-2-yl)amine

A detailed analysis of the molecular orbitals contained in the electronic transitions in the UV-spectra and a detailed synthesis and conformational study of N-(hexyl)-N-(5-(3-hydroxynaphthyl-2-yl)-1,3,4-oxadiazol-2-yl)amine (NOH) were conducted using the method of TD-DFT (B3LYP/6-311 + G (d,p)). All the theoretical results were found to be in line with the experimental values. For the most stable conformer, the optimized structure parameters (bond lengths, bond angles), vibrational modes and their assignments and were calculated using DFT/B3LYP functional and 6-311 +G(d,p) basis set. The basic vibrational modes were determined by PED, the experimental and computed values were found to support each other. The chemical shifts of 1H-NMR and 13C-NMR were specified using the method of GIAO and compared with the experimental chemical shifts. The frontier orbital energy gap, global chemical reactivity restrictive such as the chemical potential, global hardness, electronegativity, index of electrophilicity, global softness of the molecule were also studied. The Natural Bond Orbital (NBO) analysis was performed to find out the stability and strength of the molecule. Based upon the experimental solvent influence and the theoretical examinations, the long wavelength bands were attributed to π → π* transitions induced by HOMO–LUMO intra-molecular charge transfer from the naphthyl ring to the 1,3,4-oxadiazole. Beside these, electrophilic index, EHOMO (− 5.88 eV), ELUMO (1.89 eV) and energy gap (3.99 eV) were computed to investigate the bio activity, reactivity and stability of the NOH. Kamlet–Taft and Catalan solvatochromism of synthesized 1,3,4-oxadiazole derivative were discussed. The Kamlet–Taft and Catalan solvent parameter sets were used to determine the effect of specific and non-specific solvent–solute interactions on the shifts of UV–Vis absorption maxima.

Synthesis and properties of blue-light-emitting Oligo(fluorene-co-dibenzothiophene-S,S-dioxide)s

An effective synthetic route for preparation of oligo(fluorene-co- dibenzothiophene-S,S-dioxide)s (trimer SOF2, pentamer SOF4, heptamer SOF6 and nonamer SOF8) based on meta- or para-linked dibenzothiophene-S,S-dioxide (SO) unit as the core was developed by convergence method, for which the intermediates unilateral boric acid esters were prepared by one-step palladium-catalysed Suzuki cross-coupling reaction. The resulting oligomers exhibited excellent thermal stability with thermal decomposition temperature exceeding 415 °C, and high photoluminescent quantum yield in the solid state (52–81%). The UV–vis absorption and photoluminescence emission maxima of the oligomers exhibited gradual bathochromic shifts from the trimer to the nonamer, approaching those of the previously reported polymer PFSO10 containing 10 mmol% of the SO unit in the polyfluorene backbone, demonstrating the similar photophysical properties of the nonamer SOF8 and polymer PFSO10. The highest occupied molecular orbital energy level gradually decreased and the lowest unoccupied molecular orbital energy level steadily increased from the trimer SOF2 to the nonamer SOF8. The obtained oligomers displayed pure blue-light emission with the maximal emission peaked at about 440 nm and superior EL spectral stability compared with PFSO10 upon varying the current density from 100 mA cm−2 to 500 mA cm−2, in addition to more balanced hole and electron fluxes. With the device configuration of ITO/PEDOT:PSS/oligomer/CsF/Al, a maximum luminous efficiency of 2.75 cd A−1 with Commission Internationale de l’Eclairage (CIE) coordinates of (0.16, 0.15) was obtained for the device based on 37SOF8. The efficiency increased by 88% compared with the device based on 37PFSO10 (1.46 cd A−1). A similar enhancement in efficiency was also achieved for the device based on 28SOF8. These results indicate that the obtained oligomers are very promising candidates for structurally well-defined blue-light- emitting materials with high efficiency and reproducibility.

Synthesis and Spectroscopic Characterisation of Some Novel Butadienyl Asycyanine Colorants having Lepidine Moiety

Twenty-one novel chromophoric chain β-substituted butadienyl asycyanine colorants have been synthesized by catalytic condensation of (i) dimethylaminostyryl phenyl ketone, (ii) 4ʹ-dimethylaminostyryl-4ʹ-nitrophenyl ketone and (iii) 4ʹ-dimethylaminostyryl-4ʹ-methoxyphenyl ketone with seven lepidinium methyliodide salts in ethanolic DMF medium using piperidine as basic catalyst. These colorants were synthesized with the objective to study the effect of electron acceptor and electron donor group substituent at 4ʹ-position in the chain β-phenyl nucleus on visible absorption maxima. The newly prepared colorants were found to exhibit uniform increase in absorption maxima i.e. Red shift (RS), when collated with analogues having no substituent in the β-phenyl nucleus. Again the absorption maxima of the title colorants were found to be higher than the absorption maxima of previously prepared butadienyl colorants having quinoline mioety of same conjugated system.

Role of the bifurcated intramolecular hydrogen bond on the physico-chemical profile of the novel azo pyridone dyes

A series of novel 5-(4-substituted phenylazo)-1-carboxymethyl-3-cyano-6-hydroxy-4-methyl-2-pyridones had been synthesized and characterized. The study includes spectral determination of the possible tautomeric forms and the intramolecular hydrogen bonding pattern. The influence of the bifurcated intramolecular hydrogen bond on the spectral properties has been discussed. The dyes exist in hydrazone form both solid state and in most of the employed solvents. Equilibrium between hydrazone and anion forms has been studied in N,N-dimethylformamide and N,N-dimethylacetamide. For quantitative elucidation of solvent effects on UV–Vis absorption maxima, a linear solvation energy relationship concept has been employed using Kamlet-Taft's and Catalán's equations. Antioxidative activity of the synthesized dyes has been chemically tested and two derivatives (hydroxy and methoxy) are qualified as promising antioxidant molecules.

Direct C-H coupling polymerization of asymmetric monomer: Synthesis and properties of regioregular poly(alkyl thiophene-3-carboxylates)

A series of poly(alkyl thiophene-3-carboxylates), herein referred to as poly(3-alkylesterthiophenes) (P3ET) (P1-P6) with high head-to-tail (HT) coupled regioregularity up to ∼92% were synthesized by a direct CH coupling polymerization (DCHCP). The substitutions with various alkyl ester side-chains on the 3-position of the thiophene ring were performed by changing the length and size of alkyl groups, with a view to investigate the role of the alkyl ester side chain on DCHCP reaction as well as on the crystallinity, optical and electrochemical properties of these resultant polymers. It was found that the longer and bigger size alkyl ester side chains on 3-position of thiophene monomers, the higher HT regioregularity of the corresponding polymer products. X-ray diffraction (XRD) measurements manifested that all polymers (P1-P6) existed in not highly ordered state in solid films especially in the π-stacking direction. Red shift of the UV–Vis absorption maxima of the resultant polymers in the film state confirmed more effective electron delocalization along the polymer chain than that in solution state. Cyclic voltammetry (CV) study indicated that the introduction of 3-alkyl ester side chain on the thiophene ring lowered the products' highest occupied molecular orbital (HOMO) energy level and enhanced their electrochemical band gaps significantly in comparison with the corresponding HT regioregular poly(3-alkylthiophenes).

Synthesis of 5-(5-methyl-benzofuran-3-ylmethyl)-3H- [1, 3, 4] oxadiazole-2-thione and investigation of its spectroscopic, reactivity, optoelectronic and drug likeness properties by combined computational and experimental approach

This paper reports the synthesis of 5-(5-methyl-benzofuran-3-ylmethyl)-3H- [1, 3, 4] oxadiazole-2-thione (5MBOT) and characterization by FT-IR, FT-Raman, 1H NMR, 13C NMR and UV spectral studies. The density functional theory (DFT) calculations have been executed for the 5MBOT using B3LYP/6-31++G (d, p) basis set. The fundamental modes of the vibrations were designated by the potential energy distribution (PED), and the computed and experimental values support each other. The 1H NMR and 13C NMR chemical shifts of 5MBOT were estimated by gauge-including atomic orbitals (GIAO) method and compared with the experimental chemical shifts. The UV–Vis method used to study the visible absorption maxima (λmax) by using Time-Dependent DFT. Further, the Mulliken population analysis (MPA), natural population analysis (NPA) charges, thermodynamic properties at different temperatures were presented. The calculated HOMO and LUMO energies show that charge transfer within the molecule. The natural bonds orbital (NBO) also computed. Optoelectronic properties have been carried out by combination of DFT calculations and molecular dynamics (MD) simulations, in order to assess the potential of this structure for applications in organic electronics. Further, the study encompassed calculations of reorganization energies for holes and electrons and charge transfer rates. DFT calculations have been also used in order to identify locations possibly sensitive towards the autoxidation mechanism, which correlates between bond dissociation energy for hydrogen abstraction and the mechanism. The MD simulations have been used to understand interaction of 5MBOT with water molecules. Molecular docking studies reveals the antifungal activity of 5MBOT may be due to hydrogen bonding and hydrophobic interactions with different antifungal proteins.

Solvent, structural, quantum chemical study and antioxidative activity of symmetrical 1-methyl-2,6-bis[2-(substituted phenyl)ethenyl]pyridinium iodides

15 symmetric 1-methyl-2,6-bis[2-(substituted phenyl)ethenyl]pyridinium iodides were synthesized in this work. Their structures were characterized using IR, 1H and 13C NMR, and UV–Vis spectroscopy. DFT calculations indicated that s-trans/s-trans conformation prevail in all compounds. The effects of specific and non-specific solvent–solute interactions on the UV–Vis absorption maxima shifts were evaluated using linear solvation-free energy relationships (LSER), i.e., Kamlet–Taft and Catalan models. A linear free energy relationship (LFER) in the form of single substituent parameter equations (SSP) was used to postulate quantitative structure–property relations of substituent effect on NMR data. TD-DFT results showed dependence of electronic transition on the substituent effects. The push–pull character of these compounds was analyzed by differences in 13C chemical shift of the ethylenic double bond in 2- and 6-positions of cross-conjugated with pyridinum central ring. Also, the quotient of the occupations for the bonding π and anti-bonding π* orbitals of this bond was considered. Good correlations of the selected parameter between double bond lengths with π*/π and 13C chemical shift differences of the bridging group proved them to be adequate descriptor of push–pull character. Synthesized compounds were screened for the antioxidant activity, using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical methods, and results demonstrated moderate antioxidant potential.

Molecular structure, vibrational spectra, NMR, UV, NBO, NLO, HOMO-LUMO and molecular docking of 2-(4, 6-dimethyl-1-benzofuran-3-yl) acetic acid (2DBAA): Experimental and theoretical approach

This paper reports the experimental and theoretical FT-IR, FT-Raman, 1H NMR, 13C NMR and UV–Vis spectral studies on 2-(4,6-dimethyl-1-benzofuran-3-yl) acetic acid (2DBAA). The DFT and HF calculations have been performed for the 2DBAA by using B3LYP/6-311++G (d, p) and 6-311++G (d, p) basis sets, respectively. The experimental geometrical parameters were compared with theoretical data. The fundamental modes of vibrations were assigned by PED, the computed and experimental values support each other. The 1H NMR and 13C NMR chemical shifts were estimated by GIAO method and compared with the experimental chemical shifts. The UV–Vis data of the molecule were used to study the visible absorption maxima (λmax) by using Time-Dependent DFT. The HOMO-LUMO energy distribution was computed which proves the charge transfer inside the molecule. The natural bonds orbital (NBO) and NLO properties were also computed. Further, the Mulliken charges, thermodynamic properties at different temperatures were presented. The molecular docking studies reveal that 2DBAA play a crucial role in binding with different proteins to exhibit antimicrobial activity.

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

The ratios of E/Z isomers of sixteen synthesized 1,3-dihydro-3-(substituted phenylimino)-2H-indol-2-one were studied using experimental and theoretical methodology. Linear solvation energy relationships (LSER) rationalized solvent influence of the solvent–solute interactions on the UV–Vis absorption maxima shifts (νmax) of both geometrical isomers using the Kamlet-Taft equation. Linear free energy relationships (LFER) in the form of single substituent parameter equation (SSP) was used to analyze substituent effect on pKa, NMR chemical shifts and νmax values. Electron charge density was obtained by the use of Quantum Theory of Atoms in Molecules, i.e. Bader's analysis. The substituent and solvent effect on intramolecular charge transfer (ICT) were interpreted with the aid of time-dependent density functional (TD-DFT) method. Additionally, the results of TD-DFT calculations quantified the efficiency of ICT from the calculated charge-transfer distance (DCT) and amount of transferred charge (QCT). The antimicrobial activity was evaluated using broth microdilution method. 3D QSAR modeling was used to demonstrate the influence of substituents effect as well as molecule geometry on antimicrobial activity.

Biosynthesis of zinc oxide nanoparticles using leaf extract of Calotropis gigantea: characterization and its evaluation on tree seedling growth in nursery stage

Green synthesis of zinc oxide nanoparticles was carried out using Calotropis leaf extract with zinc acetate salt in the presence of 2 M NaOH. The combination of 200 mM zinc acetate salt and 15 ml of leaf extract was ideal for the synthesis of less than 20 nm size of highly monodisperse crystalline nanoparticles. Synthesized nanoparticles were characterized through UV–Vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), EDX (energy dispersive X-ray), and AFM (atomic force microscopy). Effects of biogenic zinc oxide (ZnO) nanoparticles on growth and development of tree seedlings in nursery stage were studied in open-air trenches. The UV–Vis absorption maxima showed peak near 350 nm, which is characteristic of ZnO nanoparticles. DLS data showed that single peak is at 11 nm (100%) and Polydispersity Index is 0.245. XRD analysis showed that these are highly crystalline ZnO nanoparticles having an average size of 10 nm. FTIR spectra were recorded to identify the biomolecules involved in the synthesis process, which showed absorption bands at 4307, 3390, 2825, 871, 439, and 420 cm−1. SEM images showed that the particles were spherical in nature. The presence of zinc and oxygen was confirmed by EDX and the atomic % of zinc and oxygen were 33.31 and 68.69, respectively. 2D and 3D images of ZnO nanoparticles were obtained by AFM studies, which indicated that these are monodisperse having size ranges between 1.5 and 8.5 nm. Significant enhancement of growth was observed in Neem (Azadirachta indica), Karanj (Pongamia pinnata), and Milkwood-pine (Alstonia scholaris) seedlings in foliar spraying ZnO nanoparticles to nursery stage of tree seedlings. Out of the three treated saplings, Alstonia scholaris showed maximum height development.