Visible Studies Research Articles

Comparative Study: Synthesis, Characterization, and ORR Activity of Pot and TiO2-Pot Nanocomposites

o-toluidine was polymerized with the incorporation of different amount of titanium dioxide (TiO2) by chemical oxidation method using potassium perdisulphate as oxidizing agent. Comparative studies were carried out with different nanocomposites of varying compositions of TiO2/PoT against poly-o-toluidine (PoT). The resulting poly-o-toluidine – TiO2 nanocomposites (PoTTNCs) were characterized by UV–Vis and FTIR spectral studies. TiO2 has a deep influence in the crystallinity of PoT chains order in nanocomposite structure as observed in the XRD pattern. Electrochemical characterization studies were carried out to compare the improved performance of varied compositions of TiO2/PoT with respect to PoT in different atmospheres.

Combustion synthesis CuO nanoparticles: Application to photocatalytic activity

Copper oxide nanoparticle (NPs) was prepared by a green Chemistry approach. The synthesized NPs were characterized by XRD, SEM, FT-IR, and UV–Vis spectrophotometer. The XRD peaks matches with the standard X-ray diffraction patterns confirming monoclinic crystal phase. FT-IR absorption exhibits the existence of metal oxygen stretching bond at 422 cm−1. SEM study shows that the particles were highly porous in nature having irregular shape and are agglomerated. EDX spectrum confirms the presence of Cu and O in the synthesized NPs. The band gap was found to be 1.65 eV from UV– Vis studies. An enhanced photo degradation of Rose Bengal dye was indicated by synthesized NPs.

Comments Regarding “Volumetric, UV–Vis and FT IR Studies of Isoniazid in Diethylsulfoxide Solutions”

A polemic is given concerning the volumetric properties and comparisons presented in the published paper by Markarian and coworkers.

Exploring the binding interactions of janus green blue with serum albumins from spectroscopic and calorimetric studies aided by in silico calculations

Binding interactions of the phenazinium dye Janus green blue (JGB) with human and bovine serum albumins (BSA – and BSA) have been explored for the first time from multi-spectroscopic and calorimetric measurements aided by in silico calculations. The formation of ground state complexes between JGB and the respective serum albumins have been suggested from the UV–Vis and steady-state fluorescence spectroscopic studies. The nonlinear Stern Volmer (SV) plots at higher concentrations of JGB primarily indicate the formation of more than one ground state complexes in BSA –/BSA–JGB systems. Modified SV plots and isothermal titration calorimetry (ITC) studies however signify the possibilities of one type of binding complexes between HSA/BSA – JGB systems. Binding constants and the thermodynamic parameters associated with the HSA/BSA–JGB complexes have also been estimated from the ITC studies. Förster distances (R0 ) for HSA–JGB and BSA–JGB complexes are estimated from Förster resonance energy transfer (FRET) results. Variations in the micro-environment of the Tyr and Trp residues of the serum proteins in presence of JGB have been observed from the synchronous fluorescence measurements. The conformational changes in the protein structures induced by the dye JGB have been revealed from 3 D fluorescence and circular dichroism (CD) studies. The experimental observations are supported by in silico calculations. This in depth investigation on the interactions of serum albumins with JGB may provide the fundamental information toward exploring the therapeutic efficacy of JGB as a potent drug molecule. Communicated by Ramaswamy H. Sarma

Optical characterization of toluene-based Schiff base metal complexes for optoelectronic applications

In the present research work, Schiff base ligand was synthesized by the condensation reaction of 3,4-diaminotoluene with salicylaldehyde. Ligand was used for complexation with various metals such as Mn, Fe, Co, Ni, Cu and Zn. Characterization was made by IR, NMR, UV–Vis and fluorescence studies. The structural characterizations were made on the basis of resonance peaks observed in 1HNMR spectra and presence of bands in FTIR spectra. Shifting of peaks in 1HNMR spectra and functional group positions in the FTIR spectra are discussed in relation with complexation. Optical characterizations were made on the basis of transitions in absorption and emission processes. Out of the metal complexes studied, Zn complex shows maximum fluorescence intensity. The Zn complex in solution form also shows strong glow when exposed to UV lamp. Photometric parameters, quantum yield and HOMO-LUMO gap were estimated in order to see the possible application of Zn complex in display devices.

Molecular docking, photocatalytic activity and biomedical investigations of some metal complexes

Metal(II)–(furfural-L-his) complexes with a potentially bidentate furfural-L-his have been synthesized. Furfural-L-his and its Co/Ni/Cu/Zn(II)–(furfural-L-his) complexes have been optimized by DFT. The structural features were determined from their elemental analyses, molar conductance, magnetic, UV–Vis, IR, mass, 1H NMR and EPR spectral studies. On the basis of electronic spectral data and magnetic measurements, suitable geometry has been proposed for each complex. The redox behaviour of Cu(II)–(furfural-L-his) complex has been studied by cyclic voltammetry. Thermal decomposition profiles are consistent with the proposed formulation of Co/Ni/Cu/Zn(II)–(furfural-L-his) complexes. PXRD studies reveal that furfural-L-his and Zn(II)–(furfural-L-his) complex are of nanomeric structure. SEM images of furfural-L-his exhibit flake-like morphology. Photodegradation of methylene blue dye indicates that they are photocatalyticaly efficient. NBO and NPA shown considerable reduction in the formal charge on metal ions. Docking analysis with EGFR and cyclooxygenase-2 receptor has been performed to find the best binding energy. Antimicrobial, antioxidant and anti-inflammatory activity against standard at variable concentrations revealed that the Co/Ni/Cu/Zn(II)–(furfural-L-his) complexes show enhanced antimicrobial, free radical scavenging and anti-inflammatory activities as compared to furfural-L-his. Furfural-L-his and Cu(II)–(furfural-L-his) complex have been tested against human ovarian cancer cells, which showed that Cu(II)–(furfural-L-his) complex exhibited promising anticancer activity. Communicated by Ramaswamy H. Sarma

Understanding the structure and conformation of bovine hemoglobin in presence of the drug hydroxyurea: multi-spectroscopic studies supported by docking and molecular dynamics simulation

Binding interaction between the small antitumor drug Hydroxyurea (HU) and Bovine Hemoglobin (BHb) has been explored in details from multi-spectroscopic and computational studies. The formation of ground state complex between BHb and HU has been suggested from the electronic UV–Vis and steady-state fluorescence spectroscopic studies. The quenching in fluorescence of BHb in presence of HU at varied concentrations has been analyzed from the SV plots. Static type of quenching has been suggested from time-resolved fluorescence spectroscopic studies. Binding parameters associated with the BHb-HU complex have also been estimated from the temperature dependent fluorescence spectroscopic studies. Alterations in the micro-environment of the Tyr and Trp residues of BHb in presence of HU have been observed from the synchronous fluorescence measurement. The result obtained from CD spectroscopic measurements signify partial unfolding in the secondary structure of BHb due to binding with HU molecule. The experimental observations are supported by theoretical studies. Molecular docking and molecular dynamics simulations have been performed to investigate the structural stability and compactness of BHb in the binding interaction between BHb and HU. The interaction of BHb with HU is expected to provide fundamental insights towards understanding the therapeutic effectiveness of HU upon interaction with BHb used in chemo-, radio therpeutic procedures and also in the treatment of SCD.

Antioxidant, antihemolysis, and retinoprotective potentials of bioactive lipidic compounds from wild shrimp (Litopenaeus stylirostris) muscle

ABSTRACT The oxidative stress damage on cells is an example of roles in the pathogenesis of different degenerative diseases and the search of compounds that can slow this oxidation is continuous. The aim of this work was to obtain bioactive fractions from wild shrimp (Litopenaeus stylirostris) muscle, in order to evaluate their protective capacity and chemo-structurally characterize them. ABTS and DPPH, and FRAP assays suggested that bioactive fractions possess free radical-scavenging capacity, and reducing power, respectively. An inhibitory effect observed on AAPH-induced hemolysis and results from an H2O2-derived radicals-scavenging assay (retinoprotective) suggest that these fractions can exert their protective activity in human cells. UV–Vis, fluorescence, 13C-, 1H-NMR, and ESI-MS studies performed on the most bioactive fraction, suggests that their main components are eicosapentaenoic acid, dioctyl phthalate, and a possibly novel indolocarbazole alkaloid derivative. These results suggest that these compounds are good candidates to further investigations as possible chemoprotective agents.

Synthesis, thermal analysis, spectroscopy and magnetic properties of some transition metals complexes derived from new azo compound

Abstract A new Azo compound (C17 H13ClN2O4S) (E)-4-chloro-5-((2-hydroxynaphthalen-1-yl)diazenyl)-2-methylbenzenesulfonic acid (L) was synthesized. The prepared compound was used as a ligand to prepare monomeric transition complexes [M(L)(H2O)2Cl2 via reaction of ligand (L) with hydrate metal salts M(II) where [M = Manganese (II), Cobalt(II), Nickel(II), Copper (II)] in a (1:1) ratio. The data were obtained from 13C NMR, UV–VIS and FT-IR studies, elemental microanalysis, TGA, molar conductance, metal content, magnetic moment measurements and thermal analysis confirmed the formation of ligand and their complexes and all the prepared complexes have octahedral geometrical structures. The FTIR spectra revealed that ligand to the metals in a uninegative bidentate, with N donor sites of azo group and the deprotonated naphtholic O. The data of thermal analysis shows that the water molecules (coordinated & hydrated) and anions are removed in a successive one or two steps immediately followed by decomposition of ligand in the consecutive steps. The magnetic moment values at room temperature of synthesized complexes are 5.2, 4.3, 3.2 and 1.3 B.M for complexes Mn(II), Co(II), Ni(II) and Cu(II), respectively, suggesting that the complexes are paramagnetic.

Detection of Hg2+ ion using highly selective fluorescent chemosensor in real water sample and in-vitro cell study upon breast adenocarcinoma (MCF-7)

ABSTRACTA novel rhodamine-based chemosensor (R) was designed and synthesised for selective recognition of Hg2+ ion in real water samples collected from different places. The chemosensor was prepared in green condition with high yield. The selectivity of R was examined with various metal ions, among which only Hg2+ was identified selectively with off–on mechanism along with enhancement of fluorescence. Metal ions recognition has been carried out using UV–vis and fluorescence studies taking µM concentration of chemosensor R in HEPES buffer. The detection limit of R was calculated and found to be 4.4 × 10–9 M. Quantum chemical (DFT) calculation was carried out in order to acquire knowledge about the stability of R in presence of Hg2+ ions. Cell viability and fluorescence microscopic experiments showed R as cytocompatible and can be used as a fluorescent probe for detecting Hg2+ in living cells.

Synthesis, optical characterization, and TD-DFT studies of novel mero/bis-mero cyanine dyes based on N-Bridgehead heterocycles

Novel mero/bis-mero cyanine dyes based on N-Bridgehead imidazo[1,2-g]quinolino[2,1-a][2,6]naphthyridine have been synthesized and characterized to evaluate intramolecular charge transfer (ICT) effect on the energy gap (E0-0). The UV–vis and emission spectral studies revealed that dyes are absorbed in the region of λmax 485–577 nm and emitted at 567–673 nm. Their solvatochromic behavior in solvents of various polarities, CCl4, C6H6, H2O, CHCl3, acetone, and DMF, was studied to emphasize the effect of solvent polarity on the absorption maxima, molar extinction coefficients of the dyes, and excitation energy of the dyes. Their electron cloud delocalization in HOMO/LUMO levels were studied by DFT using Gaussian 09 software. Time-dependent density functional theory (TD-DFT) was applied to theoretically explore the first excitation energy (E0-0) of these dyes, which was in good agreement with experimental results.

Synthesis, characterization, theoretical simulation, and DNA-nuclease activity of a newly synthesized Mn–oximato complex

A new [MnII(sal-oxime)2(H2O)2] complex has been synthesized and characterized by various spectroscopic techniques (IR, UV–vis, ESI-MS, and EPR studies). The molecular geometry of the complex was further established by DFT study. TD-DFT calculations also showed a good agreement with the experimental results of the complex. The DNA-binding activity of the complex has been studied by various physicochemical tools such as UV–vis spectroscopy and viscosity measurements. The intrinsic binding constant (Kb) of the complex with CT-DNA was calculated to be (2.40 ± 0.2) × 103 M−1. The results of the DNA-binding experiments were also supported by molecular docking. The compound showed a good nuclease activity which was assessed by gel electrophoresis technique.

Selective optical detection of HSO4− via hydrolysis of a simple Schiff Base

A very simple Schiff Base derived from 1-Naphthylamine and 4-(Trifluoromethy) benzaldehyde (L) was prepared as a selective colorimetric and turn-on fluorescent sensor for hydrogen sulfate. In the CH3CN:H2O (3:2, v/v) solvent system, L shows a highly selective colorimetric response to HSO4− ions by changing its color from yellow to colorless immediately. In addition, the weakly fluorescent receptor L shows a highly selective enhancement of fluorescence intensity at 425 nm for HSO4− upon excitation at 320 nm. The recognition process is proven to be hardly influenced by the other tested competitive anions. The sensing is suggested to involve a hydrolysis process promoted by HSO4− which has been further supported by UV–Vis, 1H NMR and HRMS spectroscopic studies. Applicability of L to detect HSO4− in tap water has been demonstrated. An easy-to-prepare test strip of L has also been made for the naked-eye detection of HSO4− in real samples.

Synthesis of asymmetrical tridendate Schiff bases and metal complexes and investigation of anticarcinogen effects on human colon and cervical cancers

ABSTRACTThe metal complexes of Zn(II), Ni(II), Cu(II) and Pb(II) with asymmetrical Schiff bases were synthesized. The asymmetrical Schiff base was obtained through the condensation of 1,2-phenylenediamine, 4-methyl-1,2-phenylenediamine, 2-hydroxy-1-napthaldehyde and biphenyl-4-carbaldehyde. The new Schiff base ligands (L1' and L2') and their metal complexes were characterized by TG/DTG, FT-IR, 1H-NMR, UV–Vis, ESR, powder XRD, elemental analysis, magnetic moment and fluorescence studies. The powder XRD studies indicate that Co(II) and Cu(II) complexes are amorphous, while Ni(II) and Zn(II) complexes are crystalline. The anticarcinogenic effects of L1' and L2' were also investigated against colon (SW-620) and cervical cancer (HeLa) cell lines and compound L2' was found to possess the highest anticarcinogenic potential, with 16.7 µM and 27.5 µM of IC50 values for HeLa and SW620 cells, respectively.

Spectroscopic characterisation and structural modelling of new hydrogen-bonded charge transfer complex between picric acid and 3-aminoquinoline

ABSTRACTNew charge transfer hydrogen-bonded (HBCT) complex between the electron donor 3-aminoquinoline with the electron acceptor picric acid has been synthesised and characterised experimentally and theoretically using a variety of physicochemical techniques. The experimental work included the use of UV–vis, IR and 1H NMR studies to characterise the complex in different hydrogen-bonded solvents. The studied reaction proceeded based on 1:1 stoichiometric ratio and the stability constant recorded high values. The solid complex was prepared and characterised by elemental analysis that confirmed its formation in 1:1. Both IR and NMR studies supported the existence of proton and charge transfers in the formed complex. In complemented with experimental results, molecular modelling using DFT using 31–6G(d,p) basis set was carried out in the gas phase where the existence of both charge and hydrogen transfers was reconfirmed in the obtained complex in full consistency with experimental results.

A bifunctional 2,2′:6′,2″-terpyridine-based ligand for ratiometric Cu(II) sensing

Synthesis and characterization of the bifunctional sensor receptor ligand N-([2,2′:6′,2″-terpyridine]-4′-yl)methyl)-N-propylacrylamide (1) and the model ligand N-([2,2′:6′,2″-terpyridine]-4′-yl)methyl)-N-propylisobutyramide (2) are described. Ligand 1 is a receptor for Cu(II) that is copolymerizable with N-isopropylacrylamide giving a ratiometric sensor of weakly bound Cu(II) in environmental waters. Ligand 2 is a model for copolymerized 1 whereby the reactive acrylamide group is replaced by isobutyramide. Solution speciation of complexes of Cu(II) and Zn(II) with 2 were investigated spectroscopically and their solid-state structures were studied through single-crystal X-ray diffraction. Solution UV–vis and fluorescence studies show a preference of 2 toward Cu(II) over Na(I), Zn(II), Cu(II), Co(II), Mn(II), Ni(II), Cd(II), and Pb(II) in accord with the Irving–Williams series and other coordination principles. Solution speciation determined in a weakly coordinating aqueous-organic (60 : 40 DMF/H2O) medium indicates 1 : 1 Cu(II):2 binding as desired in that formation of [Cu(2)2]2+ would crosslink the polymer sensor. The crystal structures of [Cu(2)(NO3)2] and [Zn(2)(NO3)2]·MeOH·1/2Et2O display distorted octahedral geometries where 2 coordinates meridionally and two nitrate groups occupy the remaining sites around the metal center.

Synthesis, characterization, preliminary biological screening, and interaction studies of the bis(pyridinium)amine compound, 4,4'-[(2-aminophenyl)azanediyl]bis(1-methylpyridin-1-ium)triflate with biological macromolecules

Bis(pyridinium)amine 4,4'-[(2-aminophenyl)azanediyl]bis(1-methylpyridin-1-ium)triflate ([H2L][TfO]2) was synthesized and characterized by elemental analysis, UV–Vis, fluorescence, FT-IR, 1H, and 13C NMR spectroscopies, mass spectrometry, and a single crystal X-ray structure analysis. The potential of the title compound to interact with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) was investigated with the help of UV–Vis, florescence and docking studies. UV–Vis spectroscopy indicated that the binding of [H2L][TfO]2 with CT–DNA took place via a groove binding mode. [H2L][TfO]2–BSA was characterized by moderate binding constant, electrostatic interaction and spontaneous association. [H2L][TfO]2 Displayed excellent enzyme inhibition activity with Trypsin and acetylcholine esterase. [H2L][TfO]2 was found to be an efficient antioxidant, scavenging the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) in a dose dependent manner. [H2L][TfO]2 exhibited activity against six microbes selected for the study.

Two new fluorescent Zn2+ sensors exhibiting different sensing mode with subtle structural changes

Two novel receptors HL-1 and HL-2 without and with hydroxyl groups were designed and synthesised. Both receptors showed highly selective coordination towards Zn2+ and exhibited diverse sensing behaviour due to the structural variations. HL-1 showed monotonous ‘turn-on’ response towards Zn2+ while HL-2 displayed highly Zn2+ sensitive ‘turn on’ and ‘ratiometric’ properties. Detailed Job plot experiment, single crystal data, 1H NMR, ESI-MS, UV–vis and density functional theory calculation studies were conducted to understand the binding modes of HL-1 and HL-2 with Zn2+. These results revealed the binding stoichiometric ratio between receptors and Zn2+ were 1:1 with low detection limits and high binding constants.

Binuclear Cu(II) Schiff base complexes as prescursors for the synthesis of CuO nanoparticles: anticancer activity against MCF-7 cell line

Homobinuclear Cu(II) complexes 1 and 2 were synthesized and characterized by elemental analysis, FTIR, 1H NMR, Mass, UV–vis, magnetic moment, ESR and TGA studies. The synthesized complexes 1 and 2 were used as precursors for the synthesis of CuO Nps by calcination method. CuO Nps were characterized by FTIR, XRD, scanning electron microscopy (SEM), and EDX. XRD peaks clearly indicated the monoclinic structure of CuO. CuO nanoparticles were synthesized with average particle size 3–4 and 5–10 nm. The morphologies and size of the obtained products were further investigated by SEM. Presence of essential constituents of CuO Nps was investigated by EDX studies. The Anticancer activity of the precusors 1&2 and its nanoparticles have been analyzed against the MCF-7 cell line by MTT assay. The Precusor 1 with IC50 value 12.66 μM was found to have high anticancer activity than other compounds.Synopsis:Binuclear Cu(II) Schiff base complexes 1 & 2 were synthesized from the ligands L1 and L2, respectively.Binuclear Cu(II) complexes were successfully used as a precursor for the synthesis of CuO Nps.The ligands, precusors, and the CuO Nps were analyzed for their anticancer activity against the MCF-7 cell line.Precursor 1 synthesized from the ligand L1 shows high activity than other compounds due to the presence of the heterocyclic moiety.

Toward designing efficient rice-shaped polyaniline@bismuth oxide nanocomposites for sensor application

Efficient rice-shaped polyaniline@bismuth oxide (PANI@Bi2O3) nanocomposites were synthesized by in situ sol–gel method. The sol of polyaniline was added to the gel of Bi2O3 in different mixing volume ratios of inorganic reactant and with a fixed mixing volume ratio, i.e., 1:1, of organic polymer. The physicochemical characterization was carried out by SEM, XRD, FTIR, UV–Vis and simultaneous TGA studies. PANI@Bi2O3 were deposited on a silver electrode (AgE, surface area, 0.0216 cm2) to give an efficient sensor with a fast response toward the toxic 3-methoxy phenol in liquid phase. The calibration plot is linear (r 2 = 0.9809) over the 0.09 nM to 0.09 mM 3-methoxy phenol concentration ranges. The sensitivity is ~0.8796 µAcm−2 µM−1, and the detection limit is 0.016 ± 0.002 nM (signal-to-noise ratio, at a SNR of 3), which leads to a promising future sensitive sensor development using organic–inorganic nanocomposites by reliable I–V method for the potential applications of hazardous phenolic compounds in environmental and healthcare fields. Schematic diagram for the synthesis of rice-shaped polyaniline@Bi2O3 nanocomposite.