S. Munusamy

Synthesis and characterization of chromium(III) Schiff base complexes: Antimicrobial activity and its electrocatalytic sensing ability of catechol

A series of acyclic Schiff base chromium(III) complexes were synthesized with the aid of microwave irradiation method. The complexes were characterized on the basis of elemental analysis, spectral analysis such as UV-Visible, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) spectroscopies and electrospray ionization (ESI) mass spectrometry. Electrochemical analysis of the complexes indicates the presence of chromium ion in +3 oxidation state. Cr (III) ion is stabilized by the tetradentate Schiff base ligand through its nitrogen and phenolic oxygen. From the spectral studies it is understood that the synthesized chromium(III) complexes exhibits octahedral geometry. Antimicrobial activity of chromium complexes was investigated towards the Gram positive and Gram negative bacteria. In the present work, an attempt was made to fabricate a new kind of modified electrode based on chromium Schiff base complexes for the detection of catechol at nanomolar level.

Synthesis, growth and photoluminescence behaviour of Gd2O2SO4:Eu3+ nanophosphors: the effect of temperature on the structural, morphological and optical properties

Gd2(SO4)3·8H2O, Gd2O2SO4, and Gd2O2SO4:Eu3+ nanoparticles have been synthesized in the presence of Gd3+ ions and sodium dodecyl sulphate (SDS) by the simple complexation-thermal decomposition (CTD) method. The structural analysis, growth mechanism and optical properties of the Gd2(SO4)3·8H2O, and Gd2O2SO4 are described by the diffraction pattern, functional group analysis, Raman, morphology, elemental analysis, and absorbance spectra. The most intriguing factor was that the Gd2O2SO4 nanoplates are in the range of 42–50 nm without adding any external stabilizer. The results revealed that the Gd2O2SO4 nanoparticles with an orthorhombic structure have a band gap of 3.12 eV. Furthermore, Gd2O2SO4 shows an intense red photoluminescence associated with the 5D0 → 7F2 transition in the presence of Eu3+. The results suggest that the Gd2O2SO4:Eu3+ nanophosphors, may have a beneficial approach in the field of biomedical application as luminescent probe/labels.

Manganese sesquioxide to trimanganese tetroxide hierarchical hollow nanostructures: effect of gadolinium on structural, thermal, optical and magnetic properties

Various hollow manganese oxide (bixbyite Mn2O3 and hausmannite Mn3O4) nanoparticles (NPs) with different morphologies were obtained from a single precursor, manganese oxalate (MnC2O4). To synthesize a Mn3O4 stacked nanostructure rather than coral-like Mn2O3 nanospheres, as synthesized MnC2O4 was thermally decomposed at 700 °C in the presence of Gd3+, through the oriented arrangement mechanism. The formation process and structural variation arising from varying the thermal treatment (450 °C and 700 °C) and the cationic dopant Gd3+ were analyzed by FTIR, TGA, and XRD. The unexpected size reduction, and significant physicochemical properties were analyzed using various techniques such as FESEM coupled with EDAX, HR-TEM, DRS-UV-vis, EPR, EIS and VSM. The addition of gadolinium induces particle size reduction and a phase transition from cubic Mn2O3 to tetragonal Mn3O4, which leads to the suppression of the electrical conductivity, and changes in the optical band gap. The prepared Mn3O4 nanocrystals exhibit ferromagnetic behavior below Tc ≈ 45 K and weak paramagnetic behavior at room temperature.

Copper vanadate nanoparticles: synthesis, characterization and its electrochemical sensing property

Copper vanadate (Cu2V2O7) nanoparticles were synthesized by a simple thermal decomposition method. The synthesized copper vanadate nanorods were characterized by X-ray diffraction analysis, and it is found that the synthesized sample belongs to monoclinic Cu2V2O7. Fourier transform infrared spectroscopy (FT-IR) confirms the formation of Cu–O bond in the sample. Ultraviolet–visible (DRS-UV–visible) spectroscopy and photoluminescence spectroscopy reveals the optical property of the Cu2V2O7 nanoparticles. The nanobar-like morphology was confirmed by both scanning electron microscopy and high resolution transmission electron microscopy. Further, the electrochemical sensing behavior of Cu2V2O7 nanoparticles was investigated by cyclic voltammetry using lidocaine as an analyte. The electrochemical sensing experiment suggests that the Cu2V2O7 nanoparticles will become a potential candidate in the field of drug sensor.

Polyaniline Nanorods: Synthesis, Characterization, and Application for the Determination of para-Nitrophenol

ABSTRACT A para-nitrophenol sensor based on a 5-sulfosalicylic acid doped polyaniline nanorods modified glassy carbon electrode is reported. The formation of 5-sulfosalicylic acid doped polyaniline was characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electroactivity of the 5-sulfosalicylic acid doped polyaniline nanorods was studied by cyclic voltammetry and differential pulse voltammetry and high response was observed for the reduction of para-nitrophenol. The calibration curve for para-nitrophenol was linear from 6.7 × 10−6 M to 112.1 × 10−6 M. The sensitivity and limit of detection were 24 nA µM−1 and 3.2 × 10−6 M, respectively. The sensor was simple, inexpensive, and employed for the determination of para-nitrophenol in tap water with recoveries from 97.6 to 101.0%.

Solid state synthesis of copper tungstate nanoparticles and its electrochemical detection of 4-chlorophenol

Copper tungstate (CuWO4) nanoparticles were prepared by Solid state synthesis. The CuWO4 nanoparticles were synthesized by reacting 1:1 mole ratio of copper chloride and sodium tungstate. The XRD pattern reveals that the synthesized CuWO4 has anorthic (triclinic) structure. In addition, the average grain size, lattice parameter values were also calculated using XRD data. The FT-IR analysis confirm the presence of Cu-O and W-O bonds in CuWO4 nanoparticles. The electrochemical sensing behavior of CuWO4 nanoparticles towards 4-chlorophenol was investigated using cyclic voltammetry.

A strategy to promote the electroactive platform adopting poly(o-anisidine)-silver nanocomposites probed for the voltammetric detection of NADH and dopamine

A study on the voltammetric detection of NADH (β-nicotinamide adenine dinucleotide), Dopamine (DA) and their simultaneous determination is presented in this work. The electrochemical sensor was fabricated with the hybrid nanocomposites of poly(o-anisidine) and silver nanoparticles prepared by simple and cost-effective insitu chemical oxidative polymerization technique. The nanocomposites were synthesized with different (w/w) ratios of o-anisidine and silver by increasing the amount of o-anisidine in each, by keeping silver at a fixed quantity. The XRD patterns revealed the semi-crystalline nature of poly(o-anisidine) and the face centered cubic structure of silver. The presence of silver in its metallic state and the formation of nanocomposite were established by XPS analysis. Raman studies suggested the presence of site-selective interaction between poly(o-anisidine) and silver. HRTEM studies revealed the formation of polymer matrix type nanocomposite with the embedment of silver nanoparticles. The sensing performance of the materials were studied via cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques. Fabricated sensor with 3:1 (w/w) ratio of poly(o-anisidine) and silver exhibited good catalytic activity towards the detection of NADH and DA in terms of potential and current response, when compared to others. Several important electrochemical parameters regulating the performance of the sensor have been evaluated. Under the optimum condition, differential pulse voltammetry method exhibited the linear response in the range of 0.03 to 900μM and 5 to 270μM with a low detection limit of 0.006μM and 0.052μM for NADH and DA, respectively. The modified electrodes exhibited good sensitivity, stability, reproducibility and selectivity with well-separated oxidation peaks for NADH and DA in the simultaneous determination of their binary mixture. The analytical performance of the nanocomposite as an electrochemical sensor was also established for the determination of NADH in human urine and water samples and DA in pharmaceutical dopamine injections with satisfactory coverage.

Molybdenum oxide nanocubes: Synthesis and characterizations

Molybdenum oxide nanoparticles were prepared by Solid state synthesis. The MoO3 nanoparticles were synthesized by using commercially available ammonium heptamolybdate. The XRD pattern reveals that the synthesized MoO3 has orthorhombic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MoO3 nanoparticles. DRS-UV analysis shows that MoO3 has a band gap of 2.89 eV. FE-SEM analysis confirms the material morphology in cubes with nano scale.

MnMoO4 nanolayers : Synthesis characterizations and electrochemical detection of QA

MnMoO4 nanolayers were prepared by precipitation method. The MnMoO4 nanolayers were synthesized by using commercially available (CH3COO)2Mn.4H2O and Na2WO4.2H2O. The XRD pattern reveals that the synthesized MnMoO4 has monoclinic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MnMoO4 nanolayers. DRS-UV analysis shows that MnMoO4 has a band gap of 2.59 eV. FE-SEM and HR-TEM analysis along with EDAX confirms the material morphology in stacked layers like structure in nano scale. Synthesized nanolayers were utilized for the detection of biomolecule quercetin (QA).MnMoO4 nanolayers were prepared by precipitation method. The MnMoO4 nanolayers were synthesized by using commercially available (CH3COO)2Mn.4H2O and Na2WO4.2H2O. The XRD pattern reveals that the synthesized MnMoO4 has monoclinic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MnMoO4 nanolayers. DRS-UV analysis shows that MnMoO4 has a band gap of 2.59 eV. FE-SEM and HR-TEM analysis along with EDAX confirms the material morphology in stacked layers like structure in nano scale. Synthesized nanolayers were utilized for the detection of biomolecule quercetin (QA).

A voltammetric biosensor based on poly(o-methoxyaniline)-gold nanocomposite modified electrode for the simultaneous determination of dopamine and folic acid

Dopamine (DA) and Folic acid (FA) are co-existing compounds in biological fluids that plays a vital role in central nervous system and human metabolism. DA is an important neurotransmitter in the brains neural circuits and its diminution often results in Parkinsons disease. Folate is another form of folic acid, which is known as one of the B vitamins. It is utilized as an additive by women during pregnancy in order to prevent the neural tube defects. The present study reports on the fabrication of electrochemical sensor for the simultaneous determination of DA and FA using poly(o-methoxyaniline)-gold (POMA-Au) nanocomposite. The POMA-Au nanocomposite was prepared via insitu chemical oxidative polymerization method and characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The suitability of POMA-Au nanocomposite as a modifier for the electrocatalytic detection of DA and FA in aqueous solution was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CA) techniques. The fabricated POMA-Au/GCE sensor exhibited sharp and intense peaks towards the electro-oxidation of DA and FA as compared to bare electrode. The sensor exhibited the promising electron mediating behavior with well separated oxidation peaks with a potential difference of about 350.0 mV. The linear calibration plots of DA and FA were obtained from 10.0 to 300.0 μM and 0.5 to 900.0 μM with the detection limits of 0.062 μM and 0.090 μM, respectively. The reliability of this sensor was verified to be precise as well as sensitive for the determination of DA and FA in pharmaceutical samples and human urine samples.