Determination of Chloramphenicol in Pharmaceutical Samples at Electrochemically Pretreated Glassy Carbon Electrode

This study focuses on the importance of electrochemical pretreatment of glassy carbon electrode (GCE) for the determination of chloramphenicol (CAP) in pharmaceutical formulations using square wave voltammeter. Electrochemical pretreatment of the electrode greatly enhanced the reduction peak current (Ip) of CAP that it shows a reduction peak current response at -0.032 V vs. Ag/AgCl at the GCE in 0.05 M acetate buffer of pH 5. Detailed experiments were carried out to establish the electrochemical property, the optimal buffer and its pH, electrode pretreatment potential, effect of concentration and square wave voltammetric parameters. Following optimization of the instrumental parameters and pH of buffer solution, the peak current response for the reduction of CAP shows an enhanced response, 5.82 times greater than the bare GCE. The method was successfully applied to three CAP containing pharmaceutical samples: CAP eye drop, CAP palmitat oral suspension and CAP as sodium succinate and the level of CAP in these samples was verified.

A Tetranuclear Dysprosium Schiff Base Complex Showing Slow Relaxation of Magnetization

A tetranuclear dysprosium Schiff base complex was isolated by reacting dysprosium chloride with 2-hydroxy-3-methoxybenzaldehyde and 2-(aminomethyl)pyridine in-situ under basic conditions. The isolated Dy(III) complex was characterized by elemental analyses, single crystal X-ray diffraction and molecular spectroscopy. The complex crystallizes in the triclinic space group P-1 with unit cell parameters of a = 10.2003 (4), b = 13.8602 (5), c = 14.9542 (6), α = 94.523 (3), β = 109.362 (4), and γ = 99.861 (3). The magnetic properties of 1 have been investigated by DC and AC susceptibility measurements. The DC measurements reveal weak exchange coupling of antiferromagnetic nature. In the AC measurement, the complex shows a slow relaxation of magnetization in the absence of an external magnetic field

Photoelectrochemical cells based on emeraldine base form of polyaniline

Photoelectrochemical cells (PECs) have been fabricated using the emeraldine base form of polyaniline (EB) as a photoactive material and Eu2+/Eu3+ redox couple in methanol as an electrolyte. A PEC with a structure: Glass/ITO/EB/electrolyte/Pt produces an open-circuit voltage (V OC) of -0.132 V and a short-circuit current (I SC) of 0.64 µA cm-2 under 50 mW cm-2 white light illumination from Xe lamp. In an effort to increase the photoresponse, a PEC with a structure: Glass/ITO/EB:Nc-TiO2/Electrolyte/Pt has been devised in which a composite film of EB and nanocrystalline TiO2 (Nc-TiO2) is used as a photoactive material. The cell shows a V OC of -0.205 V and an I SC of 105 µA cm-2 when illuminated under the same conditions

Triangulo -{ErIII^{III}$_{3}} complex showing field supported slow magnetic relaxation

The triangulo-{Er$_{3}$} complex [Er$_{3}$Cl(o-van)$_{3}$(OH)$_{2}$(H$_{2}$O)$_{5}$]Cl$_{3}$·nH$_{2}$O (n = 9.4; H(o-van) = o-vanillin) (1) was generated by an in situ method. The isolated Er(III) complex 1 was characterized by elemental analysis and molecular spectroscopy. The results of single crystal X-ray diffraction studies have shown that 1 is built up of trinuclear [Er$_{3}$Cl(o-van)$_{3}$(OH)$_{2}$(H$_{2}$O)$_{5}$]$^{3+}$ complex cations, chloride anions and water solvate molecules. Within the complex cation the three Er(III) central atoms are placed at the apexes of a triangle which are bridged by three (o-van)$^{–}$ ligands with additional chelating functions and two μ$_{3}$-OH$^{–}$ ligands. Additionally five aqua and one chlorido ligands complete the octa-coordination of the three Er(III) atoms. AC susceptibility measurements reveal that the compound exhibits slow magnetic relaxation with two relaxation modes

Investigations on the Spin States of Two Mononuclear Iron(II) Complexes Based on N-Donor Tridentate Schiff Base Ligands Derived from Pyridine-2,6-Dicarboxaldehyde

Iron(II)-Schiff base complexes are a well-studied class of spin-crossover (SCO) active species due to their ability to interconvert between a paramagnetic high spin-state (HS, S = 2, $^{5}$T$_{2}$) and a diamagnetic low spin-state (LS, S = 0, $^{1}$A$_{1}$) by external stimuli under an appropriate ligand field. We have synthesized two mononuclear FeII complexes, viz., [Fe(L$^{1}$)$_{2}$](ClO$_{4}$)$_{2}$.CH$_{3}$OH (1) and [Fe(L$^{2}$)$_{2}$](ClO$_{4}$)$_{2}$.2CH$_{3}$CN (2), from two N$_{6}$–coordinating tridentate Schiff bases derived from 2,6-bis[(benzylimino)methyl]pyridine. The complexes have been characterized by elemental analysis, electrospray ionization–mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FTIR), solution state nuclear magnetic resonance spectroscopy, $^{1}$H and $_{13}$C NMR (both theoretically and experimentally), single-crystal diffraction and magnetic susceptibility studies. The structural, spectroscopic and magnetic investigations revealed that 1 and 2 are with Fe–N$_{6}$ distorted octahedral coordination geometry and remain locked in LS state throughout the measured temperature range from 5–350 K

<b>The photoresponse behavior of a MEH-PPV sensitized titanium dioxide photoelectrochemical cell</b>

A solid-state photoelectrochemical cell based on polymer-sensitized nanocrystalline titanium dioxide (nc-TiO2) was constructed and studied for its photoresponse behavior. Poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and Poly[oxymethylene-oligo(oxyethylene)] (POMOE), complexed with I3-/I- redox couple were used as a polymer-sensitizer to TiO2 and as a solid polymer electrolyte, respectively. The device produced a short-circuit current of 0.145 mA/cm2, and an open-circuit voltage of 410 mV under the irradiance of 100 mW/cm2. The power conversion efficiency and the fill factor were 0.03 % and 0.5, respectively. The monochromatic induced photon-to-current conversion efficiencies for backside (ITO/nc-TiO2/MEH-PPV) and for front side (ITO/PEDOT) illuminations were 1.8 % and 1.4 %, respectively

<b>Synthesis and characterization of poly[3-(2’,5’-diheptyloxy-phenyl)thiophene] for use in photoelectrochemical cells</b>

Poly[3-(2',5'-diheptyloxyphenyl)thiophene], PDHOPT, has been prepared electrochemically from its monomer for solar cell application. PDHOPT exhibits a band gap of 2.1 eV. The redox properties of PDHOPT were characterized using cyclic voltammetry. The estimated energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are -5.3 eV and -3.2 eV, respectively. PDHOPT sensitizes nanocrystalline titanium dioxide (nc-TiO₂) in liquid-state photoelectrochemical cells. Devices where the photoactive electrode consists of nc-TiO2/PDHOPT composite film show improved performance over those that consist of only PDHOPT. Devices made of TiO₂/PDHOPT composite film produced an open-circuit voltage of 0.52 V, a short-circuit current of 29 μA/cm², and a fill factor of 0.54 when illuminated with white light intensity of 80 mW/cm²

Isotherms and Kinetic Studies of Copper Removal from Textile Wastewater and Aqueous Solution Using Powdered Banana Peel Waste as an Adsorbent in Batch Adsorption Systems

Heavy metals that are present in surface water and wastewater are becoming a severe environmental problem. Because of its toxicity, heavy metal removal has become the main priority for environmental concerns. Banana peels are low-cost agricultural waste that could be used for heavy metal adsorption in wastewater. The main objective of this study is to evaluate the effective powdered banana peel for the removal of copper (II) from aqueous solutions and real wastewater. The banana peels were collected from domestic waste and ground to get a particle size of 150 µm. Powdered banana peel waste adsorbent (PBPWA) contained moisture content, ash content, volatile matter, and bulk density of 3.8%, 3.5%, 37.5%, and 0.02 g/cm3, respectively. The Fourier-transform infrared spectroscopy (FTIR) results showed that the alkyne, aldehyde, and amide functional groups were dominant in the powdered banana peel surface, and the scanning electron microscope showed the morphology of the adsorbent. Physicochemical characteristics of the raw wastewater revealed that the concentration of Cu (II), Pb (II), COD, BOD5, and Cd (II) were 2.75 mg/L, 2.02 mg/L, 612.16 mg/L, 185.35 mg/L, and 0.01 mg/L, respectively. At pH 5, adsorbent dose of 2g/100 mL, initial copper (II) concentration of 80 mg/L, and contact time of 90 min, the maximum removal efficiency of synthetic wastewater was 96.8% and textile wastewater was 69.0%. The adsorption isotherm fitted well with the Langmuir isotherm model at R2 = 0.99. The kinetics of copper (II) adsorption followed the second-order kinetic model better. Finally, these studies showed that banana peel bio-adsorbent is a potential adsorbent for heavy metal removal from synthetic and textile wastewater

Spin state of two mononuclear iron(II) complexes of a tridentate bis(imino)pyridine N-donor ligand: Experimental and theoretical investigations

Investigations on the spin states of octahedral Fe(II) complexes have received special attention due to their clear discrimination in the spin states of the d-orbitals. As a means to further understand the factors that influence the spin-crossover (SCO) phenomenon in Fe(II) systems, we herein report two mononuclear Fe(II) complexes, [FeL2](ClO4)2·2CH3OH (1) and [FeL2](BF4)2·CH3CN·CH3OH (2), derived from a novel N3-donor Schiff base ligand, 2,6-bis[(3-methylbenzylimino)methyl]pyridine (L) with varying counteranion and the diamagnetic [ZnL2](BF4)2 congener for a comparative investigation. The complexes have been synthesized and characterized by electrospray-ionization mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, single-crystal X-ray diffraction (XRD) and magnetic susceptibility studies. Structural and magnetic investigations reveal that both 1 and 2 show Fe__N6 distorted octahedral geometry and are locked in the diamagnetic LS state throughout the entire explored temperature range from 1.8 to 400 K. The LS state of [FeL2]2+ is also confirmed by comparing the experimentally found structural parameters, NMR chemical shifts and excitation energies in the visible region with density functional theory (DFT) calculations