Publications

Spectral characteristics and fluorescence quenching of N,N′-bis(4-pyridyl)-3,4:9,10-perylenebis(dicarboximide) (BPPD)

Influence of redox electrolyte on the device performance of phenothiazine based dye sensitized solar cells

We report on a new organic dye based on phenothiazine for DSC application.

CCDC 877330: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A hybrid electro-responsive SWNT/PEDOT: PSS-based membrane towards soft actuator applications

The flexible soft actuators of conducting polymers can directly convert electrical stimulus into mechanical motions, which can be used for robotics and biomimetic applications. Herein, an electro-responsive membrane actuator based on poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), functionalized single-walled carbon nanotube was fabricated using solution casting method with poly(vinyl alcohol) as a base intermediate polymer membrane. The poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) was evenly ornamented onto the single-walled carbon nanotube/poly(vinyl alcohol) membrane (single-walled carbon nanotube/ poly(vinyl alcohol)/ poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)) surfaces through dip coating and verified by scanning electron and transmission electron microscopy analysis. The desirable bending response of the fabricated single-walled carbon nanotube/ poly(vinyl alcohol)/poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) membrane with time at different voltages and generated tip force makes it a promising material as a new-generation conductive polymer-based soft actuator. A permutation of the electrical conductivity, more surface area, and admirable electromechanical properties of the single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) components consequences in the composite electrode exhibited excellent actuation performance compared to the ionic polymer-metal composite actuators with Pt electrodes surface. The fabricated actuator membrane can be employed for artificial muscles, robotics, and other bio-mimetic applications.

Introductory Chapter: Humidity Sensors

Presence versus Proximity: The Role of Pendant Amines in the Catalytic Hydrolysis of a Nerve Agent Simulant

Abstract Amino‐functionalized zirconium‐based metal‐organic frameworks (MOFs) have shown unprecedented catalytic activity compared to non‐functionalized analogues for hydrolysis of organophosphonate‐based toxic chemicals. Importantly, the effect of the amino group on the catalytic activity is significantly higher in the case of UiO‐66‐NH 2 , where the amino groups reside near the node, compared to UiO‐67‐ m ‐NH 2 , where they are directed away from the node. Herein, we show that the proximity of the amino group is crucial for fast catalytic activity towards hydrolysis of organophosphonate‐based nerve agents. The generality of the observed amine‐proximity‐dictated catalytic activity has been tested on two different MOF systems which have different topology. DFT calculations reveal that amino groups on all the MOFs studied are not acting as Brønsted bases; instead they control the microsolvation environment at the Zr 6 ‐node active site and therefore increase the overall catalytic rates.

Conductometric Study of Complexation of Macrocyclic Compounds with Zinc(II) and Copper(II) Ions in Aqueous-Organic Solvent Mixtures

The conductance behavior of Zn2+ and Cu2+ and their complexes with two ligands (crown ethers) have been inspected in 10, 20, 30, and 40% DMF–water mixed solvent at 298.15, 308.15, 318.15, and 328.15 K. The conductance study indicates a 1 : 1 complexation mode amongst the metal ions and ligands hereby studied. The order of stability constants with crown ethers was found to be Cu(II) > Zn(II). The stability constant for Zn2+ ion with crown ether complexes in 10 and 40 wt % solvent composition varies in the order of benzo-18-crown-6 > benzo-15-crown-5. The stability constant for Cu2+ ion with crown ether complexes in 10% solvent composition varies in the order of benzo-18-crown-6 > benzo-15-crown-5, and for 40% solvent composition, it is benzo-18-crown-6 > benzo-15-crown-5. The enthalpy and the entropy of complexation were estimated from the variation of stability constants with respect to the variation of temperature. The observed results elicit that the complexation is enthalpy stabilized, but entropy destabilized.

CCDC 954877: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Metal organic frameworks as catalysts in solvent-free or ionic liquid assisted conditions

This Critical Review describes the use of Metal Organic Frameworks as Solid Catalysts under Solvent-Free or Ionic Liquid Assisted conditions.

Erratum to “Synthesis and biological evaluation of some thiazolidinone derivatives of steroid as antibacterial agents” [Eur. J. Med. Chem. 44 (2009) 2597–2600]

Efficient solar photocatalyst based on cobalt oxide/iron oxide composite nanofibers for the detoxification of organic pollutants

A Co3O4/Fe2O3 composite nanofiber-based solar photocatalyst has been prepared, and its catalytic performance was evaluated by degrading acridine orange (AO) and brilliant cresyl blue (BCB) beneath solar light. The morphological and physiochemical structure of the synthesized solar photocatalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). FESEM indicates that the Co3O4/Fe2O3 composite has fiber-like nanostructures with an average diameter of approximately 20 nm. These nanofibers are made of aggregated nanoparticles having approximately 8.0 nm of average diameter. The optical properties were examined by UV-visible spectrophotometry, and the band gap of the solar photocatalyst was found to be 2.12 eV. The as-grown solar photocatalyst exhibited high catalytic degradation in a short time by applying to degrade AO and BCB. The pH had an effect on the catalytic performance of the as-grown solar photocatalyst, and it was found that the synthesized solar photocatalyst is more efficient at high pH. The kinetics study of both AO and BCB degradation indicates that the as-grown nanocatalyst would be a talented and efficient solar photocatalyst for the removal of hazardous and toxic organic materials.

Alumina-coated Ag nanocrystal monolayers as surfaceenhanced Raman spectroscopy platforms for the direct spectroscopic detection of water splitting reaction intermediates

A novel Ag-alumina hybrid surface-enhanced Raman spectroscopy (SERS) platform has been designed for the spectroscopic detection of surface reactions in the steady state. Single crystalline and faceted silver (Ag) nanoparticles with strong light scattering were prepared in large quantity, which enables their reproducible self-assembly into large scale monolayers of Raman sensor arrays by the Langmuir-Blodgett technique. The close packed sensor film contains high density of sub-nm gaps between sharp edges of Ag nanoparticles, which created large local electromagnetic fields that serve as "hot spots" for SERS enhancement. The SERS substrate was then coated with a thin layer of alumina by atomic layer deposition to prevent charge transfer between Ag and the reaction system. The photocatalytic water splitting reaction on a monolayer of anatase TiO2 nanoplates decorated with Pt co-catalyst nanoparticles was employed as a model reaction system. Reaction intermediates of water photo-oxidation were observed at the TiO2/solution interface under UV irradiation. The surface-enhanced Raman vibrations corresponding to peroxo, hydroperoxo and hydroxo surface intermediate species were observed on the TiO2 surface, suggesting that the photo-oxidation of water on these anatase TiO2 nanosheets may be initiated by a nucleophilic attack mechanism.

Influence of Polyol/Salt Additives on the Drug-Mediated Phase Separation and Thermodynamic Properties of Triton X-100

Herein, we investigated the impact of different additives [polyols (glucose, galactose, and maltose)/electrolytes (KCl, K2SO4, and K3PO4·7H2O)] on the interaction between quinolone antibiotic drug, ciprofloxacin hydrochloride (CFH), and Triton X-100 (TX-100) via the cloud point (CP) measurement technique. The magnitudes of CP of TX-100 were observed to be reduced with the enlargement of TX-100 concentration. The CP values show U-shaped variation as a function of CFH concentration in the aqueous medium. The CP values dwindle in the existence of electrolyte, which continues with the rise of electrolyte concentration. The observed CP values in the electrolyte medium follow the order CPK3PO4·7H2O > CPK2SO4 > CPKCl. The CP values reduced in the presence of organic additives (polyols) also. The executed magnitudes of Gibbs free energy (ΔGc°) of clouding were positive in all cases, signifying the nonspontaneous phenomenon. The ΔGc° values reduce with TX-100 concentration. The values of enthalpy of clouding (ΔHc°) and entropy of clouding (ΔSc°), as well as different transfer properties of thermodynamic parameters, were estimated and interpreted in detail. Excellent entropy–enthalpy compensation was observed in all cases.

4-(2,7-Dimethyl-4-oxo-1,3-thiazolo[4,5-<i>d</i>]pyridazin-5-yl)benzenesulfonamide

The thia-zole-pyridazine fused-ring system of the title compound, C(13)H(12)N(4)O(3)S(2), is approximately planar (r.m.s. deviation = 0.037 Å); the benzene ring connected to the fused-ring system through the N atom is twisted by 39.3 (1)°. The amine group uses an H atom to form a hydrogen bond to the ketonic O atom of an inversion-related mol-ecule to generate a dimer; adjacent dimers are linked by an N-H⋯O hydrogen bond to form a linear chain.

Glassy Carbon Electrodes Decorated with HgO/CNT Nanocomposite and Modified with a Conducting Polymer Matrix for Enzyme‐Free Ascorbic Acid Detection

Abstract In an alkaline solution, mercuric oxide decorated carbon nanotube nanocomposites (HgO.CNT NCs) were manufactured utilizing an uncomplicated wet‐chemical approach. Ultra‐Violet spectroscopy (UV‐Visible), Fourier Transform Infra‐red spectroscopy (FTIR), Powder X‐ray Diffraction (XRD), X‐ray Photo‐electron Spectroscopy (XPS), and Field Emission Scanning Emission Microscopy (FESEM), X‐ray Electron Dispersive Spectroscopy (XEDS) techniques were applied to examine the HgO.CNT NCs that had been prepared. Ascorbic acid sensor was developed upon light coating of HgO.CNT NCs on polished Glassy carbon electrode (GCE) modified with nafion (Nf). Analytical performance of the selected ascorbic acid sensor was achieved such as sensitivity, Limit of quantification (LOQ), Limit of detection (LOD), Linear dynamic range (LDR), extended reliability, interference effect experimentation, and actual sample inspection using a consistent current‐voltage approach. Calibration curve of the suggested sensor was observed to be linear ( R 2 =0.9957) throughout a broad range of ascorbic acid concentrations (100.0 pM∼100.0 mM) at a voltage of 0.8 V. The calibration curve yielded analytical parameters such as sensitivity (632.91 pAμM −1 cm −2 ), LOQ (255.0 pM), LOD (76.50 pM), and LDR (100.0 pM ∼1.0 mM) for the proposed ascorbic acid sensor (GCE/HgO.CNT NCs/Nf). The wet‐chemical synthesis of HgO.CNT NCs is a good development of nanocomposite‐oriented sensor advancement in medical sciences with non‐enzymatic detection of biological substances. This proposed sensor applied to selective ascorbic acid detection in biological samples and obtained logical outcomes.

Generation of MoS2 quantum dots by laser ablation of MoS2 particles in suspension and their photocatalytic activity for H2 generation

The structural, electro-optical, charge transport and nonlinear optical properties of 2-[(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)methylidene]indan-1,3-dione

Ultrasound-assisted synthesis and photophysical investigation of a heterocyclic alkylated chalcone: a sensitive and selective fluorescent chemosensor for Fe³⁺in aqueous media

Alkylated pyridine chalcone (AIPO) has been synthesized by reaction of 1-allyl-1H-indole-3-carbaldehyde with 2-acetyl pyridine. The chalcone structure was characterized by spectral and elemental analysis. The absorption and emission in ten solvents with different polarities were used to calculate the photophysical parameters for this compound. This heterocyclic fluorescent compound serves as a selective probe for recognition of Fe3+. A 1:1 bonding stoichiometry between AIPO and Fe3+ has been detected by Benesi–Hildebrand, Stern–Volmer and Job-plot methods. The binding stoichiometric ratio was further confirmed by the density functional theory (DFT) calculations.