Synthesis,characterization, and biological evaluation of new copper complexes of naphthyl pyrazole ligands

Two naphthalene pyrazole ligands were synthesized using KOH/DMSO and Cu catalyst and characterized with FT-IR, ESI-MS, ¹H, and ¹³C NMR spectroscopies. The crystal structures of 1-(2-methylnaphthalen-1-yl)-1H-pyrazole (MeNap-Pz) ligand have been determined with X-ray crystal structure analysis. Reaction of the ligands with Cu(NO₃)₂x3.5H₂O gave two new complexes and characterized with magnetic susceptibility, molar conductance, FT-IR, LCMS-MS, ICP-OES, NMR, thermogravimetric analysis, and ESR spectra. The spectral data of the ligands are coordinated to the metal ion through the nitrogen atoms of the pyrazole ring. Consequently, it has been determined that [Cu(MeNap-Pz)₂(NO₃)]NO₃.2H₂O complex showed square planar geometry and [Cu(NapMe-Pz)₂(NO₃)₂].H₂O complex showed octahedral geometry. All compounds were screened for in vitro antibacterial activity and copper complexes have been shown to be effective on bacteria.     

Absorption spectrum of monomeric pseudoisocyanine: A new perspective and its implications for formation and spectral response of J-aggregates in solution and in thin films

We argued against the current spectral assignment for absorption spectrum of monomeric PIC which is widely accepted since the pioneering works of Scheibe and Jelley [G. Scheibe, Angew. Chem. 49 (1936) 563; E.E. Jelly, Nature 138 (1936) 1009]. A new spectrum is presented along with its conceptual basis. The hypothesized spectrum attributes the previous 0–0 (≈525 nm) and 0–1 (≈490 nm) assignments, respectively, to intermediates acting as the precursor of J-aggregates and to the 0–0 transition of monomeric PIC and brings the spectrum in accord with the seemingly universal spectral fingerprint of cyanines. The hypothesis is used to analyze and interpret the temperature dependence of the UV–vis absorption of PIC aggregates in saline aqueous solution by incorporating the J-band simulations within frenkel exciton formalism. Its implications for aggregate formation kinetics are given on the basis of current spectroscopic evidence. The hypothesis readily answers several long-standing questions: Why compared to many other cyanines at least an order of magnitude higher dye concentration is needed to form J-aggregates of PIC? Why are there no precursors, since aggregation is expected to be a consecutive process? A large number of observations on steady-state and time-resolved spectral properties, and aggregation kinetics in solution/thin films are likely to find reasonable explanations within this hypothesis.     

A novel method for the production of conductive ring spun yarn

To take the advantages of spun yarns such as porosity, softness, bending as well as usability as yarn/fabric forms, this study worked on an alternative conductive yarn production method. Different from widely used application methods, a conductive nanosuspension was applied to viscose, cotton and polyester open fibre bundles with different feeding amounts during the ring spinning with a specially developed apparatus. Reduced graphene oxide (rGO) synthesized with a single step process instead of two-step processes was used to impart conductivity. Following to yarn production, winding, knitting and washing processes were realized to evaluate the changes in yarn conductivity and the usability of the yarns in the post-spinning processes. In addition to tensile properties of the yarns and air permeability of the fabrics, electrical resistance and environmental impact of the method was compared with immersion and drying process. The results indicated that alternative method allows the production of conductive (lower resistance than 100 kΩ) but also strong, flexible, washable and breathable electronic textile products with an environmentally friendly process. There has been no effort, as yet, to get conductivity in this manner. Therefore, the developed method can be considered to be a new application in the functional yarn production field. The produced conductive yarns can be converted into fabric form by weaving, knitting and embroidery. Therefore, they can also be seen as an ideal as the platforms for future wearable electronics.

     

Reentrant phase transition and network parameters of hydrophobically modified poly[2-(diethylamino)ethylmethacrylate-co-N-vinyl-2-pyrrolidone/octadecyl acrylate] hydrogels

Hydrophobically modified poly[2-(diethylamino)ethylmethacrylate-co-N-vinyl-2-pyrrolidone/octadecyl acrylate] [P(DEAEMA-NVP/OA)] hydrogels with different OA content were prepared by free-radical crosslinking copolymerization of corresponding monomers in tert-butanol. The swelling equilibrium of the hydrogels was investigated as a function of temperature and hydrophobic comonomer content in pure water. An interesting feature of the swelling behavior of the P(DEAEMA-NVP/OA) hydrogels was the reentrant phase transition where the hydrogels collapse once and reswell as temperature increased. The average molecular mass between crosslinks and polymer-solvent interaction parameter (χ) of the hydrogels were calculated from equilibrium swelling values. The enthalpy (ΔH) and entropy (ΔS) changes appearing in the χ parameter for the hydrogels were determined by using the Flory-Rehner theory. It was observed that the experimental swelling data of the hydrophobic hydrogels at different temperature agreed with the Flory-Rehner theory, that provided that the sensitive dependence of χ parameter on both temperature and polymer concentration is taken into account.     

Electrochemical Behavior and Ultrasensitive,Simple and Effective Voltammetric Determination of Acetaminophen Using Modified Glassy Carbon Electrode Based on 4-Hydroxyquinoline-3-carboxylic Acid

An electrochemical oxidation of acetaminophen (ACOP) has been successfully performed by using glassy carbon electrode covered with 4-hydroxyquinoline-3-carboxylic acid (4HQ3CA) to reinforce electrode's feature. To characterize the modified electrode (4HQ3CA/GC), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Fourier transform infrared spectroscopy (FT-IR) techniques were used. The finding optimum conditions (supporting electrolyte, pH) and the electrochemical determination studies were performed with differential pulse voltammetry (DPV). It was decided that the supporting electrolyte medium suitable for ACOP determination was Britton-Robinson (BR) buffer and the effect of pH change on the oxidation peak of ACOP in this media was investigated. The effect of changing scan rate on the oxidation peak of ACOP was examined and this study showed that the oxidation process of ACOP on the 4HQ3CA/GC modified electrode surface was diffusion and adsorption controlled process. A wide concentration range from 0.0025 μM to 141 μM with a limit of detection (LOD) of 5.98×10⁻¹⁰ M (3 s/m) was obtained. This prepared sensor was carried out for the determination of ACOP in pharmaceutical sample.     

A Diverse‐Stimuli Responsive Chemiluminescent Probe with Luminol Scaffold and Its Electropolymerization

A diverse‐stimuli responsive chemiluminescent system, SNS‐Lum, and its electropolymerization to give PSNS‐Lum, which is the first example of conjugated polymers with pendant luminol arms inducing chemiluminescence in the presence of super oxide radical anion under neutral conditions, are highlighted.     

Investigation of nucleation and grain growth in 2-dimensional systems by using generalized Monte Carlo simulations

In this study, nucleation and grain growth was studied by using 2-dimensional generalized Monte Carlo simulations and experiments. As an attempt to improve the JMAK model, we proposed a new differential equation to be able to model nucleation and growth phenomena using nonextensive thermostatistics. One of the reasons that we would like to perform generalized Monte Carlo simulations in studying of nucleation and grain growth phenomena is that the generalized Monte Carlo algorithm was shown to be more effective than the standard Monte Carlo algorithm and also than the standard Molecular Dynamic algorithm in locating the minimum energy configuration. Therefore, for a given temperature, the fact that a configuration of the system with lower energy could be obtained by using the generalized Monte Carlo simulation means that a different textural configuration of grain growth could be also expected. In this respect, it is possible to say that the nonextensive statistics might be an appropriate tool in studying of nucleation and growth phenomena.     

Selective and sensitive determination of dopamine via suppressing ascorbic acid using an N-(1-H-indole-3yl) methylene thiazole-2-amine thin film-modified glassy carbon electrode

The selective determination of dopamine (DA) was performed using a glassy carbon (GC) electrode modified with N-(1-H-indole-3yl) methylene thiazole-2-amine (IMT2A). IMT2A was deposited on the GC electrode by cyclic voltammetry. This modified electrode demonstrated an electrocatalytic effect on the oxidation of DA in the presence of uric acid (UA) and ascorbic acid (AA) using differential pulse voltammetry (DPV) method in 0.1 M phosphate buffer solution (PBS) of pH 7. Selective determination was realized in elimination of AA response on the IMT2A-modified electrode. The oxidation peak currents increased linearly with two concentration intervals of DA at pH 7 phosphate buffer. One of them is 0.25–9.15 μM, and the other is 9.15–95.1 μM. The limit of detection (LOD) was found as 0.086 μM. The proposed electrode was applied to the determination of DA in pharmaceutical preparations and human urine sample with satisfactory results.

     

Novel Multiporphyrin Functionalized Single-Walled Carbon Nanotubes

Porphyrin monomers, 5,15–bis(4-(2,5,8,11-tetraoxatridecan-13-yloxy)phenyl)-10,20-bis(3-iodophenyl)porphyrin zinc (5a) and 5,10–bis(4-(2,5,8,11-tetraoxatridecan-13-yloxy)phenyl)-15,20-bis(3-iodophenyl)porphyrin zinc (5b), and their oligomers 6a and 6b were synthesized and characterized. The titration experiment of the monomers was carried out in THF by changing the solution percent of water. The optical properties (UV–vis and fluorescence spectra) of the monomers that possess slightly red-shifted optical spectra in water compared to the spectra obtained in THF are reported. The newly prepared porphyrin constructs were also mixed with SWCNTs to generate noncovalent hybrid materials.     

Polyimides for electronics applications

A variety of options exists for lithographically defining polyimides for microelectronics applications. The two investigated here, photosensitive polyimide and wet etching of low-stress polyimides, offer lower cost, higher throughput solutions compared with dry etch processes. Via sizes of less than 25 μm and film thicknesses of greater than 14 μm are difficult to process using these techniques: however, for applications such as interlayer dielectrics for high-density packaging or solder masks for flip chip die attachment, these limitations may not be insurmountable. Photosensitive polyimide can be patterned with fewer steps, but the overall quality of the film in terms of surface planarity and residual stress is not as good as wet etching of conventional polyimide.