Spectroscopic study of interaction of styrylcyanine dye Sbt and its derivatives with bovine serum albumin

The spectral-fluorescent characteristics of styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino) styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and homodimers, dyes conjugated with two chromophores in aqueous solutions without and in the presence of bovine serum albumin (BSA), are studied. It is established that in the presence of BSA for dyes Dbt-5 and Dbt-10, an increase of the absorptivity, a slight broadening and the emergence of new band on the short wavelength range with λ_max=410 nm is observed; also hypsochromic shift of the absorption and fluorescence at 30 nm and 7 nm, respectively for the dye D-183 is observed. The intensity of the fluorescence emission fundamental band in all the studied dyes in the presence of BSA increases by 3.5 to 55 times. The binding constant (K) and number of binding sites (N) of studied dyes with BSA are determined. The dependence of the binding constants with BSA from the dipole moment of dye molecules is identified, which shows that in addition to the electrostatic attraction forces between molecules of styrylcyanine dyes with BSA, hydrophobic interactions are essential. It is shown that the aggregation of dye affects the processes of interaction of the dyes with the BSA.     

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

The photophysical properties such as electronic absorption, molar absorptivity, emission spectra, fluorescence quantum yield and fluorescence lifetime of N,N′-bis(4-pyridyl)-3,4:9,10-perylene bis(dicarboximide) (BPPD) have been measured in different solvents. Both electronic absorption and fluorescence spectra are not sensitive to medium polarity, while the fluorescence quantum yield (?_f) is solvent dependent. The ground state geometry has been computed by using density functional theory (DFT), the transition from HOMO to LUMO from perylene core with maximum absorption at 512 nm and HOMO–LUMO energy difference equal 2.53 eV. BPPD dye undergoes molecular aggregation to dimmer or higher aggregates in dimethyl sulfoxide (DMSO). Crystalline solids of BPPD gives excimer-like emission at 676 nm. The fluorescence quenching of BPPD is also studied using hydrated ferric oxide nanoparticle (FeOOH), and the Stern–Volmer rate constants (K_sv) were calculated as 8×10⁶ and 9.2×10⁶ M^?1 in ethanol and ethylene glycol, respectively.     

Sonochemical synthesis of two nanostructured silver(I) coordination polymers based on semi-rigid bis(benzimidazole) ligands

Nanoparticles of two silver(I) coordination polymers (CPs), [Ag₂(L1)₂(DCTP)]_n (1) and [Ag₂(L2)(DCTP)]_n (2) (L1 = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, L2 = 1,4-bis(benzimidazol-1-yl)-2-butene, H₂DCTP = 2,5-dichloroterephthalic acid), were synthesized by the sonochemical approach and hydrothermal method. Both CPs were characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction, scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). CP 1 exhibits a 2D 4-connected sql net with the point symbol {4⁴.6²}. While CP 2 displays a 2D 3,4-connected 3,4L13 net with the point symbol {4.6²}₂{4².6².8²}. The structural diversity indicates that semi-rigid bis(benzimidazole) co-ligands play important roles in tuning the structures of the mixed Ag(I) CPs. The ultrasound irradiation time, temperature, and power showed significant effects on the morphology and growth process of the nanoparticles of two silver(I) CPs. The luminescence and photocatalytic properties of the nanoparticles of CPs 1–2 on the degradation of methyl blue (MB) were also investigated in detail.     

Ultrasonically assisted hydrothermal synthesis of activated carbon–HKUST-1-MOF hybrid for efficient simultaneous ultrasound-assisted removal of ternary organic dyes and antibacterial investigation: Taguchi optimization

Activated carbon (AC) composite with HKUST-1 metal organic framework (AC–HKUST-1 MOF) was prepared by ultrasonically assisted hydrothermal method and characterized by FTIR, SEM and XRD analysis and laterally was applied for the simultaneous ultrasound-assisted removal of crystal violet (CV), disulfine blue (DSB) and quinoline yellow (QY) dyes in their ternary solution. In addition, this material, was screened in vitro for their antibacterial actively against Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO1) bacteria. In dyes removal process, the effects of important variables such as initial concentration of dyes, adsorbent mass, pH and sonication time on adsorption process optimized by Taguchi approach. Optimum values of 4, 0.02 g, 4 min, 10 mg L⁻¹ were obtained for pH, AC–HKUST-1 MOF mass, sonication time and the concentration of each dye, respectively. At the optimized condition, the removal percentages of CV, DSB and QY were found to be 99.76%, 91.10%, and 90.75%, respectively, with desirability of 0.989. Kinetics of adsorption processes follow pseudo-second-order model. The Langmuir model as best method with high applicability for representation of experimental data, while maximum mono layer adsorption capacity for CV, DSB and QY on AC–HKUST-1 estimated to be 133.33, 129.87 and 65.37 mg g⁻¹ which significantly were higher than HKUST-1 as sole material with Q_m to equate 59.45, 57.14 and 38.80 mg g⁻¹, respectively.     

Sonochemical assisted hydrothermal synthesis of ZnO: Cr nanoparticles loaded activated carbon for simultaneous ultrasound-assisted adsorption of ternary toxic organic dye: Derivative spectrophotometric,optimization, kinetic and isotherm study

Chromium doped zinc oxide nanoparticles (ZnO: Cr-NPs) was synthesized by ultrasonically assisted hydrothermal method and characterized by FE-SEM, XRD and TEM analysis. Subsequently, this composite ultrasonically assisted was deposited on activated carbon (ZnO: Cr-NPs-AC) and used for simultaneous ultrasound-assisted removal of three toxic organic dye namely of malachite green (MG), eosin yellow (EY) and Auramine O (AO). Dyes spectra overlap in mixture (major problem for simultaneous investigation) of this systems was extensively resolved by derivative spectrophotometric method. The magnitude of variables like initial dyes concentration, adsorbent mass and sonication time influence on dyes removal was optimized using small central composite design (CCD) combined with desirability function (DF) approach, while pH was studied by one-a-time approach. The maximized removal percentages at desirability of 0.9740 was set as follow: pH 6.0, 0.019 g ZnO: Cr-NPs-AC, 3.9 min sonication at 4.5, 4.8 and 4.7 mg L⁻¹ of MG, EY and AO, respectively. Above optimized points lead to achievement of removal percentage of 98.36%, 97.24%, and 99.26% correspond to MG, EY and AO, respectively. ANOVA for each dyes based p-value less than (<0.0001) suggest highly efficiency of CCD model for prediction of data concern to simultaneous removal of these dyes within 95% confidence interval, while their F-value for MG, EY and AO is 935, 800.2, and 551.3, respectively, that confirm low participation of this them in signal. The value of multiple correlation coefficient R², adjusted and predicted R² for simultaneous removal of MG is 0.9982, 0.9972 and 0.9940, EY is 0.9979, 0.9967 and 0.9930 and for AO is 0.9970, 0.9952 and 0.9939. The adsorption rate well fitted by pseudo second-order and Langmuir model via high, economic and profitable adsorption capacity of 214.0, 189.7 and 211.6 mg g⁻¹ for MG, EY and AO, respectively.     

Synthesis of magnetic γ-Fe2O3-based nanomaterial for ultrasonic assisted dyes adsorption: Modeling and optimization

γ-Fe₂O₃ nanoparticles were synthesized and loaded on activated carbon. The prepared nanomaterial was characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The γ-Fe₂O₃ nanoparticle-loaded activated carbon (γ-Fe₂O₃-NPs-AC) was used as novel adsorbent for the ultrasonic-assisted removal of methylene blue (MB) and malachite green (MG). Response surface methodology and artificial neural network were applied to model and optimize the adsorption of the MB and MG in their individual and binary solutions followed by the investigation on adsorption isotherm and kinetics. The individual effects of parameters such as pH, mass of adsorbent, ultrasonication time as well as MB and MG concentrations in addition to the effects of their possible interactions on the adsorption process were investigated. The numerical optimization revealed that the optimum adsorption (>99.5% for each dye) is obtained at 0.02 g, 15 mg L⁻¹, 4 min and 7.0 corresponding to the adsorbent mass, each dye concentration, sonication time and pH, respectively. The Freundlich, Langmuir, Temkin and Dubinin–Radushkevich isotherms were studied. The Langmuir was found to be most applicable isotherm which predicted maximum monolayer adsorption capacities of 195.55 and 207.04 mg g⁻¹ for the adsorption of MB and MG, respectively. The pseudo-second order model was found to be applicable for the adsorption kinetics. Blank experiments (without any adsorbent) were run to investigate the possible degradation of the dyes studied in presence of ultrasonication. No dyes degradation was observed.     

Effect of two sonochemical procedures on achieving to different morphologies of lead(II) coordination polymer nano-structures

Micro and nano-structures of a lead(II) coordination polymer, [Pb₂(2-Me-8-Hq)₂(MeOH)₂]_n (1), [2-Me-8-HqH = 2-methyl-8-hydroxyquinoline]_, were synthesized by two sonochemical methods. These new micro and nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compound 1 was structurally characterized by single-crystal X-ray diffraction and consists of primary dimeric unit of [Pb₂(2-Me-8-Hq)₂(MeOH)₂]. Self assembly between the dimmeric units of [Pb₂(2-Me-8-Hq)₂(MeOH)₂] from Pb-O bonds results in formation of a one-dimensional lead(II) coordination polymer. The Pb^II-ion in compound 1 has PbO₆N₁ coordination sphere with a stereo-chemically ‘active’ electron lone pair on the metals. By a reversible solid-state structural transformation, we successfully prepared [Pb₂(2-Me-8-Hq)₂]_n (2) by thermal desolvation of 1. Thermal stability of compound 1 was studied by thermo gravimetric and differential thermal analyses. In addition nano-structure of PbO was prepared from calcination process of compound 1 at 873 K.     

Degradation of reactive,acid and basic textile dyes in the presence of ultrasound and rare earths [Lanthanum and Praseodymium]

Degradation of five textile dyes, namely Reactive Red 141 (RR 141), Reactive Blue 21 (RB 21), Acid Red 114 (AR 114), Acid Blue 113 (AB 113) and Basic Violet 16 (BV 16) in aqueous solution has been carried out with ultrasound (US) and in combination with rare earth ions (La³⁺ and Pr³⁺). Kinetic analysis of the data showed a pseudo-first order degradation reaction for all the dyes. The rate constant (k), half life (t_1/2) and the process efficiency (φ) for various processes in degradation of dyes under different experimental conditions have been calculated. The influence of concentrations of dyes (16–40 mg/L), pH (5, 7 and 9) and rare earth ion concentration (4, 12 and 20 mg/L) on the degradation of dyes have also been studied. The degradation percentage increased with increasing rare earth amount and decreased with increasing concentration of dyes. Both horn and bath type sonicators were used at 20 kHz and 250 W for degradation. The sonochemical degradation rate of dyes in the presence of rare earths was related to the type of chromophoric groups in the dye molecule. Degradation sequence of dyes was further examined through LCMS and Raman spectroscopic techniques, which confirmed the sonochemical degradation of dyes to non-toxic end products.     

Molecular organization and aggregation in Langmuir and Langmuir-Blodgett films of azo dye/liquid crystal mixtures

A study of azo dye/liquid crystal mixtures in monolayers formed at air-water (Langmuir films) and air-solid substrate (Langmuir-Blodgett films) interfaces was performed. Three azo dyes with various molecular structure and two liquid crystal materials: 4-octyl-4′-cyanobiphenyl (8CB) and trans-4-octyl(4′-cyanophenyl)-cyclohexane (8PCH) were used. The morphology of Langmuir films was monitored by means of a Brewster angle microscope (BAM). Moreover, a surface pressure and electronic absorption spectra of the monolayer spread on the water surface of dye/liquid crystal mixtures as a function of a mean molecular area were simultaneously recorded. In addition, the absorption for Langmuir-Blodgett films deposited on quartz plates was measured. Information about intermolecular interactions in the mixtures of the nonamphiphilic dye and the liquid crystal with polar terminal group was obtained. Conclusions about the formation of self-aggregates between dye molecules have been drawn. The influence of the dye molecular structure and its concentration on aggregates’ geometry was found.     

Ultrasonic-assisted synthesis of 1,4-disubstituted 1,2,3-triazoles via various terminal acetylenes and azide and their quorum sensing inhibition

An efficient synthesis of 1,4-disubstituted 1,2,3-triazole derivatives was studied. 1,4-Disubstituted 1,2,3-triazoles containing isoxazole and thymidine structures were synthesized in 84–96% yields starting from various terminal isoxazole ether alkynes and β-thymidine azide derivatives via a 1,3-dispolar cycloaddition using copper acetate, sodium ascorbate as the catalyst under ultrasonic assisted condition. All the target compounds were characterized by HRMS, FT-IR, ¹H NMR and ¹³C NMR spectroscopy. Furthermore, the quorum sensing inhibitory activities of synthesized compounds were evaluated with Chromobacterium violaceum (C. Violaceum CV026) based on their inhibition of violacein production, with compound C₁₀-HSL as a positive control. The compounds 8a, 8c and 8f exhibited considerable levels of inhibitory activity against violacein production, and IC₅₀ values were 217 ± 19, 223 ± 20 and 42.8 ± 4.5 μM, respectively, which highlighted the potential of these compounds as lead structures for further research towards the development of novel QS inhibitors.     

Preparation of solution-based YBCO films with BaSnO3 particles

The YBCO films with BaSnO₃ (BSO) particles were prepared on LAO (0 0 1) substrates by metal organic deposition using trifluoroacetates (TFA-MOD) via introducing SnCl₄ powders into the YBCO precursor solution. It was found that with the increase of the SnCl₄ contents, the slower decomposition and higher temperature for nucleation during the reaction were requested compared to that of pure YBCO film. The YBCO films with different contents of Sn with dense surface and well c-alignment were obtained under optimized heat treatment, and the BaSnO₃ phases were detected by XRD analysis. Litter effect of BSO particles on the T_c and J_c values of YBCO films was found. All YBCO films with BSO particles had T_c values over 90 K and J_c values over 1 MA/cm². A significant enhancement of J_c was observed for YBCO films with BSO particles compared to that of pure YBCO film by the field dependence of J_c values. The best property was obtained for YBCO film with 6 mol.% Sn at 77 K under magnetic field. The results showed that the J_c value of YBCO film with 6 mol.% Sn was enhanced by a factor of 2 in 2 T, and over a factor of 10 beyond 4 T compared to that of pure YBCO film.     

Nonlinear refractive index of some anthraquinone dyes in 1294-1b liquid crystal

Third order nonlinear refractive index of three anthraquinone dyes, i.e., Solvent Blue 59, Solvent Blue 35 and Solvent Green 3 doped in 1294-1b nematic liquid crystal (NLC) were studied by the single beam Z-scan technique using a continuous-wave He–Ne laser at 632.8 nm. The negative nonlinear refractive index (n₂) in the order of 10^? 5 cm²/w for all samples was obtained. We believe that, this large nonlinearity is owing to Janossy effect and the difference in the nonlinear refractive index of our dyes can be described by the structures of dyes and the interactions between dyes and 1294-1b molecules. So as to understand the effect of dye structure on nonlinearity enhancement, the dichroic ratio of these dyes in 1294-1b was measured using polarized spectroscopy.     

Superconducting characteristics and microstructure of polycrystalline Zn-doped In2O3 films

In order to investigate the relation among the superconducting transition T_c, carrier density n, resistivity ρ and the microstructure in the polycrystalline (In₂O₃)_1?x–(ZnO)_x films, we prepared specimen films by post annealing of amorphous films with x = 0.025 at various annealing temperature T_a and for annealing time t_a = 1 h and 4 h. As for microstructures, we have investigated the distribution of elements by scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). We have found followings: (1) The annealed films clearly show the superconductivity of which T_c depends on T_a, t_a and n. This indicates that the superconductivity is determined by the combination of crystallinity and carrier density. (2) The data on STEM–EELS spectra mapping of indium plasmon indicate that droplets of the pure indium phase exist inside a film, where the distribution of these droplets dispersed. Therefore, it seems that droplets do not form an electrical conducting path, that is, it is possible that observed superconductivity is due to intrinsic characteristic of polycrystalline (In₂O₃)_1?x–(ZnO)_x films.     

Phase growth control in low temperature PLD Co: TiO2 films by pressure

This paper reports on the structural and optical properties of Co-doped TiO₂ thin films grown onto (0001)Al₂O₃ substrates by non-reactive pulsed laser deposition (PLD) using argon as buffer gas. It is shown that by keeping constant the substrate temperature at as low as 310 °C and varying only the background gas pressure between 7 Pa and 70 Pa, it is possible to grow either epitaxial rutile or pure anatase thin films, as well as films with a mixture of both polymorphs. The optical band gaps of the films are red shifted in comparison with the values usually reported for undoped TiO₂, which is consistent with n-type doping of the TiO₂ matrix. Such band gap red shift brings the absorption edge of the Co-doped TiO₂ films into the visible region, which might favour their photocatalytic activity. Furthermore, the band gap red shift depends on the films’ phase composition, increasing with the increase of the Urbach energy for increasing rutile content.     

Sonochemical synthesis of nanoscale mixed-ligands lead(II) coordination polymers as precursors for preparation of Pb2(SO4)O and PbO nanoparticles; thermal,structural and X-ray powder diffraction studies

Nano-structures of two new Pb(II) two-dimensional coordination polymers, [Pb(μ-4-pyc)(μ-NCS)(μ-H₂O)]_n (1) and [Pb(μ-4-pyc)(μ-N₃)(μ-H₂O)]_n (2), 4-Hpyc = 4-pyridinecarboxylic acid were synthesized by a sonochemical method. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compounds 1 and 2 were structurally characterized by single crystal X-ray diffraction and consist of two-dimensional polymeric units. The thermal stability of compounds 1 and 2 were studied by thermal gravimetric and differential thermal analyses and compared. Pb₂(SO₄)O and PbO nanoparticles were obtained by calcination of the nano-structures of compounds 1 and 2 at 600 °C, respectively.     

Intercomparison of Fluctuation Induced Conductivity of Cu0.5Tl0.5Ba2Can−1CunO2n+4−y (n = 2, 3, 4) superconductor thin films

An intercomparison of Fluctuation Induced Conductivity (FIC) of Cu_0.5Tl_0.5Ba₂Ca_n?1Cu_nO_2n+4?y (n = 2, 3, 4) [CuTl-12(n ? 1)n] superconductor thin films is given. We tried to find any correlation between the critical temperature and the parameters extracted from the excess conductivity data i.e. cross-over temperature, pseudogap temperature and fluctuation amplitudes. We found that the critical temperature seems to depend on the fluctuation amplitude; greater the fluctuation amplitude higher is the critical temperature.     

Sonochemical synthesis of nano-scale mixed-ligands lead(II) coordination polymers as precursors for preparation of PbO and PbBr(OH) nano-structures; thermal,structural and X-ray powder diffraction studies

Nano-structures of two new lead(II) two-dimensional coordination polymers, [Pb₂(2-pyc)₂(I)₂]_n (1) and [Pb₂(2-pyc)₂(Br)₂]_n (2), {2-Hpyc = 2-pyridinecarboxilic acid } were synthesized by a sonochemical method that produce the coordination polymers at nano-size. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compounds 1 and 2 were structurally characterized by single crystal X-ray diffraction and consist of two-dimensional polymeric units. The thermal stability of compounds 1 and 2 were studied by thermal gravimetric and differential thermal analyses. PbO and PbBr(OH) nano-structures were obtained by calcination of the nano-structures of compounds 1 and 2 at 400 °C, respectively.     

Effect of electrostatic interaction on the methylene blue and methyl orange adsorption by the pristine and functionalized carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were functionalized with cysteamine groups by several percentage of mass as adsorbents, then kinetics adsorption capacity was investigated for methylene blue (MB) and methyl orange (MO) as anionic and cationic dyes adsorbate molecules, respectively. The effect of temperature (from 283 to 303 K), contact time and initial concentration of the MB and MO dyes in a solution (10 to 40 ppm) was considered. The optimal contact time was found to be about 60 min. Some kinetics model such as pseudo-first-order, pseudo-second-order, intra-particle diffusion and the Elovich were tested. The adsorptions of MB dye on the pristine and functionalized MWCNT surfaces were found to be the intra-particle diffusion and the pseudo-second-order kinetic model, respectively and for adsorption of MO dye by the pristine and low functionalized MWCNTs and highly functionalized tubes, found to be the pseudo-second-order and intra-particle diffusion kinetic model, respectively, based on the chi-square statistic (X²) and also high correlation coefficient (R²) values.     

Ultrasonic synthesis of two nanostructured cadmium(II) coordination supramolecular polymers: Solvent influence,luminescence and photocatalytic properties

Two nanoparticles of cadmium(II) coordination polymers (CPs) formulated as [Cd(L)(DCTP)]_n (1) and [Cd(L)₂(DCTP)·2H₂O]_n (2) (L = 1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H₂DCTP = 2,5-dichloroterephthalic acid) were prepared by the sonochemical approach in different solvents and characterized by elemental analysis, IR spectra, scanning electron microscopy (SEM), and powder X-ray diffraction. Structural determination reveals that CP 1 displays a 2D four-connected sql net layer, Whilst CP 2 exhibits a 1D “V”-like chain structure. Luminescence properties, thermal behavior, and photocatalytic activities of the nanoparticles of CPs 1 and 2 on the degradation of methylene blue were investigated. The photocatalytic mechanism is carried out by introducing t-butyl alcohol (TBA) as a widely used OH scavenger. Furthermore, the influence of solvents, reaction time, and ultrasound irradiation temperature on the morphology and size of the nanostructure CPs 1 and 2 were investigated. The results indicated that an increase of time and ultrasound irradiation temperature decreased the nanostructured size.     

Nb doping effect on TiO2−x films for bolometer applications

Nb-doped TiO_2−x thin films were deposited using a 1 at% niobium doped titanium target by RF reactive magnetron sputtering at various oxygen partial pressures (pO₂). The films appeared amorphous in the pO₂ range of 4.4–4.7% with resistivity ranging from 0.39 Ω cm to 2.48 Ω cm. Compared to pure TiO_2−x films, the resistivity of the Nb-doped TiO_2−x films did not change sensitively with the oxygen partial pressure, indicating that the resistivity of the films can be accurately controlled. 1/f noise parameter of Nb-doped TiO_2−x films were found to decrease largely while the measured temperature coefficient of resistance (TCR) of the films was still high. The obtained results indicate that Nb-doped TiO_2−x films have great potential as an alternative bolometric material.