Yellow Solution Research Articles

Facile In-Situ Synthesis of Biopolymer Capped Nano Sized Silver Particles: Smartphone Aided Paper-Based Selective Detection of CYS and TC Drugs in Biological and Drug Samples

Herein we are reporting, the in-situ synthesis of polydopamine capped silver nanoparticles (PDA-AgNPs) and its cysteamine (CYS) and tetracycline (TC) drugs sensor applications. The synthesized PDA-AgNPs was characterized by UV–Visible, Fourier Transformed–Infrared, X-Ray Diffraction, Zeta Potential, and High Resolution-Transmission Electron Microscope techniques. We have utilized PDA-AgNPs as probes for the detection of CYS and TC by spectrophotometry method. The addition of CYS has led to a decrease in the absorption of PDA-AgNPs. The yellow color solution becomes colorless and observed the aggregated particles in the TEM image. In contrast, the addition of TC, into the same solution, absorption of PDA-AgNPs was increased. The color of the solution became dark yellow and the particles are obtained de-aggregation. Based on the Surface Plasmon Resonance (SPR) band absorption changes, the detection limit of CYS and TC was calculated to be 180 nM and 17 nM, respectively. Interestingly, 600-fold of common interferences did not interfere with the detection of CYS and TC. PDA-AgNPs was successfully utilized to detect CYS and TC in serum, urine, and drug samples. Finally, we have prepared a paper-based colorimetric kit for on-site monitoring of CYS and TC.

Tuning Magnetic Relaxation in Square-Pyramidal Dysprosium Single-Molecule Magnets Using Apical Alkoxide Ligands

Tuning Magnetic Relaxation in Square-Pyramidal Dysprosium Single-Molecule Magnets Using Apical Alkoxide Ligands

Synthesis, structural and electrical conduction of some dual doped semiconductor oxides nanoparticles for photocatalytic degradation of Victoria blue-B and Brilliant yellow under solar light irradiation

In this study, the nanoparticles of undoped and dual (codoped) doped semiconductor oxides such as Bi2O3, Bi1.9Sm0.038Cu0.062O3; Co3O4, Co2.902Mn0.049Dy0.049O4; V2O5, V1.91Ni0.043Gd0.047O5; Cu2O, Cu1.927Mn0.036Yb0.037O; CeO2, and Ce0.938Ni0.028Zn0.034O2 were synthesized by tartarate and hydroxide coprecipitation method. The composition, structure, morphology, surface and optical properties of undoped and dual doped semiconductor oxides have been investigated by X-ray fluorescence spectroscopy (XRF), Energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), Scanning electron micrographs (SEM), X-ray photoelectron spectroscopy (XPS), BET surface area analyzer and UV–Vis diffuse reflectance absorption spectra (UV–vis DRS). The XRD and SEM studies showcase monodispersion of undoped and dual (co-doped) doped semiconductor oxides in the average grain size range of 36–65 nm with a monoclinic structure for Bi2O3 and its doped oxide, cubic structure for Co3O4, Cu2O, CeO2 and their respective doped oxides and orthorhombic structure for V2O5 and its doped oxide. Rietveld refinements of XRD pattern and XPS results confirmed that the dual dopants exist in + 2 or + 3 states and successfully incorporated into the semiconductor oxide matrix. BET surface areas for these oxides were found in the range of 25.3–65.4 m2g−1. The band gap energy (Eg) of undoped and doped semiconductor had a direct transition to fall between 2.10 and 3.12 eV as estimated from the optical absorption data (UV–vis DRS) and found absorption band edge (λg) in the visible-light range. The d.c. electrical conductivity and thermo-electric power measurements for all compounds showed n-type semiconductor except undoped and doped Cu2O and Co3O4 compounds showed p-type semiconductivity. The photo catalytic activity of undoped and dual doped semiconductor oxides in the Victoria blue-B (VB) and Brilliant yellow (BY) solutions were studied in sunlight irradiation. A set of optimized conditions such as the amount of these oxides, initial dye concentration, pH, contact time and dopants on the photodegradation of these dyes were investigated in detail. The dual doped semiconductor oxides showed a noteworthy enhancement in the degradation of VB and BY dyes under exposure to sunlight. The enhanced photocatalytic activity can be attributed to the incorporation of multivalent dopants in semiconductor oxide matrix promoted the separation of photogenerated charges, inhibited the recombination of photogenerated carriers, and thus prolonged the charges lifetime to participate in the photocatalytic reaction. The kinetic measurements indicate the dominance of pseudo-first order rate constant for Victoria blue-B (VB) were higher than that of Brilliant yellow (BY) in all cases, indicating that the photocatalytic degradation of VB was easier and more rapid than BY dye during the adsorption and also ascribed to different molecular structure to these dyes. A tentative reaction mechanism has also been proposed for this photocatalytic reaction.

Optical Properties of New Terbium(III) Ternary Complexes Containing Anionic 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione and Neutral Sensitizers in Solution, Solid and PMMA Thin Films: Intra and Interphase Colour Tuning.

Four new terbium(III) ternary complexes, [Tb(fod)3 (indazole)] (1), [Tb(fod)3 (tptz)] (2), [Tb(fod)3 (impy)] (3) and [Tb(fod)3 (tppo)2 ] (4) with 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione, (Hfod) and N and O donors are synthesized and structurally characterized. The photoluminescence of the complexes are studied in solid, chloroform solution and thin PMMA hybrid films (PMMA is a poly(methyl methacrylate)). The ligand-based emission is dominant in solution of 3 and 4. The effect of ancillary ligands on the photoluminescence of terbium(III) ion is investigated. The mechanism of energy transfer is discussed and correlates the luminescence of acceptor terbium ion with the triplet state energy level of donor ligands. Among the four complexes studied, the luminescence from 1 is most intense followed by 2, 4 and 3. The Commission International de I'Eclairage (CIE) color coordinates of these complexes are calculated and presented. The complexes 3 and 4 show intraphase color tuning when excited under different UV wavelengths. The emission color of [Tb(fod)3 (tppo)2 ] (4) changes from pure blue to turquoise green via almost pure white under 360, 328 and 280nm UV excitation wavelengths respectively. The [Tb(fod)3 (impy)] (3) show similar results. The complex [Tb(fod)3 (tptz)] (2) displays interphase color tuning from yellow (solution) to turquoise green (solid) and fascinatingly incorporation of complex in PMMA polymer generates white light under same excitation wavelength (360nm).

Electrochemical Regulation of Antibacterial Activity Using Ferrocene-Containing Antibiotics

Electrochemical Regulation of Antibacterial Activity Using Ferrocene-Containing Antibiotics

A Visual and Ratiometric Chemosensor Using Thiophene Functionalized Hydrazone for the Selective Sensing of Pb2+ and F- Ions.

Herein, a simple, efficient ratiometric chemosensor was reported for the selective sensing of Pb2+ and F- ions using thiophene functionalized hydrazone as a chemical probe. Hydrazone moiety was developed by utilizing thiophene/naphthalene as a platform for the particular recognition of cation and anion. The structures of the precursor (Z)-(1-(5-bromothiophen-2-yl)ethylidene)hydrazine (ABTH) and the final probe 1-((Z)-(((Z)-1-(5-bromothiophen-2-yl)ethylidene)hydrazono)methyl)naphthalen-2-ol (NAPABTH) were confirmed by 1H, 13C-NMR and LC-MS spectroscopic methods. The interaction of NAPABTH with Pb2+ and F- ions was visually observed by the formation of pink and dark yellow solutions, respectively. The detection limits were found to be very low for Pb2+ as 1.06ppm and for F- ions as 3.72nM. This visual detection of Pb2+/F- ions with satisfactory outcomes obtained from UV-Vis titrations. The sensing mechanistic pathways and stoichiometric ratios were obtained from DFT and Job's plot, respectively. The observed results are highly promising as highly selective chemosensor with lower detection limits for Pb2+ and F- ions. This strategy could exhibit tremendous applications for the selective sensing of heavy metal cations with rapid sensitivity for the design of new devices.

Spectrophotofluorometric Study of Amaranth with Fluorescent Carbon Dots and its Analytical Application

Hydrothermal carbonization of bottle gourd as the carbon source has been performed to synthesize fluorescent carbon dots . The carbon dots were formed in the form of yellow brown aqueous solution, soluble in water and stable towards light. Characterization of fluorescent carbon dots was done using TEM, UV-vis and fluorescence spectroscopy. Spectrophotofluorometric method has been followed for the study of common food colorant Amaranth present in foodstuffs using fluorescent carbon dots. Conditions optimized during analysis were reaction pH, concentration of Amaranth, concentration of C-dots, thermal effect, time period, etc. Results showed that Amaranth could result in fluorescence quenching of carbon dots due to interaction of surface –COOH, –SO3H group with Amaranth dye. The present method offers good linear range of 0.20-25.0 μM with LOD 0.019 μM and highly selective and therefore, method have been applied successfully for the detection of Amaranth in foodstuffs.

Using of Salicylaldehyde Reagent in Spectrophotometric Determination of Niclosamide Via Schiff Base Reaction

The present method includes spectrophotometric determination of niclosamide (NICS) via Schiff base reaction in an alcoholic medium (ethanol) after reducing the nitro group in NICS by added zinc powder in an acidic medium to produce a primary amine group which can be coupled with the salicylaldehyde (SSA) reagent to give a yellow solution whose absorption is followed at the wavelength of 405 nm. Beer's law limitation for the proposed method was in the range of concentrations of 4.0-30 μg. ml-1. The molar absorbance value was 8.701 x 104 l mol.-1 cm.-1 and Sandell's sensitivity value was 0.0376 μg. cm-2. The effect of the reaction components was studied separately by changing one of the components and keeping the other constant, and the optimal conditions were chosen for all these studied components. The proposed method has been successfully applied for the determination of NICS in a pharmaceutical formulation (Yumesan tablets). The recovery percentage of the medicinal compound under study (niclosamide) from the tablet pharmaceutical preparation (Yumesan) via applying the suggested method was not less than 96.36%, and the values of each of the low detection limit (LOD), the low quantitation limit (LOQ), the relative error percentage (RE%), and the relative standard deviation percentage (RSD%), their values were calculated as they are listed 0.9778 μg. ml-1, 3.259 μg. ml-1, -3.61% and not more than 3.67% respectively.

Redox-Regulated Dynamic Self-Assembly of a Lindqvist-Type Polyoxometalate Complex

Dynamic regulation of self-assembly is of vital importance in chemistry, biology and material science thanks to its great potential for development of smart materials and devices. Polyoxometalates (POMs) are a class of functional inorganic nanoclusters, which has become one of the excellent building blocks for supramolecular self-assemblies, especially when covalently or non-covalently modified by organic species. As typical stimuli-responsive functional clusters, the POMs could be photochemically or electrochemically reduced to mixed-valence states, of which the structural integrity remains even after encountering stepwise multi-electron redox process. The intriguing photochromism of the POMs in different states exhibits distinct photophysical properties, which motivates us to exploit the dynamic self-assemblies of POM-based complexes. The divalent Lindqvist-type hexamolybdate cluster [Mo6O19]2- is one of the least negative-charged POMs, which is the ideal building blocks to construct novel assembly structures. Based on this motivation, herein, a single chain surfactant-encapsulated polyoxometalate (POM) complex (ODTA)2[Mo6O19] was prepared by simple counterion replacement of Lindqvist-type (TBA)2[Mo6O19] with octadecyltrimethylammonium (ODTA) in acetonitrile solution. The structure of the POM complex was confirmed by 1H nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and elemental analysis. The solution of complex (ODTA)2[Mo6O19] in the mixed solvents of acetonitrile and isopropanol with the volume ration of 4 to 1 exhibited reversible photochromism upon alternate UV light irradiation and air exposure. Upon UV light irradiation, the light yellow transparent solution of (ODTA)2[Mo6O19] turned into blue quickly. The new broad absorption band appearing at ca.751 nm assigned to the MoV → MoVI intervalence charge-transfer (IVCT) transition, indicated the formation of reduced POM, as revealed by UV-Vis absorption spectra. After exposed to air, the blue solution was bleached. The alternate photochromism could be conducted for multiple cycles. Helical self-assembled morphology of (ODTA)2[Mo6O19] was formed in acetonitrile/isopropanol, characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) methods. More interestingly, morphology transformation of the complex from helical strips to spherical assemblies occurred accompanied by photochromism occurrence. The morphology evolution during the photochromism process experienced from shortened helical strips through sea urchin-like aggregates to spherical assemblies. Most significantly, the helical assemblies could be recovered again after air oxidation, implying the reversible morphology transformation driven by redox stimulus. The redox-modulated reversible self-assembly is driven by the variation of electrostatic attraction between organic cations and inorganic anions as well as the electrostatic repulsion between inorganic ionic clusters, proved by X-ray photoelectron spectroscopy (XPS) and 1H NMR spectra. The results will contribute to better understanding the mechanism of dynamic assemblies and inspire the precise fabrication of advanced smart materials.

THERMOCAPILLARY MONITORING USING PARTICLE IMAGE VELOCIMETRY ASSOCIATED WITH DYNAMIC LASER SPECKLE

Thermocapillarity is a physical phenomenon used in many industrial processes, mainly in the field of miniaturization. Thermocapillary forces are the base of thermocapillary pumping (TCP), in which a drop of liquid moves through a microchannel or flat surface after temperature gradient occurs. The objective of this work was to study the thermocapillary convection during pumping without inserting external particles, monitored by the Particle Image Velocimetry (PIV) technique. The experiment consisted of a Pasteur tube containing a yellow fluorescein solution (0.02, 0.04, 0.06, 0.08, and 0.1 Molar), illuminated by a laser beam of 545 nm, 40 mW. After 2 minutes of illumination, the thermocapillary movement occurred at a distance of 0.05 mm below the meniscus when using a laser beam of 545 nm, 3 mW. The images were captured by a charge-coupled device (CCD) camera and processed using the PIV technique. The results showed an internal conversion capacity between the intersystem crossing, vibrational, and relaxation phenomena, also demonstrating the potential for applying the proposed approach. The images presented velocity distribution caused by thermocapillarity. The PIV was a useful tool for convective flow analysis if connected to appropriate image processing and enhancement techniques. In conclusion, the research showed the images with velocity distribution caused by thermocapillarity.

Nucleophilic Acylation with Aromatic Aldehydes to 2 Bromoacetonitrile: An Umpolung Strategy for the Synthesis of Active Methylene Compounds.

A novel one-pot N-heterocyclic carbene (NHC)-catalysed acylation of 2- bromoacetonitrile with aromatic aldehydes is reported. The protocol involves carbonyl umpolung reactivity of aldehydes in which the carbonyl carbon attacks nucleophilically (as d1 nucleophile) on the electrophilic terminal of 2-bromoacetonitrile to afford 3-aryl-3-oxopropanenitrile. The salient features of this procedure are short reaction time, operational simplicity, ambient temperature, no by-product formation and high yields. A flame-dried round bottom flask was charged with Imidazolium salts (3a) (0.20 mmol). Aldehyde 1a (1.0 mmol), 2-bromoacetonitrile 2 (1.0 mmol), and THF / t-BuOH 5 mL; 10:1) were added at positive nitrogen pressure followed by the addition of DBU (0.15 mmol) through stirring. The resulting yellow- orange solution was stirred at room temperature for 5-6 h. After completion of the reaction (TLC monitored), the reaction mixture was concentrated under reduced pressure. The product was purified using hexane / EtOAc (10:1) as an eluent to provide analytically pure compound 4a. Physical data of representative compounds and the NMR spectroscopic data are in agreement with the literature value. The salient features of this procedure are short reaction time, operational simplicity, ambient temperature, no by-product formation and high yields. To sum up, we have developed a convenient, efficient and one-pot route for 3-oxo-3- phenylpropanenitrile synthesis from NHC promoted direct nucleophilic acylation of aromatic aldehydes using 2- bromoacetonitrile. This method provided a wide range of products and good yields. To best of our knowledge, this is the new report for the synthesis of 3-oxo-3-phenylpropanenitrile through NHC promoted nucleophilic acylation of aromatic aldehyde.

Ferroelectric and photocatalytic behavior of Mn- and Ce-doped BaTiO3 nanoceramics prepared by chemical route

Partially doping of Ce and Mn at Ba and Ti site of BaTiO3 was done to study the dielectric and impedance behavior of Ba1−xCexTi1−xMnxO3 (x = 0.1, abbreviated as BCTM0.1) ceramics. We approach through chemical method to prepare a homogeneous nanosized material. The materials have 10.87 nm, 9.70 nm average crystallite and particle size respectively. The X-ray diffraction and Raman and EDX studies were employed to identify the phase purity and composition. Ferroelectric property was studied at a function of frequency and temperature. The relaxor behavior was observed during dielectric and impedance spectroscopy study. The ac and dc conductivity were also studied. Good photocatalytic activity of BCTM0.1 was observed for congo red (CR) and titan yellow (TY) dye solution with the % of degradation efficiency >95% and >82% respectively.

Dyeing mechanism and photodegradation kinetics of gardenia yellow natural colorant

In this study, gardenia yellow solution is used to dye 100% cotton fabric. The dyeing rate curve and adsorption isotherms were recorded to explore the thermodynamic model and to calculate the corresponding parameters. A definite concentration of gardenia yellow solution was placed under the xenon arc lamp for irradiation to test its photodegradability. Absorbance of the solution was measured at different degradation times and the corresponding varying curve of the absorbance was drawn to explore the photodegradation reaction order of the natural colorant and consistent parameters were calculated. The experimental results proved that the dyeing of cotton fabric with gardenia yellow colorant followed the pseudo second order kinetic model whereas adsorption isotherm followed the Langmuir model and the photodegradation process followed the second order kinetic model. Values of different parameters were calculated: reaction rate constant k = 2.26 × 10–3 (mg · L−1)1−m h−1, the correlation coefficient R2 = 0.994, and half decay time t1/2 = 5.82 h.

A three-dimensional microfluidic mixer of a homogeneous mixing efficiency fabricated by ultrafast laser internal processing of glass

We design a compact three-dimensional (3D) micromixer based on the Baker’s transformation concept and fabricate it in fused silica by ultrafast laser direct writing. One of the issues in the micromixer is the unbalanced mixing efficiencies between the center and boundary areas of the microfluidic channel. We overcome this problem by periodically exchanging the microstreams in the center and near the boundary which gives rise to improved mixing efficiency and uniformity. The performance of the fabricated micromixer is examined by mixing a blue and a yellow ink solution, showing efficient mixing with a high throughput.

Smartphone Assisted Colourimetric Detection and Quantification of Pb2+ and Hg2+ Ions Using Ag Nanoparticles from Aqueous Medium

Pollution of aquatic bodies with Lead and Mercury is a serious environmental issue, and there exists an unmet need to develop easy and portable detection techniques. Herein, we report a silver nanoparticle (AgNP) based system exhibiting high selectivity and distinct spectrophotometric behaviour towards these metal ions in the aqueous medium. Though many of the metal ions did not influence the characteristic plasmon spectral profile of AgNPs, Mercury caused the disappearance of absorbance at ~400 nm. Consequently, the yellow solution became colourless at around 7.6 ppm of Hg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ions. While the presence of Pb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ions induced a decrease in the initial plasmon intensity with the concomitant emergence of a new red-shifted band above 500 nm. As a result, the colour of the solution turned from yellow to red. These colour changes are found to fall well within the spectral responses of R, G and B filters of the digital camera. By making use of this, an android mobile application was developed for digitizing the colour values and for doing further quantitative analysis. The estimated concentration value by this method was found to be in good match with those obtained from absorbance measurement. The achieved lower detection limits were ~ 0.8 ppm for Hg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> and ~ 1.5 ppm for Pb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ions. This illustrates the potential of the proposed combination of smartphone enabled system with AgNPs for easy discrimination and quantification of these two metal ions from the aqueous medium.

Water and air friendly alkali metals synthesis of the h-BN-C QDTs and the utilization in the non-volatile resistive switching memory devices

A novel and facile hydrothermal route was designed to produce h-BN-C quantum dots (h-BN-C QDTs) using h-BN powder as a precursor and Potassium Sodium Tartare as an intercalant. The resulting yellow solution possessed mono or few-layers of quantum dots with an average size of ~2.5 nm. Due to the incorporation of functional groups (carbon, oxygen) on the surface of h-BN, an enhancement of photo luminescent magnitude and a blue shift were observed in photoluminescence spectra from h-BN-C QDTs solution. Further, h-BN-C QDTs exhibits a bright blue fluorescence under the irradiation by a 365 nm UV light. Next, h-BN QDTs was utilized as the dielectric active layer by using simple drop casting method between the electrodes and fabricated the nonvolatile resistive switching devices. The fabricated devices exhibited the nonvolatile bipolar resistive switching characteristics with 103 ON/OFF ratio and turned ON and OFF threshold voltages of −1.9 V and +1.4 V, respectively. Further, the switching mechanisms of h-BN-C QDTs were found to be space charged trapping. It provides a route toward tailoring the optical and electrical properties of the h-BN materials and can be utilized in the future potential applications.

Dioxygen Activation by Internally Aromatic Metallacycle: Crystallographic Structure and Mechanistic Investigations.

SummaryMononuclear metal-peroxo species are invoked as the key intermediates in metalloenzymatic or synthetic catalysis. However, either transience or sluggishness reactivity of synthetic analogs of metal-peroxo species impedes our understanding of oxygen activation mechanism. Herein, we designed and characterized a dioxygen-derived mononuclear osmium-peroxo complex, in which the peroxo ligand is stabilized by internally aromatic metallacycle. We demonstrate that the osmium-peroxo species shows catalytic activity toward promoterless alcohol dehydrogenations. Furthermore, computational studies provide a new mechanism for the osmium-peroxo-mediated alcohol oxidation, starting with the concerted double-hydrogen transfer and followed by the generation of osmium-oxo species. Interestingly, the internally aromatic metallacycle also plays a vital role in catalysis, which mediates the hydrogen transfer from osmium center to the distal oxygen atom of Os–OOH moiety, thus facilitating the Os–OOH→Os=O conversion. We expect that these insights will advance the development of aromatic metallacycle toward aerobic oxidation catalysis.

Colorimetric Sensor Based on β-Cyclodextrin-Functionalized Silver Nanoparticles for Zidovudine Sensitive Determination.

Zidovudine (ZDV) is an antiviral drug against HIV that was approved by the FDA on March, 1987. It is a reverse transcriptase inhibitor. This type of drug stops the reproduction of DNA and decreases the amount of the virus in the patients' blood. Due to the ability of forming various molecular bonds, silver nanoparticles (AgNPs) are widely used for the detection of large range of agents, including drugs. In this study, we synthesized AgNP-modified β-cyclodextrin (β-CD) using green synthesis for the sensitive and selective zidovudine (ZDV) determination. Characterization of nanoparticles was done using different methods including infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and also, X-ray diffraction (XRD) patterns. The AgNP λ-max peak was at approximately 405 nm. In the presence of ZDV, yellow solution was turned to red color, and surface plasmon absorption band was dramatically centered at 560 nm. ZDV was determined in the range of 50–500 μM, and the detection limit value was obtained as 42 μM. The sensor was used to determine ZDV in tablets with good recovery.

Optimization and modeling of reactive yellow adsorption by surface modified Delonix regia seed: Study of nonlinear isotherm and kinetic parameters

Surface modified activated carbon (Delonix regia seeds) as an adsorbent was prepared and utilized for quick and adequately removing reactive yellow dye from aqueous solution. The adsorbent material was described exploiting Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Batch adsorption study was done to consider the factor affecting parameters (initial reactive yellow dye concentration, solution pH, sorbent dose and temperature). Optimum values of each parameters were calculated as pH of 2.0, temperature of 303 K (30 °C), contact time of 60 mins and 2.5 g/L and 1 g/L of adsorbent dosage for RDRS and SMDRS respectively for the removal of reactive yellow dye 145. Adsorption results were displayed to characterize fundamental parameters, for example, the adsorption isotherm and kinetics. The evaluated results are studied with four isotherms models and based on higher R2 values (0.9515) and lower errors values (SSE-0.46; RMSE-1.888), Freundlich isotherm models were observed to be best fitted. The kinetic model outcomes determined by fitted with contact time data, pseudo-second-order kinetic model shown best-fitted model. The maximum monolayer adsorption capacity (qm) value for the reactive yellow removal was found to 24.15 mg/g. Thermodynamic results reveals that the adsorption of reactive yellow 145 dye onto RDRS and SMDRS are spontaneous, exothermic in nature and randomness at the adsorbent-solution interface during sorption process based on its ΔGo, ΔHo and ΔSo respectively. It was exhibited that the unaffectedly modest and good-natured surface modified Delonix regia seeds have a solid adsorption and removal capacity for dyes.

Diamino malenonitrile-linked naphthalimide in selective sensing of F-, CN-, Hg2+ and Cu2+ under different experimental conditions

ABSTRACT Diaminomalenonitrile-linked naphthalimide 1 has been designed and synthesised. It shows selective sensing of F−, CN−, Cu2+ and Hg2+ under different experimental conditions. While compound 1 in CH3CN exhibits colour change from yellow to greenish blue or green in the presence of F−, AcO−, CN− and H2PO4 −, it shows a colour change from yellow to light green selectively in presence of CN− in aqueous CH3CN. The selectivity of 1 for F− in pure CH3CN is achieved by using Ca2+ ion as chelating agent. Besides anion sensing, the probe exhibits different colour attributes towards Hg2+ and Cu2+ ions in aqueous CH3CN. While the yellowish solution of 1 is discharged to almost colourless in presence of Cu2+ ions, a light red colour is observed in the presence of Hg2+ ions. The interaction study has been performed by NMR, UV-vis, fluorescence and mass spectroscopic techniques. A theoretical study has been invoked to understand the deprotonation of 1 that occurs in presence of basic anions.