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Two new complexes of europium (III) and erbium (III) were synthesized from diaminodiphenylether bridged spacer in 1:1 molar ratio of ligand and metal salt, whereas the ligand was synthesized in 1:2 molar ratio of diaminodiphenylether and aldehyde. The synthesized complexes were structurally analyzed through nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), energy-dispersive X-ray diffraction (EDX), UV–visible and photoluminescence spectroscopy. In both synthesized complexes, the metals were found in coordination to nitrogen and oxygen atoms of the azomethine (HC = N) and hydroxyl (–OH) groups as evident by FTIR and NMR spectral results in both synthesized complexes. Molar conductivity data for Eu(III) and Er(III) observed in the range of 129–135.5 Ω−1cm2 mol−1 determined that both complexes were 1:2 electrolytes. The presence of characteristic peaks for Eu, C, O and N was clearly identified in energy-dispersive X-ray diffraction, which confirmed its successful synthesis. Furthermore, the luminescence behavior of the complexes was investigated in the solution state with dichloromethane (DCM). Upon excitation at 274 nm, both complexes exhibited two emission bands centered at 379 nm to 399 nm and 519 nm for Eu(III) and Er(III). Consequently, the good emission properties illustrated that the synthesized complexes featured their potential as promising cost-effective luminescent materials. [ABSTRACT FROM AUTHOR]

An environmentally benign magnetic gold nanoparticles (AuNPs) catalyst supported onto thioctic acid functionalized silica-coated magnetite nanoparticles, Au–RS–SR–NH–SiO2–Fe3O4,without employing any toxic reductant or capping agent was successfully synthesized. The Phaleria macrocarpa (Scheff.) Boerl (P. macrocarpa) fruit aqueous extract was used as the reducing and stabilizing agents for the biosynthesis of AuNPs. The catalytic performance of the magnetic AuNPs catalyst was evaluated for the reduction of 4-nitrophenol into 4-aminophenol in the presence of NaBH4. A three-factor Box–Behnken design coupled with response surface methodology was applied to evaluate the effects of several operating parameters, namely, volume of NaBH4, 4-nitrophenol concentration, and weight of Au–RS–SR–NH–SiO2–Fe3O4 on the conversion of 4-nitrophenol. The reduction of 4-nitrophenol using Au–RS–SR–NH–SiO2–Fe3O4 was welldescribed by a quadratic polynomial model. A significant quadratic model with p value ˂.0001 and R2 = 0.9958 was achieved using the analysis of variance (ANOVA). The conversion of 4-nitrophenol to 4-aminophenol was maintained at 90% after five cycles. [ABSTRACT FROM AUTHOR]

Graphical abstract A nickel(II) complex with a new Schiff base derived from 2,4-dihydroxyacetophenone has been synthesized and spectroscopically characterized. Density Functional Theory (DFT) approach was successfully used for investigation of its structural and spectral characteristics. Antibacterial assay was done and DFT calculations were used to explain its antibacterial activity. Abstract The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H NMR chemical shift values of the title molecule, N,N ′-bis-(4-hydroxy-α-methylsalicylidene)ethylenediamine nickel(II) complex, (C 18 H 18 N 2 NiO 4) in the ground state have been calculated using density functional theory (DFT) method with general (GEN) and 6-311++G(d,p) basis set, respectively. The theoretical results were compared with the experimental data. Calculated results show that DFT can well reproduce the structure of the title compound. The theoretical vibrational frequency and 1H NMR chemical shift values show good agreement with experimental data. In addition, by using time dependent (TD)-DFT method, a good agreement between the predicted electronic absorption and experimental values are observed. [ABSTRACT FROM AUTHOR]

Thioctic acid functionalized silica coated magnetite nanoparticles, RS-SR-NH-SiO2-Fe3O4, has been synthesized and its ability for the recovery of Au(III) in aqueous solutions was assessed. The results of the adsorption thermodynamics and kinetics showed that this magnetic adsorbent has good adsorption capacity for Au(III) and the best interpretation for the experimental data was given by the Langmuir isotherm model. The adsorption kinetics of RS-SR-NH-SiO2-Fe3O4was well fitted with the pseudo-second-order rate equation. The thermodynamic parameters ΔG, ΔH and ΔS were also evaluated and the overall adsorption process was exothermic and spontaneous in nature. [ABSTRACT FROM AUTHOR]

Au Pd bimetallic nanospheres were synthesized via a green approach based on an in situ seed-mediated growth method using Etlingera elatior ( EE ) leaf extract as a bioreducing and capping agent. The synthesized bimetallic Au 1 Pd 1 , Au 1 Pd 10 , Au 10 Pd 1 and monometallic Au and Pd nanoparticles were characterized using various spectroscopic and microscopic techniques. This study reveals the morphology control of anisotropic Au nanoparticles, which can be achieved by the addition of palladium into the aqueous reaction mixture. Furthermore, the catalytic ability of each nanoparticle to catalyze the reduction of 4-nitrophenol to 4-aminophenol were investigated. The bimetallic nanoparticles are more efficient in catalyzing the reduction of 4-nitrophenol than monometallic Au and Pd whereby the Au 1 Pd 1 was the most efficient, with a rate constant, k, of 24.0 × 10 −3 min −1 . [ABSTRACT FROM AUTHOR]

The effects of precipitation temperature on both structural and magnetic properties of polyethylene glycol-coated MnZnFe O nanoparticles are presented. Samples were prepared via co-precipitation method at different precipitation temperatures ranged 25-100 C. X-ray diffraction analysis revealed that both crystallite size and lattice constant of the nanoparticles increased with increasing of temperature. FESEM images verified the existence of crystalline ferrites of diameter ranged 7.49-9.41 nm. FTIR spectra evidenced the effect of precipitation temperature on Fe -O stretching vibration in the ferrites. These MnZnFe O nanoparticles exhibited the highest saturation magnetization 20.938 emu/g at 75 C. Correlations among precipitation temperature alteration, structural morphology, and magnetic response are established. [ABSTRACT FROM AUTHOR]

A green and cost-effective biosynthetic approach for the preparation of icosahedral gold nanoparticles (AuNPs) using an aqueous leaf extract ofPolygonum minusas reducing and stabilising factor is described. The reduction of Au3+ions to elemental Au rapidly occurred and is completed within 20 minutes at room temperature. The size of the nanoparticles is highly sensitive to the AuCl4−/leaf extract concentration ratio and pH. Transmission electron microscopy and X-ray diffraction data indicated that the nanoparticles were in a crystalline shape (face-centred cubic), mostly icosahedral and nearly monodispersed with an average size of 23 nm. Cyclic voltammetric studies suggested that flavonoids, such as quercetin and myricetin present in the leaf extract had a tendency to donate electrons to Au3+ions and the formation of elemental Au was possible due to the transfer of electrons from these flavonoids to Au3+ions. Infrared absorption of the AuNPs and the leaf extract revealed that the oxidised (quinone) form of quercetin and myricetin were presumably the main stabilising agents in the formation of stable nanoparticles. The present biosynthesis of AuNPs was simple, rapid, cost-effective and environmentally friendly. The newly prepared biostabilised icosahedral AuNPs show good catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). [ABSTRACT FROM AUTHOR]

Four air and moisture-stable palladium(II)-Schiff base complexes, N,N'-bis(-methylsalicylidene)propane-1,3-diamine palladium(II) (2a), N,N'-bis(4-methyl--methylsalicylidene)propane-1,3-diamine palladium(II) (2b), N,N'-bis(3,5-di-tert-butylsalicylidene)propane-1,3-diamine palladium(II) (2c), and N,N'-bis(4-methoxy-salicylidene)propane-1,3-diamine palladium(II) (2d), have been successfully synthesised and characterised by CHN elemental analyses and conventional spectroscopic methods. These complexes were investigated as catalysts in the phosphine-free Mizoroki-Heck cross-coupling reactions of aryl bromides with methyl acrylate. [ABSTRACT FROM AUTHOR]

The title compound, C26H22NP, is a Schiff base derived from triphenyl­phosphine with a 4-methyl­phenyl­amine group attached to one of the benzene rings of the phosphine in the o-position. The azomethine C=N bond length is 1.259 (3) Å and the dihedral angle between the benzene ring and its 4-methyl­phenyl­amine substituent is 40.02 (2) Å. The geometry at the P atom is approximately tetra­hedral. [ABSTRACT FROM AUTHOR]

Efficient far-field coupling of longitudinal plasmon modes of gold nanorods makes them prospective for optical imaging. A facile one-step hydrothermal synthesis of stabilized gold nanorods in an aqueous solution at 85 °C is reported. High aspect ratio of these nanorods ranging from 10 to 57 is achieved using methyltrioctylammonium chloride (TOMAC) as a phase transfer reagent. The growth of {100} and {110} facets being more favorable to conception is facilitated via the capping agent (TOMAC). These highly elongated nanorods reveal visible luminescence at around 410 nm, which is attributed to the ligand–metal charge transition mechanism. We affirm that such plasmonic nanorods acquiring superior nonlinear optical properties can be used as a vehicle for single-particle measurements. [ABSTRACT FROM AUTHOR]

Using Methyltrioctylammonium chloride (Aliquat 336) as a shaping and stabilizing agent for the first time, quasi-spherical and multi-faceted gold (Au) nanoparticles (NPs) are synthesized via seed mediated protocol. These slightly elongated NPs devoid of any centre of symmetry are found to possess some twin defects on their surfaces as confirmed by TEM analysis. Their Surface plasmon resonance band is evidenced at 534 nm. The growth progression is examined through the formation of translational Au NPs during the reaction. Such Aliquat 336 stabilized NPs are demonstrated to achieve minimal ligand density. This is attributed to the formation of hexagonally patterned self-assembled monolayer of ligand molecules over the surface of Au NPs. TGA and DLS experiments are performed to quantify the ligand density on the surface of these multi-faceted Au NPs. EDX, FTIR, and XPS measurements are accomplished to determine the structure and binding of ligand molecules to Au surface. Further, these NPs are found to be luminescent with violet emission under an excitation at 320 nm. The admirable features of the results suggest that our method may constitute a basis for the facile synthesis of functionalized and luminescent multi-faceted Au NPs with minimal ligand density, potential for sundry biomedical applications. [ABSTRACT FROM AUTHOR]

The coating of Polyethylene Glycol (PEG) on zinc substituted manganese ferrite nanoparticles has been reported in the present study. Single phase nanoferrites bearing the chemical formula Mn (1− x ) Zn ( x ) Fe 2 O 4 (0.0≤ x ≤1.0) were produced under low reaction temperature of 75 °C and their morphological, structural and magnetic characterizations were performed. The prepared ferrites were characterized using X-ray diffraction (XRD), field emission scan electron microscopy images (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM) techniques. XRD revealed the formation of spinel single-phase structure for the samples with Zn-content. The crystallite sizes estimated using Scherer formula were in the range 4.50–15.89 nm. The characteristic bands of PEG as observed in its Fourier transform infrared spectrum technique were also present in PEG layer on Mn–Zn ferrite nanoparticles, hence confirming its presence. The presence of PEG on Mn (1− x ) Zn ( x ) Fe 2 O 4 nanoparticles, spherical formation of PEG coated Mn (1− x ) Zn ( x ) Fe 2 O 4 nanoparticles and reduced agglomeration in the Mn (1− x ) Zn ( x ) Fe 2 O 4 nanoparticles were revealed by FE-SEM. The measurements of magnetic properties at room temperature by VSM showed that all samples behaved superparamagnetic with magnetization ( M ) and coercivity in the range of 1.86–20.66 emu/g and 12.922–30.253 Oe, respectively. The M–H loop of all the samples is narrow with low value of coercivity and retentivity; indicating the superparamagnetic nature of these samples. [ABSTRACT FROM AUTHOR]

Abstract: A series of Cu-doped Cd0.1Zn0.9S solid solution with various amounts of Cu dopant was successfully prepared by hydrothermal method. The properties and the photocatalytic activity of the prepared samples for hydrogen production under visible light irradiation were compared to those prepared by co-precipitation method. The Cu-doped Cd0.1Zn0.9S samples prepared by hydrothermal method showed both improved crystallinity and photoabsorption ability as compared to the undoped sample. On the other hand, even though Cu-doped Cd0.1Zn0.9S prepared by co-precipitation method also showed improved photoabsorption ability in the visible light region, the samples showed poor crystallinity compared to the undoped one. With the same amount of Cu dopant, all samples prepared by hydrothermal method were found to exhibit higher photocatalytic activity for hydrogen production than the samples prepared by co-precipitation method. It was revealed that the amount of Cu dopant, crystallinity and narrow band gap energy are important factors to obtain highly active and stable photocatalysts. [Copyright &y& Elsevier]

Abstract: A series of Cd 0.1 Sn x Zn 0.9 −2x S solid solution was successfully synthesized by hydrothermal method and employed as photocatalyst for photocatalytic hydrogen evolution under visible light irradiation. The structures, optical properties and morphologies of the solid solutions were studied by X-ray diffraction, diffuse reflectance UV–visible spectroscopy and field emission scanning electron microscopy. From the characterizations, it was confirmed that Sn can form solid solution with Cd 0.1 Zn 0.9 S and the high crystallinity can be maintained as well. Among all samples, the highest photocatalytic activity was observed on Cd 0.1 Sn 0.01 Zn 0.88 S photocatalyst, with average rate of hydrogen production 3.52 mmol/h, which was ca. 1.5 times higher than the Cd 0.1 Zn 0.9 S photocatalyst. In addition to the high activity, the Cd 0.1 Sn 0.01 Zn 0.88 S also showed high stability at long irradiation time. The role of Sn in preventing electron-hole recombination and photocorrosion was proposed. [Copyright &y& Elsevier]

Abstract: A detailed characterization study on titanosilicate ETS-10 derived from rice husk ash (RHA) as silica source is reported. It can be prepared through a hydrothermal synthesis route in the absence of seed of ETS-4 and an organic template agent. The effect of different titanium source, crystallization time and temperature as well as the effect of different molar composition on the crystallization and purity of ETS-10 was investigated. The commercial colloidal silica source, Ludox-30 was also used for comparison purpose. A number of characterization techniques namely, Fourier transform infrared, Raman, diffuse reflectance UV–Vis and solid state nuclear magnetic resonance spectroscopic as well as X-ray diffraction, thermogravimetric, field emission scanning electron microscopic, and BET surface area analyses have been employed to correlate the preparation techniques and starting materials with the main features of the ETS-10. A highly pure and crystalline ETS-10 could be obtained from the gels of molar composition TiO2:3.75SiO2:1.5NaOH:0.54KF:21.25H2O at 493K and 52h of crystallization time. ETS-10 derived from RHA was found comparable with ETS-10 prepared using Ludox in terms of their physicochemical properties. [Copyright &y& Elsevier]

[Display omitted] • AgNPs was successfully synthesized within 5 h using aqueous Persicaria odorata extract at room temperature. • Phytochemical content analysis showed high values reflecting strong reducing ability of P. odorata extract. • FTIR spectra shows significant role of amine and polyphenol in reducing and stabilizing AgNPs. • Antibiotic-AgNPs enhanced antibacterial activity due to significant increment of inhibition zone compared to AgNPs/antibiotic alone. For many years, combination therapies with two or more antimicrobial agents have gained interest to address the problem of emerging antibiotic resistance. Several studies have shown that the addition of AgNPs enhances the antimicrobial activity of antibiotics against resistant pathogens. However, the antibacterial activity of phytosynthesised silver nanoparticles (AgNPs) in combination with antibiotics has not been extensively studied. Therefore, this study aimed to investigate the antibacterial activity of the phytosynthesised AgNPs with different antibiotics against two common pathogenic bacteria, namely methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. A green method was used to produce AgNPs, where Persicaria odorata extract acted as a reducing and stabilising agent in the aqueous synthesis process. The production of AgNPs was verified through various analytical techniques, including ultraviolet–visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy and energy-dispersive X-ray. Notably, strong absorption spectrum corresponding to the surface plasmon resonance peaks of AgNPs was found at 436 nm, with particles ranging from 10 to 35 nm. The disc diffusion technique was used to investigate the antibacterial activity of AgNPs, both alone and in combination with antibiotics. Initially, the MRSA and P. aeruginosa showed 100 % resistance to antibiotics, especially ampicillin. However, the disc diffusion result exhibit a significant increase in the inhibition zone when ampicillin-AgNPs, cefoxitin-AgNPs and chloramphenicol-AgNPs were used in combination. In short, the findings of this study showed that AgNPs exhibit a promising synergy when used in combination with antibiotics, opening up possibilities for future combination therapies against antibiotic-resistant pathogens. [ABSTRACT FROM AUTHOR]

A series of novel polycyclic structures, with an imidazothiazole central core, were successfully synthesized through the anodic oxidation of catechols in the presence of 2-imidazolidine thione, as nucleophiles in aqueous solution. The cyclic voltammetric results indicated that one-pot multi-step sequential reactions occur between the electrochemically derived o-benzoquinones intermediates and nucleophiles affording fused polyheterocyclic compounds. The mechanism of these catalyst-free, tandem reactions are proved as ECECE or ECECCE pathways using potentiostatic and galvanostatic coulometries. In addition, the electrosyntheses of fused imidazo[2,1- b]thiazoles have been successfully performed in ambient conditions in an undivided cell using an environmentally friendly method with high atom economy and current efficiency. The novel fused polyheterocycles were fully characterized by FT-IR, H NMR, C NMR, and HR-MS spectrometric methods. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A benzoylthiourea derivative (LTU) and its metal complexation of palladium(II) chloride (MLTU) has been successfully synthesized and characterized via typical spectroscopic and analytical techniques namely IR, 1H and 13C Nuclear Magnetic Resonance, UV-Visible and Gas Chromatography Flame Ionization Detector (GC-FID). The Infrared spectrum for LTU shows four significant bands of interest namely v(N-H), v(C=O), v(C-N) and v(C=S) and the values were observed within the range. The 1H NMR spectrum for the compound shows expected protons for N-H at δH 10.95 ppm and δH 11.15 ppm while the 13C NMR spectrum shows resonances of carbonyl (C=O) carbon and thiones (C=S) at δC 168.26 ppm and δC 180.56 ppm, respectively. From UV-Vis spectrum, it shows the presence of n-л ⋆л→л⋆electronic transitions which are expected to be attributed from the phenyl ring, carbonyl (C=O) and thiones (C=S) chromophores. Complexation of LTU with palladium(II) chloride was done to afford MLTU which in turn, was tested as homogeneous catalyst in Sonogashira cross-coupling reaction. The reaction was monitored by GC-FID at 6 hours reaction period. The percentage conversion of 4- bromoacetophenone to the coupled product was 75.73% indicated that MLTU can act as an ideal potential catalyst in the Sonogashira reaction. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report rapid and selective nanogold-based colorimetric sensors for metal ions. [•] We report employing of an interfacial coordination chemistry in colorimetric sensor. [•] Pyridine derivatives on gold nanoparticles act as sensors for Cu2+ and Ag+ ions. [•] Cu2+-metal-induced aggregation of modified small gold nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: A new trinuclear di-n-butyltin(IV) complex with pyruvic acid-N(4)-cyclohexylthiosemicarbazone (H2PACT) ligand was synthesized and characterized by elemental analyses, molar conductivity, UV–Vis, FT-IR, 1H, 119Sn NMR spectroscopy and single crystal X-ray study. Single crystal X-ray diffraction data revealed that this complex was trinuclear cyclic fashion with the pyruvic acid-N(4)-cyclohexylthiosemicarbazone ligand. In the trinuclear di-n-butyltin(IV) complex, the ligand (H2PACT) is coordinated to the central tin(IV) atoms via the carboxylato-O, the azomethine-N and the thiolato-S atoms. The trinuclear tin system is formed by the bridges through the carbonyl oxygen atom of the carboxylate moieties and making the tin atom of seven coordinated in distorted pentagonal bipyramidal geometry. Single crystal X-ray data indicates that the complex (1) crystallized in cubic system with space group I-43d, a = b = c = 30.3273(17) Å, α = β = γ = 90°, Z = 16, μ(MoKα) = 1.209 mm−1, F(000) = 12,144, and final R 1 = 0.0390, wR 2 = 0.0843 for observed reflections 4582(I > 2σ(I)). [Copyright &y& Elsevier]

Abstract: The reaction of 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone [HBPCT, (1)] ligand with organotin(IV) chloride(s) lead to the formation of three new organotin(IV) complexes: [MeSnCl2(BPCT)] (2), [PhSnCl2(BPCT)] (3) and [Ph2SnCl(BPCT)] (4). The ligand (1) and its organotin(IV) complexes (2–4) have been synthesized and characterized by CHN analyses, molar conductivity, UV–Vis, FT-IR and 1H NMR spectral studies. The single crystal X-ray diffraction studies indicated that [PhSnCl2(BPCT)] (3) is six coordinated and adopts strongly a distorted octahedral configuration with the coordination through pyridine-N, azomethine-N and thiolato-S atoms of the ligand. The crystal system of [PhSnCl2(BPCT)] (3) is orthorhombic with space group P2ac2n and the unit cell dimensions: a =28.1363(5)Å, b =9.5970(2)Å, c =9.4353(2)Å. [ABSTRACT FROM AUTHOR]

• Palladium(II)-Pivaloyl thiourea complexes successfully synthesized and characterized. • The Pd(II) complexes gave significant results in the Sonogashira catalytic activity. • MC3 with no substitution exhibit the best catalyst as it gave a high conversion rate. We report herein the synthesis of Pd(II) complexes featuring pivaloylthiourea derivatives to investigate their catalytic behaviour in Sonogashira cross-coupling reactions as the homogenous catalyst. The SN 2 reactions have resulted in pivaloyl thiourea derivatives ligands with general formula (CH 3) 3 C(O)NHC(S)NHR introducing different substituent groups of NO 2 (L1), OCH 3 (L2), and H (L3) prior to form complexation with Pd(II) (MC1 , MC2 , and MC3 respectively). All synthesised compounds were characterised via typical selected spectroscopic and analytical methods. Hence, catalytic screening activity revealed that Pd(II)-pivaloyl thiourea catalysed, featuring MC3, is the best catalyst as it gave a high conversion rate up to 99%. [ABSTRACT FROM AUTHOR]