β-Functionalized ethylchalcogenolate complexes of lead(II): Synthesis, structures and their conversion into lead chalcogenide nanoparticles

The reactions of Pb(OAc)₂·3H₂O with NaER yield homoleptic colorless to yellow complexes of composition, [Pb(ER)₂] (ER = SCH₂CH₂NMe₂ (1), SeCH₂CH₂NMe₂ (2) and SeCH₂CH₂COOMe (3)). These complexes were characterized by elemental analyses, UV–Vis and ¹H NMR data. Molecular structures of [Pb(ECH₂CH₂NMe₂)₂] (E = S or Se) have been established by single crystal X-ray diffraction analyses. These molecules have a distorted trigonal bipyramidal configuration around lead with the nitrogen atoms of the chelating chalcogenolate ligands occupying the axial positions. Thermal behavior of these complexes was studied by TG analysis. Pyrolysis in a furnace or in HDA (hexadecylamine) gave PbE nanoparticles which were characterized by UV–Vis, photoluminescence, XRD, EDAX, and TEM measurements.     

Functionalization of silver and gold nanoparticles using amino acid conjugated bile salts with tunable longitudinal plasmon resonance

The vital bioactivities of bile salts are physiologically important molecules. The concept of using bile acids and their conjugates in nanoscience is a novel idea, which opens up fascinating prospects and gives way for various versatile properties. Here in, we report novel strategy for the synthesis of aqueous stable, silver and gold nanoparticles (Ag & AuNPs) using naturally occurring amino acid conjugated sodium salt of taurocholate (NaTC) and glycocholate (NaGC) as reducing and capping agents. The formation of nanoparticles was kinetically monitored using UV–vis spectroscopy at different time intervals. It was noticed, that the rate of reduction of AgNO₃ is much faster than the HAuCl₄ at fixed concentration of bile salts. Furthermore, the size and shape of the NPs are controlled and achieved by changing the nature of bile salts. The synthesized nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques for morphological studies. The interaction between nanoparticles with bile salts was investigated using FT-IR spectroscopy, cyclic voltammetry (CV) and thermogravimetric analysis (TGA).     

Structural and fluorescence properties of phenolphthalein bridged cyclotriphosphazatrienes

This study dealt with the reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆ (trimer) (1) with phenolphthalein (2) to give the phenolphthalein bridged compounds 3, 4 and 5. The phenolphthalein bridged cyclotriphosphazatriene derivatives are reported for the first time. The new compounds (3–5) are characterized by elemental analysis, mass spectrometry, UV–vis, FT-IR, ¹H, ³¹P NMR and fluorescence spectroscopy. The more bridged phenolphthalein groups show the higher intensity of the absorption bands in the UV–vis spectra. Fluorescence spectrum of compound 3 shows a small band in the lower spectral range, while the spectra of compounds 4 and 5 show more intense and a band in higher spectral range.     

1-Substituted 5-thiotetrazoles as novel capping agents for stabilization of gold nanoparticles

Stable and nearly monodispersed gold nanoparticles with sizes of 2.8–4.7 nm are easily prepared by the reduction of tetrachloroaurate salts in a toluene-water system in the presence of 1-R-5-thiotetrazoles (R = Et, t-Bu, 1-adamatyl). The prepared gold nanoparticles were characterized by TEM, XRD, UV–Vis, FTIR and TGA.     

The microwave-assisted synthesis and characterization of novel, octakis(2-hydroxyethoxy)resorcinarene bridged polymeric metallophthalocyanines

The new metallophthalocyanine (Zn, Cu, Ni, Co) polymers containing 4,6,10,12,16,18,22,24-octakis(2-hydroxyethoxy)-2,8,14,20-tetramethylresorcinarene are described. Firstly, 4,6,10,12,16,18,22,24-octakis(2-hydroxyethoxy)-2,8,14,20-tetramethylresorcinarene compound (1) was synthesized by treating resorcinarene with 2-chloroethanol under microwave irradiation. Then, tetrakis(4,5-bis(2-hydroxyethoxy))phthalonitrile substituted resorcinarene compound (2) and octakis(4-(2-hydroxyethoxy))phthalonitrile substituted resorcinarene compound (3) were synthesized by treating compound (1) with 4,5-dichloro-1,2-dicyanobenzene and 4-nitro-1,2-dicyanobenzene, respectively, under microwave irradiation. The chlorides Cu (II), Ni (II), Co (II), were employed in order to synthesize the corresponding metallophthalocyanine polymers (2b–d and 3b–d) and Zn(CH₃COO)₂ was used for the preparation of zinc phthalocyanine polymers (2a and 3a). All products were synthesized by microwave-assisted synthesis method. The structures were characterized by elemental analyses, ¹H NMR, ¹³C NMR, UV–Vis and FTIR spectroscopy.     

A facile approach to synthesize poly(4-vinylpyridine)/multi-walled carbon nanotubes nanocomposites: highly water-dispersible carbon nanotubes decorated with gold nanoparticles

A facile approach to attach high-density and uniform gold nanoparticles on individual multi-walled carbon nanotubes (MWNTs) is achieved. By simple grinding, water-soluble linear polymers poly(4-vinylpyridine) (PVP)-wrapped around nanotubes and thus rendered them reversibly soluble in water, ethanol, and DMF. Individual tubes are clearly observed after PVP-wrapped nanotubes were spin-coated onto a silicon wafer. Subsequently, Au nanoparticles were densely decorated on the individual MWNTs by in situ reduction of HAuCl₄ in the homogeneous aqueous solution of MWNTs–PVP to form stable water-dispersible Au/PVP/MWNTs hybrid. Morphology of Au nanoparticles was determined by scanning electron microscope and atomic force microscope. The diameter of the Au nanoparticles is controlled in the range of 3.5 to 13.5 nm. The presence of gold nanoparticles with decreased particle size was also detected by UV–Vis spectroscopy.     

New platinum compounds containing the diphosphine ligand 2-(ferrocenylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (fbpcd): Synthesis, redox behavior, and X-ray diffraction structures of PtCl2(fbpcd) and Pt(mnt)(fbpcd)

The reaction of the redox-active diphosphine ligand 2-(ferrocenylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (fbpcd) with PtCl₂(1,5-cod) furnishes the platinum(II) compound PtCl₂(fbpcd) (2). Treatment of 2 with disodium maleonitriledithiolate (Na₂mnt) yields the chelating thiolate compound Pt(mnt)(fbpcd) (3). Both 2 and 3 have been fully characterized in solution by IR, UV–Vis, and NMR spectroscopies, and their molecular structures established by X-ray crystallography. The redox properties of the fbpcd ligand and compounds 2 and 3 have been investigated by cyclic voltammetry, and the composition of the HOMO and LUMO levels in these systems have been determined by extended Hückel MO calculations, the results of which are discussed with respect to electrochemical data.     

Co(III) complexes of Me-salpn and Me-salbn and the ring size effect on the coordination modes and electrochemical properties: The crystal structures of trans-[Co(Me-salpn)(py)2]PF6 and cis-α-[Co(Me-salbn)(4-Mepy)2]BPh4 · 4-Mepy

The synthesis and characterization of a series of cobalt(III) complexes of the general type [Co(N₂O₂)(L₂)]⁺ are described. The N₂O₂ Schiff base ligands used are Me-salpn (H₂Me-salpn = N,N′-bis(methylsalicylidene)-1,3-propylenediamine) (1–3) and Me-salbn (H₂Me-salbn = N,N′-bis(methylsalicylidene)-1,4-butylenediamine) (4–5). The two ancillary ligands L include: pyridine (py) 1, 3-metheylpyridine (3-Mepy) 2, 1-methylimidazole (1-MeIm) 3, 4-methylpyridine (4-Mepy) 4 and pyridine (py) 5. These complexes have been characterized by elemental analyses, IR, UV–Vis, and ¹H NMR spectroscopy. The crystal structures of trans-[Co^III(Me-salpn)(py)₂]PF₆, 1, and cis-α-[Co^III(Me-salbn)(4-Mepy)₂]BPh₄ · 4-Mepy, 4, have been determined by X-ray diffraction. Examination of the solution and crystalline structures revealed that the outer coordination sphere of the complexes exerts a noticeable influence on the inner coordination sphere of the Co(III) ion. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Co^III–Co^II is electrochemically irreversible, which is accompanied by the dissociation of the axial (R-py)–cobalt bonds. It has also been observed that the Co(III) state is stabilized with increasing the flexibility of the ligand environment.     

{XW12O40 [Cu(en)2(H2O)]3} (X=V, Si): Two novel tri-supported Keggin POMs with transition metal complexes

Two novel polyoxometalate derivatives, {X^IVW^VI₁₀W^V₂O₄₀[Cu(en)₂(H₂O)]₃} [X=V (1), Si (2); en=ethylenediamine], have been hydrothermally synthesized and characterized by elemental analyses, IR, UV–Vis, XPS, EPR, TG and single crystal X-ray diffraction analyses. They represent the first classical Keggin polyoxoanion supported by three transition metal complex moieties, which further act as the neutral molecular unit for the construction of the interesting three-dimensional supramolecular frameworks. The magnetic properties of 1 have also been studied in the temperature range of 4–300 K, and its magnetic susceptibility obeys the Curie–Weiss law, showing antiferromagnetic coupling.     

Chemical characterization and evaluation of antimicrobial and cutaneous wound healing potentials of gold nanoparticles using Allium saralicum R.M. Fritsch

The use of herbal medicines dates back a long way in history. Herbal medicines have been widely used all over the world since ancient times and have been recognized by physicians and patients for their good therapeutic value as they have fewer adverse effects than modern medicines. Recently, researchers have used gold nanoparticles synthesized by plants in the prevention, control, and treatment of infectious disorders and cutaneous wounds. The aims of this study were to synthesize gold nanoparticles from aqueous extract of Allium saralicum R.M. Fritsch (AuNPs) and assess their therapeutic capacities. The nanoparticles were characterized by UV–visible spectroscopy (UV–Vis), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FT-IR results offered polysaccharides and protein in A. saralicum were the sources of reducing power, reducing gold ions to AuNPs. According to XRD analysis, the crystal size of the nanoparticles was 41.6 nm. TEM and FE-SEM images exhibited average diameters of 45 nm for the biosynthesized nanoparticles. The synthesized AuNPs had great cell viability on HUVECs line and showed this method was nontoxic. The 2,2-diphenyl-1-picrylhydrazyl free radical scavenging test indicated similar antioxidant potentials for A. saralicum, AuNPs, and butylated hydroxytoluene. To determine the antifungal and antibacterial properties of HAuCl₄, A. saralicum, and AuNPs, agar diffusion tests were used. The aim of the application both HAuCl₄ and A. saralicum in microbial tests was to investigate the synergism effects between them. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were specified by macro-broth dilution assay. AuNPs exhibited higher antifungal and antibacterial effects than all standard antibiotics (p ≤ 0.01). The MIC and MBC of AuNPs against all bacteria were in the ranges 1–4 mg/ml and 2–8 mg/ml, respectively. The MIC and MFC of AuNPs against all fungi were in the ranges 1–4 mg/ml and 2–4 mg/ml, respectively. In vivo part, AuNPs ointment group raised significantly (p ≤ 0.01) the wound contracture, vessel, hydroxyl proline, hexuronic acid, fibrocyte, fibroblast, and fibrocytes/fibroblast rate and decreased significantly (p ≤ 0.01) the wound area, total cells, and lymphocyte compared to other groups in rats. The results of FT-IR, UV–Vis, XRD, TEM, and FE-SEM analyses confirm that the aqueous extract of A. saralicum leaves can be used to yield gold nanoparticles with a notable amount of remedial effects without any cytotoxicity against HUVECs.     

Synthesis, characterization and crystal structure determination of platinum(IV) complexes containing, bipyridine derivatives and chloride, [Pt(5,5′-dmbipy)Cl4] and [Pt(6-mbipy)Cl4]

The complex [Pt(5,5′-dmbipy)Cl₄] (1) (5,5′-dmbipy is 5,5′-dimethyl-2,2′-bipyridine) was prepared from the reaction of H₂PtCl₆·6H₂O with 5,5′-dimethyl-2,2′-bipyridine in methanol. The same method was employed to make [Pt(6-mbipy)Cl₄] (2) (6-mbipy is 6-methyl-2,2′-bipyridine). Both complexes were characterized by elemental analysis, IR, UV–Vis, ¹H NMR, ¹³C NMR and ¹⁹⁵Pt NMR spectroscopy. Their solid state structures were determined by the X-ray diffraction method.     

Simultaneous determination of DTPA,EDTA, and NTA by UV–visible spectrometry and HPLC

In this study, UV–visible spectrophotometry (UV–Vis) and high-performance liquid chromatography (HPLC) were used for simultaneous analysis of chelating agents diethylenetriamine pentaacetic acid (DTPA), ethylenediamine tetraacetic acid (EDTA), and nitrilotriacetic acid (NTA), as their metal chelates in dishwashing detergents, natural waters, and pulp mill water. The total amounts of the chelating agents in dishwashing detergents were verified by potentiometric titration with Fe(III) solution. Nickel(II) chelates were determined by UV–Vis and iron(III)chelates by HPLC and titration. Recoveries of DTPA, EDTA, and NTA from a standard mixture of analytes by UV–Vis were 107±7, 101±12 and 94±13%, respectively, and the recovery of the total amount of complexing agents was 99±4%. The limits of detection for DTPA, EDTA, and NTA were 667, 324, and 739 mol L^–1, respectively. In HPLC measurements the optimized mobile phase contained 0.03 mol L^–1 sodium acetate, 0.002 mol L^–1 tetrabutylammonium bromide, and 5% methanol at pH 3.15 and the detection was by UV–Vis detection at 254 nm. All three complexing agents could be separated from each other in a simultaneous analysis in less than 5 min. The limits of detection were 0.34, 0.27, and 0.62 mol L^–1 for DTPA, EDTA, and NTA, respectively. The total amounts of the analytes measured in the dishwashing detergents by the three techniques were found to be highly comparable (ANOVA: F=0.04, P=0.96). R² values were 0.99 for EDTA, 0.99 for NTA, and 0.99 for all the results when UV–Vis and HPLC determinations were compared using regression lines. The UV–Vis and HPLC methods were proved to be viable also for analyses of natural and pulp mill waters. The absence of matrix interferences was verified by the standard addition technique.     

Surface characterization and catalytic evaluation of copper-promoted Al-MCM-41 toward hydroxylation of phenol

The Mobil Composition of Matter No. 41 (MCM-41) containing Cu and Al with Si/Al ratios varying from 100 to 10 and 1 to 6 wt.% of Cu was synthesized under hydrothermal and impregnation conditions, respectively. The samples were characterized by nitrogen adsorption–desorption measurements, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), and ²⁹Si and ²⁷Al magic-angle spinning–nuclear magnetic resonance (MAS–NMR) spectra. X-ray diffraction patterns indicate that the modified materials retain the standard MCM-41 structure. TPR patterns show the two-step reduction of Cu species. TPD study shows that Cu-impregnated Al-MCM-41 samples are more acidic than Al-MCM-41. From the MAS–NMR it was confirmed that most of the Al atoms are present tetrahedrally within the framework and some are present octahedrally in extraframework position. Impregnation of Cu shifted Al to the extraframework position. The catalytic activity of the samples toward hydroxylation of phenol in aqueous medium was evaluated using H₂O₂ as the oxidant at 80 °C. The effects of reaction parameters such as temperature, catalyst amount, amount of H₂O₂, and solvent were also investigated. Sample containing 4 wt.% copper-loaded Al-MCM-41-100 showed high phenol conversion (78%) with 68% catechol and 32% hydroquinone selectivity.     

Supramolecular fullerene/porphyrin charge transfer interaction studied by absorption spectrophotometric method

A detailed UV–Vis spectrometric and thermodynamic studies were done to look insight into the nature of molecular interactions of the electron donor–acceptor complexes of C₆₀ and C₇₀ with 5,10,15,20-tetrakis(octadecyloxyphenyl)-21H,23H-porphyrin (1) in chloroform and toluene. Charge transfer (CT) absorption bands were located in the visible region and vertical ionization potential of 1 was determined utilizing CT transition energy. Low values of oscillator and transition dipole strengths suggested that the complexes were almost of neutral character in ground states. The high binding constant value for the C₇₀–1 complex indicated high selectivity of 1 molecule towards C₇₀. Experimental as well as theoretically determined of enthalpies of formation value substantiated the trend in K values for fullerene–1 complexes.     

Preparation and Characterization of Heparin‐Stabilized Gold Nanoparticles

A simple method for preparing gold nanoparticles in aqueous solution has been developed by using glycosaminoglycan‐heparin as reducing and stabilizing agent and HAuCl₄ as precursor. The obtained gold nanoparticles were characterized by UV‐vis spectroscopy, resonance light scattering spectroscopy (RLS), transmission electron microscopy (TEM) and electrophoresis technology. The influence of reactant concentration for the preparation of gold nanoparticles was investigated. The results indicated that the gold nanoparticles carried negative charges in the aqueous solution and the size and shape of the gold nanoparticles could be controlled by changing the concentration of the heparin. Moreover, the gold nanoparticles obtained with relatively high concentration of heparin were very stable and had relative narrow size distribution.     

Room Temperature Synthesis of Gold Nanokites in Polyvinyl Alcohol‐Sodium Dodecyl Sulfate Aggregations Aqueous Solution

Controlled synthesis of asymmetrical gold nanokites was realized by reducing HAuCl₄ with polyvinyl alcohol (PVA) in PVA‐sodium dodecyl sulfate (SDS) aggregations aqueous solution at room temperature without any additional reducing agents. The crystal structures, optical property and growth process of the gold nanokites were investigated by X‐ray diffraction (XRD), Vis‐NIR spectrum and transmission electron microscope (TEM). HAuCl₄ concentration dramatically influenced the morphologies of the products. When HAuCl₄ concentration was increased from 0.5 mmol·L⁻¹ to 2.2 mmol·L⁻¹, the products changed from network‐like nanostructures to nanokites, nanoleaves and microplates. SDS was indispensable for the formation of gold nanokites and without SDS super‐branched structures became the dominant products.     

Coordination chemistry of di-2-pyridylketone. Synthesis, spectroscopic investigations, X-ray studies and DFT calculations of Re(III) and Re(V) complexes

The paper presents a combined experimental and computational study of Re(III) and Re(V) complexes containing di-2-pyridylketone and its gem-diol form – [ReCl₃(dpk-N,O)(PPh₃)] (1), [ReCl₃(dpk-N,N′)(OPPh₃)] (2) and [ReOBr₃(dpk-OH)]·2(dpkH⁺Br⁻) (3). All the complexes have been characterized spectroscopically and structurally (by single-crystal X-ray diffraction). The complex 2 has been additionally studied by magnetic measurement. The magnetic behavior of 2 is characteristic of mononuclear octahedral Re(III) complex with d⁴ low-spin (³T_1g ground state) and arise because of the large spin–orbit coupling (ζ = 2500 cm⁻¹), which gives diamagnetic ground state. DFT and time-dependent (TD)DFT calculations have been carried out for [ReCl₃(dpk-N,N′)(OPPh₃)] and [ReOBr₃(dpk-OH), and their UV–vis spectra have been discussed on this basis.     

Antioxidant properties of gold nanoparticles studied by ESR spectroscopy

The Au-containing nanocomposites were synthesized by UV irradiation followed by the thermal treatment of chitosan oligomer solutions doped by HAuCl₄. The size of the formed gold nanoparticles depends on the concentration of the dopant, which is proved by UV—Vis absorption spectroscopy and small-angle X-ray scattering (SAXS). The antioxidant activity of the gold nanoparticles with respect to hydroxy radicals significantly depends on the specific surface of the particles, which was found using the secondary radical spin-trapping technique. The change in the ^·OH radical concentration was monitored by the intensity of the ESR signal of the adduct of the spin trap (α-phenyl-N-tert-butylnitrone) with the Me^·radicals formed in the reaction of ^·OH with DMSO. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 509–512, March, 2008.     

Gold-copolymer nanoparticles: Poly(ε-caprolactone)/poly(N-vinyl-2-pyrrolydone) Biodegradable triblock copolymer as stabilizer and reductant

Block copolymers have been extensively used in the synthesis of many types of nanoparticles, where generally are considered as stabilizer and protective agent. In this work a double function of the biodegradable triblock copolymer poly(N-vinyl-2-pyrrolidone)-b-poly(ε-caprolactone)-b-poly(N-vinyl-2-pyrrolidone), (PVP–PCL–PVP) in the gold nanoparticle-copolymer synthesis is reported.Gold-copolymer composed nanoparticles were synthesized using the triblock copolymer (PVP–PCL–PVP) and potassium tetrachloro aurate (III), both in aqueous solution. The copolymer work as both, reductant and stabilizer agent. The obtained nanoparticles were characterized by FT-IR, dynamic light scattering (DLS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The shape and the size of the obtained nanoparticles are dependent on the copolymer/salt of gold concentration ratio used in the synthesis.To complement the experimental results about the copolymer role in the nanoparticles synthesis, computational tools were used to characterize the reactivity of the reactant species.     

Synthesis, spectroscopic, thermal Studies, antimicrobial activities and crystal structures of Co(II), Ni(II), Cu(II) and Zn(II)-orotate complexes with 2-methylimidazole

The 2-methylimidazole complexes of Co(II), Ni(II), Cu(II) and Zn(II) orotates, mer-[Co(HOr)(H₂O)₂(2-meim)₂] (1), mer-[Ni(HOr)(H₂O)₂(2-meim)₂] (2), [Cu(HOr)(H₂O)₂(2-meim)] (3) and [Zn(HOr)(H₂O)₂(2-meim)] (4), were synthesized and characterized by elemental analysis, spectral (UV–Vis and FT-IR) methods, thermal analysis (TG, DTG and DTA), magnetic susceptibility, antimicrobial activity studies and single crystal X-ray diffraction technique. The complexes 1 and 2 have distorted octahedral geometries with two monodentate 2-methylimidazole and one bidentate orotate and two aqua ligands. The complexes 3 and 4 have distorted square pyramidal and trigonal bipyramidal geometry, respectively, with one 2-methylimidazole, bidentate orotate and aqua ligands. The orotate coordinated to the metal(II) ions through deprotonated nitrogen atom of pyrimidine ring and oxygen atom of carboxylate group as a bidentate ligand. The antimicrobial activities of 1 and 4 were found to be more active gram (+) than gram (−) and 4 could be use for treatment Staphylococcus aureus.