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The medical properties of metals have been explored for centuries in traditional medicine for the treatment of infections and diseases and still practiced to date. Platinum-based drugs are the first class of metal-based drugs to be clinically used as anticancer agents following the approval of cisplatin by the United States Food and Drug Administration (FDA) over 40 years ago. Since then, more metals with health benefits have been approved for clinical trials. Interestingly, when these metals are reduced to metallic nanoparticles, they displayed unique and novel properties that were superior to their bulk counterparts. Gold nanoparticles (AuNPs) are among the FDA-approved metallic nanoparticles and have shown great promise in a variety of roles in medicine. They were used as drug delivery, photothermal (PT), contrast, therapeutic, radiosensitizing, and gene transfection agents. Their biomedical applications are reviewed herein, covering their potential use in disease diagnosis and therapy. Some of the AuNP-based systems that are approved for clinical trials are also discussed, as well as the potential health threats of AuNPs and some strategies that can be used to improve their biocompatibility. The reviewed studies offer proof of principle that AuNP-based systems could potentially be used alone or in combination with the conventional systems to improve their efficacy. [ABSTRACT FROM AUTHOR]

Three new 2-pyrral amino acid Schiff base palladium (II) complexes were synthesized, characterized and their activity against six bacterial species was investigated. The ligands: Potassium 2-pyrrolidine-L-methioninate (L1), Potassium 2-pyrrolidine-L-histidinate (L2) and Potassium 2-pyrrolidine-L-tryptophanate (L3) were synthesized and reacted with dichloro(1,5-cyclooctadiene)palladium(II) to form new palladium (II) complexes C1, C2 and C3, respectively. 1H NMR, FTIR, UV–Vis, elemental analysis and conductivity measurements were used to characterize the products. The antibacterial activities of the compounds were evaluated against Gram-positive Staphylococcus aureus (S. aureus, ATCC 25923), methicillin-resistant Staphylococcus aureus (MRSA, ATCC 33591), Staphylococcus epidermidis (S. epidermidis, ATCC 12228) and Streptococcus pyogenes (S. pyogenes, ATCC 19615) and, gram-negative Pseudomonas aeruginosa (P. aeruginosa, ATCC 27853) and Klebsiella pneumoniae (K. pneumoniae, ATCC 13883) using the agar well diffusion assay and microtitre plate serial dilution method. The palladium complexes were active against the selected bacteria with the imidazole ring containing complex C2 and indole heterocyclic ring containing complex C3 showing the highest activity. [ABSTRACT FROM AUTHOR]

Cadmium telluride (CdTe) has been successfully prepared by a simple wet chemical process at different reaction temperatures. Temperature is one parameter that thermodynamically plays an important role in controlling the growth rate, morphology, size and size distribution of the as-prepared nanoparticles (NPs). Effect of this parameter was investigated on the growth, structural and optical properties of CdTe NPs. It was observed that the Powder X-ray diffraction (XRD) pattern for samples prepared at 50 °C had many impurities from unreacted precursors while those prepared at > 100 °C displayed polycrystalline NPs. The XRD results revealed that the structure of the CdTe NPs was cubic with the planes (111), (220), (311) being the main observed peaks. The crystallite sizes obtained from Scherrer formula increased with the increase in growth temperature (2.86-3.62 nm grown at 50-200 °C respectively). The scanning electron microscopy micrographs showed that the morphology of the nanoparticles possessed spherical-shaped particles over the entire surface. This was further confirmed by high resolution transmission electron microscopy micrographs which also displayed increase in the particle size with an increase in the growth temperature. In the optic study, the photoluminescence (PL) spectra displayed a red shift (540-560 nm) in emission as growth temperature increased from 50 to 200 °C. The highest PL peak intensity was realized at a growth temperature of 150 °C. Absorption band maxima were observed to shift towards longer wavelength for higher growth temperatures. The optical band gap decreased with increase in the growth temperature from 2.67 to 2.08 eV for 50-200 °C respectively. [ABSTRACT FROM AUTHOR]

South Africa is a mineral-rich country and one area in which minerals can be very important is catalysis. Over an extended period of time, homogeneous catalysis has grown to become very useful, particularly in the chemical and pharmaceutical industries. The organometallic compounds required in the catalysis industry have advanced from metallocenes to an alternative in the form of α-diimines. Most α-diimines are prepared from iminopyridyl moieties and are most active with nickel and palladium transition metals. This review providesa history of homogeneous catalysis and a discussion on iminopyridines, with the main focus on the nickel and palladium complexes formed from them. There follows a discussion of the bimetallic nickel and palladium complexes in various catalytic applications such as Suzuki and Heck coupling, with the main focus on ethylene polymerisation. The limitations are addressed and possible solutions presented to overcome those challenges. Several reviews in the related topics are to be found in the literature but not the α-diimine with iminopyridines and bimetallic nickel and palladium metals. [ABSTRACT FROM AUTHOR]

The ligands 2-(diphenylphosphino)benzyl-(2-thiophene)methylimine ( V) and 2-(diphenylphosphino) benzyl-(2-thiophene)ethylimine ( VI) were prepared from 2-(diphenylphosphino)benzaldehyde and thiophene amines with very good yields. An equimolar reaction of V and VI with either PdCl(cod) (cod = cyclooctadiene) or PdClMe(cod) afforded palladium(II) complexes I-IV. The molecular structure of II was confirmed by X-ray crystallography. The coordination geometry around the palladium atom exhibited distorted square planar geometry at the palladium centre. Complexes I, II, and IV were evaluated as catalysts for Heck coupling reactions of iodobenzene with methyl acrylate under mild reaction conditions; 0.1 mole % catalyst, EtN base, MeCN reflux for 8 h, 80°C; isolated yield on a 10 mmol scale with catalyst I (64 %), II (68 %), and IV (58 %). They all exhibited significant activities. [ABSTRACT FROM AUTHOR]

CdSe flower-like nanorods (NRs) were successfully synthesized by Sol-gel technique where a simple aqueous technique was applied. The effects of different selenium (Se) concentration in the precursor solution on the material properties were studied. The X-ray diffraction (XRD) analyses show that a cubic zinc blende crystal structure was formed. Variation in the crystallite sizes were observed for different amounts of Se used in the precursor. The sizes estimated from various techniques were in the range 3-5 nm. The XRD peak intensity reached an optimum when 8 mL of 0.5 M of reduced selenium was used. The surface topography obtained from the scanning electron microscope showed densely packed and uniformly distributed flower-like rod/blade-like shaped CdSe NRs. The Fourier transform infrared spectrophotometer gave the stretching vibrations of the CdSe NRs with some bands belonging to the capping agent and the solvent. Thermal analysis conducted portrayed the 8 mL sample to be more stable than other samples at various temperatures. The photoluminescence (PL) studies displayed a red shift in the emission peaks (550-575 nm) as the selenium concentration was increased from 4 to 12 mL. This was then followed by an increase in the PL peak intensity which reached a maximum at 8 mL of Se used during the synthesis. The band gap energies calculated from the absorption spectra decreased from 3.27 to 2.79 eV with an increase in the Se concentration. The percentage transmittance of CdSe NRs varied with different amounts of Se in the precursor solution. [ABSTRACT FROM AUTHOR]

Abstract: Two new salicylaldiminato-copper(II) complexes, [Cu(L1)2] (1) and [Cu(L2)2] (2) (where HL1=4-tert-Butyl-2-[(thiophen-2-ylmethylimino)-methyl]-phenol and HL2=2,4-Di-tert-butyl-6-[(thiophen-2-ylmethylimino)-methyl]-phenol), endowed with a pendant thiophenyl moiety, were synthesized and characterized using standard spectroscopic techniques (FT-IR, UV-Vis, MS) and elemental analysis. Complexes 1 and 2 were unequivocally characterized by single crystal X-ray crystallography, which confirmed bidentate bis-chelation of the deprotonated -L1 and -L2 ligands to the copper (II) centres via the phenoxo and imine atoms forming square planar complexes. The copper(II)-hydroperoxo derivatives of 1 and 2 ([(L1)2CuII-OOH] (3) and [(L2)2CuII-OOH] (4)) were also synthesized and the formation of the active intermediate in solution studied. Complexes 1 and 2 were tested as catalyst precursors in cyclohexane oxidation under mild reaction conditions using hydrogen peroxide (H2O2) as a terminal oxidant, and were found to catalyse oxidation of the substrate with yields comparable to similar mononuclear and even multinuclear copper complexes.Graphical Abstract:  Synopsis Synthesis, characterisation, and molecular structure of salicylaldiminato-copper(II) complexes, and their catalytic evaluation in the oxidation of cyclohexane employing hydrogen peroxide as a terminal oxidant have been studied. The complexes catalysed conversion of cyclohexane with appreciable yields. [ABSTRACT FROM AUTHOR]