Synthesis, thermal stability, electronic features, and antimicrobial activity of phenolic azo dyes and their Ni(II) and Cu(II) complexes

Four water soluble azo dyes, 4-(isopropyl)-2-[(E)-(4-chlorophenyl)diazenyl]phenol (L ¹), 4-(isopropyl)-2-[(E)-(2,4-dichlorophenyl)diazenyl]phenol (L²), 4-(sec-butyl)-2-[(E)-(4-chlorophenyl) diazenyl]phenol (L ³), 4-(sec-butyl)-2-[(E)-(2,4-dichlorophenyl)diazenyl]phenol (L ⁴), and their Cu(II) and Ni(II) complexes were synthesized and characterized using spectroscopic methods. Examination of their thermal stability revealed similar decomposition temperature of approximately 260–300°C and that they were more thermally stable than their metal complexes. Ni(II) complexes of ligands L² and L⁴ were more stable than the other coordination compounds. Among the synthesized ligands, L² and the complexes Cu(L³)₂ and Ni(L⁴)₂ showed both antimicrobial and antifungal activity. However, the other ligands and the complexes were poorly active against selected microorganisms.     

Reactions of cyclochlorotriphosphazatriene with 2-mercaptoethanol. Calorimetric and spectroscopic investigations of the derived products

Abstract

The reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆ (1) with 2-mercaptoethanol, 2-HS-CH₂-CH₂-OH (2), in (1:1, 1:2 and 1:3) mole ratios, in excess of NaH, in THF and diethylether solutions yield a total of 6 novel products: one mono spiro, N₃P₃Cl₄[O-CH₂-CH₂-S] (3); one mono-substituted open chain, N₃P₃Cl₅[S-CH₂-CH₂-OH] (4); one dispiro, N₃P₃Cl₂[O-CH₂-CH₂-S]₂ (5); one tri-substituted open chain, N₃P₃Cl₃[S-CH₂-CH₂-OH]₃ (6); one tris-spiro, N₃P₃[O-CH₂-CH₂-S]₃ (7) and one disubstituted open chain, N₃P₃Cl₄[S-CH₂-CH₂-OH]₂ (8) derivatives. The spiro products (3, 5 and 7) are formed as the major products in this system and all of the synthesized compounds are found to be stable at room temperature. The structures of the derived compounds were elucidated by elemental analysis, TLC-MS, ³¹P and ¹H NMR spectral data. For evaluation of melting behavior of derivatives (6) and (7), thermal transition peaks and their corresponding enthalpies were determined via DSC technique.     

Synthesis, characterization, thermal and optical properties of styrene derivatives having pendant p-substituted benzylic ether groups

The derivatives of styrene monomer, 4-chlorophenyl-4-vinylbenzyl ether (M1), 4-methoxyphenyl-4-vinylbenzyl ether (M2), 4-ethylphenyl-4-vinylbenzyl ether (M3) and 1-naphtylphenyl-4-vinylbenzyl ether (M4) were synthesized. The normal free radical polymerization of monomers in 1,4-dioxane were performed by using 2,2′-azobisisobutyronitrile as an initiator at 65 °C. The monomers and their homopolymers were characterized by FT-IR, NMR and elemental analyses measurements. The thermal stability of polymers was investigated by thermogravimetric and differential scanning calorimetric analysis. Thermal degradation activation energies of the polymers were calculated by the Ozawa and Kissinger methods. In addition, photo-stability tests of the polymers under near-UV irradiation were performed.     

A one-dimensional silver(I) coordination polymer with saccharin and pyrazine: synthesis,crystal structure,thermal analysis,FTIR spectra,and DFT studies

A silver(I) complex of saccharinate (sac) with pyrazine (pyz), [Ag(sac)(pyz)] _n , has been synthesized and characterized by elemental analysis, IR, thermal analysis, and single-crystal X-ray diffractometry. The complex crystallizes orthorhombic space group Pnma with unit cell parameters of a = 13.0073(9) Å, b = 6.4907(6) Å, c = 13.4007(9) Å, V = 1131.37(15) Å³, and Z = 4. [Ag(sac)(pyz)] _n is a one-dimensional coordination polymer, in which the sac ligand acts as a monodentate ligand through the N atom and the trigonal silver centers are linked by the bridging pyz ligands. The individual chains are connected into two-dimensional supramolemular network by aromatic π(sac)···π(pyz) stacking interactions. The FTIR spectrum of [Ag(sac)(pyz)] _n has been recorded in the region and 4,000–400 cm^?1. The optimized geometry, frequency, and intensity of the vibrational bands of [Ag(sac)(pyz)] _n were obtained by density functional theory (DFT) at the B3LYP level. The vibrational frequencies were calculated and the scaled values have been compared with the experimental FTIR data. The observed and calculated frequencies are found to be in good agreement.     

Phase retrieval for high-numerical-aperture optical systems

We describe a phase retrieval approach for intensity point-spread functions of high-numerical-aperture optical systems such as light microscopes. The method calculates a generalized pupil function defined on a spherical shell, using measured images at several defocus levels. The resultant pupil functionsreproduce measured point-source images significantly better than does an ideal imaging model. Availability of pupil function information will facilitate new approaches to aberration correction in such systems.     

A novel ditopic ring-expanded N-heterocyclic carbene ligand-assisted Suzuki-Miyaura coupling reaction in aqueous media

A series of seven-membered ditopic ring-expanded N-heterocyclic carbene (dre-NHC) precursors, bearing sterically demanding and electron-rich aryl groups, were synthesised in moderate yields via the reaction of 1,2,4,5-tetrakis(bromomethyl)benzene with the corresponding N,N′-diarylformamidines in the presence of K₂CO₃ in acetonitrile under an air atmosphere. All new compounds were characterised by HRMS, NMR spectroscopy, and microanalysis, as well as X-ray crystallography for compound 1c. The development of an efficient catalytic system for the Suzuki-Miyaura coupling reaction of aryl chlorides with various boronic acids was also investigated using the in situ generated dre-NHC ligands.     

Warm-white light-emitting diodes integrated with colloidal quantum dots for high luminous efficacy and color rendering

Warm-white LEDs (WLEDs) with high spectral quality and efficiency are required for lighting applications, but current experimental performances are limited. We report on nanocrystal quantum dot (NQD) hybridized WLEDs with high performance that exhibit a high luminous efficacy of optical radiation exceeding 350lm/W(opt) and a high color rendering index close to 90 at a low correlated color temperature <3000K. These spectrally engineered WLEDs are obtained using a combination of CdSe/ZnS core/shell NQD nanophosphors integrated on blue InGaN/GaN LEDs.     

Surface Acidity of H-Birnessite: Infrared Spectroscopic Study of Formic Acid Decomposition

This paper presents the adsorption and thermal decomposition mechanism of formic acid on an H-birnessite sample. Changes in the surface and structure were characterized using infrared spectroscopy, N₂ gas adsorption–desorption, and thermal analysis techniques. The acid sites of H-birnessite were investigated by infrared and thermal analysis using pyridine as a molecular probe. Decomposition of formic acid started on H-birnessite at 120°C and was complete at 400°C. Infrared spectra revealed that the molecularly adsorbed formic acid species were transformed to a formate species, and the formate species were transformed to CO. The most stable adsorption structure for formic acid was found as a molecular monodentate configuration.