Light-Assisted Synthesis of Silver and Gold Nanoparticles by New Benzophenone Derivatives

Group 11 complexes of a bulky triazene ligand

A new triazene ligand was prepared by the reaction of the bulky aryl azide, TerMesN3, (2,6-bis(2,4,6-trimethylphenyl)phenyl azide), with the bulky N-heterocyclic carbene (NHC), SIPr (N,N'-2,6-bis(diisopropylphenyl)-3,4-dihydroimidazol-2-ylidene). The steric bulk of these two groups leads to perpendicular bonding of the NHC-N3 plane and the aryl group which provides immense steric crowding around the triazene core. The corresponding π-conjugated triazene ligand was utilized as a neutral, monodentate ligand which results in monomeric Cu(I)Cl, Ag(I)OTf, and Au(I)Cl complexes. Instability of the π-conjugated triazene Au(I)Cl complex was observed, even under inert conditions. When dissolved and photolyzed in THF with workup in isopropanol, the compound decomposes forming [(SIPrNH)2Au(I)][Au(I)Cl2] a relatively stable compound to light, moisture, and water - alongside the formation of gold nanoparticles which were characterized using scanning electron microscopy with energy dispersive spectroscopy.

Modular Synthesis of Benzoylpyridines Exploiting a Reductive Arylation Strategy

Herein we disclose a telescoped flow strategy to access electronically differentiated bisaryl ketones as potentially new and tunable photosensitizers containing both electron-rich benzene systems and electron-deficient pyridyl moieties. Our approach merges a light-driven (365 nm) and catalyst-free reductive arylation between aromatic aldehydes and cyanopyridines with a subsequent oxidation process. The addition of electron-donating and withdrawing substituents on the scaffold allowed effective modification of the absorbance of these compounds in the UV-vis region, while the continuous flow process affords high yields, short residence time, and high throughput.

Alnafisah A, Beji L, Kouki N, Morlet-Savary F, Alminderej FM, Aroua LM, Lalevée J. Photochemical Synthesis of Noble Metal Nanoparticles: Influence of Metal Salt Concentration on Size and Distribution

This paper explores the photochemical synthesis of noble metal nanoparticles, specifically gold (Au) and silver (Ag) nanoparticles, using a one-component photoinitiator system. The synthesis process involves visible light irradiation at a wavelength of 419 nm and an intensity of 250 mW/cm2. The radical-generating capabilities of the photoinitiators were evaluated using electron spin resonance (ESR) spectroscopy. The main objective of this study was to investigate how the concentration of metal salts influences the size and distribution of the nanoparticles. Proposed mechanisms for the photochemical formation of nanoparticles through photoinitiated radicals were validated using cyclic voltammetry. The results showed that the concentration of AgNO3 significantly impacted the size of silver nanoparticles, with diameters ranging from 1 to 5 nm at 1 wt% and 3 wt% concentrations, while increasing the concentration to 5 wt% led to an increase in the diameter of silver nanoparticles to 16 nm. When HAuCl4 was used instead of AgNO3, it was found that the average diameters of gold nanoparticles synthesized using both photoinitiators at different concentrations ranged between 1 and 4 nm. The findings suggest that variations in HAuCl4 concentration have minimal impact on the size of gold nanoparticles. The photoproduction of AuNPs was shown to be thermodynamically favorable, with the reduction of HAuCl4 to Au0 having ∆G values of approximately -3.51 and -2.96 eV for photoinitiators A and B, respectively. Furthermore, the photoreduction of Ag+1 to Ag0 was demonstrated to be thermodynamically feasible, with ∆G values of approximately -3.459 and -2.91 eV for photoinitiators A and B, respectively, confirming the effectiveness of the new photoinitiators on the production of nanoparticles. The synthesis of nanoparticles was monitored using UV-vis absorption spectroscopy, and their sizes were determined through particle size analysis of transmission electron microscopy (TEM) images.

Surface Modification of PP and PBT Nonwoven Membranes for Enhanced Efficiency in Photocatalytic MB Dye Removal and Antibacterial Activity

In this study, we developed highly efficient nonwoven membranes by modifying the surface of polypropylene (PP) and poly(butylene terephthalate) (PBT) through photo-grafting polymerization. The nonwoven membrane surfaces of PP and PBT were grafted with poly(ethylene glycol) diacrylate (PEGDA) in the presence of benzophenone (BP) and metal salt. We immobilized tertiary amine groups as BP synergists on commercial nonwoven membranes to improve PP and PBT surfaces. In situ Ag, Au, and Au/Ag nanoparticle formation enhances the nonwoven membrane surface. SEM, FTIR, and EDX were used to analyze the surface. We evaluated modified nonwoven membranes for photocatalytic activity by degrading methylene blue (MB) under LED and sunlight. Additionally, we also tested modified membranes for antibacterial activity against E. coli. The results indicated that the modified membranes exhibited superior efficiency in removing MB from water. The PBT showed the highest efficiency in dye removal, and bimetallic nanoparticles were more effective than monometallic. Modified membranes exposed to sunlight had higher efficiency than those exposed to LED light, with the PBT/Au/Ag membrane showing the highest dye removal at 97% within 90 min. The modified membranes showed reuse potential, with dye removal efficiency decreasing from 97% in the first cycle to 85% in the fifth cycle.