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

Abstract

Benzophenone derivatives were evaluated as new photoinitiators in combination with triethylamine (TEA) and iodonium salt (Iod) for very rapid and efficient formation of metal nanoparticles in an organic solvent, by which silver and gold ions were reduced under light at 419 nm (photoreactor) with an irradiation intensity of 250 microwatts/cm 2 . The new benzophenone derivatives combined with TEA/Iod salt showed good production of metal nanoparticles (Au 0 and Ag 0 ) and a small size of nanoparticles of around 4−13 nm. The photochemical mechanisms for the production of initiating radicals were studied using cyclic voltammetry, where a negative ΔG of around −1.96 eV was obtained, which made the process favorable. The obtained results proved the formation of amine and phenyl radicals, which led to the reduction of gold III chloride or silver ions to the gold and silver NPs. The UV−vis spectroscopy technique was used as a very beneficial tool for the surface plasmon resonance band detection of metal nanoparticles. To sum up the results, we have observed that nanoparticles (NPs) were distributed differently in different photoinitiator systems and the particle size also changed by changing the system of initiation. In comparison to the system alone, not only were the nanoparticles smaller but they were also generated within a shorter period of irradiation time for the system BP\Iod\TEA. Finally, the quenching process of benzophenone fluorescence by the gold and silver nanoparticles was investigated.

Modular Synthesis of Benzoylpyridines Exploiting a Reductive Arylation Strategy

“…Data for compounds 5a−5e and benzophenone are represented in composite spectra for comparison. In line with the literature, 19 benzophenone strongly absorbed light within the UV region (λ max = 252 nm) and showed a maximum molar absorption coefficient of around 21,000 M −1 cm −1 . Compound 5a presented a slight shift (λ max = 255 nm) compared to the parent benzophenone, while the effect is more pronounced for thiophene derivative 5d (λ max = 290 nm), as indicated by a shift of +38 nm.…”

Discovery of steroidal alkaloid metabolites and their accumulation in pigs after short-term tomato consumption

“…We hypothesize the cleavage of sugars occurs in the small intestines by beta-glucosidases expressed in epithelial cells, as seen with other plant glycosides like flavonoids [46] . Interestingly, it was found in an ex vivo pig cecum model that alpha-tomatine underwent minimal degradation after incubation with cecum suspension [47] , suggesting that gut microbial metabolism may also play a lesser role in the hydrolysis of alpha-tomatine and potentially other tomato steroidal alkaloids.…”

Photochemical Synthesis of Noble Metal Nanoparticles: Influence of Metal Salt Concentration on Size and Distribution

“…Ketone components are critically important as Type II photoinitiators. For instance, benzophenone [ 32 ], thioxanthone [ 33 ], camphorquinone [ 34 ], etc. all show bimolecular photo-behavior in the formation of initiating species.…”

“…Through intersystem crossing, the singlet excited state decays into the triplet excited state. The ketone derivatives in the triplet excited state absorb hydrogen from the hydrogen donor such as alcohols [ 45 ], amines [ 32 ], ethers [ 46 ], or thiols [ 47 ], leading to the formation of a radical produced from the carbonyl compound (ketyl-type radical) and another radical derived from the hydrogen donor [ 45 ]. These radicals reduce metal ions to produce metal nanoparticles [ 48 ].…”

“…The electron donation ability of BP triplets leads to the direct reduction of Ag + to Ag 0 . In a recent study, a combination of triethylamine and iodonium salt, which are benzophenone derivatives, were tested as potential new photoinitiators for the rapid and efficient formation of metal nanoparticles in an organic solvent, where silver and gold ions were reduced under light at 419 nm [ 32 ].…”