Surface-grafted macromolecular nanowires with pedant fluorescein chromophores by dense non-aggregated nanoarchitectonics as versatile photoactive platforms.

In this paper, we present a facile method of synthesis and modification of poly(glycidyl methacrylate) brushes with 6-aminofluorescein (6AF) molecules. Polymer brushes were obtained using surface-grafted atom transfer radical polymerization (SI-ATRP) and functionalized in the presence of triethylamine (TEA) acting both as a reaction catalyst and an agent preventing aggregation of chromophores. Atomic force microscopy (AFM), FTIR, X-ray photoelectron spectroscopy (XPS) were used to study the structure and formation of obtained photoactive platforms. UV-Vis absorption and emission spectroscopy and confocal microscopy were conducted to investigate photoactivity of chromophores within the macromolecular matrix. Owing to the simplicity of fabrication and good ordering of the chromophore in a thin nanometric layer, the proposed method may open new opportunities for obtaining light sensors, photovoltaic devices, or other light-harvesting systems.

Deciphering Photoluminescence in an Aryl Iodides-Gold Nanoparticles System: Au-Mediated Homocoupling Reaction at a Low Temperature.

The study of photoactive materials often unveils intriguing findings, showcasing the value of an interdisciplinary approach. We examined the purported metal-enhanced luminescence thought to result from the chemisorption of aryl iodides on poly(N-vinylpyrrolidone)-stabilized gold nanoparticles. Our discovery deviates from previous assumptions: the fluorescence observed does not originate from excimers of iodophenols chemisorbed on Au:PVP. Instead, it arises from biphenol products, resulting from a gold-mediated Ullmann homocoupling reaction that occurs within the system. Notably, this reaction, known for its demanding nature, proceeds in methanol under purely ambient conditions: room temperature and air atmosphere, without the need for a base. Therefore, these findings not only offer a complete understanding of the observed luminescence but also provide a substantial contribution to the field of carbon-carbon coupling reactions.

Reaction kinetics of sonochemical oxidation of potassium hexacyanoferrate(II) in aqueous solutions.

We studied sonochemical reactions resulting from ultrasonic treatment of potassium hexacyanoferrate(II) in aqueous solutions using a custom-built apparatus working at 536 kHz. We concluded that primary reactions are completely dominated by oxidation of Fe(II) to Fe(III) and did not find any evidences for degradation of cyanide. At the highest concentration used in the present study (0.1 M) we detected formation of pentacyanoaquaferrate(II) complex, which is most probably formed in reactions between hexacyanoferrate(III) anions and hydrogen atoms or hydrated electrons formed in sonochemical processes. We also determined that hydroxyl radicals formation rate in our system, (8.7 ± 1.5)∙10-8 M∙s-1, is relatively high compared to other reported experiments. We attribute this to focusing of the ultrasonic wave in the sample vessel. Finally, we suggest that oxidation rate of hexacyanoferrate(II) anions can be a convenient benchmark of efficiency of sonochemical reactors.