20662-88-8Relevant articles and documents
Oxazolium Iodide Modified Perovskites for Solar Cell Fabrication
Salado, Manuel,Shirzadi, Erfan,Kazim, Samrana,Fei, Zhaofu,Nazeeruddin, Mohammad Khaja,Dyson, Paul J.,Ahmad, Shahzada
, p. 279 - 284 (2018)
Perovskites solar cells are gaining interest due to their attractive solar-to-electricity conversion efficiencies; however, they suffer from certain problems, such as suboptimal ion migration and stability issues. We report here on the inclusion of a phenyloxazolium salt (2-phenyl-3-methyloxazolium iodide) in perovskite solar cells based on methyl ammonium lead triiodide (MAPbI3). The fabricated solar cells not only displayed improved photovoltaic properties, but importantly the oxazolium cations can protect the perovskite layers from UV exposure as they down-convert electromagnetic irradiation; that is, the photons in the UV are absorbed and re-emitted at a different wavelength. The loading of 2-phenyl-3-methyloxazolium iodide in the perovskite precursor solution was optimized, the resulting perovskite films characterized, and the solar cells fabricated from them evaluated for their performance. Overall, this simple approach serves to optimize the performance parameters of perovskites films for solar cell applications.
Reaction Conditions for the Regiodivergent Direct Arylations at C2- or C5-Positions of Oxazoles using Phosphine-Free Palladium Catalysts
Shi, Xinzhe,Soulé, Jean-Fran?ois,Doucet, Henri
, p. 4748 - 4760 (2019/09/12)
Two sets of reaction conditions for the regiodivergent C2- or C5- direct arylations of oxazole are reported. In both cases, phosphine-free catalysts and inexpensive bases were employed allowing the access to the arylated oxazoles in moderate to high yields. Using Pd(OAc)2/KOAc as catalyst and base, regioselective C5-arylations were observed; whereas, using Pd(acac)2/Cs2CO3 system, the arylation occurred at the C2-position of oxazole. The higher reactivity of C5-H bond of oxazole as compared to the C2-H bond in the presence of Pd(OAc)2/KOAc system is consistent with a concerted metalation deprotonation mechanism; whereas the C2-arylation likely occurs via a simple base deprotonation of the oxazole C2-position. Then, from these C2- or C5-arylated oxazoles, a second palladium-catalyzed direct C?H bond arylation affords 2,5-diaryloxazoles with two different aryl groups. We also applied these sequential arylations to the straightforward synthesis of 2-arylphenanthro[9,10-d]oxazoles via three C?H bond functionalization steps. The Ru-catalyzed C?H arylation of the aryl unit of 2-aryloxazoles is also described. (Figure presented.).
Widely Exploited, Yet Unreported: Regiocontrolled Synthesis and the Suzuki–Miyaura Reactions of Bromooxazole Building Blocks
Solomin, Vitalii V.,Radchenko, Dmytro S.,Slobodyanyuk, Evgeniy Y.,Geraschenko, Oleksandr V.,Vashchenko, Bohdan V.,Grygorenko, Oleksandr O.
, p. 2884 - 2898 (2019/03/07)
An approach to synthesis of 2-, 4-, and 5-bromooxazoles is described. The method was optimized, and its scope was extended to all three isomeric parents, as well as various alkyl- and aryl-substituted bromooxazoles. It was found that direct regiocontrolled lithiation followed by reaction with electrophilic bromine source was common for all substrates and led exclusively to the target substituted 2-, 4- and 5-bromooxazoles on multigram scale. The utility of the multipurpose building blocks obtained in this work was demonstrated in the Suzuki–Miyaura cross-coupling reaction under parallel synthesis conditions.