892552-97-5Relevant academic research and scientific papers
Investigations on the Photochemical Reaction Mechanisms of Selected Dibenzoylmethane Compounds
Wang, Junxiao,Guo, Yan,Wang, Jialin,Ma, Jiani
, p. 7594 - 7602 (2021)
In this work, combined time-resolved spectroscopies of femtosecond transient absorption, nanosecond transient absorption, and DFT calculations were performed to unravel the photocyclization reaction mechanisms of selected dibenzoylmethane (DBM) derivatives, including 2-chloro-1,3-diphenylpropan-1,3-dione (1a), 2-chloro-1-(3,5-dimethoxyphenyl)-3-phenylpropan-1,3-dione (1b), 2-chloro-2-fluoro-1,3-diphenylpropan-1,3-dione (1c), and 2-chloro-2-fluoro-1,3-di(4-methoxyphenyl)propan-1,3-dione (1d). Photocyclization reaction mechanisms for 1a and 1b are similar, where a C-Cl heterolysis occurs yielding an α-ketocation intermediate, followed by cyclization to generate the cation species. On the other hand, 1c and 1d undergo dechlorination primarily producing a radical species, which further experiences cyclization yielding cyclized radical species. The dominant factor leading to the different reaction mechanisms is the involvement of a fluorine atom bonded at α-C. Due to the meta-effect, the p-methoxy substitution on the benzene ring inhibits the photocyclization reaction and reduces the yield of photocyclization.
Antenna-functionalized dendritic β-diketonates and europium complexes: synthetic approaches to generation growth
Li, Shangfeng,Zhu, Weihong,Xu, Zhongyu,Pan, Jianfeng,Tian, He
, p. 5035 - 5048 (2007/10/03)
Six dendritic β-diketonates and their corresponding europium complexes were synthesized. These dendritic β-diketonate ligands consist of dibenzoylmethane cores, Fre?chet-type poly(aryl ether) dendrons, and the carbazole-grafted peripheral functional groups. The designs of dendrimers are on the basis of high light-harvesting capability and dendron functionalization in virtue of the high extinction coefficient and carrier-injection adjustment of carbazole units. Different approaches to generation growth were utilized: the first generation europium complexes through etheral connectivity were developed via convergent synthetic approach; the second and third generation dendrons through esteral connectivity were developed by a hyperbranch core approach containing the advantages of convergent and divergent approaches. Their chemical structures were well characterized. Preliminary results show that the dendron-functionalized carbazole units not only tune the carrier-transporting capability, but also exhibit strong light-harvesting potential, resulting in a strong intense emission from the central Eu(III) ion via sensitization.
