有机分子的荧光在功能材料的开发中得到了广泛的研究。阐明分子运动与荧光量子产率 (FQY) 之间的关系有助于开发强度可控的荧光团。在此,比较了溶液和固态 9,9-二甲基芴-二基桥联二硅杂环[nnn]烷烃的 FQY。合成了两种大笼衍生物C18 ( n = 18) 和C22 ( n = 22),并使用 NMR 光谱和 X 射线晶体学表征了它们的结构。溶液中的 FQY 几乎相同;然而,大笼C22的固态FQY小于小笼C18的FQY. 使用固态2 H NMR,与C18- d 3相比, C22 - d 3的氘化荧光团中的2 H 核测量到更短的自旋晶格弛豫时间,表明氘化荧光团的轻微运动,例如解放, 在笼子内会导致更有效的放松。因此, C22的较低 FQY归因于解放运动,其发生在接近荧光时间尺度的时间尺度上。这项研究的结果有望有助于环境响应荧光材料的分子设计。
for the synthesis of fluorene and its derivatives starting from 2-iodobiphenyls and CH2Br2. A range of fluorene derivatives can be synthesized under relatively mild conditions. The reaction proceeds via a tandem palladium-catalyzed dual C–C bond formation sequence through the key dibenzopalladacyclopentadiene intermediates, which are obtained from 2-iodobiphenyls through palladium-catalyzed C–H activation
Palladium-Catalyzed Cycloisomerization of 2-Ethynylbiaryls to 9-Methylidene Fluorenes
作者:Hongyu Guo、Sheng Zhang、Xiujuan Feng、Xiaoqiang Yu、Yoshinori Yamamoto、Ming Bao
DOI:10.1021/acs.orglett.2c00534
日期:2022.4.15
presence of weak acid at low temperature to afford 9-methylidene fluorenes in satisfactory to high yields. This new type of cycloisomerization of 2-ethynylbiaryls is operationally simple and scalable and exhibits high functional-group tolerance. Various synthetically useful functional groups, such as halogen atoms, as well as formyl, acetyl, methoxycarbonyl, cyano, and nitro groups, remain intact during
Highly Efficient and Versatile Synthesis of Polyarylfluorenes via Pd-Catalyzed C−H Bond Activation
作者:Seung Jun Hwang、Hyun Jin Kim、Sukbok Chang
DOI:10.1021/ol901854f
日期:2009.10.15
A facile protocol for the Pd-catalyzed preparative synthesis of fluorene derivatives has been developed. While a wide range of fluorenes; were easily obtained with high efficiency and selectivity under mild conditions, excellent functional group tolerance was also demonstrated. On the basis of Hammett and KIE studies, the present reaction is proposed to proceed via a base-assisted deprotonative metalation pathway.