Effect of Structure on the Spin–Spin Interactions of Tethered Dicyanomethyl Diradicals
作者:Rui Zhang、Joshua P. Peterson、Logan J. Fischer、Arkady Ellern、Arthur H. Winter
DOI:10.1021/jacs.8b08628
日期:2018.10.31
Stable organic radicals with switchable spin states have attracted attention for a variety of applications, but a fundamental understanding of how radical structure effects the weak bonding interactions between organic radicals is limited. To evaluate the effect of chemical structure on the strength and nature of such spin interactions, a series of 14 tethered aryl dicyanomethyl diradicals were synthesized
具有可切换自旋态的稳定有机自由基已经引起了各种应用的关注,但对自由基结构如何影响有机自由基之间的弱键相互作用的基本理解是有限的。为了评估化学结构对这种自旋相互作用的强度和性质的影响,合成了一系列 14 个系链芳基二氰甲基双自由基,并研究了双自由基的结构和热力学性质。这些研究表明二聚体的性质和双自由基-二聚体平衡的平衡热力学参数对接头的连接点、接头的长度和基团本身的取代基高度敏感。取决于这些变量,分子内 Ka 的值从小到 5 到大到 105 不等。连接的邻位取代双自由基的 X 射线晶体结构显示,双自由基在结晶状态下形成分子内 sigma 二聚体,具有延长的 CC 键 (1.637 Å)。自由基结构的细微变化会影响自旋相互作用的性质,因为将自由基上的二甲氨基取代基固定成环以形成环戊二烯衍生的双自由基导致观察到的最弱的键合相互作用(Δ Gbonding = 1 kcal mol-1)和将自旋配对物种从
Synthesis, Structures, and Properties of Triskelion-Shaped Fluorophores Bearing Coumarins with Nitrogen-Containing Donor Groups
作者:Masafumi Ueda、Mirai Kokubun、Yasuhiro Mazaki
DOI:10.1246/bcsj.20210310
日期:2021.12.15
Triskelion-shaped π-fluorophores bearing coumarins with nitrogen-containing donor groups (1a, 1b, and 1c) were successfully synthesized via intramolecular Ullmann coupling. X-ray crystal structure analysis revealed that 1a and 1b adopt curved propeller-shaped structures similar to that of parent compound 1-H. A theoretical study suggested that compounds 1a-1c possess two different molecular surfaces
Synthesis of Some Newo-Substituted Arylcarbamates and Related Compounds
作者:José E. Barbarini、Roberto Rittner、Nelci F. Höehr、Jerzy Suwinski
DOI:10.1006/bioo.1996.1053
日期:1997.2
Seven new 2-substituted-5-N',N'-dimethylaminophenyl N,N-dimethylcarbamates and three other compounds of similar structures have been synthesized aiming at obtaining potent anti-ChE agents. It has been found that the 2-substituents, regardless of their character, decrease the biological activity of the carbamates. (C) 1997 Academic Press.
Synthesis of 2-arylbenzofuran-3-carbaldehydes <i>via</i> an organocatalytic [3+2] annulation/oxidative aromatization reaction
A novel organocatalytic [3+2] annulation/oxidative aromatizationreaction of enals with 2-halophenols or β-naphthols is reported. This process enables chemo- and regioselective access to 2-arylbenzofuran-3-carbaldehydes without the use of transition metals or strong oxidants. Preliminary mechanistic studies reveal that an unprecedented, organocatalytic, direct α-arylation pathway is involved.