Mukhopadhyay Arindam, Hossen Tousif, Ghosh Indrajit, Koner Apurba Lal, Nau Werner M, Sahu Kalyanasis, Moorthy Jarugu Narasimha
Department of Chemistry, Indian Institute of Technology, Kanpur, 208016, India.
Department of Chemistry, Indian Institute of Technology, Guwahati, 781039, India.
Chemistry. 2017 Oct 20;23(59):14797-14805. doi: 10.1002/chem.201701787. Epub 2017 Sep 21.
Influence of helicity on the excited-state as well as chiroptical properties of two sets of regiohelical coumarins that are differentiated by "inward" and "outward" disposition of the pyran-2-one ring has been investigated. A subtle difference in the helicities manifests in divergent excited-state properties and significant differences in the dipole moments. The latter permit heretofore unprecedented regiodifferentiation in the O-H⋅⋅⋅O hydrogen-bond assisted electron-transfer quenching by phenols. Furthermore, the enantiopure hexahelical coumarins exhibit strong Cotton effects and lend themselves to a very high differentiation in the specific rotations and anisotropic dissymmetry factors. The specific rotation observed for 6-in turns out being the highest of the values reported for all hexahelicenes reported so far.
研究了螺旋度对两组区域螺旋香豆素激发态以及手性光学性质的影响，这两组香豆素通过吡喃-2-酮环的“向内”和“向外”排列来区分。螺旋度的细微差异表现为激发态性质的不同以及偶极矩的显著差异。后者使得在酚类物质的O-H⋅⋅⋅O氢键辅助电子转移猝灭中实现了前所未有的区域分化。此外，对映体纯的六螺旋香豆素表现出强烈的科顿效应，并且在比旋光度和各向异性不对称因子方面具有非常高的区分度。6-内型的比旋光度是迄今为止报道的所有六螺烯中最高的。
