%0 Generic %A Mukhopadhyay, Arindam %A Jana, Kanyashree %A Hossen, Tousif %A Sahu, Kalyanasis %A Moorthy, Jarugu Narasimha %D 2019 %T Coumarin-Annelated Regioisomeric Heptahelicenes: Influence of Helicity on Excited-State Properties and Chiroptical Properties %U https://acs.figshare.com/articles/dataset/Coumarin-Annelated_Regioisomeric_Heptahelicenes_Influence_of_Helicity_on_Excited-State_Properties_and_Chiroptical_Properties/9710180 %R 10.1021/acs.joc.9b01126.s006 %2 https://acs.figshare.com/ndownloader/files/17399231 %K excited-state properties %K molar ellipticities %K pyran -2-one moiety %K Coumarin-Annelated Regioisomeric Heptahelicenes %K regioisomeric pairs %K Excited-State Properties %K intramolecular charge transfer %K anisotropic dissymmetry factors %K cause decrease %K chiroptical properties %K heptahelical coumarins exhibit helicity-dependent chiroptical properties %K Chiroptical Properties %K Theoretical calculations point %K Cotton effects %K coumarin-annelated heptahelicenes %K fluorescence quantum %X Two regioisomeric pairs of heptahelical mono- and biscoumarins that are differentiated by “inward” and “outward” disposition of the pyran-2-one moiety have been synthesized and investigated to understand the influence of helicity on excited-state and chiroptical properties. A slight variation in the helicities is found to manifest in contrasting excited-state properties of coumarin-annelated heptahelicenes; in addition to the intramolecular charge transfer, structural relaxation in the excited state is shown from theoretical calculations to cause decrease in the fluorescence quantum yield for a system with higher helicity. The optically pure enantiomers of heptahelical coumarins exhibit helicity-dependent chiroptical properties, namely, specific rotations, molar ellipticities, Cotton effects, and anisotropic dissymmetry factors. Theoretical calculations point to factors that are not readily explicable. %I ACS Publications