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|Type:||Artigo de periódico|
|Title:||A theoretical investigation on the dual-mode photoswitching mechanism of some chiroptical systems|
|Abstract:||The synthesis of dual-mode optical molecular switching systems has been recently achieved. These systems were based on chiral helical-shaped alkenes in which the chirality can be reversibly modulated by light. In this work we report a theoretical study on the geometric and spectroscopic properties of these structures using the well-known semiempirical methods PM3 (parametric method 3) and ZINDO/S-CI (Zerner's intermediate neglect of differential overlap/spectroscopic-configuration interaction). Our results show that there are two stable conformers very close in energy for each possible molecular helicity presenting a barrier of similar to 40 kcal/mol for bond rotation along the main molecular axis. Under protonation these barriers increase significantly and might explain why the protonation leads to the blocking of the switching process. We propose a scheme for the switching mechanism based on charge transfer and conformational changes during the isomer interconversion.|
|Editor:||Amer Chemical Soc|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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