Internal dynamics in helical molecules studied by X-ray diffraction, NMR spectroscopy and DFT calculations. Issue 4 (12th January 2017)

• Record Type: Journal Article
• Authors: Dračínský, Martin; Storch, Jan; Církva, Vladimír; Císařová, Ivana; Sýkora, Jan
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 4(2017)
• Page Start: 2900
• Page End: 2907
• Publication Date: 2017-01-12
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp07552e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Unexpected flexibility of helical molecules is observed both in solution and solid phases. Abstract : The conformational behaviour of a prototype helical molecule, [6]helicene, and its derivatives was studied in solution and the solid state. Available crystal structures of [6]helicene revealed surprisingly large flexibility of this molecule and variable-temperature NMR experiments provided unusual temperature dependence of chemical shifts of hydrogen, carbon and fluorine atoms in the peripheral aromatic rings of [6]helicene and tetrafluoro[6]helicene. These chemical shift changes were interpreted as a consequence of the helicene 'pitch' opening with elevated temperature, and the experimental data were corroborated by DFT calculations of the chemical shift dependence on the helicene conformation and by variable-temperature DFT molecular dynamics simulations.