title: Unusual Chiroptical Properties of the Cryptophane-222 Skeleton.
abstract: Enantiopure cryptophane-222 derivative (1) devoid of substituents was obtained via high-performance liquid chromatography (HPLC) using chiral stationary phases. The chiroptical properties of 1 were determined from polarimetry, electronic circular dichroism (ECD), synchrotron radiation circular dichroism (SRCD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) experiments and were compared to those of the cryptophane-A (2) derivative. Unusual polarimetric results were obtained for 1 in CHCl3solvent as the sign of the optical rotation (OR) values changes in the nonresonance region above 365 nm, whereas no change was observed in the CH2Cl2solvent. ECD spectra in the1Laand1Lbregions were very similar for the two solutions and could not explain these unusual polarimetric properties. In contrast, SRCD spectra in the1Bbregion revealed spectral differences for the two solutions, which have been associated with conformational changes of the three linkers by time-dependent density functional theory (TDDFT) calculations. DFT calculations of the OR support that conformational changes may explain the polarimetric results obtained for the two solvents. Finally, TDDFT calculations of the ECD as well as DFT calculations of the VCD and ROA allowed the attribution of the (-)589-PP absolute configuration for 1 in solution, as determined from the X-ray structures of 1.
authors.affiliation: Ecole Normale Supérieure de Lyon, CNRS UMR 5182, Laboratoire de Chimie, Lyon 1 University , 69364 Lyon, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Pitrat
authors.affiliation: Institut des Sciences Moléculaires, CNRS UMR 5255, Bordeaux University , 33405 Talence, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Daugey
authors.affiliation: Centrale Marseille, CNRS, iSm2, Aix-Marseille University , 13397 Marseille, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Jean
authors.affiliation: Centrale Marseille, CNRS, iSm2, Aix-Marseille University , 13397 Marseille, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vanthuyne
authors.affiliation: Synchrotron SOLEIL , L'Orme des Merisiers, 91192 Gif sur Yvette, France.
authors.forename: Frank
authors.initials: F
authors.lastname: Wien
authors.affiliation: Institut des Sciences Moléculaires, CNRS UMR 5255, Bordeaux University , 33405 Talence, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Ducasse
authors.affiliation: Ecole Normale Supérieure de Lyon, CNRS UMR 5182, Laboratoire de Chimie, Lyon 1 University , 69364 Lyon, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Calin
authors.affiliation: Institut des Sciences Moléculaires, CNRS UMR 5255, Bordeaux University , 33405 Talence, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Buffeteau
authors.affiliation: Ecole Normale Supérieure de Lyon, CNRS UMR 5182, Laboratoire de Chimie, Lyon 1 University , 69364 Lyon, France.
authors.forename: Thierry
authors.identifier: 0000-0001-9746-4706
authors.initials: T
authors.lastname: Brotin