화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.112, No.36, 8464-8470, 2008
Conformational changes in cryptophane having C-1-symmetry studied by vibrational circular dichroism
Vibrational circular dichroism (VCD) measurements and density functional theory (DFT) calculations were used to obtain the absolute configuration of a cryptophane molecule having C-1-symmetry (labeled cryptophane-H H). This molecule exhibits chiroptical properties different from those published for cryptophane-A having D-3-symmetry [Brotin et al. J. Am. Chem. Soc. 2006, 128, 5533-5540]. In particular, we have shown that the conformation of the aliphatic linkers is very dependent on the solvent used and its ability to enter (CDCl3 solution) or not (C2D2Cl4 Solution) in the cryptophane cavity. Calculations performed at the DFT (B3PW91/6-31G*) level establish, besides the absolute configuration, the preferential anti and gauche conformations of the aliphatic linkers of the chloroform@cryptophane-H complex and the empty cryptophane-H molecule, respectively. Polarimetric measurements performed in several solvents reflect also the change of conformation of the bridges upon guest encapsulation.