Determination of the absolute configuration of 2,2'-diphenyl-[3,3'-biphenanthrene]-4,4'-diol (VAPOL) using chiroptical spectroscopic methods

PHYS 560

Ana G. Petrovic,, Sarah E. Vick,, and Prasad L. Polavarapu, Department of Chemistry, Vanderbilt University, Nashville, TN 37235
The use of 2,2'-diphenyl-[3,3'-biphenanthrene]-4,4'-diol (VAPOL) as a chiral ligand for enantioselective catalysis necessitates a reliable determination of its absolute configuration. Based on the X-ray analysis of its phosphoric amide derivative, the configuration of VAPOL has been suggested as (+)589nm-(S). Chiroptical spectroscopic methods, namely vibrational circular dichroism (VCD), electronic circular dichroism (ECD) and optical rotatory dispersion (ORD) offer unambiguous approaches for configurational assignment, yet no such studies have been reported on VAPOL. Exciton coupling model has been used in the literature to suggest the absolute configuration using ECD spectra. However chiral biphenanthryl systems are one class of molecules where the application of exciton model does not yield unambiguous conclusions. In this work, configurational assignment of C2-symmetric VAPOL is determined from combined theoretical and experimental chiroptical spectra that include VCD, ECD and ORD.


General Posters
7:30 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Physical Chemistry

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007