Optical rotations were
measured on an Autopol IV, model A21200 APIV/1W, digital
polarimeter (Rudolph Research Analytical). UV spectra were
measured on an Agilent 8453 UV−visible spectrophotometer from
190 to 400 nm using a 1 cm cell. FTIR spectra were measured on a
PerkinElmer Spectrum One instrument. Samples were deposited in
solution on NaCl disks and dried as films before measurement