Raman spectroscopic characterization of different regioisomers of monoacyl and diacyl chlorogenic acid

We have investigated the Raman spectra of different regioisomeric forms of monoacyl and diacyl chlorogenic acids. Raman spectra of 3-caffeoylquinic acid, 4-caffeoylquinic acid, 5-caffeoylquinic, 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, 4,5-di-O-caffeoylquinic acid, and a synthetic derivative of 3-feruloylqunic acid were recorded using visible Raman spectroscopic technique and vibrational bands are assigned. Additionally, a theoretical study of 5-caffeoylquinic acid was performed using Gaussian 03.