Vibrational circular dichroism (VCD) spectroscopy has been used to determine the absolute configurations (ACs) of many chiral pharmaceuticals and natural products.  Relying heavily on the visual identification of matched bands at various frequencies, the VCD spectrum comparison poses a great challenge due to the approximations in the theoretical models, the conformation sampling, the spectrum dependency on chirality and conformation, etc. The resulting AC assignments often lack quantitative error assessments unless the tedious band-to-band correlation analysis or an emerging automatic method is applied.

This web site provides such a tool for the VCD community. The SimIR/VCD method computes a quantitative similarity between an observed and a calculated spectrum. It has been shown that the similarity, Sv, is a random variable and its normal distribution character can be used to estimate error in the corresponding AC determination.  A |Sv| >0.2 is usually required for a confident (>90%) AC assignment. For more details, see the following references.

1.“A novel computational method for comparing vibrational circular dichroism spectra” Shen J, Zhu C, Reiling S, Vaz R. Spectrochim Acta A Mol Biomol Spectrosc. (2010) 76, 418-22.

2. “Revisiting Vibrational Circular Dichroism Spectra of (S)-(+)-Carvone and (1S,2R,5S)-(+)-Menthol using SimIR/VCD Method” Jian Shen, Yi Li, Roy Vaz, Hiroshi Izumi,    J. Chem. Theory Comput., 2012, 8 (8), pp 2762–2768 DOI: 10.1021/ct300110q

 3. "Enantiomeric characterization and structure elucidation of Otamixaban"Jian Shen, Jiping Yang, Winfried Heyse, Harald Schweitzer,Norbert Nagel, Doris Andert, Chengyue Zhu, Vincent Morrison,Gregory A. Nemeth, Teng-Man Chen, Zhicheng Zhao,Timothy A. Ayers, Yong-Mi Choi, Journal of Pharmaceutical Analysis 2014;4(3):197–204 

4. "Enantiomeric characterization and structure elucidation of LH601A using vibrational circular dichroism spectroscopy" Jian ShenSadagopan MageshLin ChenLongqin HuYanan He,Spectrochim Acta A Mol Biomol Spectrosc2018 Mar 5;192:312-317.doi: 10.1016