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Updated: Jan 14, 2026

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores
Published on: August 19, 2013
How Important Are Dimers for Interpreting the Chiroptical Properties of Carboxylic Acids? A Case Study with
Andrew R Puente1, Prasad L Polavarapu1
1Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States.
Abstract:
Chiroptical spectroscopy is sensitive to the formation of intermolecular interactions for chiral molecules. Experimental Vibrational Circular Dichroism (VCD), Vibrational Raman Optical Activity (ROA), and Optical Rotatory Dispersion (ORD) data of (-)-[5]-ladderanoic acid in chloroform have been analyzed using theoretical predictions for both monomeric and dimeric structures of (R)-[5]-ladderanoic acid to better understand their utility for the interpretation of experimental data. B3LYP, B3PW91, and M06-2X functionals, with and without dispersion corrections, and the 6-31+G(2d,p) basis set were used for theoretical predictions. It is found that dimer contributions are important to better reproduce the experimental vibrational absorption and associated VCD spectra, and a monomer:dimer ratio of 30:70 is indicated at the B3LYP level. However, no significant improvement is evident from dimer contributions to reproduce the experimental Raman and associated ROA spectra, and a monomer:dimer ratio of 100:0 is indicated at the B3LYP level. Boltzmann population-weighted specific rotations are predicted to be negative for both monomeric and dimeric conformations of (R)-[5]-ladderanoic acid, and quantitative agreement with the experimental ORD of (-)-[5]-ladderanoic acid is obtained with a 70:30 mixture of monomers and dimers.
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