We have developed a working strategy for accurate enantiomeric excess (ee) determination based on induced helical aggregation of achiral perylenebisimide (PBI) dyes. PBI dyes functionalized with boronic acid moieties were shown to be effective chirality sensors for α-hydroxy carboxylates. Seven α-hydroxy carboxylates tested showed strong induced Cotton effects in the perylene absorption region around λ=500nm, which were utilized for enantiomeric excess determination and chemo-discrimination of the analytes, with an average absolute error of 2% in ee determination and 100% correctness in analyte classification. Responses in the absorption spectra, which arise from the guest-enhanced aggregation, allow the determination of the sample concentration, thus enabling analysis of samples of unknown concentration and ee. The simplicity of the strategy, the ease of sample preparation, and the accuracy demonstrated, can potentially facilitate screening procedures in asymmetric synthesis.
Wu, X., Chen, X-X., Song, B-N., Huang, Y-J., Li, Z., Chen, Z., James, T. D., & Jiang, Y-B. (2014). Induced helical chirality of perylenebisimide aggregates allows for enantiopurity determination and differentiation of α-hydroxy carboxylates by using circular dichroism. Chemistry - A European Journal, 20(37), 11793-11799. https://doi.org/10.1002/chem.201402627