# Cavitand-Mediated Photodimerization of Chalcones: The Effect of Supramolecular Influences and Temperature on Reaction Selectivity

## TL;DR

This paper explores how using γ-CD cavities can control the selectivity of chalcone photodimerization, leading to high yields of specific products.

## Contribution

The study introduces the use of γ-CD to enhance the selectivity and yield of chalcone photodimerization through supramolecular control.

## Key findings

- γ-CD CMP of chalcones yielded high dimer yields (>70%) with syn HH as the major product.
- Computational analysis linked complex stability to stereoisomer predominance in the product mixture.
- Temperature changes influenced dimer selectivity, favoring a single stereoisomer.

## Abstract

The photocycloaddition (PCA) of chalcones represents an important reaction pathway for accessing substituted cyclobutanes, which is a molecular framework with utility in synthetic chemistry, materials science, and medicine. In the past, our group has demonstrated the utility of the large cavity of γ-CD as a container for encapsulating two photo reactants for directing the PCA of several classes of aryl alkenes with high stereo- and regioselectivity: the cavitand-mediated photodimerization (CMP) approach. The CMP of chalcones reported in this work further demonstrates the effectiveness of this approach as high yields of dimers were observed in the photoreactions, while they were non-reactive in the solid state and yielded only the isomerization product in homogeneous media. The γ-CD CMP of chalcones yielded predominantly dimerized products in very good to high yields (>70%), composed of a mixture of three dimers in different proportions with syn HH as the major product. Computational analysis of the ground state complex structures revealed a strong correlation between the stability of the complex and predominance of the stereoisomer in the mixture. Further insights were deduced from temperature-dependence studies, which showed a shift in dimer selectivity tending towards a single stereoisomer.