NMR Analyses of-1,3-Bridged Calix[4]arene Conformations

Calix[4]arenes are cyclic oligomers known for their unique molecular architecture that provides a versatile platform for various applications in supramolecular chemistry. When strategically coupled with fluorescent molecules, their molecular recognition enables highly selective and sensitive chemosensors. The introduction of bridging groups at 1,3 phenolic positions within the calix[4]arene framework has the potential to yield distinctive structural features and enhanced functional properties. Despite their opportunities, calix[4]arene preparation requires careful characterization of conformationally restricted rotomers. We used a combination of experimental and computational techniques to elucidate the three-dimensional structure and conformational dynamics of a 1,3-bridged calix[4]arene derivative. Nuclear magnetic resonance (NMR) spectroscopy, Density Functional Theory (DFT) based optimization, and Boltzmann-weighted NMR chemical shift calculations are used to determine the precise molecular structure of the binding domain in our novel calix[4]arene derivative, including conformation, bond distance, and angle details.