Selective Theophylline Complexation: Molecular Structure and Conformational Change

What is it about?

The research described in the content focuses on the molecular structure and selective complexation of diethyl (1,3-phenylene)dicarbamate (1) with theophylline (TEO) and caffeine (CAF) by conformational change. The study was conducted by researchers from the Instituto de Farmacobiología, Universidad de la Cañada, Universidad de Colima, and the Facultad de Química the Universidad Nacional Autónoma de México. The formation of the 1-TEO complex was preferred and involves the conformational change of one of the ethyl carbamate groups of 1 from the endo conformation to the exo conformation to allow the formation of intermolecular interactions. The formation of an hydrogen bond between 1 and TEO triggers the conformational change of 1. CAF molecules are unable to form an hydrogen bond with 1, making the conformational change and, therefore, the formation of the complex impossible. The study was conducted using IR spectroscopy, solid-state nuclear magnetic resonance, and single-crystal X-ray diffraction to monitor the conformational change and selective binding.

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Photo by Jason D on Unsplash

Photo by Jason D on Unsplash

Why is it important?

This research is important because it evaluates the ability of receptor 1 to form host-guest complexes with TEO and CAF by mechanochemistry. It provides insights into the conformational changes of 1 that trigger the formation of noncovalent interactions between 1 and TEO. This study contributes to the understanding of the intermolecular interactions and the design of molecular receptors for various applications such as drug delivery systems, molecular diagnostics, biomaterials, artificial molecular machines, sensors, and biosensors. Key Takeaways: 1. Receptor 1 forms a host-guest complex only with TEO and not with CAF due to the formation of N-H...O hydrogen bonds between 1 and TEO. 2. The conformational change of 1 is triggered by the N-H...O hydrogen bond with TEO. 3. The formation of the 1-TEO complex is evidenced by IR spectroscopy, solid-state 13 C nuclear magnetic resonance, powder X-ray diffraction, and single-crystal X-ray diffraction. 4. The study contributes to the understanding of intermolecular interactions and the design of molecular receptors for various applications.