Organic Host Encapsulation Effects on Nitrosobenzene Monomer-Dimer Distribution and C-NO Bond Rotation in an Aqueous
Ramkumar Varadharajan1, Sarah Ariel Kelley2, Vindi M Jayasinghe-Arachchige1
1Department of Chemistry, University of Miami, Coral Gables, Miami, Florida 33146, United States.
ACS Organic & Inorganic Au
|March 1, 2023
Summary
The medium and host environment control the dynamics of nitrosocumene derivatives. Water and organic hosts like octa acid influence monomer-dimer equilibria and intramolecular rotations, impacting molecular behavior.
Area of Science:
- Supramolecular Chemistry
- Physical Organic Chemistry
- Chemical Dynamics
Background:
- Intermolecular and intramolecular dynamics of organic molecules are crucial for their reactivity and function.
- The influence of solvent and host environments on molecular equilibria and rotations is a key area of chemical research.
- Nitrosocumene derivatives exhibit interesting electronic and structural properties relevant to host-guest chemistry.
Purpose of the Study:
- To investigate the intermolecular (monomer-dimer equilibrium) and intramolecular (rotational) dynamics of 4-nitrosocumene (1a) and 4-(N,N-dimethylamino)nitrosobenzene (1b).
- To determine the effect of the medium (water) and host environments (organic capsules, cavitands) on these molecular dynamics.
- To elucidate the mechanisms by which water and host structures influence molecular equilibria and intramolecular motions.
Main Methods:
- Spectroscopic techniques to monitor monomer-dimer equilibria.
- Computational modeling to understand host-guest interactions.
- Variable temperature studies to probe rotational dynamics.
- Synthesis and characterization of nitrosocumene derivatives and host molecules.
Main Results:
- Water shifts the monomer-dimer equilibrium towards the dimer, likely due to dipolar stabilization.
- Organic hosts selectively encapsulate the monomer form of 4-nitrosocumene (1a).
- Encapsulation within the octa acid duplex (OA2) favors monomer inclusion and restricts intramolecular C-N rotations of guest 1b.
Conclusions:
- The medium and host environment play a critical role in controlling both intermolecular and intramolecular dynamics of nitrosocumene derivatives.
- Water's ability to stabilize polar dimers is analogous to its effect on organic cycloaddition reactions.
- Host-guest complexation offers a powerful strategy to modulate molecular equilibria and internal motions, with implications for molecular recognition and catalysis.
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