Thermodynamic Evaluation of Aromatic CH/π Interactions and Rotational Entropy in a Molecular Rotor

Abstract

A molecular rotor built with a stator formed by two rigid 9β-mestranol units having a 90° bent angle linked to a central phenylene rotator has an ideal structure to examine aromatic CH/π interactions. Energies and populations of the multiple solution conformations from quantum-mechanical calculations and molecular dynamics simulations were combined with variable-temperature (VT) (1)H NMR data to establish the enthalpy of this interaction and the entropy associated with rotation about a single bond. Rotational dynamics in the solid state were determined via VT cross-polarization magic-angle spinning (13)C NMR spectroscopy.

Beyond static structures: Putting forth REMD as a tool to solve problems in computational organic chemistry

“…The dynamics of a recently investigated molecular rotor (Fig. ), is a further illustrative case study highlighting the importance of accessing conformational states associated with both entropically and enthalpically favored regions.…”

“…b). The overall picture is clearly visible in the variable temperature 1 H NMR experiment but the REMD data provides significantly deeper insight into the dynamic process by revealing the relative conformational population evolution when varying the temperature as well as the direct temperature dependence of the measure properties (Fig. b).…”

Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy

“…Parts III and IV deal with combined and heterogeneous systems, respectively.I ti sw orth remembering that many dynamic processes are often accompanied by little or no observable chemical change andh ave previously been overlooked. [20] Part I: Processes without Bond Breaking…”

Reverse Intramolecular Stacking in o‐Xylene Bridge Symmetrical Dimers of 2‐Thiopyridine Derivative: Assessment of the Conformational Stability

“…To date, various models have been reported for the progressive study of intramolecular stacking phenomena as well as their conformational studies, between symmetrical or dissymmetrical dimers of aromatic and heteroaromatic system, linked through various spacers The stacking phenomenon occurred due to the presences of aromatic or heteroaromatic system because these systems are prone to realizing all possible types of non‐covalent interactions The non covalent interaction, i.e.…”

“…[1][2][3][4][5] The stacking phenomenon occurred due to the presences of aromatic or heteroaromatic system because these systems are prone to realizing all possible types of noncovalent interactions. [6][7][8][9] The non covalent interaction, i.e. present in aromatic systems are known as aromatic interactions.…”