# Investigating Bay-Substituted 6,7-Dihydrodibenzo[b,j][4,7]phenanthroline, a Class of Tunable Hindered Rotors: Synthesis and Molecular Dynamics

## TL;DR

This paper describes a new method to synthesize a class of molecules with tunable hindered rotors and explores their structure-property relationships.

## Contribution

A convenient synthesis of bay-substituted 6,7-dihydrodibenzo[b,j][4,7]phenanthroline derivatives and insights into their hindered rotor behavior.

## Key findings

- Unsymmetrical bay-substituted systems can be synthesized via Friedländer condensation under mild conditions.
- π–π interactions between polycyclic aromatic hydrocarbons scale with π-surface coverage areas.
- Intramolecular interactions in the rigid phenanthroline framework influence hindered rotational motions.

## Abstract

We developed a convenient and flexible synthesis of 6,7-dihydrodibenzo­[b,j]­[4,7]­phenanthroline derivatives with bay region substituents
via Friedländer condensation. Thanks to the mild reaction conditions,
unsymmetrical bay-substituted systems also become accessible. The
rigid phenanthroline framework holds various functional groups in
the bay region in enough proximity for intramolecular interactions
to manifest. Measuring the hindered rotational motions in this system
unveils subtle structure–property relationships. Most notably,
through rotamer distribution, π–π interactions
between polycyclic aromatic hydrocarbons were found to scale with
the π-surface coverage areas.