Synthesis and Evaluation of Molecular Rotors with Large and Bulky <i>tert</i>-Butyldiphenylsilyloxy-Substituted Trityl Stators

Abstract

The search for voluminous stators that may accommodate large rotator units and speed rotational dynamics in the solid state led us to investigate a simple and efficient method for the synthesis of molecular rotors with <i>tert-</i>butyldiphenylsilyl-protected (TBDPS) triphenylmethyl stators. Additionally, solid state characterization of these systems with two-, four-, and six-TBDPS groups provided us with a description of their crystallinity and thermal stability. Among them, molecular rotor <b>7c</b> with the largest and most symmetric stator resulting from six peripheral silyl groups showed the best tendency to crystallize, and the study of its isotopologue <b>7c</b>-<i>d</i>₄ by solid state ²H NMR revealed a 2-fold motion of the 1,4-diethynylphenylene-<i>d</i>₄ rotator in the kHz regime