Synthesis of steroidal molecular compasses: exploration of the controlled assembly of solid organic materials
In this work, five steroid-flanked derivatives of p-nitroaniline were studied to assess the influence of these rigid, chiral frameworks on the solid-state patterning of a dipolar dye, striving to drive the self-assembly of noncentrosymmetric crystals, which is of interest in the development of organic materials for nonlinear optics and piezoelectricity. The featured compounds were prepared using Sonogashira cross-coupling reaction with 17α-ethynyl steroids as a single key step. The structures of these new steroidal derivatives were established using one and two dimensional NMR 1H and 13C experiments. Single X-ray diffraction analysis unequivocally confirmed the presence of the steroidal molecular compasses 8 and 11, whose potential applicability for organic materials is preliminarily assessed via computational modeling, finding candidates for nonlinear optics, organic electronic materials and molecular recognition.