A study of the effects of subunit pre-orientation for diarylpyrrole esters; design of new aryl-heteroaryl fluorescent sensors

The synthesis, single crystal X-ray structures, spectroscopic properties and molecular mechanics calculations of three systematically substituted 3,5-diaryl-1H-pyrrole-2-carboxylic acid ethyl esters 1a-c are described. The goal is to develop design principles for the generation of new class of fluorescent switches constructed from an aryl-heteroaryl architecture containing a virtual (C₀) spacer. The spectroscopic effects of the electron donor p-dimethylamino substituent of 1b and the combined steric and electron donor impact of the o-methyl-p-dimethylamino groups of compound 1c were investigated to determine the required structural motifs to achieve orthogonal pre-orientation of the sensor subunits.