Planar Chiral Analogues of PRODAN Based on a [2.2]Paracyclophane Scaffold: Synthesis and Photophysical Studies

We describe the synthesis and photophysical characterization of differently substituted planar chiral analogues of PRODAN based on a [2.2]­paracyclophane scaffold. This experimental and theoretical study highlights that the (chir)­optical properties of the new “phane” compounds, which incorporate an electron-withdrawing propionyl moiety and an electron-donating dimethylamino group at their para or pseudo-para positions, strongly depend on their substitution patterns. In particular, for this series of molecules, a more pronounced solvatochromism and clear chiroptical behaviors are observed when the two substituents are placed on the two rings of the pCp core in a non-“co-planar” arrangement (pseudo-para derivative). This observation may help design new pCp-based luminophores with finely tuned photophysical properties.