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

[2.2]Paracyclophane-based coumarins: effective organo-photocatalysts for light-induced desulfonylation processes

Herein, we demonstrate for the first time that coumarins derived from [2.2]paracyclophane (pCp) can act as effective organo-photocatalysts and promote the reductive cleavage of sulfonamides under light-irradiation. In the presence of these original compounds, photodesulfonylation reactions occur under mild conditions at low catalyst loadings in the presence of Hantzsch ester. Theoretical and experimental investigations are described, which elucidate the reaction mechanism and the nature of the active species involved in the photocatalytic process. This proof-of-concept study paves the way for further application of pCps in the field of photocatalysis.

Synthesis of Two Novel Optically Active #-Shaped Cyclic Tetramers Based on Planar Chiral [2.2]Paracyclophanes

This study reports the synthesis of optically active cyclic tetramers comprising four stacked π-electron systems from two enantiomerically pure [2.2]paracyclophane compounds (bis-(para)-pseudo-ortho- and bis-(para)-pseudo-meta-tetrasubstituted [2.2]paracyclophane compounds). Depending on the combination of the absolute configurations of the planar chiral pseudo-ortho- and pseudo-meta-[2.2]paracyclophane units, the cyclic tetramers formed either parallel-#- or weave-#-structures. The optical and chiroptical properties of both structures were investigated experimentally and theoretically. In particular, the weave-#-shaped cyclic tetramer exhibited good chiroptical properties and emitted circularly polarized luminescence (CPL) with a high anisotropy factor (|g_lum | value of the order of 10^-3 ) and a CPL brightness (B_CPL ) higher than 100.