Optically Active Phenylethene Dimers Based on Planar Chiral Tetrasubstituted [2.2]Paracyclophane

Abstract

Optically active phenylethene dimers based on a planar chiral 4,7,12,15-tetrasubstituted [2.2]paracyclophane were synthesized. We succeeded in controlling the molecular motion by binding luminophores in close proximity with the [2.2]paracyclophane scaffold. For example, aggregation-induced emission (AIE)-active luminophores were converted to show intense photoluminescence (PL) even in a diluted solution at room temperature and the resulting compound worked as a single-molecule thermoresponsible material around room temperature. Because of the AIE-active unit, the molecular motion could be easily activated by heating, leading to variable and reversible PL intensity. Furthermore, the π-conjugated systems with the planar chirality of 4,7,12,15-tetrasubstituted [2.2]paracyclophane provided excellent characteristics on circular dichroism (CD) and circularly polarized luminescence (CPL). The obtained dimers showed high CPL performances both in a diluted solution and in an aggregation state. We succeeded in proving that simple molecular designs composed of only carbon and hydrogen atoms could create versatile optical functionalities.

Control of Axial Chirality by Planar Chirality Based on Optically Active [2.2]Paracyclophane

“…As indicated, mirror‐image CD and CPL spectra were obtained, with positive and negative signals being observed for the ( S p )‐ and ( R p )‐isomers, respectively, in the longest wavelength regions. This mirror‐image relationship was comparable to those previously reported for X‐shaped molecules based on polyaryleneethynylenes [4d,e, 10a] and polyarylenevinylenes [10b] . In addition, they were opposite signs to the V‐shaped polyarylenes that were recently prepared [11] .…”

Preparation and Synthetic Applications of [2.2]Paracyclophane Trifluoroborates: An Efficient and Convenient Route to Nucleophilic [2.2]Paracyclophane Cross‐Coupling Building Blocks

“…Besides this fundamental curiosity, PCP has received increasing attention for its wide applications as a planar chiral ligands in asymmetric synthesis, purely carbon and hydrogen based optical materials, molecular junctions and as a rigid backbone in light‐emitting diode TADF emitters …”

Beyond Simple Substitution Patterns – Symmetrically Tetrasubstituted [2.2]Paracyclophanes as 3D Functional Materials

“…Chujo and co‐workers further reported optically active PC compounds to study the influence of aggregation on emission properties . They prepared enantiopure samples of compound 26a (R = phenyl) from 47 , together with an analogue comprising an extended peripheral π‐system.…”

“…Synthesis of the series of chiral CP comprising dendrimers 57 and the X‐shaped molecules 58 and 59 for aggregation studies, the extended model compounds 60 and 61 , which were analyzed as CPL emitters, and the V‐shaped model compound 63 …”