Molecular Insights into [2.2]Paracyclophane-Based Functional Materials: Chemical Aspects Behind Functions

Abstract

Many of the functions and features of practically useful materials are the province of molecular-level chemistry and their modulation at different length-scale. This report illustrates the molecular-level chemistry behind functions and features of the [2.2]paracyclophane-based materials with a particular focus on the most recent explorations on through-space conjugated small-molecule organic emitters, π-stacked macrocyclic molecules and polymers, poly(p-phenylenevinylene)s featuring well-defined donor-acceptors sequence control, and surface engineering of technologically-relevant parylenes that finds broad applications across the field of chemical science and technology. This report largely deals with the potential and opportunities associated with molecular features and functions of planar chirality, conformational behaviors, strain-induced non-planarity of the aromatics, the profound impacts of through-space conjugation and π-electron interactions/delocalization on optoelectronic properties of the π-conjugated organic emitters, polymers and extended structures consisting of cyclophanes. A special focus is put on the concept of supramolecular polymers using chemically-programmed chiral cyclophanes via non-covalent stacking and controlled conformational arrangements. Illustrating cyclophane as precursors/monomers and fabrication strategies for their incorporation in structurally-controlled (poly(p-xylylene)s formed via chemical vapor deposition polymerization and post-deposition fabrication for interface engineering is described. Demonstrating a rather different approach of electronically-dictated ring-opening metathesis polymerization employing strained cyclophane-diene precursors that generate conjugated poly(p-phenylenevinylene)s with well-defined (i.e., low dispersity) and donor-acceptor sequence control is also discussed. This report will serve as an indispensable one-stop reference for organic, and polymer chemists, as well as material scientists working with cyclophanes for research innovations.