Covalently Scaffolded Inter‐π‐System Orientations in π‐Conjugated Polymers and Small Molecule Models

Abstract

Organic π-conjugated polymers have emerged as one of the most fascinating classes of materials as they have found utility in a host of plastic electronics technologies. The distance between π-systems and their relative orientation dictate energy/charge transfer, conductivity, and photophysical properties of these materials in bulk. This Feature Article discusses π-conjugated polymers and model compounds in which specific inter-π-system interactions are covalently enforced and the effect that the scaffolding has on optoelectronic properties.

Halogen Bonding in the Design of Organic Phosphors

“…This should be regarded as a transmolecular π-π conjugation 1 [23][24][25][26] which can reduce the triplet energy of Phe. Thus, Phe exists in the cocrystal as two states: an isolated state with π-holeÁ Á Áπ bonding between the 1,4-DBrTFB and Phe molecules in the columns and a delocalized state for Phe molecules located at inter-column positions, which may be significant in the modulation of luminescent behavior.…”

Fabrication of conjugated polymeric nanochannels from star-shaped supramolecular liquid crystals containing two different photoreactive groups

“…[1][2][3][4][5][6][7][8] The intriguing properties of π-conjugated materials can be controlled as a function of nanostructure and self-assembly process in supramolecular assemblies. For the construction of nanostructured materials, the self-assembly of small molecules into supramolecular polymers has been widely adopted.…”

Conjugated Polymers Featuring Oxacyclophane‐Scaffolded π‐Stacking Interactions

“…Theoretical studies have suggested that a face‐to‐face π‐stacking interaction with a plane‐to‐plane distance of 3.2–4.0 Å is ideal for facilitating charge mobility through a CP film . Some investigators have sought to alleviate the complication of inter‐π‐system interaction influences on polymer properties by appending the polymers with sterically encumbered substituents to prevent close contacts between polymer chains .…”

“…Some investigators have sought to alleviate the complication of inter‐π‐system interaction influences on polymer properties by appending the polymers with sterically encumbered substituents to prevent close contacts between polymer chains . Other researchers have devised molecular scaffolding and covalent crosslinking strategies to constrain adjacent polymer chains in near‐ideal orientations to improving charge/energy transport through a material . Two of the scaffolding most relevant to the current work are the [2.2]paracyclophane (i.e., in P3 , Figure B) and the oxacyclophane (i.e., in M5 , M6 , CyM , and CyP , Figure ) scaffolding units.…”

“…Two of the scaffolding most relevant to the current work are the [2.2]paracyclophane (i.e., in P3 , Figure B) and the oxacyclophane (i.e., in M5 , M6 , CyM , and CyP , Figure ) scaffolding units. The [2.2]paracyclophane unit enforces a rigid face‐to‐face π‐stacking interaction between its two phenyl rings at a separation of 2.98 Å, a distance smaller than what can be achieved with polymer chains that are not covalently scaffolded . As a result, the through‐space interaction across adjacent segments held in place by the [2.2]paracyclophane unit would not be predictive of free polymer chains in a film.…”