Synthesis and Electronic Properties of Triperyleno[3.3.3]Propellanes: Towards Two‐Dimensional Electronic Structures

Abstract

Threefold symmetric triperyleno[3.3.3]propellanes (TPRPs), which are composed of three perylene units peri‐fused on [3.3.3]proppellane, have been synthesized and their electronic properties characterized. Unsubstituted TPRP assembles into two‐dimensional honeycomb‐like networks. TPRP displays a bathochromic‐shifted absorption band in its absorption spectrum and shows well‐separated one‐electron redox waves in a cyclic voltammogram, due to a homoconjugative interaction between perylene moieties. A radical cation species of tert‐butyl substituted TPRP shows spin delocalization over the whole of the molecule, which is derived from effective overlap of HOMOs among three perylene moieties.

Molecular and Spin Structures of a Through‐Space Conjugated Triradical System

“…In recent studies, we explored the properties of throughspace conjugated molecules that possess the trinaphtho-[3.3.3]propellane (TNP, Figure 1) framework, a paddlewheel structure with D 3h symmetry. [14][15][16] This effort showed that homoconjugation occurs between the three areneblades in both the neutral and charged states the π-expanded TNPs. Moreover, we observed that the strength of this electronic interaction depends on the structure and substituents on the arenes blades.…”

Homoconjugation enhances the photophysical and electrochemical properties of a new 3D intramolecular charge transfer iptycene displaying deep blue emission

“…This is indicative of electronic communication between the fins, in-line with literature precedent. 7,8 The extinction coefficients for 1 are notably larger than for 2. Specifically, we note that the ICT band is ca.…”

“…5,6 The three fused benzene "fins" of triptycene are able to communicate through the spatial overlap of their molecular orbitals, termed homoconjugation. 7,8 These properties have been broadly exploited in the development of molecular motors, [9][10][11] metal organic frameworks (MOFs) 12,13 , porous organic crystals, [14][15][16] non-fullerene acceptors for OPVs [17][18][19][20] and catalysts. [21][22][23] The ICT methodology has been applied to some triptycene derived compounds which are shown in Figure 1.…”

Simultaneous enhancement of thermally activated delayed fluorescence and photoluminescence quantum yield via homoconjugation

“…Experimentally this is observed as a significantly greater than factor of three increase in extinction coefficient (ɛ) compared with a single fin congener. [38][39][40] Recently, we extended this phenomenon to ICT transitions. 41 Upon trimerization of a fluorescent luminophore through a homoconjugated iptycene core, large enhancements in ICT parameters such as ɛ, kr, and PLQY (i.e.…”

“…In this work we will exploit two precedents: 1) the increase of TADF efficiency afforded by weakly coupling numerous chromophores, 5,6 and 2) the enhancement of ICT radiative processes via homoconjugation. [38][39][40][41] This allows the improvement of the radiative decay and krISC of a TADF luminophore simultaneously.…”