Open Access[2.2.2.2]Paracyclophanetetraenes (PCTs): cyclic structural analogues of poly(p‑phenylene vinylene)s (PPVs)
Author(s) -
Matthias Pletzer,
Felix Plasser,
Martina Rimmele,
Martin Heeney,
Florian Glöcklhofer
Publication year - 2022
Publication title -
open research europe
Language(s) - English
Resource type - Journals
ISSN - 2732-5121
DOI - 10.12688/openreseurope.13723.2
Subject(s) - phenylene , photoluminescence , conjugated system , cyclic voltammetry , materials science , aromaticity , alkoxy group , organic electronics , absorption (acoustics) , electronic structure , polymer , photochemistry , electrochemistry , chemistry , electrode , computational chemistry , molecule , optoelectronics , organic chemistry , physics , alkyl , transistor , voltage , quantum mechanics , composite material
Background : Poly( p -phenylene vinylene)s ( PPV s) and [2.2.2.2]paracyclophanetetraene ( PCT ) are both composed of alternating π-conjugated para -phenylene and vinylene units. However, while the former constitute a class of π-conjugated polymers that has been used in organic electronics for decades, the latter is a macrocycle that only recently revealed its potential for applications such as organic battery electrodes. The cyclic structure endows PCT with unusual properties, and further tuning of these may be required for specific applications. Methods : In this article, we adopt an approach often used for tuning the properties of PPV s, the introduction of alkoxy (or alkylthio) substituents at the phenylene units, for tuning the optoelectronic properties of PCT . The resulting methoxy- and methylthio-substituted PCT s, obtained by Wittig cyclisation reactions, are studied by UV-vis absorption, photoluminescence, and cyclic voltammetry measurements, and investigated computationally using the visualisation of chemical shielding tensors (VIST) method. Results : The measurements show that substitution leads to slight changes in terms of absorption/emission energies and redox potentials while having a pronounced effect on the photoluminescence intensity. The computations show the effect of the substituents on the ring currents and chemical shielding and on the associated local and global (anti)aromaticity of the macrocycles, highlighting the interplay of local and global aromaticity in various electronic states. Conclusions : The study offers interesting insights into the tuneability of the properties of this versatile class of π-conjugated macrocycles.