Exploring π–π interactions and electron transport in complexes involving a hexacationic host and PAH guest: a promising avenue for molecular devices

Abstract

Single isolated molecules and supramolecular host–guest systems, which consist of π–π stacking interactions, are emerging as promising building blocks for creating molecular electronic devices. In this article, we have investigated the noncovalent π–π interaction and intermolecular electron charge transport involved in a series of host–guest complexes formed between a cage-like host (H⁶⁺) and polycyclic aromatic hydrocarbon (PAH) guests (G1–G7) using different quantum chemical approaches. The host (H⁶⁺) consists of two triscationic π-electron-deficient trispyridiniumtriazine (TPZ³⁺) units that are bridged face-to-face by three ethylene-triazole-ethylene. Our theoretical calculations show that the perylene and naphthalene inclusion complexes G7⊂H and G1⊂H have the highest and lowest interaction energies, respectively. In addition, energy decomposition analysis (EDA) indicated that the dispersion interaction term, ΔE^disp, significantly contributes to the host–guest interaction and is correlated with the existence of π–π van der Waals interaction. Using the nonequilibrium Greens function (NEGF) method in combination with density functional theory (DFT), the current–voltage (I–V) curves of the complexes were estimated. The conductance values increased when the guests were embedded inside the host cavity. Notably, the complex G7⊂H has the maximum conductance value. Overall, this study provided the electron transport of the PAH inclusion host–guest complex through π–π interaction and provided a direction for the fabrication of future supramolecular molecular devices.