Hexabenzocoronene–Benzimidazole Hybrid Architectures and Faraday Rotation of the First Hexabenzocoronene–Phthalocyanine

TL;DR

Scientists created a new hybrid molecule combining hexabenzocoronene and phthalocyanine, which shows strong light absorption and potential for use in Faraday rotation.

Contribution

The first synthesis and characterization of a HBC–phthalocyanine hybrid molecule with notable Faraday rotation properties.

Findings

The HBC–Pc hybrid molecule has a high molar absorption coefficient and extended absorption up to 460 nm.

The hybrid molecule achieved a Verdet constant of −1.4 × 10⁵ deg T⁻¹m⁻¹ at 700 nm, indicating strong Faraday rotation.

DFT calculations confirmed the electronic structure and lower HOMO/LUMO gap in HBC–Pc compared to other HBC compounds.

Abstract

The synthesis and characterization of a first example of a Ni‐phthalocyanine (Pc) hybrid molecule carrying four hexa‐peri‐hexabenzocoronene (HBC) substituents and of three HBC‐benzimidazole derivatives is reported. These π‐electron rich chromophores exhibit a high molar absorption coefficient with extended absorption up to 460 nm. Particularly, HBC‐Pc absorbs throughout most of the UV–vis range with the Pc Q‐band located at 672 nm. This enables its investigation as a Faraday rotator where it displayed a remarkable Verdet constant of −1.4 × 105 deg T−1m−1 at 700 nm assigned to Faraday A‐term activity. Electrochemical measurements supported by DFT calculations elucidated the electronic structure of the molecules together with excited state molecular orbital analysis using TDDFT. Here, HBC‐Pc showed a HOMO/LUMO gap considerably lower than the other HBC‐based compounds due to the introduction of the Pc scaffold.

The synthesis of four hexabenzocoronene (HBC) benzimidazole hybrid molecules is shown, culminating in tetra‐HBC‐Ni‐phthalocyanine (Pc). Its application as a Faraday rotator reveals a remarkable Verdet constant. The compounds are fully characterized and their optoelectronic properties investigated by electrochemistry, UV–vis, and fluorescence spectroscopy. Density functional theory (DFT) calculations support the experimental data.

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