On the photophysics of nanographenes – investigation of functionalized hexa-peri-hexabenzocoronenes as model systems. Issue 2 (7th January 2021)

• Record Type: Journal Article
• Authors: Haines, Philipp; Reger, David; Träg, Johannes; Strauss, Volker; Lungerich, Dominik; Zahn, Dirk; Jux, Norbert; Guldi, Dirk M.
• Is Part Of: Nanoscale. Volume 13:Issue 2(2021)
• Page Start: 801
• Page End: 809
• Publication Date: 2021-01-07
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d0nr06802k
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : In this study, the syntheses of edge-functionalized hexa- peri -hexabenzocoronene and investigations by steady-state and time-resolved photospectroscopic techniques, which are completed by electron density distribution calculations, are reported. Abstract : In this study, we report on hexa- peri -hexabenzocoronenes (HBCs) as representative models for nanographenes. To this end, we synthesized a family of functionalized HBCs and investigated the impact of the substituents on the π-extended systems of the HBCs. DFT and TD-DFT calculations suggested a charge transfer character, which intensified as the electron density withdrawing effects of the substituents (–M-effect) increased. Unambiguous corroboration of the charge transfer character in the case of NO2 -substituents was realized via steady-state absorption and fluorescence experiments, which focused on the dependencies on the solvent polarity and temperature featuring. Going beyond HBCs with NO2 -substituents, time-correlated single photon counting, and femtosecond and nanosecond transient absorption spectroscopy unveiled long-lived singlet and triplet excited states. As a complement, we performed electrochemical and spectroelectrochemical measurements. These measurements were carried out to shed light onto the nature of the functionalized HBCs as electron acceptors and/or donors, on the one hand, and their corresponding spectroscopic signatures, on the other hand. All of the aforementioned information enabled intermolecular charge separation assays with, for example, suitable electron acceptors by steady-state and time-resolved spectroscopy.