Dibenzo[hi,st]ovalene as Highly Luminescent Nanographene: Efficient Synthesis via Photochemical Cyclodehydroiodination, Optoelectronic Properties, and Single-Molecule Spectroscopy

• DOI: 10.1021/jacs.9b08320
• Publication Date: 2019-10-07T18:09:06Z
• Authors: Qiang Chen; Stefan Thoms; Sven Stöttinger; Dieter Schollmeyer; Klaus Müllen; Akimitsu Narita; Thomas Basché
• Keywords: Quantum yield

Dibenzo[hi,st]ovalene (DBOV), as a new nanographene, has demonstrated promising optical properties, such red emission with high fluorescence quantum yield of 79% and stimulated emission, well thermal stability photostability, which indicated its promise light-emitting gain material. However, the previous synthetic routes required at least 12 steps. This obstructed access to different derivatives, e.g., obtain crystals suitable for X-ray diffraction analysis tune optoelectronic properties. Here, we report an efficient pathway DBOV based on sequential iodination-benzannulation bi(naphthylphenyl)diyne, followed by photochemical cyclodehydroiodination (PCDHI). protocol included fused bischrysene key intermediate furnished scalable amounts meso-substituted derivatives substituents. 2,6-dimethylphenyl groups could be used single-crystal analysis, revealing precise structure core. The properties were investigated UV-vis absorption spectroscopy, cyclic voltammetry, density functional theory calculations. Single-molecule spectroscopy room low temperatures provided novel insights into photophysics embedded in polymer film. As result weak coupling transitions matrix, single-molecule spectra 4.5 K showed narrow vibronic lines. autocorrelation function covering 9 orders magnitude time displayed contrast photon antibunching bunching, from decay rate triplet population depopulation rates retrieved. Remarkably, intersystem crossing state decreased more than order temperature, demonstrating that temperature can crucial parameter boost single aromatic hydrocarbon.