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The effects have been studied of mono- and dibenzannulation of a benzyl radical with hybrid density functional theory (B3LYP) and quadratic configuration interaction theory (QCISD). Bond dissociation energies and enthalpies are reported that were determined at the common level QCISD/6-311G**//B3LYP/6-31G* for the benzylic C-H bonds of toluene 1H, the monobenzannulated polycyclic aromatic hydrocarbons (PAH) 1- and 2-methylnaphthalene 2H and 3H, the dibenzannulated PAHs 9-methylanthracene 4H and 9-methylphenanthrene 5H, and the model hydrocarbons 1-phenylpropene 6H and propene 7H. The conformational preferences and the symmetries of 1H-7H and of their corresponding radicals 1-7 have been determined. The analysis of the electron and spin density distributions of radicals 1-7 at the QCI level are reported, and these high-level data are discussed in comparison to results obtained with density functional theory and with an awareness of a general perception shaped by Hückel molecular orbital theory. The results show in a compelling fashion that electron and spin delocalization onto an annulated arene is not the decisive principle for stabilization of the benzyl radicals formed by homolysis of the methylated PAHs C10H7-CH3 and C14H9-CH3, and instead, the analysis of QCI spin density distributions suggests that spin delocalization onto annulated arenes is avoided as much as possible while spin polarization does occur to a significant extent.

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Fluoride anions play a key role in human health and chemical engineering, such as in organic synthesis and biological processes. The development of high-sensitivity naked-eye detection sensors for fluoride anions in organic solutions is crucial and challenging. In this study, (3Z,3 ′ Z)-3,3 ′-[4,4,9,9-tetrakis(4-hexylphenyl)-4, 9-dihydro-s-indaceno(1,2-b:5,6-b ′)dithiophene]-2,7-diylbis(methan-1-yl-1-ylidene) bis (6-bromo-indolin-2-one) (IDTI) was designed and used as a fluoride chemosensor for the first time. IDTI is a highly sensitive fluoride sensor with a detection limit of as low as 1 × 10 −7 M. In addition, upon the reaction of IDTI with fluoride anions in a tetrahydrofuran (THF) solution, color changes from red to yellow under ambient light and from purple to green under UV light were detectable by the naked eye. These studies indicate that IDTI is a promising fluoride chemosensor.

The C38H32 hydrocarbon 1-methyl-1,3,6-triphenyl-7-[(E)-2-phenyl-propenyl]-1,2-dihydronaphthalene (I) presents a novel framework that combines the functionalities of a 1,6-diarene-substituted 1,2-dihydronaphthalene (DHN) with a 1,4-distyrylbenzene (DSB). The hydrocarbon was synthesized, the crystal structure of (±)-I was determined, and a detailed analysis of intermolecular interactions is presented. The crossed bis-diarene I has the capability to engage in arene−arene interactions in two nearly orthogonal directions, and various types of arene−arene interactions cooperate in the formation of its lamellar crystal architecture. While the DSB units alternate within both the R- and the S-substructures, the homochiral substructures feature opposing polarity along the long axes of the DHN-based diarenes, and hence the possibility exists for polar quasiracemic crystals. Importantly, the analysis of arene−arene contacts provides strong evidence that chemical modifications of the arenes attached to the DHN unit are possible without fundamental impediments of the lattice architecture.