Diels–Alder reactions of acenaphthylene-5,6-dicarboximide (AI) derivatives with the corresponding dienes afforded some derivatives of π-extended fluoranthene imide, namely N-(2-ethylhexyl)-7,10-diphenylfluoranthene imide (DPFI) and N-(2-ethylhexyl)-7,8,9,10-tetraphenylfluoranthene imide (TPFI), N-(n-octyl)-benzo[k]fluoranthene imide (BFI), and N-(n-octyl)-naphtho[k]fluoranthene imide (NFI). Molecular structures of TPFI and BFI reveal that the core π-skeletons have a highly planar structure, and the molecules form a dimeric structure in the crystals. The absorption spectra exhibit bathochromic shift with π-extension of the core π-skeletons. On the other hand, DPFI and TPFI show the long-wavelength emission related to BFI, probably due to π-extension toward the phenyl substituents in the excited states. BFI and NFI exhibited an interesting concentration-dependent 1H-NMR behavior in CDCl3, suggesting self-aggregation formation. Moreover, BFI and NFI show moderate and remarkable solvatofluorochromism in solutions (BFI for ΔλEM = 67 nm, NFI for ΔλEM = 116 nm), respectively, while DPFI and TPFI show weak solvatofluorochromism. The density functional theory calculations demonstrate that the considerable spatial separation between the HOMO and LUMO coefficients in the NFI molecule. The result indicates that the ground-to-excited state transition of NFI should have intramolecular charge transfer (ICT) character.

A soluble directly 2,2′‐linked tetracene dimer was synthesized. Dimerization of 8‐bromo‐2,3‐dihexyl‐5,12‐tetracenequinone afforded the corresponding bitetracenequinone, which was converted into a tetracene dimer by sequential addition of 1‐hexynyllithium and SnCl2/HCl. The synthesized tetracene dimer with four hexyl and four 1‐hexynyl groups was highly soluble in CH2Cl2 and THF, and the solutions were unstable under air and room light. The compound was studied by X‐ray single crystal analysis, UV/Vis, and fluorescence spectroscopy, cyclic voltammetry, and density functional theory (DFT) calculations. In the crystal, two tetracene rings take a coplanar conformation although DFT calculations demonstrated that such a molecular structure is energetically unfavorable. The tetracene dimer had red‐shifted absorption maxima and large molar extinction coefficients compared with the corresponding tetracene monomer. The tetracene dimer also showed amphoteric redox properties and p‐type semiconducting behavior.

The Front Cover shows a piece of ice in one glass and water in another glass; the former represents the solid phase of an unsubstituted directly‐2,2'‐linked tetracene dimer (2,2'‐TD), and the latter is the solution of the multi‐substituted 2,2'‐TD. The unsubstituted 2,2'‐TD reported by Rehan's group in 2017 could not be characterized, which may have been be due to its low solubility. On the other hand, the multi‐substituted 2,2'‐TD was highly soluble in organic solvents and could be characterized by several techniques such as NMR, UV/Vis spectroscopy, and X‐ray crystallography. More information can be found in the Full Paper by T. Honda, C. Kitamura et al.