Synthesis of Functional Carbo-benzenes with Functional Properties: The C2 Tether Key

International audienceBeyond demonstration of conceptual relevance and synthetic feasibility of aryl/alkyl-substituted representatives, carbo-benzene mols. started to gain prospects of broader impact through the emergence of alkynyl derivs. This is first illustrated by examples of di- and hexaalkynyl- carbo-benzenes, a carbo-naphthalene, a carbo-biphenyl, and two carbo-terphenyls. A focus is then given to dialkynyl derivs. by ref. to the peripherally C 2-extruded parents. In the centrosym. quadrupolar series, the C 2expansion or ethynylogation effect is more particularly considered for 9 H-fluoren-2-yl, tris(O- n-alkyl)pyrogallyl, indol-3-yl, 4-anilinyl, and tetraphenyl- carbo-Ph substituents on the following resp. properties: two-photon absorption, chem. stability, columnar mesogenicity, on-surface photoinduced charge sepn. vssingle-mol. conductance, and redn. potential. Topical results and prospects of application are discussed on the basis of crystallog., spectroscopic, and electrochem. analyses vsDFT-calcd. nuclear and electronic structures. For the sake of the discussion consistency, complementary exptl. and computational results are disclosed in the dianilinyl series. Overall, it is shown that combined advances in strategy, protocols, and substrate scope of acetylenic synthesis remain crucial for the development of yet poorly explored but promising types of mol. materials. 1 Introduction 2 Hexaalkynyl- carbo-benzene 3 ortho-Dialkynyl- carbo-benzene 4 para-Dialkynyl- carbo-benzenes 4.1 Bistrimethylsilylethynyl- carbo-benzene 4.2 Bisfluorenylethynyl- carbo-benzene 4.3 Bistrialkoxyarylethynyl- carbo-benzenes 4.4 Bisindolylethynyl- carbo-benzene 4.5 Bisanilinylethynyl- carbo-benzene 5 Carbo-oligo(phenyleneethynylene)s 6 Conclusions