Carbo‐biphenyls and Carbo‐terphenyls: Oligo(phenylene ethynylene) Ring Carbo‐mers |
| |
| Authors: | Dr Chongwei Zhu Dr Albert Poater Dr Carine Duhayon Dr Brice Kauffmann Dr Alix Saquet Valérie Maraval Prof Dr Remi Chauvin |
| |
| Affiliation: | 1. CNRS, LCC (Laboratoire de Chimie de Coordination), Toulouse Cedex 4, France;2. Université de Toulouse, UPS, ICT-FR 2599, Toulouse Cedex 9, France;3. Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Girona, Catalonia, Spain;4. Université de Bordeaux, CNRS, INSERM, UMS3033/US001, Institut Européen de Chimie et Biologie, Pessac, France |
| |
| Abstract: | Ring carbo‐mers of oligo(phenylene ethynylene)s (OPEn, n=0–2), made of C2‐catenated C18 carbo‐benzene rings, have been synthesized and characterized by NMR and UV‐vis spectroscopy, crystallography and voltammetry. Analyses of crystal and DFT‐optimized structures show that the C18 rings preserve their individual aromatic character according to structural and magnetic criteria (NICS indices). Carbo‐terphenyls (n=2) are reversibly reduced at ca. ?0.42 V/SCE, i.e. 0.41 V more readily than the corresponding carbo‐benzene (?0.83 V/SCE), thus revealing efficient inter‐ring π‐conjugation. An accurate linear fit of E1/2red1 vs. the DFT LUMO energy suggests a notably higher value (?0.30 V/SCE) for a carbo‐quaterphenyl congener (n=3). Increase with n of the effective π‐conjugation is also evidenced by a red shift of two of the three main visible light absorption bands, all being assigned to TDDFT‐calculated excited states, one of them restricting to a HOMO→LUMO main one‐electron transition. |
| |
| Keywords: | alkynes aromaticity bi-/terphenyl carbo-benzenes OPEs |
|
|
