title: Borazino-Doped Polyphenylenes.
abstract: The divergent synthesis of two series of borazino-doped polyphenylenes, in which one or more aryl units are replaced by borazine rings, is reported for the first time, taking advantage of the decarbonylative [4 + 2] Diels-Alder cycloaddition reaction between ethynyl and tetraphenylcyclopentadienone derivatives. Because of the possibility of functionalizing the borazine core with different groups on the aryl substituents at the N and B atoms of the borazino core, we have prepared borazino-doped polyphenylenes featuring different doping dosages and orientations. To achieve this, two molecular modules were prepared: a core and a branching unit. Depending on the chemical natures of the central aromatic module and the reactive group, each covalent combination of the modules yields one exclusive doping pattern. By means of this approach, three- and hexa-branched hybrid polyphenylenes featuring controlled orientations and dosages of the doping B3N3rings have been prepared. Detailed photophysical investigations showed that as the doping dosage is increased, the strong luminescent signal is progressively reduced. This suggests that the presence of the B3N3rings engages additional deactivation pathways, possibly involving excited states with an increasing charge-separated character that are restricted in the full-carbon analogues. Notably, a strong effect of the orientational doping on the fluorescence quantum yield was observed for those hybrid polyphenylene structures featuring low doping dosages. Finally, we showed that Cu-catalyzed 1,3-dipolar cycloaddition is also chemically compatible with the BN core, further endorsing the inorganic benzene as a versatile aromatic scaffold for engineering of molecular materials with tailored and exploitable optoelectronic properties.
authors.affiliation: School of Chemistry, Cardiff University , Park Place Main Building, Cardiff CF10 3AT, United Kingdom.
authors.forename: Davide
authors.initials: D
authors.lastname: Marinelli
authors.affiliation: School of Chemistry, Cardiff University , Park Place Main Building, Cardiff CF10 3AT, United Kingdom.
authors.forename: Francesco
authors.initials: F
authors.lastname: Fasano
authors.affiliation: Department of Chemistry, University of Namur (UNamur) , Rue de Bruxelles 61, Namur 5000, Belgium.
authors.forename: Btissam
authors.initials: B
authors.lastname: Najjari
authors.affiliation: Elettra-Sincrotrone Trieste , S.S. 14 Km 163.5 in Area Science Park, 34149 Basovizza, Trieste, Italy.
authors.forename: Nicola
authors.identifier: 0000-0003-0288-3233
authors.initials: N
authors.lastname: Demitri
authors.affiliation: School of Chemistry, Cardiff University , Park Place Main Building, Cardiff CF10 3AT, United Kingdom.|Department of Chemistry, University of Namur (UNamur) , Rue de Bruxelles 61, Namur 5000, Belgium.
authors.forename: Davide
authors.identifier: 0000-0001-5717-0121
authors.initials: D
authors.lastname: Bonifazi