Fullerene Derivatives Substituted with Differently Branched Phenyleneethynylene Dendrons: Synthesis, Electronic and Excited State Properties

Abstract

Fullerene derivatives functionalized with isomeric phenyleneethynylene‐based dendrons possessing either 1,3,5‐triethynylbenzene or 1,2,4‐triethynylbenzene branching units have been prepared. The electrochemical properties of these compounds are not strongly dependent on the branching patterns since the corresponding redox processes are localized either on the C60 cage (acceptor unit) or on the dialkyloxybenzene moieties (donor units) at the dendron periphery. The photophysical investigations performed in CH2Cl2 have revealed an ultrafast dendron → C60 energy transfer in all these hybrid systems. Importantly, the different π‐conjugation patterns in the two series have a dramatic effect on their electronic properties as attested by the differences observed in their absorption and emission spectra. The lower lying absorption onset and the wider spectral profile of the dyads with 1,2,4‐triethynylbenzene branching units when compared to their 1,3,5‐triethynylbenzene analogues clearly points out an improved light harvesting capability. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The development of phenylethylene dendrons for blue phosphorescent emitters

“…18 We chose to form the 1,2-diphenylethylene units within the dendrons by hydrogenation of diphenylacetylene 27 rather than stilbene 28,29 units as the former can be prepared under milder conditions and with excellent yields. 30,31…”

Fullerene for organic electronics

“…To contrast the interplay between competitive energy and charge transfer processes, several phenylenevinylene-based dendrons bearing dibutylaniline (2a,b) or dodecyloxynaphthalene (3a,b) electron donors have been designed. 12,13 Efficient and rapid energy transfer dominates the intramolecular deactivation of the excited dendrons, generating the fullerene singlet excited state in nearly quantitative yields. A spectroscopic and kinetic analysis, however, confirms the presence of an alternative intramolecular charge transfer reaction which yields the C 60 À -dendron + radical ion pair state.…”

A Mild and General Method for the Synthesis of 5-Substituted and 5,5-Disubstituted Fulleroprolines

“…Fullerene[60]-derived molecular and supramolecular structures offer significant potential as novel medicinal chemical agents and nanostructured devices. Fulleroprolines and fulleropyrrolidines have emerged as convenient scaffolds for building such molecular architectures . The fulleroprolines are readily prepared from 1,3-dipolar cycloaddition reactions of fullerene[60] and azomethine ylide.…”

“…The cis selectivity of these reactions can be explained by the reactive conformation B in which 1,2-allylic strain is minimized. An alternative 1,3-dipolar cyclization pathway is also possible (path b), and although related 1,3-dipolar cycloadditions are known, − they require high reaction temperatures (e.g., above 110 °C), likely to be required to generate the 1,3-dipole (e.g., C , Scheme ). If the former mechanism (path a) is operating, then this work would represent the first example of the Mannich reaction applied to a dihydrofullerene.…”