Dramatic femtosecond nonlinear absorption at a strongly coupled porphyrin-graphene nanoconjugate

Edge-functionalization of graphene is emerging as a powerful chemical method for the construction ofπ-delocalized highlyplanar graphene nanoconjugates that are not accessible through surface-supported syntheses.Herein,a graphene-porphyrin nanoconjugate via a robust pyrazine(pz)linkage has been obtained by condensing 2,3-diamino-5,10,15,20-tetraphenylporphyrin(DA-TPP)with ortho-quinone(o-quinone)moieties at edge sites of graphene oxide(GO).The as-prepared GO-pz-TPP exhibits an intense absorption extending from 375 to 900 nm and a high quenching yield(98%)of fluorescence,indicating a strong electronic coupling effect between GO and TPP units.GO-pz-TPP displays strong nonlinear optical(NLO)absorption and giant NLO coefficients with 800 and 1,030 nm fs laser,in sharp contrast to traditional graphene-porphyrin nanohybrids only NLO-active towards ns laser.Such a dramatic NLO performance towards femtosecond pulsed laser has not been achieved in any carbonchromophores nanohybridized materials to date.This work validates theπ-extended edge-functionalization strategy as a means to tune the NLO properties of graphene,thereby providing a new paradigm for the assembly of versatile optoelectronic materials.