Domino reaction for the controlled functionalization of sp2 carbon allotropes

摘要

Graphene and graphene related materials are a hot research topic in the materialudscience and are becoming a reality of increasing importance in many applicationudfields. Indeed, graphene has high charge-carrier mobilities, in-plane thermaludconductivity and very high elastic modulus. It is increasingly acknowledged thatudapplication of carbon nanomaterials such as graphene has to be assisted byudfunctionalization, which allows to tune electronic and solubility properties, phaseformingudand self-assembly behaviour.udIn this work, functionalization of graphene layers was performed with 2-(2,5-uddimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP) [3].udSP is a serinol derivative obtained from the neat reaction of 2-amino-1,3-udpropandiol with 2,5-hexanedione, with atom economy of about 85%, almostudquantitative yield and thus high atom efficiency, the only byproduct being water,udin the absence of solvent and catalyst [1, 2, 3]. Functionalization was obtained byudsimply mixing nanosized high surface area graphite with SP, giving eitherudmechanical or thermal energy. Very high functionalization yield was found, largerudthan 90% and even almost quantitative. Few layers graphene were isolated fromudstable water suspensions. Reaction of SP was applied to other sp2 carbonudallotropes, such as carbon nanotubes and carbon black. Many different applicationsudwere developed: from conductive inks to carbon papers and aerogels.udThe reaction occurring between SP and graphene layers was investigated. Adductsudof a high surface area nanosized graphite were prepared with a model molecule,ud1,2,5-trimethyl-1H-pyrrole (TMP). Pristine TMP, HSAG, products formed by theudreaction and HSAG-TMP adducts were studied by means of Fourier transformedudinfrared spectroscopy (FT-IR), 1H-NMR and thermogravimetric analysis. DFTudmodelling was carried out to predict IR spectra of HSAG-TMP reaction products andudadducts. Reaction pathway is presented. Domino reaction appears to occur:udcarbocatalyzed oxidation of the pyrrole compound lead to the formation ofudactivated double bond, able to give rise cycloaddition with the graphitic substrate.udSuch a facile and sustainable functionalization method allows the controlledudintroduction of functional groups on graphitic substrate without appreciablyudaltering their structure.