Shedding Light on the Chemistry and the Properties of Münchnone Functionalized Graphene.

Giulia Neri,Antonio Rescifina,Enza Fazio,Angela Scala,Placido Giuseppe Mineo,Antonia Nostro,Anna Piperno

doi:10.3390/nano11071629

Giulia Neri, Antonio Rescifina + Show 5 more

Open Access

https://doi.org/10.3390/nano11071629

Copy DOI

Abstract

Münchnones are mesoionic oxazolium 5-oxides with azomethine ylide characteristics that provide pyrrole derivatives by a 1,3-dipolar cycloaddition (1,3-DC) reaction with acetylenic dipolarophiles. Their reactivity was widely exploited for the synthesis of small molecules, but it was not yet investigated for the functionalization of graphene-based materials. Herein, we report our results on the preparation of münchnone functionalized graphene via cycloaddition reactions, followed by the spontaneous loss of carbon dioxide and its further chemical modification to silver/nisin nanocomposites to confer biological properties. A direct functionalization of graphite flakes into few-layers graphene decorated with pyrrole rings on the layer edge was achieved. The success of functionalization was confirmed by micro-Raman and X-ray photoelectron spectroscopies, scanning transmission electron microscopy, and thermogravimetric analysis. The 1,3-DC reactions of münchnone dipole with graphene have been investigated using density functional theory to model graphene. Finally, we explored the reactivity and the processability of münchnone functionalized graphene to produce enriched nano biomaterials endowed with antimicrobial properties.

Highlights

Published: 22 June 2021During the last decade, several groups have pioneered cycloaddition chemistry for the chemical modification of a wide array of carbon-based nanomaterials, including fullerene, carbon nanotubes, graphene, and carbon quantum dots, either in their pristine or functionalized forms [1,2,3,4,5]
Among the different types of cycloaddition reactions employed for the covalent functionalization of the graphene sp2 network, it is arguable that the 1,3-dipolar cycloaddition (1,3-DC) and, in particular, the cycloaddition of azomethine ylides, is the most heavily used
The cycloaddition reaction was performed in toluene or

Summary

Introduction

Published: 22 June 2021During the last decade, several groups have pioneered cycloaddition chemistry for the chemical modification of a wide array of carbon-based nanomaterials, including fullerene, carbon nanotubes, graphene, and carbon quantum dots, either in their pristine or functionalized forms [1,2,3,4,5]. Among the different types of cycloaddition reactions employed for the covalent functionalization of the graphene sp network, it is arguable that the 1,3-dipolar cycloaddition (1,3-DC) and, in particular, the cycloaddition of azomethine ylides, is the most heavily used. The 1,3-DC of azomethine ylides on the graphene layer was exploited to introduce fused pyrrolidine rings on both the basal plane and the edge of the graphene sheet (Figure 1, pathway a). The dipole azomethine ylides were obtained by the condensation of an amino acid and an aldehyde under moderate–high temperature (above 80 ◦ C) [13]. Computational studies have predicted, in some cases, difficulties in the reaction progress on graphene for dipoles different from azomethine ylide, several successful examples of 1,3-DC reactions of different dipoles have been currently reported in the literature.

Methods

Results

Conclusion