Facile and sustainable functionalization of graphene layers with pyrrole compounds

Abstract

A facile and sustainable functionalization of graphene layers was performed with pyrrole compounds (PyC) prepared through the Paal-Knorr reaction of a primary amine with 2,5-hexanedione. A good number of primary amines were used: hexanamine, dodecanamine, octadecanamine, 2-aminoacetic acid, 2-amino-1,3-propanediol, 3-(triethoxysilyl)propan-1-amine. The reactions were characterized by good yield, up to 96 %, and indeed satisfactory atom efficiency, up to 80 %. The functionalization of graphene layers was obtained by mixing PyC with a high surface area graphite and heating at a temperature range from 130 °C to 150 °C for 3 h. The yield of functionalization reaction was larger than 60 % and also up to about 90 % for the pyrrole compounds from dodecanamine and 2-amino-1,3-propanediol, respectively. The cycloaddition reaction between the graphene layers and the pyrrole compound, oxidized in two position, is proposed as working hypothesis to account for such efficient functionalization. Raman spectroscopy revealed that the structure of the graphitic substrate remained substantially unaltered, after the reaction. Stable dispersions of HSAG adducts with different PyC were prepared in solvents with different solubility parameters and HRTEM analysis showed the presence of aggregates of only few layers of graphene. Qualitative results of dispersion tests were used to calculate the Hansen sphere for the HSAG adduct with the pyrrole compound based on dodecanamine so to provide a first estimate of its Hansen solubility parameters. This work paves the way for the facile and sustainable modification of the solubility parameters of graphene layers and for the predictive assessment of their compatibility with different environments.

Tuning the Solubility Parameters of Carbon Nanotubes by Means of Their Adducts with Janus Pyrrole Compounds

“…Moreover, the main goal was to identify a method able to promote the functionalization of most, if not all, the families of sp 2 carbon allotropes. Functionalization of graphene layers, carbon black and CNTs was achieved with pyrrole compounds (PyCs) obtained from the Paal–Knorr reaction of a primary amine with a diketone, 2,5-hexanedione (2,5-HD) [ 41 , 42 , 43 , 44 ]. The synthesis of the PyCs was performed in the absence of solvents and catalysts, by simply mixing and heating the reagents, with water as the only co-product.…”

A Graphene‐Based Supramolecular Nanoreactor for the Fast Synthesis of Imines in Water

“…Recently, the functionalization of graphene layers with pyrrole derivatives, such as 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP) has been shown as an effective, simple, and environmentally friendly method to improve their dispersibility in several solvents (e.g., water) preserving at the same time the graphene layers structure and properties. [20][21][22] Hence, a reasonable hypothesis is that pyrrolebearing polymeric surfactants could further improve the water dispersibility of functionalized graphene layers via supramolecular interactions. At the same time, the confined space inside the micelles could provide the lipophilic microenvironment as well as the active catalytic component necessary to carry out organic reactions between reagents slightly soluble in water.…”

“…[28] In particular, the HSAG/SP mass ratio was set equal to 4 and the functionalization yield was higher than 95%. [20][21][22] Subsequently, it was dispersed in THF with the block-copolymers PEG-EPq and precipitated in water (Figure 1b). The stability of the obtained adduct was estimated by tracking the change of its concentration during time via UV-spectrophotometry ( Figure S6, Supporting Information).…”

Novel nanobiocomposite hydrogels based on gelatin/chitosan and functionalized graphene

“…Functionalization of graphene layers was performed as reported in [5][6], by giving thermal energy to the GnP/serinol pyrrole adduct.…”