Catechol‐Functionalized Carbon Nanotubes as Support for Pd Nanoparticles: a Recyclable System for the Heck Reaction

Abstract

Carbon nanotubes have been covalently functionalized with catechol moieties through the formation of the corresponding aryl radicals obtained by reacting 4‐aminocatechol with isoamyl nitrite. The functionalized multiwalled carbon nanotubes have been in turn used to immobilize Pd(II) ions on its surface forming catechol‐Pd complexes, which were reduced to Pd nanoparticles (NPs). The so‐obtained hybrid material has been characterized by means of thermogravimetric analysis coupled with differential scanning calorimetry (TGA‐DSC), X‐ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). This latter technique allowed to estimate the nanoparticle size (5.7±2.8 nm) whereas a palladium loading of 20.3 wt % has been found by inductively coupled plasma optical emission spectroscopy (ICP‐OES). The carbon nanotube‐catechol‐Pd hybrid was used as catalyst in two C−C coupling reactions, namely Suzuki and Heck reactions, resulting recyclable for at least 9 times in the latter process. During the reuse Pd nanoparticles increase their dimension to 19.3±11.7 nm.

Anion–π catalysis on carbon allotropes

“…Numerous reports on catalysis with carbon nanotubes have appeared [45,46,[82][83][84][85][86][87][88][89][90][91][92][93][94]. They serve as catch-and-release scaffolds in different variations, and, less frequently, as (photo)redox partners.…”

In Situ Electro-organic Synthesis and Functionalization of Catechol Derivative on Carbon Black and Its Interference-free Voltammetric pH Sensor Application ∗

“…Catechol (CA; 1,2-dihydroxy benzene, E o ' ∼0.2 V vs Ag/AgCl in pH 7) is a redox-active bio-organic molecule that exists as a messenger in the neural network system. Development of CA functionalized carbon network matrix is a cutting edge research in the interdisciplinary areas such as bioinspired muscle systems, 1 molecular recognition units, 2 biocompatible organic coating, 3 organic photovoltaic devices, 4 pseudocapacitor-based energy materials, 5 adhesives and biodegradable membranes, 6 organic synthesis-Heck reactions, 7 cancer prodrugs, 8 3D-bioprinting, 9 skin wound healing application, 10 dye-sensitized solar energy conversion reaction (as a cofactor), 11 electron-transfer relay in the bio-electrocatalytic reaction, 12,13 electrocatalytic unit for cysteine, 14 hydrazine, 15 hexavalent chromium, 16 sulfide 17 etc. Indeed, turning the redox property and preparation of stable CA-based functionalized systems, especially CA-confined carbon electrodes, are challenging research interest.…”