Encapsulation of mixed-valence copper oxide nanoparticles in aluminum carboxymethylcellulose composite microspheres: an efficient synergistic catalyst for boosting aldehyde–alkyne–amine coupling reactions

• Published in: Cellulose (London) Vol. 30; no. 14; pp. 8691 - 8708
• Main Authors: Xiao, Liang, Xu, Zhian, Fan, Xuetao, Li, Yiqun
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.09.2023; Springer Nature B.V
• Subjects: Aldehydes; Alkynes; Aluminum; Biocompatibility; Bioorganic Chemistry; Carbonyl groups; Carbonyls; Catalysis; Catalysts; Ceramics; Chemical reactions; Chemistry; Chemistry and Materials Science; Composites; Copper; Copper oxides; Couplings; Crosslinking; Dispersion; Encapsulation; Glass; Hydroxyl groups; Inductively coupled plasma; Infrared spectroscopy; Microspheres; Nanocomposites; Nanoparticles; Natural Materials; Organic Chemistry; Original Research; Oxidation; Photoelectrons; Physical Chemistry; Polymer Sciences; Spectrum analysis; Sustainable Development; Thermal stability; Thermogravimetric analysis; Valence; Mixed-valence; Nanocomposite microspheres; Synergistic catalysis; A; coupling reaction; Copper oxide
• ISSN: 0969-0239; 1572-882X
• DOI: 10.1007/s10570-023-05370-x

Carboxymethylcellulose (CMC) is an efficient alternative to synthetic polymeric analogues for utilization as a green stabilizer and reducing agent in the preparation of unique metal nanoparticles due to its attractive features such as multifunctional reactivity, excellent coordination ability, good shaping ability, low cost, green and renewability, biodegradability and biocompatibility. Herein, a practical and straightforward approach was developed for the fabrication of nanocomposite microspheres (Cu I/II ONPs@Al–CMC) composed of CuO nanoparticles with Cu(I/II) mixed-valence and CMC, in which the Cu(I) oxidation state dispersed on the surface of Cu I/II O NPs was in situ generated through partial reduction of hydroxyl groups of CMC without needing any additional reductant in the Al 3+ crosslinking process. Their composition and structure were systematically characterized by means of inductively coupled plasma, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG) techniques. The resulting Cu I/II ONPs@Al–CMC nanocomposite microspheres with CMC three-dimensional (3D) networks can serve as micro- or nano-reactors towards solvent-free aldehyde–alkyne–amine (A 3 ) coupling reactions under mild conditions. The obvious synergistic effect was observed in the control experiments for the A 3 -couplings model reaction. The control experiments showed that Cu I/II ONPs@Al–CMC nanocomposite microspheres exhibited markedly greater reactivity than native Cu II O NPs counterparts. Also, the introduction of Al 3+ could facilitate the activation of the carbonyl groups of aldehydes, thus improving the conversion of aldehydes into desired products. The hot filtration test and recycling experiments confirmed that the catalysis is heterogeneous nature, and the catalysts have thermal stability to be reused up to five successive cycles without losing their activity. Graphical abstract Mixed-valence copper oxide nanoparticles (Cu I/II O NPs) encapsulated by Al 3+ ions crosslinked carboxymethylcellulose (Al–CMC) have been fabricated successfully, which show markedly synergistic performance in aldehyde–alkyne–amine (A 3 ) coupling reactions.