AUTHOR=Moglie Yanina , Buxaderas Eduardo , González Cabrera Agoney , Díaz Díaz David 

TITLE=Critical assessment of copper-alginate hydrogel beads as recyclable and heterogeneous catalysts for aqueous azide‒alkyne cycloaddition

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 13 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2025.1644592

DOI=10.3389/fchem.2025.1644592

ISSN=2296-2646

ABSTRACT=IntroductionWe report a reproducible and sustainable catalytic system based on copper ion-crosslinked alginate hydrogels for the synthesis of 1,2,3-triazoles via aqueous 1,3-dipolar cycloaddition at room temperature. The catalyst, derived from a biodegradable matrix, is prepared through a simple, energy-efficient method and operates under mild, eco-friendly conditions.MethodsCopper(II)-alginate hydrogels were prepared by ionic crosslinking. Sodium ascorbate was identified as a key reducing agent to generate catalytically active Cu(I) species. Different catalyst morphologies (hydrogel, aerogel, xerogel) were evaluated. Structural and morphological characterization was performed using FT-IR, SEM, EDX, TGA, and AAS.ResultsThe Cu(II)-alginate hydrogel (Cu(II)-AHG) exhibited the highest performance, delivering >95% yields within 3 h using only 2 mol% catalyst. The system tolerated a broad range of terminal alkynes and operated under predominantly heterogeneous conditions. The catalyst was recyclable up to four times with minimal loss in activity.DiscussionThe catalyst's efficiency is attributed to its mesoporous structure and chemical integrity. These findings support the potential of alginate-based materials as sustainable supports for transition metal catalysis and contribute to the advancement of green and circular synthetic methodologies.