Chitosan is a natural polymer derived from chitin through the deacetylation process. It has emerged as a key ingredient in sustainable wastewater treatment, due to its biodegradability, non-toxicity, and low cost. This biopolymer possesses abundant functional groups, such as -NH₂ and -OH, that efficiently interact with pollutants. This review offers a comprehensive evaluation of pollutant separation techniques involving chitosan-based materials, including adsorption, membrane filtration, flocculation, and photocatalysis. It further examines the underlying adsorption mechanisms, emphasizing how pollutants interact with chitosan and its derivatives at the molecular level. Special focus is given to various modifications of chitosan, alongside a comparative assessment of different chitosan-based adsorbents (hydrogels, nanoparticles, nanocomposites, microspheres, nanofibers, etc.), highlighting their performance in removing heavy metals, dyes, and emerging organic pollutants. The reviewed performance of these polymeric materials from 2015–2025 not only gives an insight about the recent advancement but also points the need for the design of high-performing chitosan-based adsorbents with applications in real water matrices.

Chitosan (CS) is a biodegradable and biocompatible polysaccharide, obtained by the deacetylation of chitin. It has gained significant attention as a versatile material for biomedical applications due to its mucoadhesive properties, ease of chemical modification and intrinsic pharmacological activities. This review synthesizes two decades (2005–2025) of literature, focusing on chemical modifications of chitosan for pharmacological purposes and their therapeutic implications in non-communicable diseases (NCDs) and wound healing. Evidence highlights the roles of chitosan-based materials in anticancer, anti-inflammatory, antidiabetic, antihypertensive, and neuroprotective activities, alongside their integration in advanced wound healing strategies. Clinical trials have demonstrated the translational potential of chitosan-based materials. In general, chitosan-based materials exhibit promising dual functions as bioactive agents and drug carriers, necessitating additional investigation in clinical and regulatory frameworks to accelerate therapeutic adoption. In contrast to other studies, this study offers a mechanistic and integrative viewpoint that links chitosan’s chemical modification techniques with their pharmacological effects and clinical translation potential, providing novel perspectives on structure–activity correlations and therapeutic design.

Rhodium(I) carbonyl complexes of the form [Rh^I(N,O-ScBa)(CO)(PR₃)] (R = Ph or Cy), with N,O-ScBaH a mono anionic bidentate Schiff base ligand, 2-(cyclopentyliminomethyl)-5-methylphenol (5-Me-Sal-CyPH), and bearing different phosphine ligands on Rh(I), are reported. N,O-ScBaH was also varied to be 2-(cyclohexyliminomethyl)phenol (Sal-CyH) and 2-(isopropyliminomethyl)-5-methylphenol (5-Me-Sal-IPropH) to investigate the effects of different substituent groups on the periphery of the Schiff bases on metal center reactivity. The structural characterization of two sample complexes is described and an extensive spectroscopic kinetic-mechanistic study utilizing UV/vis, infrared and ³¹P NMR spectroscopy of the iodomethane oxidative addition is presented. Iodomethane oxidative addition led exclusively to Rh^III-alkyl complexes as final products, while an associative activation is inferred from the large negative ΔS^≠ value. The relative reactivity of the [Rh^I(N,O-ScBa)(CO)(PR₃)] complexes when stepwise varying PR₃ (PPh₃, PPh₂Cy, PPhCy₂ and PCy₃) as tertiary phosphine ligands follow a surprising similar reactivity relationship as observed for a range of isostructural [Rh^I(X,O-Bid)(CO)(PR₃)] complexes, with X = O, N or S in corresponding oxinate, acetylacetonate and thioureate mono anionic X,O-Bid ligands. This suggests systematic and responsive dynamic behavior of the PR₃ ligands, independent of the bidentate chelate at the Rh(I) metal center. A variation of more than two orders-of-magnitude in reactivity was observed. Graphical Abstract