Exploring various ligand classes for the efficient sequestration of stannous cations in the environment.

Abstract Metal pollution, coming from both natural and anthropogenic sources, has become one of the most serious environmental problems. Various strategies have been tested with the aim of removing heavy metals from environment. In this contribution, containing a robust experimental work together with a critical literature analysis, the sequestering ability of a variety of ligands towards Sn2+ cation will be evaluated in the conditions of several natural fluids, i.e. sea water, fresh water, human blood plasma, urine and saliva. 13 structural and 11 thermodynamic descriptors will be selected for a total of thirty-eight molecules belonging to different classes (carboxylic acids, amines, amino acids, phosphonates, polyelectrolytes etc. …). For the filling of those missing data relative to the 11 thermodynamic descriptors, different strategies will be adopted, including simple correlations and Nipals algorithm. The evaluation of the sequestering ability of the ligands is assessed in terms of estimation of pL 0.5 (total concentration of ligand required to bind the 50% of metal in solution), an empirical parameter that takes into account all the side reactions in solutions and does not depend on the speciation scheme. Partial least square calculations were performed to model the pL 0.5 and to determine its correlation with the abovementioned descriptors. The possibility to design and build up new tailor-made molecules capable of effectively sequester Sn2+ in various conditions is crucial for practical applications in biosphere, hydrosphere and lithosphere. Graphical abstract Unlabelled Image Highlights • The data published for the interaction of Sn2+ with 38 molecules are surveyed. • A chemometric approach for the estimation of unknown thermodynamic data is given. • Amino groups and thiols are important for the efficient sequestration of Sn2+. • The work is useful for applications in biosphere, hydrosphere and lithosphere. • PLS coefficients help in design new ligands for the efficient sequestration of Sn2+. [ABSTRACT FROM AUTHOR]