Exploring the Chelating Potential of an Easily Synthesized Schiff Base for Copper Sensing
Jesús Sanmartín-Matalobos,
Ana García-Deibe,
Morteza Zarepour-Jevinani,
Manuel Aboal-Somoza,
Pilar Bermejo-Barrera,
Matilde Fondo
Affiliations
Jesús Sanmartín-Matalobos
Coordination and Supramolecular Chemistry Group (Suprametal), Department of Inorganic Chemistry, Faculty of Chemistry, Universidade de Santiago de Compostela, Avenida das Ciencias s/n, 15782 Santiago de Compostela, Spain
Ana García-Deibe
Coordination and Supramolecular Chemistry Group (Suprametal), Department of Inorganic Chemistry, Faculty of Chemistry, Universidade de Santiago de Compostela, Avenida das Ciencias s/n, 15782 Santiago de Compostela, Spain
Morteza Zarepour-Jevinani
Coordination and Supramolecular Chemistry Group (Suprametal), Department of Inorganic Chemistry, Faculty of Chemistry, Universidade de Santiago de Compostela, Avenida das Ciencias s/n, 15782 Santiago de Compostela, Spain
Manuel Aboal-Somoza
Trace Element, Speciation and Spectroscopy Group (GETEE) - Health Research Institute of Santiago de Compostela (IDIS), Strategic Grouping in Materials AEMAT, Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, Universidade de Santiago de Compostela, Avenida das Ciencias, s/n, 15782 Santiago de Compostela, Spain
Pilar Bermejo-Barrera
Trace Element, Speciation and Spectroscopy Group (GETEE) - Health Research Institute of Santiago de Compostela (IDIS), Strategic Grouping in Materials AEMAT, Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, Universidade de Santiago de Compostela, Avenida das Ciencias, s/n, 15782 Santiago de Compostela, Spain
Matilde Fondo
Coordination and Supramolecular Chemistry Group (Suprametal), Department of Inorganic Chemistry, Faculty of Chemistry, Universidade de Santiago de Compostela, Avenida das Ciencias s/n, 15782 Santiago de Compostela, Spain
The present study deals with the investigation of Cu2+, Ni2+ and Pd2+ chelating potential of the Schiff base, (E)-N-(2-((2-hydroxybenzylidene)amino)benzyl)-4-methylbenzenesulfonamide (H2SB). Crystal structures of Ni(HSB)2, Pd(HSB)2 and Cu(HSB)2 have been elucidated from single crystal X-ray diffraction data. NMR spectroscopy showed the presence of two conformers of Pd(HSB)2 in solution, both with an E configuration of the ligand. The determination of binding constants by fluorescence quenching showed that affinity of H2SB to Cu2+ in solution is higher than for Ni2+ and Pd2+. Since there is a high demand for selective, sensitive, rapid and simple methods to detect copper in aqueous samples (both as Cu2+ ions and as CuO NPs), we have explored H2SB as an optical chemosensor. H2SB interacts with increasing concentrations of Cu2+ ions, giving rise to a linear increase in the absorbance of a band centered at about 392 nm. H2SB displays a high selectivity toward Cu2+, even in the presence of the most common metal ions in water (Ca2+, Mg2+, Na+, K+, Al3+ and Fe3+), and some heavy transition metal ions such as the soft acids Pd2+ and Cd2+. H2SB also interacts with increasing concentrations of CuO NPs, which gives rise to a linear decrease in its fluorescence intensity (λem = 500 nm, λex = 390 nm). Quenching has occurred as a result of the formation of a non-fluorescent ground-state surface complex H2SB−CuO NPs. The limits of detection and quantification of CuO NPs were 9.8 mg/L and 32.6 mg/L, respectively. The presence of TiO2, Ag and Au NPs does not interfere with the determination of CuO NPs.
