Synthesis, sorption and metallochromy properties of organosilicon derivatives of 1-acetylguanidine

Increased interest in carbofunctional organosilicon monomers (silanes) and polymers (silsesquioxanes) is associated with the fact that these compounds are promising reagents and building blocks, materials for micro-electronics, agriculture and medicine, complexones, catalysts, and efficient sorbents. Thus, functional polysilsesquioxanes surpass mineral and organic sorbents in sorption properties. Moreover, they have the highest chemical and thermal stability. Along with sorption activity carbofunctional organosilicon compounds of both monomeric and polymeric structures can possess metallochromic properties. All this paves the way for the large-scale development of analytical systems for the creation of new complex test methods for the determination, concentration and separation of metals from solutions. In the present study the functional monomer N-[3-(triethoxysilyl)propyl]acetylguanidine 1 was synthesized by the condensation reaction of 1-acetylguanidine and 3-triethoxysilyl-propylamine. Poly-N-[3-silsesquioxanyl) propyl]acetylguanidine 2 was obtained by hydrolytic polycondensation of compound 1. The composition and structure of compounds 1 and 2 were confirmed by IR and 1H NMR spectroscopy, as well as by elemental analysis. Polymer 2 was studied as a sorbent for ions of heavy metals, such as Hg (II), and noble metals Ag (I), Au (III), Rh (II), Pd (II), Pt (IV) from solutions of their salts in hydrochloric or nitric acid. For polymer 2, the values of static sorption capacities have been calculated. The latter depend on the nature of the metal and have values from 78 mg/g (for platinum) to 366 mg/g for rhodium. The graphs of the degree of metal extraction depending on the sorption time and acid concentration have been plotted. A sorption mechanism is proposed, which is realized due to the chelate interaction of the metal cation (M+) with the amide groups of compounds 1 and 2. The interaction of monomer 1, in the form of indicator paper, and polymer 2, in the powder form, with salts of the studied metals is accompanied by intense specific coloration (metallochromy). Color tables of the samples after their contact with the Ag (I), Au (III), Pd (II), Pt (IV), Rh (III), Hg (II) salts are given.