The formation of metal (M=Co(II), NI(II), and Cu(II)) complexes by aminosilanes immobilized within mesoporous molecular sieves

The immobilization of APTMS (3-(2-aminoethylamino)propyltrimethoxysilane) a nd AAPTMS(3-(2-(2-aminoethyl)aminoethylamino)propyltrimethoxysilane) on the surface of high quality mesoporous molecular sieves MCM-41 and MCM-48 have been confirmed by F.T.-IR spectroscopy, Raman spectroscopy, Si-29 solid st ate NMR, and a surface polarity measurement using Reichardt's dye. The form ation of metal (Co(II), Ni(II), and Cu(II)) complexes by immobilized aminos ilanes have been investigated by photoacoustic spectroscopy(PAS). The assig nment of UV-Vis. PAS bands makes it possible to identify the structure of m etal complexes within mesoporous molecular sieves. Co(II) ion may be coordi nated mainly in a tetrahedral symmetry by two APTMS onto MCM-41, and in an octahedral one by two AAPTMS. Both NI(II) and Cu(II) coordinated by aminosi lanes within MCM-41 form possibly the octahedral complexes such as [Ni(APTM S)(2)(H2O)(2)](2+), [Ni(AAPTMS)(2)](2+), [Cu(APTMS)(2)(H2O)(2)](2+), and [C u(AAPTMS)(H2O)(3)](2+), respectively. The PAS band shapes of complexes onto MCM-48 are similar to those of corresponding MCM-41 with the variation of PAS intensity, Most of metal ion(II) within MCM-41 and MCM-48 are coordinat ed by aminosilanes without the impregnation on the surface.