The reaction of [Ti(eta(5)-C(5)H(5))(2)Cl(2)] (1), with
3-mercaptopropyltrimethoxysilane or 3-mercaptopropyltriethoxysilane in the presence of
triethylamine leads to the formation of the thiolate complexes [Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OMe)(3)}(2)] (2) and [Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OEt)(3)}(2)] (3), respectively. Complexes 2 and 3 have been characterized by traditional methods, in addition, structural studies based on DFT calculations are reported. 1-3 have been grafted onto dehydroxylated
MCM-41 to give the novel materials MCM-41/[Ti(eta(5)-C(5)H(5))(2)Cl(2)] (S1), MCM-41/[Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OMe)(3)}(2)] (S2) and MCM-41/[Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OEt)(3)}(2)] (S3) which have been characterized by
powder X-ray diffraction, X-ray fluorescence,
nitrogen gas sorption, multinuclear MAS NMR spectroscopy, thermogravimetry, UV spectroscopy, SEM and TEM. Materials S2 and S3 present much higher values of Ti wt% (ca. 3%) than S1 (ca. 1%), indicating the higher functionalization rate induced by the substitution of the chloro
ligands by the thiolato
ligands in the starting
titanocene derivatives. The cytotoxicity of the non-functionalized
MCM-41 and S1-S3 toward human
cancer cell lines such as
adenocarcinoma HeLa, human
myelogenous leukemia K562 and human
malignant melanoma Fem-x has been studied. In addition the cytotoxicity of these materials on normal immunocompetent cells such as stimulated (PBMC+PHA) and non-stimulated (PBMC-PHA) peripheral blood mononuclear cells have been also studied. M(50) values (quantity of material needed to inhibit normal cell survival by 50%) of the studied surfaces show that non-functionalized
MCM-41 was not active against any of the studied cells, while the functionalized surfaces S1-S3 were active against all the tested human
cancer cells. The cytotoxic activity of surfaces S2 and S3 were very similar, however, S1 showed lower cytotoxic activity. This phenomenon indicates that the cytotoxicity of the
titanocene-functionalized materials strongly depends on the
titanium content.