Examinando por Autor "Cruz, Paula"

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Heterogeneous oxidative desulfurization catalysed by titanium grafted mesoporous silica nanoparticles containing tethered hydrophobic ionic liquid: A dual activation mechanism
(Elsevier, 2019-10-25) Cruz, Paula; Granados, Elizabeth-Adriana; Fajardo, Mariano; del Hierro, Isabel; Pérez, Yolanda
In this study, heterogeneous catalysts containing ionic liquid and/or titanium have been prepared and used for oxidative desulfurization. For the synthesis of hybrid mesoporous silica nanoparticles (ILBF4-MSN), a grafting method has been employed with the ionic liquid 1-octyl-3-(3-(triethoxysilyl)propyl)-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborate (ILBF4) which contains a long alkyl chain. Titanium hybrid mesoporous silica nanoparticles (ILBF4-x%TiCp2-MSN) and mesoporous silica nanoparticles containing titanium (TiCp2-MSN) have also been prepared using titanocene dichloride. The catalyst containing ionic liquid and titanium, ILBF4-3%TiCp2-MSN exhibited the highest desulfurization efficiency (99.1%) in model oil with high concentration of DBT and using H2O2 as oxidant. In addition, the effect of immobilization of the ionic liquid on titanium materials has been investigated by solid-state 13C, 47/49Ti and 19F NMR spectroscopy and solid state electrochemical techniques. The titanium species and ionic liquid play an important role in the oxidative desulfurization reaction since they might activate synergistically sulfur derivatives and enhance the process
Mesoporous SBA-15 Modified with Titanocene Complexes and Ionic liquids: Interactions with DNA and other Molecules of Biological Interest Studied by Solid State Electrochemical Techniques.
(Royal Society of Chemistry, 2018) del Hierro, Isabel; Gómez-Ruiz, Santiago; Pérez, Yolanda; Cruz, Paula; Prashar, Sanjiv; Fajardo, Mariano
The immobilization of two titanocene complexes on SBA-15 has been accomplished following post-synthetic procedures. The ionic liquid, 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride, has also been incorporated into the titanium containing materials to determine its influence on the interaction with molecules of biological interest. Cyclic voltammetry has been used to study the influence of the ionic liquid on the mechanism of reduction of titanocene derivatives. The interaction of titanocene and titanocene/ ionic liquid-containing mesoporous silica SBA-15 materials, with molecules of biological interest associated with important processes of metallodrug action against cancer cells, has been studied. Thus, we have carried out hydrolysis experiments on the materials functionalized with titanocene derivatives in physiological media to determine their stability and the interaction with serum/transport proteins such as transferrin and BSA and with target molecules such as guanosine, single-stranded DNA and double-stranded DNA by means of solid state voltammetry techniques. A qualitative analysis of the data based on peak current and reduction potential value changes of the couple Ti(IV)/Ti(III) in the presence of biomolecules at physiological pH, has revealed that grafted titanocene complexes show higher affinity for serum/transport proteins than for nucleic acids, indicating that the transport steps to the cells may be easier than the subsequent attack on DNA.
Modulation of the mechanism of apoptosis in cancer cell lines by treatment with silica-based nanostructured materials functionalized with different metallodrugs
(Royal Society of Chemistry, 2018-08-10) Díaz-García, Diana; Cenariu, Diana; Pérez, Yolanda; Cruz, Paula; del Hierro, Isabel; Prashar, Sanjiv; Fischer-Fodor, Eva; Gómez-Ruiz, Santiago
The mesoporous silica-based material SBA-15 (Santa Barbara Amorphous-15) has been modified with the aminodiol ligand 3-[bis(2-hydroxyethyl)amino]propyltriethoxysilane (PADOH) to give the corresponding material SBA-PADOH. Subsequent functionalization with a diorganotin(IV) compound, SnPh2Cl2 (1), and with two titanocene derivatives, TiCp2Cl2 ([Ti(η5-C5H5)2Cl2] (2)) and TiCpCpPhNfCl2 ([Ti(η5-C5H5) (η5-C5H4CHPhNf)Cl2] (3) (Ph = C6H5; Nf = C10H7)), gave the materials SBA-PADO-SnPh2 (M1), SBA-PADO-TiCp2 (M2) and SBA-PADO-TiCpCp* (M3), respectively. SBA-PADOH and M1–M3 have been characterized by various techniques such as FT-IR, XRD, XRF, solid-state NMR, nitrogen adsorption– desorption isotherms, electrochemical methods, SEM and TEM, observing that the functionalization has mainly taken place inside the pores of the corresponding porous system. In addition, mechanistic aspects of the apoptosis triggered by the synthesized materials have been studied in vitro in tumour cell lines derived from three distinct types of cancer in order to elucidate their growth inhibition and interference with the expression of tumour necrosis factor alfa (TNF-α) and the first apoptosis signal receptor (Fas or tumour necrosis factor receptor 6). It was observed that the antiproliferative and proapoptotic capacity of the materials depends on their functionalization with the different cytotoxic prodrugs (organotin or titanocene derivatives). The study shows that M1–M3 influence the metabolic activity of the tumour cells and modulate the apoptotic pathways by different mechanisms, according to the active compound inside the material.
Prolinate-based heterogeneous catalyst for Knoevenagel condensation reaction: insights into mechanism reaction using solid-state electrochemical studies
(Elsevier, 2022) Ortiz-Bustos, Josefa; Cruz, Paula; Pérez, Yolanda; Hierro, Isabel del
The carbon-carbon bond formation is essential to producing relevant organic compounds that exhibit pharmacological and biological properties. In this regard, Knoevenagel and multicondensation reactions have been employed to test the acid-base cooperativity of functionalized mesoporous silica nanoparticles with L-prolinate based groups (Prol-MSN) in comparison with choline hydroxide fragments (Chol-MSN). Thus, Prol-MSN material has shown to be a promising heterogeneous organocatalyst for condensation reactions. The use of electrochemical sensor techniques allowed through cyclic and differential pulse voltammetry studies a better understanding of the catalytic mechanism of Knoevenagel reaction for the Prol-MSN material, including the role of silanol surface groups and protic solvents.