Kenneth J. Balkus

Oxidations catalyzed by zeolite ship-in-a-bottle complexes

Abstract A brief review of oxidation reactions catalyzed by zeolite ship-in-a-bottle complexes is presented. The encapsulation of V(O)SALEN (SALEN= bis(salicylaldehyde)ethylenediimine) in zeolite NaY via the flexible ligand method is described. V(O)SALEN-NaY was found to be an effective catalyst for the room temperature epoxidation of cyclohexene using t -butylhydroperoxide ( t -BOOH) as the oxidant. The preparation of zeolite NaX in the presence of RuF 16 Pc (F 16 Pc= perfluorophthalocyanine) also results in occluded metal complex. RuF 16 Pc-NaX has been shown to be an active catalyst for the room temperature oxidation of alkanes using t -BOOH as the oxidant.

Photoluminescent properties of MCM-41 molecular sieves

Abstract The photoluminescence of as-synthesized and calcined siliceous as well as aluminosilicate MCM-41 molecular sieves was examined at 350, 300, 250 and 200 nm. The observation of high energy emission bands ( hv > 2.5 eV) from the as-synthesized siliceous MCM-41 suggests the presence of oxygen related defect sites similar to those found in amorphous silica. Examination of corresponding excitation spectra does not rule out this possibility. Upon calcination, the intensity of the photoluminescent signal decreases dramatically. Little decrease in photoluminescence intensity is observed for the calcined aluminosilicate MCM-41 molecular sieve. The intensity of the emission of the aluminosilicate MCM-41 appears to be correlated to the presence of framework aluminum (i.e. large amounts of aluminum incorporated into the framework generate a large photoluminescence signal).

Electrochemistry of zeolite-encapsulated complexes: Part 3. Characterization of iron and manganese SALEN entrapped in Y faujasite type zeolite☆

Abstract [Mn III SALEN] + and [Fe III SALEN] + complexes have been entrapped in the supercages of zeolite Y. The redox properties of these zeolite-encapsulated complexes are investigated by cyclic voltammetry in acetonitrile and dimethyl sulphoxide solutions. The results show the existence of two kinds of entrapped [Fe III SALEN] + forms within the zeolite. Their existence is related to the mechanism of their preparation and depends on the electrolytic media. The electroactivity of encapsulated Mn-SALEN towards the biomimetic activation of molecular oxygen is discussed.

The preparation and characterization of Rh(III) SALEN complexes encapsulated in zeolites X and Y

Abstract Rh(III) complexes of N,N′ -bis (salicylaldehyde) ethylenediimine or SALEN have been encapsulated in the supercages of zeolites X and Y. These ship-in-the-bottle complexes as well as the rhodium(III)-exchanged zeolites are characterized by elemental analysis, u.v.-VIS, i.r., and X-ray photoelectron spectroscopy. A detailed study of the synthesis variables that influence the encapsulation process in the case of RhSALEN-NaY is presented.

Oriented films of mesoporous MCM-41 macroporous tubules via pulsed laser deposition

All-silica mesoporous MCM-41 molecular sieve films consisting of oriented macroporous tubules have been prepared utilizing pulsed laser deposition and a series of post-hydrothermal treatments. The molecular sieve films were deposited on polished silicon wafer substrates with the pores oriented perpendicular to the surface of the substrate.

Electrochemistry of chemically modified zeolites: Discussion and new trends

Abstract Synthetic faujasite Y zeolite has been modified chemically by fixing metal complexes within the pore system. The electrochemical behavior of ferricenium, fixed by ion exchange, and Fe(III)Salen + , Mn(III)Salen + , Co(II) and Fe(II) + hexadecafluorophthalocyanines physically encapsulated into the zeolite supercages has been investigated by cyclic voltammetry. The results show a clear difference between the electrochemistry of the zeolite-exchanged cationic complexes (i.e. ferricenium) and the zeolite-encapsulated complexes (i.e. Fe(III)Salen + ) resulting from their method of fixation. Thus the use of graphite pressed powder composite electrodes allows electrochemical analysis of the intrazeolite complexes. The electron transfer and charge compensation processes are discussed.

Preparation and characterization of zeolite X membranes via pulsed-laser deposition

Zeolite X films have been prepared utilizing pulsed-laser deposition onto TiN-coated silicon wafers and porous stainless steel disks. Laser ablation of zeolite X onto TiN-coated silicon wafers followed by a hydrothermal treatment resulted in partially oriented, crystalline NaX membranes. Hydrothermal treatment of laser-deposited films on stainless steel mesh produced a coated wire mesh with a ∼3-μm-thick zeolite X film. Hydrothermal treatment of the laser-deposited films on 0.5 μm diameter pore stainless steel frits resulted in a densely packed non-continuous film.

Cyclohexane oxidation catalyzed by zeolite encapsulatedruthenium perfluorophthalocyanines

Summary Hexadecafluorophthalocyanine (F 16 Pc) complexes of Ru(II) which were prepared bythe reaction of tetrafluorophthalonitrile and Ru 3 (CO) 12 , have been encapsulated in the supercages of zeolites NaX. The X type zeolites were synthesized around the RuF 16 Pc complexes. The zeolites modified with the metal complexes were characterized by XRD, FT-IR and UV-Vis spectroscopy as well as elemental analysis. The oxidation of cyclohexane using t-butylhydroperoxide was catalyzed by the intrazeolite RuF 16 Pc complexes. Complete conversion to cyclohexanone and cyclohexanol was achieved with nearly 3000 turnovers per day. These ship-in-a-bottle RuF 16 Pc complexes show no signs of deactivation in contrast to the iron analogs, regardless of how the peroxide is administered during the reaction.

Synthesis and Characterization of Organosilane Functionalized DAM-1 Mesoporous Silica

Organic functionalized mesoporous DAM-1 containing amine, cyclopentadienyl, phenyl, and thiol groups was synthesized under acidic conditions by the direct co-condensation of TEOS or TMOS with respective organosilanes using vitamin E TPGS as the structure directing agent. Well-ordered functionalized mesoporous DAM-1 containing both amine and thiol were successfully prepared yielding ∼1 mmol g−1 of sulfur and 0.73 mmol g−1 of nitrogen when started with ∼0.088 molar ratio of APTMS/TMOS and MPTMS/TMOS. The incorporation of both amine and thiol was confirmed by forming a fluorescent isoindole from o-phthalaldehyde. The presence of cyclopentadiene in the mesopore was demonstrated by synthesizing a supported half sandwich compound CpMn(CO)3-DAM-1 from Mn2(CO)10 via photolysis. The samples were characterized by fluorescence and vibrational spectroscopy as well as x-ray diffraction and surface area measurements.

Nitric oxide- and cisplatin-releasing silica nanoparticles for use against non-small cell lung cancer

Nitric oxide (NO) and cisplatin releasing wrinkle-structured amine-modified mesoporous silica (AMS) nanoparticles have been developed for the treatment of non-small cell lung cancer (NSCLC). The AMS and NO- and cisplatin-loaded AMS materials were characterized using TEM, BET surface area, FTIR and ICP-MS, and tested in cell culture. The results show that for NSCLC cell lines (i.e., H596 and A549), the toxicity of NO- and cisplatin-loaded silica nanoparticles (NO-Si-DETA-cisplatin-AMS) is significantly higher than that of silica nanoparticles loaded with only cisplatin (Si-DETA-cisplatin-AMS). In contrast, the toxicity of NO-Si-DETA-cisplatin-AMS toward normal lung cell lines is not significantly different from that of Si-DETA-cisplatin-AMS (normal lung fibroblast cells WI-38) or is even lower than that of Si-DETA-cisplatin-AMS (normal lung epithelial cells BEAS-2B). The NO-induced sensitization of tumor cell death demonstrates that NO is a promising enhancer of platinum-based lung cancer therapy.