mesochemistry synthesis in “intermediate” dimensions geoffrey a. ozin materials chemistry...
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MESOCHEMISTRY SYNTHESIS IN “INTERMEDIATE” DIMENSIONS
Geoffrey A. OzinMaterials Chemistry Research Group
University of Toronto
CHEM 1270H: TOPICS IN INORGANIC CHEMISTRY
Tel: 416 978 2082, Fax: 416 971 2011E-mail: [email protected]
Group web-page: www.chem.toronto.edu/staff/GAO/group.html
MESOCHEMISTRYSYNTHESIS IN “INTERMEDIATE” DIMENSIONS
• Purpose of the four lectures • Introduce key physicochemical design principles that
underpin the template directed synthesis of inorganic mesoporous materials
• Focus on synthetic control of structure, composition and form
• Appreciate how the properties of materials fashioned at this intermediate length scale can be orchestrated to create a purposeful function directed to a specific field of use.
Angew Chem 2006, 45, 3216
ZEOLITESCRYSTALLINE MICROPOROUS ALUMINOSILICATES
WITH PORES AND CHANNELS IN SIZE RANGE 0.3-1NM
ISI Citations
6386
ESCAPE FROM THE 1NM ZEOLITE PRISONESCAPE FROM THE 1NM ZEOLITE PRISON
ESCAPE FROM 10 Å PRISON
• Discovery by Mobil researchers that an assembly of surfactant molecules could function as a supramolecular template for organizing and polymerizing silicates
• Produced the first fully characterized examples of periodic hexagonal and cubic forms of mesoporous silica with pore diameters 2-10 nm
• Integration of surfactant and sol-gel chemistry
Air drying
SC CO2 drying
SOL-GEL CHEMISTRY
SOL-GEL CHEMISTRY
Air drying
SOL-GEL CHEMISTRY
Base catalyzed hydrolytic poly-condensation of silicon alkoxides to silica
SOL-GEL CHEMISTRY
Acid catalyzed hydrolytic poly-condensation of silicon alkoxides to silica
• HYDROLYSIS
• (RO)3SiOR + H3O+ (RO)3SiORH+ + H2O
• 2H2O + (RO)3SiORH+ (RO)3SiOH + ROH + H3O+
• CONDENSATION
• (HO)3SiOH + H3O+ (HO)3SiOH2+ + H2O
• (HO)3SiOH + (HO)3SiOH2+ (HO)3SiOSi(OH)3 + H3O+
SOL-GEL CHEMISTRY
Lyotropics
Kraft T
CO-ASSEMBLY
SURFACTANT AND SOL-GEL CHEMISTRY
MILESTONES IN MESOPOROUS MATERIALS
• Escape from the 1 nm prison (surfactant templated synthesis)• Diagnostics (structure, property)• Structure control (H, C, L, WH)• Template removal (calcination, ion exchange, solvent extraction,
photocalcination, ozonolysis, microwave, lizard fragmentation)• Pore size control (surfactant, block copolymer, swelling additive)• Templating mechanism (micelle, liquid crystal)• Smart mesostructure (pore size expansion, metamorphic channels)• Free-standing and supported film (mesoepitaxy, pore orientation)• Topological defects (nucleation, growth, origin of curved pores and form)• Morphogenesis of curved shapes (fiber, discoid, gyroid, spiral, sphere)
MILESTONES IN MESOPOROUS MATERIALS
• Nanomeso (nanoscale particles, nanocrystalline texture)• Biomimetics (biomineralization connection, hierarchy (nm-micron length
scales), complexity, organic-inorganic nanocomposites or hybrids)• Panoscopic materials (global self-assembly over “all” scales, surfactants,
block copolymers, opals)• Patterning (microcontact printing, micromolding in capillaries,
microtransfer printing, ink jet printing, photolithography)• Smart guests (SC, M, OM, C, P)• Smart channels (terminal and bridging organofunctionality)• Beyond silica (metals, oxides, sulfides, phosphates, coordination, polymers)• Mesoreplication (carbons, metal oxides)• Function and utility (fuel cell, solar cell, battery, laser, low-k, controlled
chemical and drug release, chemical/biosensor, electrochromic display, 1D Bragg photonic crystals, low refractive index optical cladding )
pH, pH, pH
EFFECT ON SELF-ASSEMBLY MECHANISM
Temperature
Ageing conditions
Precursor
Surfactant
pHCatalyst
Concentration
Template removal
HYDROLYSIS, CONDENSATION, SELF-ASSEMBLY
ESCAPE FROM 10 Å PRISON
HEXAGONAL MESOPOROUS SILICA
100
110
200
210
hexagonal
cubic
lamellar
Nitrogen gas adsorption isothermsSmall angle X-ray diffraction
Microporous < 2 nm
Mesoporous 2 -50 nm
Macroporous > 50 nm
IUPAC CONVENTION FOR PORE SIZES
CUBIC BICONTINUOUS MESOPOROUS SILICA
Equipotential minimal energy surface
Cubooctahedral morphology
TEM image cubic mesoporous structure
Mesocrystalline glass – crystalline mesoporosity - periodic arrangement of mesopores – glassy
walls - long range order at mesoscale – short
range order at microscale
WHAT CAN WE DO WITH PMS MATERIALS?HOST-GUEST INCLUSION WITH LARGE GUESTS !!!
ORGANICALLY FUNCTIONALIZED PMS - GRAFTING
CLEVER USE OF GRAFTING CONTROLLED RELEASE OF ACTIVE COMPOUNDS
NANO-PMS SMART DRUG
DELIVERY AFM 2007
ORGANICALLY FUNCTIONALIZED PMS - COCONDENSATION
PHOTOCHEMICAL SWITCHPORE SIZE CONTROL
Synthesis of films bearing photosensitive azobenzene units: 4-(3-triethoxysilyl-propylureido) azobenzene by the coupling of triethoxysilylpropylisocyanate with 4-phenylazoaniline used as organosilane precursor in co-condensation reaction
Periodic mesoporous silica with channel walls functionalized with terminally bound alkanethiol groups that chelate and sequester toxic heavy metals.
HEAVY METAL SPONGE
PERIODIC MESOPOROUSN ORGANOSILICAS PMOs
ZOO OF PMO PRECURSORS
Acc. Chem. Res. 2005, 38, 305-312.
MATERIALS CHEMISTRY SOLUTION TO THE LOW k CHALLENGE
Periodic mesoporous organosilicates PMOs with organic cross-links!!!
Hatton, B.D., Landskron, K., Hunks, W.J., Bennett, M.R., Shukaris, D., Perovic, D.D., Ozin, G.A., New Materials Chemistry Approaches for Low Dielectric Constant Materials as Interlayer Dielectrics, Materials Today 2006, 9, 22.
METAMORPHIC CHANNEL WALLS – PMO BRIDGE TERMINAL EXCHANGE
PMO WITH ORDERED BRIDGING AROMATIC GROUPS IN THE CHANNEL WALLS
MOLECULAR MODEL OF THE ORDERING OF BRIDGING BENZENE GROUPS IN THE CHANNEL WALL OF BENZENE PMO
MOLECULAR MODEL OF THE ORDERING OF BRIDGING THIOPHENE GROUPS IN THE CHANNEL WALL OF THIOPHENE PMO
BIFUNCTIONAL PMOs
The Idea – PMO to MIPMOThe Idea – PMO to MIPMO
IMPRINTIMPRINT IMPRINTIMPRINT
the ideathe ideaIMPRINTIMPRINT
imprintimprintremovalremoval
imprintimprintmoleculemolecule
collaborationcollaborationJean-Christophe Leroux (CRC in Drug Delivery)Jean-Christophe Leroux (CRC in Drug Delivery)
Nature NanotechnologyNature Nanotechnology. . 20072007, , 22, 679-684., 679-684.
MIPMOs
Schematic of the synthesis of molecular imprinted periodic mesoporous organosilica MIPMO materials
Drug-PMOsDrug-PMOscommercially available drugs commercially available drugs
↳↳silsesquioxane PMO precursorssilsesquioxane PMO precursors↳↳assemble MIPMO structuresassemble MIPMO structures
↳↳remove the drug imprintsremove the drug imprints↳↳detoxificationdetoxification
calcium channel blockerscalcium channel blockers
VerapamilVerapamilDiltiazemDiltiazem
Drug SilsesquioxanesDrug Silsesquioxanes
MESOPOROUS MATERIALSGRAND CHALLENGES – UTILITYUTILITY
• Large (bio)molecule catalysis• Polymerization nanoreactor• Membrane separation• Chromatography stationary phase• Fuel cell anode• Lithium battery electrolytes• Electrochromic display• Solar cell photo-cathode• (Bio)chemical sensor• Drug storage and release vehicle• Heavy metal sponge• Low dielectric constant film• Low refractive index optical cladding• Lithographic masks• Nanofluidic ion channels• Nanocomposites