CHEM 1270H: TOPICS IN
INORGANIC CHEMISTRY
MESOCHEMISTRY
SYNTHESIS IN “INTERMEDIATE” DIMENSIONS
Geoffrey A. Ozin
Materials Chemistry Research Group
University of Toronto
Tel: 416 978 2082, Fax: 416 971 2011
E-mail: gozin@chem.utoronto.ca
Group web-page: www.chem.toronto.edu/staff/GAO/group.html
MESOCHEMISTRY
SYNTHESIS 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
ZEOLITES
CRYSTALLINE MICROPOROUS ALUMINOSILICATES
WITH PORES AND CHANNELS IN SIZE RANGE 0.3-1NM
ESCAPE FROM THE 1NM ZEOLITE PRISON
ISI
Citations
6386
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
SOL-GEL CHEMISTRY
Air drying
SC CO2 drying
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
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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
Surfactant
Catalyst
Temperature
pH
Concentration
Precursor
Template removal
Ageing conditions
HYDROLYSIS, CONDENSATION, SELF-ASSEMBLY
ESCAPE FROM 10 Å PRISON
100
110
200
210
HEXAGONAL MESOPOROUS SILICA
Small angle X-ray diffraction
hexagonal
Nitrogen gas adsorption isotherms
Mesoporous 2 -50 nm
Macroporous > 50 nm
cubic
Microporous < 2 nm
lamellar
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 SWITCH
PORE SIZE CONTROL
Synthesis of films bearing photosensitive azobenzene units: 4-(3-triethoxysilylpropylureido) azobenzene by the coupling of triethoxysilylpropylisocyanate with 4phenylazoaniline used as organosilane precursor in co-condensation reaction
HEAVY METAL SPONGE
Periodic mesoporous silica with channel walls functionalized with terminally bound
alkanethiol groups that chelate and sequester toxic heavy metals.
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 MIPMO
IMPRINT
IMPRINT
IMPRINT
the idea
imprint
molecule
imprint
removal
collaboration
Jean-Christophe Leroux (CRC in Drug Delivery)
Nature Nanotechnology. 2007, 2, 679-684.
MIPMOs
Schematic of the synthesis of molecular
imprinted periodic mesoporous
organosilica MIPMO materials
Drug-PMOs
commercially available drugs
↳silsesquioxane PMO precursors
↳assemble MIPMO structures
↳remove the drug imprints
↳detoxification
calcium channel blockers
Diltiazem
Verapamil
Drug Silsesquioxanes
MESOPOROUS MATERIALS
GRAND CHALLENGES – UTILITY
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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