Mesoporous materials

1. MESOCHEMISTRY
SYNTHESIS IN “INTERMEDIATE” DIMENSIONS
Geoffrey A. Ozin
Materials Chemistry Research Group
University of Toronto
CHEM 1270H: TOPICS IN
INORGANIC CHEMISTRY
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

3. 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.

4. Angew Chem 2006, 45, 3216

5. ZEOLITES
CRYSTALLINE MICROPOROUS ALUMINOSILICATES
WITH PORES AND CHANNELS IN SIZE RANGE 0.3-1NM

6. ISI
Citations
6386
ESCAPE FROM THE 1NM ZEOLITE PRISONESCAPE FROM THE 1NM ZEOLITE PRISON

7. 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

8. Air drying
SC CO2 drying
SOL-GEL CHEMISTRY

9. SOL-GEL CHEMISTRY
Air drying

10. SOL-GEL CHEMISTRY
Base catalyzed hydrolytic poly-condensation of silicon alkoxides to silica

11. 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+
→ → →

12. SOL-GEL CHEMISTRY

13. Lyotropics
Kraft T

14. CO-ASSEMBLY
SURFACTANT AND SOL-GEL CHEMISTRY

16. 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)

17. 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 )

20. pH, pH, pH
EFFECT ON SELF-
ASSEMBLY MECHANISM
Temperature
Ageing conditions
Precursor
Surfactant
pH
Catalyst
Concentration
Template removal

21. HYDROLYSIS, CONDENSATION, SELF-ASSEMBLY

22. ESCAPE FROM 10 Å PRISON
HEXAGONAL MESOPOROUS SILICA
100
110
200
210

23. 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

24. 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

25. WHAT CAN WE DO WITH PMS MATERIALS?
HOST-GUEST INCLUSION WITH LARGE GUESTS !!!

26. ORGANICALLY FUNCTIONALIZED
PMS - GRAFTING

27. CLEVER USE OF GRAFTING CONTROLLED
RELEASE OF ACTIVE COMPOUNDS

28. NANO-PMS
SMART DRUG
DELIVERY
AFM 2007

29. ORGANICALLY FUNCTIONALIZED
PMS - COCONDENSATION

30. PHOTOCHEMICAL SWITCH
PORE 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

31. Periodic mesoporous silica with channel walls functionalized with terminally bound
alkanethiol groups that chelate and sequester toxic heavy metals.
HEAVY METAL SPONGE

33. PERIODIC MESOPOROUSN
ORGANOSILICAS PMOs

35. ZOO OF PMO PRECURSORS

36. Acc. Chem. Res. 2005, 38, 305-312.

37. 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.

38. METAMORPHIC CHANNEL WALLS – PMO BRIDGE
TERMINAL EXCHANGE

39. PMO WITH ORDERED BRIDGING AROMATIC
GROUPS IN THE CHANNEL WALLS

40. MOLECULAR MODEL OF THE ORDERING OF BRIDGING BENZENE
GROUPS IN THE CHANNEL WALL OF BENZENE PMO

41. MOLECULAR MODEL OF THE ORDERING OF BRIDGING THIOPHENE
GROUPS IN THE CHANNEL WALL OF THIOPHENE PMO

42. BIFUNCTIONAL PMOs

43. The IdeaThe Idea –– PMO to MIPMOPMO to MIPMO
IMPRINTIMPRINT IMPRINTIMPRINT

44. the ideathe idea
IMPRINTIMPRINT
imprintimprint
removalremoval
imprintimprint
moleculemolecule

45. collaborationcollaboration
Jean-Christophe Leroux (CRC in Drug Delivery)Jean-Christophe Leroux (CRC in Drug Delivery)
Nature NanotechnologyNature Nanotechnology.. 20072007,, 22, 679-684., 679-684.

46. MIPMOs
Schematic of the synthesis of molecular
imprinted periodic mesoporous
organosilica MIPMO materials

47. Drug-PMOsDrug-PMOs
commercially available drugscommercially 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

48. Drug SilsesquioxanesDrug Silsesquioxanes

49. MESOPOROUS MATERIALS
GRAND 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