MESOPOROUS MATERIALS AND BEYOND - Department of ...

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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

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

ISI
Citations
6386

ESCAPE FROM THE 1NM ZEOLITE PRISON

ESCAPE FROM 10 Å PRISON


Discovery by
M
o
bil
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 CO
2

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)
3
SiOR + H
3
O
+


(RO)
3
SiORH
+
+ H
2
O



2H
2
O + (RO)
3
SiORH
+


⡒O)
3
SiOH + ROH + H
3
O
+








CONDENSATION



(HO)
3
SiOH + H
3
O
+


(HO)
3
SiOH
2
+
+ H
2
O



(HO)
3
SiOH + (HO)
3
SiOH
2
+



⡈伩
3
SiOSi(OH)
3

+ H
3
O
+







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

pH

Catalyst

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 isotherms

Small 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 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

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 MIPMO

IMPRINT

IMPRINT

the idea

IMPRINT

imprint

removal

imprint

molecule

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

Verapamil

Diltiazem

Drug Silsesquioxanes

MESOPOROUS MATERIALS


GRAND CHALLENGES


UTILITY


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