CA 02695856 2010-03-05
MOLECULE-BASED MAGNETIC POLYMERS
Cross Reference to Related Applications
[0001] This U.S. Patent Application is a continuation-in-part (CIP)
application of PCT
International Application No. PCT/US08/75311 filed on September 5, 2008, which
claims the
benefit of U.S. Provisional Patent Application Serial Nos. 60/970,723 filed on
September 7,
2007 and 60/970,752 filed on September 7, 2007, all of which are hereby
incorporated herein
by reference.
Technical Field
[0002] The invention relates to magnetic polymers and methods of making such
polymers, and magnetic fluids. More particularly, the invention relates to
magnetic polymers
and methods of making such polymers with electron-donor metallocene compounds
and
electron- acceptor organic-based compounds with unpaired electrons.
Intrinsically
homogeneous magnetic fluids (liquid magnets) and methods of preparing are also
provided.
The magnetic fluids may include a magnetic polymer in a carrier solvent.
Background of the Invention
[0003] Magnets serve an indispensable function in our technology-based society
and are
ubiquitous in all varieties of mechanical and electronic devices in science
and industry.
Traditional magnets are atom-based, and are comprised of the transition,
lanthanide, or actinide
metals, with the magnetism arising from the magnetic dipole moment that is a
product of the
presence of unpaired electrons in the d- or f-orbitals.
[0004] Previous research attempts to design and synthesize molecular organic
magnets
and high-spin molecules with intrinsic magnetic properties were unsuccessful
and very few
have been found to be of industrial use, as such molecules had a fairly low
ferromagnetic
transition temperature, commonly referred to as Curie temperature (Ta). There
remain
fundamental obstacles that seem to block the ability to resolve scientific
difficulties to
developing organic magnets with high T, (much higher than room temperature).
There are
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CA 02695856 2010-03-05
only a few examples of organic magnets that have T, above room temperature,
but such
materials are insoluble and infusible as well as unstable under ambient
environment, and thus
the problem of fabrication of magnetic films and liquid magnets still remains
unresolved.
Since the magnetic anisotropy in organometallic magnets is considerably lower
than that in the
case of metal-containing compounds arising from the weak spin-orbital coupling
between s and
p electrons, high-Ta molecular magnets have not yet been realized.
[0005] Development of molecule-based magnetic polymers would be worthwhile
because they may exhibit numerous desirable properties, including solubility,
processability,
and synthetic tenability. Such features are a direct result of the molecular
nature of molecule-
based magnetic polymers and are not shared by traditional atom-based magnets.
Molecule-
based magnetic polymers provide prospects for new nanoscale molecular
materials as
functional magnetic memory devices leading to dramatically enhanced data
processing speeds
and storage capacity in computers or many other applications. Such polymeric
magnets would
be lighter, more flexible, and less intensive to manufacture than conventional
metal and
ceramic magnets. Just for example, applications could include magnetic
shielding, magneto-
optical switching, and candidates for high-density optical data storage
systems.
[0006] The theory of magnetism is primarily based on two quantum mechanical
concepts: electron spin and Pauli Exclusion principles. From the Curie law,
the magnetic
susceptibility (x) is expressed by x = N2gp2S(S + 1)/3kBT where R is the
effective magnetic
moment, g is g-factor, N is Avogadro's number, S is the spin angular momentum,
kB is the
Boltzmann constant, and T is the absolute temperature. Thus, x is proportional
to S2 (thus high
spin is required for high magnetic properties), but inversely proportional to
T. Also, there is a
critical temperature, T, below which the ferromagnetic materials exhibit
spontaneous
magnetization. To date, the most challenging issue for the synthesis of
molecule-based
magnetic polymers is to increase the Tc to well above room temperature, which
is desirable for
industrial applications.
[0007] The conventional molecular/organic magnets used at present are all atom-
based.
They exist in the form of crystals or complexes through noncovalent bonds
(e.g., hydrogen
bonding, ionic interactions, or metal coordinations), and thus spin coupling
largely depends on
the lattice distance of the crystal, because the exchange interaction is
proportional to 1/rlo
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Some efforts have been directed to the formation of a charge-transfer (CT)
complex to design
and synthesize molecular/organic magnets. It has been noted that there are
large positive and
negative atomic densities in certain structures (e.g. aromatic radicals), and
that atoms of
positive spin density are exchange coupled most strongly to atoms of negative
spin density in
neighboring molecules. The delocalization of spin density in macromolecular
chains makes it
possible for magnetic interactions to take place across extended bridges
between magnetic
centers separated from each other, propagating through conjugated bond
linkages, which act as
molecular wires. Spin polarization, i.e., the simultaneous existence of
positive and negative
spin densities at different locations within a given radical is needed for
intermolecular
exchange interactions to bring about ferromagnetic interactions. Employing
iron or transition
metal with larger radial orbitals as magnetic centers will improve the overlap
between the
orbitals of electron acceptor (A-) and electron donor (D), namely spin
coupling. Currently,
there have been no successful attempts reported on the synthesis of molecule-
based donor-
acceptor magnetic polymers.
[0008] Magnetic polymers based on p-orbital spins typically exhibit weak
ferromagnetic
properties and thus Tc is still below 10 K even when S reaches 5000.
Therefore, it is necessary
to incorporate much stronger magnetic centers into the macromolecular chains,
such as iron or
other transition metals having the unpaired electrons located in d- or f-
orbitals.
[0009] Existing superparamagnetic nanocomposites typically contain magnetic
particles
(e.g., Fe, Co, Ni etc.) in the form of powder or flakes in a non-magnetic
polymer matrix. Due
to the tendency of aggregation of magnetic particles when added to a non-
magnetic polymer
matrix, the magnetic particles were typically treated with a surfactant or
another polymer in
order to help suppress aggregation. Owing to a much higher density of magnetic
particles
compared with that of non-metallic polymer matrix, the magnetic particles had
a tendency to
settle out at rest or during storage. Consequently, non-uniform dispersion of
magnetic particles
in the polymer matrix and poor heat dissipation during use represent
additional problems.
[0010] The volume fraction of the magnetic particles in superparamagnetic
nanocomposites is much smaller than that of the matrix polymer, and therefore
the resulting
magnetic level is not high. Thus, applications of superparamagnetic
nanocomposites are
limited.
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[0011] Further limitations of superparamagnetic nanocomposites include the
lack of
solubility in common solvents which prevents them from being used in the
preparation of
intrinsically homogeneous magnetic fluids (liquid magnets). Thus, magnetic
particles (e.g.,
iron oxide or ferrite) are suspended in a carrier liquid to prepare so-called
ferrofluids, and they
are used in industry. Thus, ferrofluids are characterized as suspensions of
magnetic particles in
a carrier fluid, which suffer from the same problem as superparamagnetic
nanocomposites in
that the magnetic particles tend to aggregate and also sediment at rest.
[0012] Ferrofluids currently in use are typically suspensions containing
magnetic
particles (iron oxide or ferrite for example) with typical volume fractions of
0.3-0.4 in a carrier
fluid (typically silicone oil). There is another type of suspensions of
magnetic particles,
referred to as magnetorheological fluid (MR) fluid. The difference between
ferrofluids ad MR
fluids lies in the size of magnetic particles. Whereas the sizes of magnetic
particles used to
prepare ferrofluids are about 5-20 nanometers (nm), the sizes of the magnetic
particles used to
prepared MR fluids are about 5-20 micrometers ( m), i.e., about 1000 times
larger the particle
size normally used for the preparation of ferrofluids. The conventional,
commercially
available MR fluids typically contain an organic additive in order to
stabilize the dispersion of
aggregates of magnetic particles. Due to the large difference in density
between the magnetic
particles (having a density of 5-6 g/cm3) and a carrier fluid (having a
density less than 1
g/cm3), the conventional MR fluids have serious technical problems. In
particular, the
magnetic particles in the conventional MR fluids settle out over a relatively
short period of
time (i.e., in a few minutes to a few hours). Another technical difficulty is
related to the lack of
redispersibility of the magnetic particles in the conventional MR fluids.
After the magnetic
particles settle, they form highly dense aggregates, the extent of which
depends on the
chemical structure of a carrier fluid. To help disperse the aggregates of
magnetic particles in a
heterogeneous MR fluid, considerable efforts have been spent on treating the
particles with a
surfactant or a polymeric gel during the preparation of such MR fluids, but
these attempts have
not resolved the deficiencies.
[0013] Notwithstanding the state of the art as described herein, there is a
need for further
improvements in molecule-based (i.e., homogeneous) magnetic fluids and
polymers. These
types of fluids and polymers (without the presence of magnetic nanoparticles)
would have
numerous applications and would enable the preparation of intrinsically
homogeneous liquid
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magnets without the need for magnetic particles, which can then replace
ferrofluids or MR
fluids that have inherent difficulties of sedimentation and aggregation of
magnetic particles,
and other deficiencies.
Summary of the Invention
[0014] In one example of the invention, molecule-based magnetic fluids and
polymers
and methods of preparing these fluids and compounds are disclosed. In a
further embodiment
of the invention, a series of monomers having multiple unpaired electrons
("spins") are
prepared and thus play the role of electron acceptor resulting in the
formation of donor-
acceptor polymers with an electron donor with at least one transition metal,
for example iron,
cobalt, or nickel that is located within a ferrocene-, cobaltocene-, or
nickelocene-containing
and biferrocene-, bicobaltocene-, or binickelocene-containing monomer. The two
monomers
can then be polymerized to obtain covalently linked molecule-based magnetic
polymers. The
synthesized polymers are soluble in organic solvents, since they may have long
flexible, bulky
side chains.
[0015] In another example of the invention, a magnetic polymer having
repeating units
of a metallocene-containing electron-donor monomer covalently bonded to a
monomer having
a plurality of unpaired electrons is disclosed. Such polymers can be
synthesized by covalent
bonding, for instance, between a metallocene-containing electron-donor monomer
and an
electron-acceptor organic-based monomer with unpaired electrons.
[0016] In a further example of the invention, a method of preparing a magnetic
polymer
is disclosed. The method includes the steps of preparing a metallocene-
containing electron-
donor monomer, preparing a monomer having a plurality of unpaired electrons,
and
polymerizing the metallocene-containing electron-donor monomer and monomer
having a
plurality of unpaired electrons to form a magnetic polymer.
[0017] In still yet another example of the invention, an intrinsically
homogeneous
magnetic fluid (liquid magnet) includes a carrier solvent without containing
any magnetic
particles, while the molecule-based magnetic polymer comprises repeating units
of an
organometallic monomer covalently bonded to a monomer having a plurality of
unpaired
electrons.
CA 02695856 2010-03-05
Brief Description of the Drawings
[0018] FIG. 1 describes examples of synthesis routes for the molecule-based
magnetic
polymers according to the invention.
[0019] FIG. 2 describes the FTIR spectrum of 2,6-diamineanthraquinone
trifluorodiacetate.
[0020] FIG. 3 describes the 1H NMR spectrum of 2,6-diamineanthraquinone
trifluorodiacetate in DMSO.
[0021] FIG. 4 describes the FTIR spectrum of 2,6-diamine- 11, 11, 12,12-
tetracyanoanthraquino-dimethane trifluorodiacetate.
[0022] FIG. 5 describes the 1H NMR spectrum of 2,6-diamine-11,11,12,12-
tetracyanoanthraquino dimethane trifluorodiacetate in DMSO.
[0023] FIG. 6 describes the FTIR spectrum of 2,6-diamine- 11, 11, 12,12-
tetracyanoanthraquino-dimethane.
[0024] FIG. 7 describes the 1H NMR spectrum of 2,6-diamine-11,11,12,12-
tetracyanoanthraquino-dimethane in DMSO.
[0025] FIG. 8 describes the 13C NMR spectrum of 2,6-diamine-11,11,12,12-
tetracyanoanthraquino-dimethane in DMSO.
[0026] FIG. 9 describes the ESR spectrum of 2,6-diamine- 11, 11, 12,12-
tetracyanoanthraquinodimethane at room temperature.
[0027] FIG. 10 describes the FTIR spectrum of 2,6-diazido-11,11,12,12-
tetracyanoanthraquino-dimethane.
[0028] FIG. 11 describes the 1H NMR spectrum of 2,6-diazido-11,11,12,12-
tetracyanoanthraquino-dimethane in CDC13.
[0029] FIG 12 describes the FTIR spectrum of 1,1'-
bis(trimethylsilyl)ferrocene.
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[0030] FIG. 13 describes the 1H NMR spectrum of 1,1'-
bis(trimethylsilyl)ferrocene in
CDC13.
[0031] FIG. 14 describes the FTIR spectrum of 1,1'-bis(diphenylphosphino)-3,3'-
bis(trimethylsilyl) ferrocene.
[0032] FIG. 15 describes the 1H NMR spectrum of 1,1'-bis(diphenylphosphino)-
3,3'-
bis(trimethylsilyl) Ferrocene in CDC13.
[0033] FIG. 16 describes the 3 'P NMR spectrum of 1,1'-bis(diphenylphosphino)-
3,3'-
bis(trimethylsilyl) ferrocene in CDC13 using phosphorus acid as an external
reference.
[0034] FIG. 17 describes the FTIR spectra of a molecule-based polymer P1.
[0035] FIG. 18 describes the 1H NMR spectra of a molecule-based polymer P1 in
CDC13.
[0036] FIG. 19 describes the GPC scan of a molecule-based polymer P1 using
polystyrene
as a standard, with a number-average molecular weight (Mn) of 38,720, weight-
average
molecular weight (Mw) of 53,670, and polydispersity (MW/ Mn) of 1.39.
[0037] FIG. 20 describes the differential scanning calorimetric (DSC)
thermogram of a
molecule-based polymer P1 at a heating rate of 10 C/min.
[0038] FIG. 21 describes the thermogravimetric analysis (TGA) trace of a
molecule-based
polymer P1 at a heating rate of 10 C/min.
[0039] FIG. 22 describes the magnetic behavior of a molecule-based polymer Pl:
plot of
magnetization versus magnetic field 200 K.
[0040] FIG. 23 describes the ESR spectra of a molecule-based polymer P1 at 300
K.
[0041] FIG. 24 describes the XRD pattern of (a) a molecule-based polymer P1
and (b) iron
oxide.
[0042] FIG. 25 describes photographs of homogeneous solutions prepared from a
molecule-based magnetic polymer P1 in tetrahydrofuran at 10 wt% and 30 wt %.
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Detailed Description of the Invention
[0043] The synthesis procedures for examples of a series of high-Ta molecule-
based
magnetic polymers and the presentation of representative properties of the
example synthesized
magnetic polymers are presented herein. These molecule-based magnetic polymers
are soluble
in common solvents, offering good processability. The term "molecule-based",
as used herein,
refers to the state of covalent bonding between elements and/or atoms during
the formation of
large molecules, i.e. polymers. The molecule-based magnetic polymers.. as
described herein,
are intrinsically homogeneous in nature. The magnetic polymers of the
invention have a high
Curie temperature or a Tc above room temperature, and more particularly well
above room
temperature. This allows the fabrication and use for a wide variety of
applications. The Curie
temperature of the magnetic polymer according to the invention will depend on
the chemical
structure of the particular molecule-based magnetic polymer, and can vary
accordingly. For
many applications, the Curie temperature of the magnetic polymer is desired to
be well above
room temperature, such as up to about 200 degrees Celsius for example, before
the magnetic
polymer begins to undergo thermal degradation. It is noted that the Curie
temperature denotes
the highest temperature at which magnetic behavior can be observed, i.e., at
temperatures
above the Curie temperature of a magnetic polymer, the polymer ceases to
exhibit magnetic
characteristics. Based on the application and environment in which the
magnetic polymer is to
be used, the Curie temperature may be above the temperatures to be expected in
such
application or environment, to prevent degradation of the magnetic
characteristics thereof.
[0044] The design and synthesis of molecule-based magnetic polymers may be
based on
the following theoretical considerations. Namely, (a) the macromolecular
chains must have
magnetic centers with unpaired electrons, (b) the unpaired electrons should
have their spins
aligned parallel along a given direction, (c) conjugated structure plays an
important role in
intramolecular spin coupling along the macromolecular chain, (d) the distance
between
electron donating center and electron accepting center should be as small as
possible, ensuring
the largest spin coupling, and (e) spin coupling must extend to three
dimensions, due to the
cooperative effect of magnetism, which can be realized from the spin
delocalization and spin
polarization along the macromolecular chains, and intermolecular exchange
interactions.
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[0045] These molecule-based magnetic polymers may provide a new generation of
ferromagnetic materials having numerous practical applications. These
applications include
diagnostics, bioassays and life sciences research, as they provide a means of
separation of
substances from complex mixtures. In brief, a ligand (e.g., antibody or
antigen), is either non-
covalently or covalently attached to the magnetic polymers through chemical
means. Other
applications include exclusion seals for computer disc drives, applications
such as seals for
bearings, for pressure and vacuum sealing devices, for heat transfer and
damping fluids in
audio speaker devices. Further applications include magnetic toner and inkjet
formulations.
Further, the magnetic polymers can be used to prepare intrinsically
homogeneous magnetic
fluids (liquid magnets) for numerous practical applications.
[0046] Intrinsically homogeneous magnetic may be used in many different
applications.
For instance, in the automotive industry, magnetic fluids may be used for
electrically
controllable shock absorbers, clutches, inertial damper, actuators, and engine
mounts. The
reason for the use of magnetic fluids in such applications lies in that an
applied magnetic field
induces an orientation of spins in electrons along the direction of magnetic
field, giving rise to
a very high resistance to flow, often referred to as "yield stress." Field-
induced yield stress is a
very unique characteristic of magnetic fluids. The rheological properties of
magnetic fluids
such as viscosity, yield stress, and stiffness can be altered by an external
magnetic field. The
unique features of these changes are fast (on the order of milliseconds for
example),
significant, and nearly completely reversible. Specifically, in the "off'
state (when no
magnetic field is applied), the magnetic centers are randomly distributed, and
thus the magnetic
fluid behaves like a Newtonian fluid, whereas, in the "on" state (when a
magnetic field is
applied), the magnetic centers would orient in the direction of applied
magnetic field, which
causes the magnetic fluid to exhibit semisolid behavior with increased yield
stress,
characteristic of Bingham fluids. The viscosity of magnetic fluids is
dependent on the
magnitude and direction of the applied magnetic field as well as the shear
rate. For example,
field-induced yield stress will help a driver to stop a car quickly.
[0047] The invention therefore is directed to molecule-based homogeneous
molecule-
based magnetic polymers, with such polymers usable as polymers and in
intrinsically
homogeneous magnetic fluids. The term "homogeneous", as used herein, refers to
a
substantially "single phase" state in which no free magnetic particles or
extraneous foreign
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particles exist in the synthesized magnetic polymer product in the bulk state,
for solids, or in
the liquid state, for fluids.
[0048] Previous attempts to synthesize molecule-based magnetic polymers were
unsuccessful. In the present invention, theoretical considerations were used
to develop the
synthesis of the chemical structures from monomers that enhance spin-spin
interactions
between the constituent components, which then leads to molecule-based
magnetic polymers
after polymerization. It was considered previously that the synthesis of
molecule-based
magnetic polymers with high T, would not be possible without using a monomer
having a
metallic element (e.g., iron. cobalt, or nickel).
[0049] Thus, as examples of the invention, a series of monomers have been
synthesized
as an electron acceptor resulting in the formation of donor-acceptor polymer
with an electron
donor with at least one transition metal-containing organometallic compound,
for example a
metallocene, that includes iron, cobalt, or nickel in ferrocene-, cobaltocene-
, or nickelocene-
containing or biferrocene-, bicobaltocene-, binickelocene-containing monomer.
The two
monomers were then polymerized to obtain covalently linked molecule-based
magnetic
polymers. A variety of polymerization approaches may be suitable, and an
example is a
Staudinger reaction between one monomer with azide groups and the other
monomer with
phosphine groups. Staudinger reaction has many advantages in that it does not
require the use
of any catalyst because most metal (like palladium) containing catalysts would
form complexes
with electron-accepting monomers and in turn lose their catalyzing properties,
as well as it
occurs in neutral conditions at room temperature. The synthesized polymers may
be soluble in
carrier fluids or solvents, because of the flexible side chains or bulky
pendent groups. Another
promising mechanism of polymerization may resort to Knoevenagel reaction.
Judicious
modification of both electron-accepting and electron-donating monomers would
enable
Knoevenagel reaction to occur in a weak-base solution under mild conditions to
afford
magnetic polymers. On the other hand, since tetracyanoethylene (TCNE) has
extremely high
reactivity with ethynyl group in the presence of strong electron donating
groups like amino
group, it is wise to synthesize metallocene-containing conjugated polymers
having ethynyl
group and amino group in such a way that TCNE can react with ethynyl group in
this polymer
after polymerization and accordingly afford the electron donating and
accepting charge transfer
complex along the macromolecular chain. The rationale behind this idea lies in
that a plethora
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of catalyst systems that are commonly employed in the synthesis of conjugated
polymers may
be used to achieve high molecular weight metallocene-containing conjugated
polymers,
circumventing the situation of possible coordination of tetracyano group with
metal ion-
containing catalysts. In an embodiment of the invention, synthesis routes for
molecule-based
magnetic polymers are shown in FIG. 1.
[0050] In one embodiment, a suitable candidate for the carrier fluid or
solvent for the
preparation of homogeneous magnetic fluid, but are not limited to, an organic
fluid, or an oil-
based fluid. Suitable carrier fluids which may be used include
tetrahydrofuran, N,N-
dimethylformamide, chloroform, dichloromethane, natural fatty oils, mineral
oils,
polyphenylethers, dibasic acid esters, neopentylpolyol esters, phosphate
esters, synthetic
cycloparaffins and synthetic paraffins, unsaturated hydrocarbon oils,
monobasic acid esters,
glycol esters and ethers, silicate esters, silicone oils, silicone copolymers,
synthetic
hydrocarbons, perfluorinated polyethers and esters and halogenated
hydrocarbons, and
mixtures or blends thereof. Hydrocarbons, such as mineral oils, paraffins,
cycloparaffins (also
known as naphthenic oils) and synthetic hydrocarbons are one of the classes of
carrier fluids
contemplated. In certain examples, aqueous based fluids are contemplated as
carrier fluids or
solvents for the magnetic polymers. In one example, the carrier fluid
comprises substantially
all one fluid. In another example, the carrier fluid is a mixture of one or
more carrier fluids. In
a further example, the carrier fluid comprises an aliphatic hydrocarbon.
[0051] The magnetic properties of molecule-based polymers would be highly
dependent upon the chemical nature of electron donating and electron accepting
units as well
as the bridge linking these units. With this understanding, the following
magnetic polymers
based on 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCNAQ), 7,7,8,8-
tetracyano-p-
quinodi-amine (TCNQ) and tetracyanoethylene (TCNE) have been synthesized.
Synthesis of TCNAQ-Based Magnetic Polymers
[0052] TCNAQ has attracted special attention due to the facile synthesis by
Lehnert's
reagent and stability of molecular structure as well as the feasibility of
modifying TCNAQ
with functional groups for polymerization. For this reason, the electron-
accepting monomers
based on TCNAQ has been synthesized and functionalized with azide groups,
which would
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react with the phosphine groups in metallocene or bimetallocene monomers to
afford the
corresponding magnetic polymers.
[0053] 1. Synthesis of TCNAQ-Based Electron Accepting Monomers
O O O
11
NH2 (CF3CO)20 O NHCCF3
H2N CF3CONa,THF CF11 3 CHN
0 0
NC CN
O
11
CH2(CN)2, TiCl4, pyridine NHCCF3 1. HCUEA, reflux for 24 h
THE 0 2. Aqueous NaHCO3
CF3CHN
NC CN
NC CN NC CN
NHZ N3
t-BuONO, TMSN3
CH3CN
H2N N3
NC CN NC CN
EXAMPLE 1
[0054] Preparation of 2,6-diazido- 11, 11, 12,12-
tetracyanoanthraquinodimethane
(TCNAQ-N3)
[0055] (i) Preparation of 2,6-diamineanthraquinone trifluorodiacetate.
[0056] The purpose of this reaction is to protect amino group. 2,6-
diamineanthraquinone
(2.4 g, 10 mmol) and sodium trifluoroacetae (4.2 g, 30 mmol) were dissolved in
50 mL
anhydrous tetrahydrofuran (THF), and then 10 mL trifluoroacetic anhydride was
added in
portions. After that, the reaction mixture was heated to reflux in a stream of
argon gas
overnight. The solution was then allowed to cool down to room temperature and
poured into
200 mL cold water. The precipitate was filtered and washed with water,
followed by
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recrystallizing from ethanol three times to give 4.0 g light yellow powder.
Yield: 92%. 1H
NMR (8, DMSO): 8.25 (m, 4H, -CH-), 8.56 (s, 2H, -CH-), 11.88 (s, 2H, -NH-).
FTIR
spectrum (cm-1): 3280 (-NHCO-), 3070, 1710 (-CO-), 1670 (quinone), 1590 (-
phenyl). The
Fourier transform infrared (FTIR) spectrum of 2,6-diamineanthraquinone
trifluorodiacetate is
shown in FIG. 2, and the (proton nuclear magnetic resonance ('H NMR) spectrum
of 2,6-
diamineanthraquinone trifluorodiacetate in DMSO is shown in FIG. 3.
[0057] (ii) Preparation of 2,6-diamine-11,11,12,12-
tetracyanoanthraquinodimethane
trifluorodiacetate
[0058] To a solution of 2,6-diamineanthraquinone trifluorodiacetate (2.1 g, 5
mmol) and
malononitrile (1.6 g, 25 mmol) in 30 mL anhydrous tetrahydrofuran was added
dropwise 3.3
mL TiC14 (30 mmol), followed by 4.8 mL anhydrous pyridine (60 mmol) over 60
min at 0 C.
After the mixture was refluxed overnight, the solvent was removed under
reduced pressure.
The residue was treated with icy water and extracted with ethyl acetate. The
combined organic
layers were dried over anhydrous MgSO4. After filtration and removal of
solvent, the crude
product was purified over silica gel column chromatography using hexane/ethyl
acetate (1:1,
v/v) as an eluent, and then recrystallized from hexane/ethyl acetate (1:3,
v/v) to afford 1.4 g
yellowish powder. Yield: 55%. 1H NMR (8, DMSO): 8.10 (d, 2H, -CH-), 8.32 (d,
2H, -CH-),
8.32 (d, 2H, -CH-), 11.96 (s, 2H, -NH-). FTIR spectrum (cm 1): 3290 (-NHCO-),
3120,
1710 (-CO-), 1600 (-phenyl). The FTIR spectrum of 2,6-diamine-11,11,12,12-
tetracyanoanthraquino-dimethane trifluorodiacetate is shown in FIG. 4, and the
1H NMR
spectrum of 2,6-diamine-11,11,12,12-tetracyanoanthraquinodimethane
trifluorodiacetate in
DMSO is shown in FIG. 5.
[0059] (iii) Preparation of 2,6-diamine-11,11,12,12-
tetracyanoanthraquinodimethane
[0060] 2,6-Diamine-11,11,12,12-tetracyanoanthraquinodimethane
trifluorodiacetate (2.6
g, 5 mmol) was dissolved in 50 mL ethyl acetate, to which 50 mL of mixed
solution of
concentrated HCUethyl acetate (1/3, v/v) was added dropwise. The reaction
mixture was heated
to reflux for 24 h, during which white precipitate was formed. After cooling
to 0 C, the
solution was slowly added to 200 mL saturated NaHCO3 aqueous solution. The
organic layer
was separated and washed three times with distilled water, and then dried over
Na2SO4, After
the solvent was removed under vacuum, the crude product was purified over
silica gel column
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chromatography using hexane/acetone (4:3, v/v) as an eluent, and then
recrystallized from
hexane/ethyl acetate (1:1, v/v) to give 1.1 g dark red powder. Yield: 65%. 1H
NMR (6,
DMSO): 6.79 (d, 4H, -NH2), 6.80 (d, 2H, -CH-), 7.29 (d, 2H, -CH-), 7.93 (d,
2H, -CH-).
13C NMR (6, DMSO): 75.9, 112.1, 116.1, 116.6, 116.8, 131.2, 134.0, 153.8,
161.9. FTIR
spectrum (cm-'): 3470 (-NH2), 3360 (-NH2), 3220 (-NH2), 2210 (-CN), 1620 (-
NH2), 1600
(-phenyl). The FTIR spectrum of 2,6-diamine- 11, 11, 12,12-
tetracyanoanthraquinodimethane is
shown in FIG. 6, the 1 H NMR spectrum of 2,6-diamine- 11, 11, 12,12-
tetracyanoanthraquinodimethane in DMSO is shown in FIG. 7, the (caron-13
nuclear magnetic
resonance) (13C NMR) spectrum of 2,6-diamine- 11, 11, 1 2,12-
tetracyanoanthraquinodimethane
in DMSO is shown in FIG. 8, and the electron spin resonance (ESR) spectrum of
2,6-diamine-
11,11,12,12-tetracyanoanthraquino-dimethane at room temperature is shown in
FIG. 9.
[0061] (iv) Preparation of 2,6-diazido- 11, 11, 12,12-
tetracyanoanthraquinodimethane
[0062] In a 250 mL round-bottom flask, 2,6-diamine-11,11,12,12-
tetracyanoanthraquino-
dimethane (3.3 g, 10 mmol) was dissolved in 50 mL anhydrous acetonitrile and
cooled to 0 C
in an ice bath. To this stirred mixture was added 4.0 mL tert-butyl nitrite
(30 mmol) followed
by 4.2 mL azidotrimethylsilane (30 mmol) dropwise. The resulting solution was
stirred at
room temperature for 20 h. The reaction mixture was concentrated under vacuum,
and the
crude product was purified by silica gel chromatography using CH2C12 as an
eluent. After
removing CH2C12, 20 mL tetrahydrofuran was added to dissolve the product and
then
precipitated in hexanes for three times, giving 2.1 g brown powder. Yield:
55%. 1H NMR (6,
CDC13): 7.29 (d, 2H, -CH-), 7.78 (s, 2H, -CH-), 8.15 (d, 2H, -CH-). FTIR
spectrum (cm-1 ):
2220 (-CN), 2110 (-N3), 1600 (-phenyl). The FTIR spectrum of 2,6-diazido-
11,11,12,12-
tetracyanoanthraquino-dimethane is shown in FIG. 10 and the 1H NMR spectrum of
2,6-
diazido- 11, 11, 12,12-tetracyanoanthraquinodimethane in CDC13 is shown in
FIG. 11.
[0063] 2. Synthesis of Electron Donating Metallocene or Bimetallocene Monomers
[0064] One of the existing problems that must be overcome to synthesize a
truly molecule-
based magnetic polymer is the solubility of the polymer in commercially
available solvents. In
one embodiment of the invention, a metallocene or bimetallocene monomer with
flexible side
chains was prepared. Previous research showed that a ferromagnetic polymer
synthesized
14
CA 02695856 2010-03-05
without flexible side chains was not soluble in organic solvents. Therefore,
when a magnetic
polymer is not soluble in a solvent, its practical use is very limited in that
the fabrication of
many useful industrial products would not be possible.
~~-Li .-Si(CH3)3
M n-BuLi C1Si(CH3)3 TM n-BuLi
TMEDA/hexane -Li c-Si(CH3)3 TMEDA/hexane
(CH3)3Si
Li-~-Si(CH3)3 O~-PPh2
M C1PPhz M
M = Fe, Co, Ni
Li Si(CH3)3 Ph2P_-_~
Si(CH3)3
Mc-Si-PPh2
[0065] The rationale for the synthesis of bimetallocenes was based upon the
fact that
doubling the number of metallocene groups would enhance significantly the
ferromagnetic
behavior of the polymers to be synthesized, because of their easy formation of
mixed-valence
Fe(II)-Fe(III) species and charge transfer complex.
O Li C1Si(CH3~-Si(CH3)3 n-BuLi
M n-BuLi M )3 M
TMEDA/hexane Li -Si(CH3)3 TMEDA/hexane
(CH3)3Si
(CH3)3Si Br
Li-Si(CH3)3 Lc~~ Br (CH3)3Si M
CHBr2CHBr2 n-BuLi O
~ CuCN/O2 M Si(CH3)3
Li- ' Si(CH3)3 Br Br
Si(CH3)3
Si(CH3)3
(CH3)3Si
(CH3)3SI PPh2
M
n-BuLi _ CIPPh2
M = Fe, Co, Ni
TMEDA/hexane M
Si(CH3)3
Ph2P~
Si(CH3)3
[006,
CA 02695856 2010-03-05
In order to reduce the shielding effects of bulky groups like trimethylsilyl
and
diphenylphosphine groups on the metallocene center, another metallocene
monomer with
phosphine having bis(diethylamino) groups was synthesized according to the
following
reaction scheme:
O O Li
n-BuLi CHBr2CHBr2 OM Br n-BuLi
TMEDA/hexane -Li Br CuCN/O2
<a--> Br CD P(NEt2)2
M PC' M
BuLi (EtzN)z-
THE M = Fe, Co, Ni
M M
Br-~ (EO)2 - '
EXAMPLE 2
[0067] Preparation of 1,1'-bis(diphenylphosphino)-3,3'-
bis(trimethylsilyl)ferrocene
[0068] (i) Preparation of 1,1'-bis(trimethylsilyl)ferrocene
[0069] A solution of 62.5 mL 1.6 M butyllithium in hexane was added to
ferrocene (7.6 g,
40 mmol) in 100 mL anhydrous hexane at 0 C, and then 15.2 mL N,N,N',N'-
tetramethyl-
ethylenediamine (TMEDA) (100 mmol) were added dropwise. This mixture was
warmed up to
room temperature and stirred for 24 h. The resulting mixture was cooled to -78
C, and
trimethylsilyl chloride was added slowly and stirred at this temperature for 2
h. Subsequently,
the reaction mixture was allowed to warm to room temperature and stirred
overnight. After the
reaction was complete, the solution was poured into 200 g ice, and extracted
with hexane (4 x
100 mL). Then, the organic layers were combined, dried over MgSO4, and
concentrated under
the reduced pressure. The residue was separated by silica gel flash
chromatography using
hexane as an eluent to give 8.6 g red liquid. Yield: 65%. 'H NMR (8, CDC13):
0.18 (d, 18H,
-Si(CH3)3), 4.28 (s, 4H, -Fe), 4.46 (s, 4H, -Fc). FTIR spectrum (cm -1): 3090
(-Fe), 2950,
1420, 1380, 1240, 1160, 1040, 818, 750, 688, 629. The FTIR spectrum of 1,1'-
bis(trimethylsilyl)ferrocene is shown in FIG. 12 and the 'H NMR spectrum of
1,1'-
bis(trimethylsilyl)ferrocene in CDC13 is shown in FIG. 13.
16
CA 02695856 2010-03-05
[0070] (ii) Synthesis of 1,l'-bis(diphenylphosphino)-3,3'-
bis(trimethylsilyl)ferrocene
[0071] 18.8 mL 1.6 M butyllithium in hexane (30 mmol) was added to 1,1'-
bis(trimethylsilyl)ferrocene (3.3 g, 10 mmol) in 100 mL anhydrous ether at 0
C, and then 4.6
mL TMEDA (30 mmol) were added dropwise. This mixture was warmed up to room
temperature and stirred for 24 h. The resulting mixture was then cooled to -78
C, and 4.6 mL
chlorodiphenylphosphine (25 mmol) was added dropwise and maintained for a
further 2 h.
After that, the reaction mixture was allowed to warm up to room temperature
and stirred for 24
h. After cooling to 0 C, it was carefully quenched with 100 mL icy water and
the organic layer
was separated, followed by washing with 100 mL distilled water twice. The
organic layer was
dried over Na2SO4, and concentrated under the reduced pressure. The residue
was separated by
silica gel column chromatography using hexane/chloroform (2:1 , v/v) as an
eluent, and then
recrystallized from hexane twice to obtain 2.8 yellow crystals. Yield: 40%. 1H
NMR (8,
CDC13): 0.01 (d, 18H, -Si(CH3)3), 3.91(d, 2H, -Fc), 4.08 (s, 2H, -Fc), 4.20
(d, 2H, -Fc), 7.25
(t, 8H, -phenyl), 7.33 (t, 8H, -phenyl), 7.62 (d, 4H, -phenyl). 31P NMR (6,
CDC13, H3PO4 as
an external reference): 20.4. FTIR spectrum (cm-1 ): 3070 (-Fc), 2950, 1590 (-
phenyl). The
FTIR spectrum of 1,1'-bis(diphenylphosphino)-3,3'-bis(trimethylsilyl)
ferrocene is shown in
FIG. 14, 1H NMR spectrum of 1,1'-bis(diphenylphosphino)-3,3'-
bis(trimethylsilyl)ferrocene in
CDC13 is shown in FIG. 15, and the (phosphine-31 nuclear magnetic resonance)
(31P NMR)
spectrum of 1,1'-bis(diphenylphosphino)-3,3'-bis(trimethylsilyl)ferrocene in
CDC13 using
phosphorus acid as an external reference is shown in FIG. 16.
[0072] 3. Polymerization of TCNAQ-Based Magnetic Polymers
NC CN
(CH3)3Si
N3PPhZ
~ THE
N3 Ph2P ~~/
NC CN Si(CH3)3
Si(CH3)3
r NC CN P=N
M
N=P OJ
I I
NC CN n
P1
17
CA 02695856 2010-03-05
(CH3)3Si NC CN
PPh2 I
(CH3)3Si M N3 THE
+
Ph 2P Si(CH3)3 N3
Si(CH3)3 NC CN
NC CN
I N
(CH3)3Si Ph
P-N
(CH3)3Si M Ph
NC CN
Ph
I Si(CH3)q
P-;~O_`
Ph Si(CH3)3
P2
P(NEt2)2 NC CN
M
N3 THE
M + \I ~~ -~
(Et2N)2P-~ N3
NC CN
NC CN
N
NEt2 \ I \
OP=N M=Fe,Co,Ni
TM NEt2
NC CN
NEtO
2 M
P-~
NEt2
P3
EXAMPLE 3
[0073] Polymerization of Molecule-Based Magnetic Polymer P1
18
CA 02695856 2010-03-05
[0074] In a 250 mL three-neck round-bottom flask was placed equimolar amounts
of
monomers, 2,6-diazido-11,11,12,12-tetracyanoanthraquinodimethane (3.9 g, 10
mmol) and
1,1'-bis(diphenylphosphino)-3,3'-bis(trimethylsilyl)ferrocene (7.0 g, 10
mmol), and then 100
mL anhydrous tetrahydrofuran was added at 0 T. The reaction mixture was
thoroughly
deoxygenated, filled with high-purity argon gas, and then slowly warmed up to
room
temperature and reacted for 72 h, followed by slightly increasing the
temperature to 35 C for
another 11 days. Then, the solution was precipitated in hexanes, filtered, and
dried in vacuo at
60 C to give 9.7 g brown product. Yield: 95%. In order to remove the low
molecular weight
fraction, gradient precipitation fractionation was employed by dissolving the
polymer in THE
followed by slowly adding hexane and then collecting the precipitating samples
in portions.
Finally, the high molecular weight fractions were combined to afford 6.0 g
product with
narrow molecular weight distribution. 'H NMR (S, CDC13): 0.01 (d, 18H, -
Si(CH3)3), 3.89 (s,
2H, -Fc), 4.38 (d, 2H, -Fc), 4.76 (d, 2H, -Fc), 6.43 (s, 2H, -phenyl), 6.30
(d, 2H, -phenyl),
7.50 (m, 20H, -phenyl), 7.74 (d, 2H, -phenyl). FTIR spectrum (cm-'): 3060 (-
Fc), 2950, 2890,
2220 (-CN), 1590 (-phenyl). The FTIR spectra of a molecule-based polymer P1 is
shown in
FIG. 17 and the 1H NMR spectra of a molecule-based polymer P1 in CDC13 is
shown in FIG.
18. The GPC measurement that P1 has an Mn of 38,720, an MW of 53,670, and
polydispersity
(MW/Mn) of 1.38 is shown in FIG. 19.
[0075] Due to its rigid conjugated structure and the strong electron donor-
acceptor
interactions (both intermolecular and intramolecular), P1 has a glass
transition temperature
(Tg) at a very high temperature of 227 C as shown in FIG.20. The thermal
degradation
temperature was determined to be above 350 C as observed from
thermogravimetric analysis
(TGA) data as shown in FIG. 21. The TGA data given in FIG. 21 indicates that
thermal
degradation would occur at temperatures above 350 T. Therefore, it can be
concluded that it is
safe to run magnetic measurements at temperatures below 350 T.
[0076] The molecule-based polymer P1 exhibits a ferromagnetic behavior as
determined
from magnetometry experiment shown in FIG. 22, and also from ESR experiment as
shown in
FIG. 23. Further it has been found that the molecule-based polymer P1 does not
contain any
trace of foreign material (e.g., iron oxide) as determined from wide-angle X-
ray diffraction
19
CA 02695856 2010-03-05
(XRD) experiment shown in FIG. 24a. For comparison, XRD patterns of iron oxide
are
shown in FIG. 24b exhibiting several X-ray intensity peaks characteristic of
typical iron oxide.
[0077] It has been found that the molecule-based polymer P1 is soluble in
common
solvents such as tetrahydrofuran, N,N-dimethylformamide, chloroform, and
dichloromethane.
Photographs of the solutions of molecule-based polymer P1 are shown in FIG 25,
demonstrating that indeed an intrinsically homogeneous magnetic fluid (i.e.,
liquid magnet) has
been prepared from the molecule-based magnetic polymer P1.
Synthesis of TCNQ-Based Magnetic Polymers
[0078] The Knoevenagel reaction is a modified version of the Aldol reaction,
where
aldehydes perform condensation with compounds with the structure Z-CH2-Z',
here Z and/or Z'
are electron withdrawing groups, such as CHO, COR, COOH, COOR, CN, NO2, SOR,
and
SO2R. Knoevenagel reaction has become a suitable approach to synthesize high
molecular
weight conjugated polymers. Since 7,7,8,8-Tetracyanoquinodimethane (TCNQ) is a
very
strong electron withdrawing group, modification of TCNQ with -CH2CN would make
this
monomer fairly ready for reacting with a electron donating monomer with
aldehyde groups.
Therefore, weak base like piperidine can be employed as a catalyst, which may
not influence
the stability of tetracyano group. Also, because the reactivity of
polymerization is high, low
temperature polymerization may become possible.
[0079] 1. Synthesis of TCNQ-Based Electron Accepting Monomers
CH3 NC,CH,CN
CH3
I2, H5IO6/CHC13 I I + NC CN Pd(PPh2)3C12 I CH3
H2O, H2SO4, AcOH NaH,THF
CH3 \
CH3 CH3 CH
NC' 'CN
NC CN NC CN
CH2Br CH2CN
NBS, AIBN/CC14 _ I I NaCN _ I I
BrCH2 DMF NCCH2
NC CN NC CN
CA 02695856 2010-03-05
[0080] 2. Synthesis of Electron Donating Metallocene or Bimetallocene Monomers
Si(CH3)3 Li Si(CH3)3 -BuLi n___ _ DMF
Si(CH3)3 TMEDA/hexane Li Si(CH3)3 H2O
(CH3)3Si
CHO
M M = Fe, Co, Ni
OHC~
Si(CH3)3
(CH3)3S4- (CH3)3Si
Br O CHO
(CH3)3Si (CH3)3Si M
4M n-BuLi DMF M = Fe, Co,]
TMEDA/hexane H2O
BrSi(CH3)3 OHC M Si(CH3)3
Si(CH3)3 S i(CH3)3
[0081] The bimetallocene monomers with aldehyde groups would stabilize the
molecule,
because the distance between two aldehyde functional groups has been largely
increased.
[0082] (3) Polymerization of TCNQ-Based Magnetic Polymers
NC CN
(CH3)3Si
CHZCN CHO
+ M Piperidine
NCCH2 OHC-'--~
NC CN Si(CH3)3
21
CA 02695856 2010-03-05
(CH3)3Si
NC CN CH
HC
CN CN Si(CH3)3 M = Fe, Co, Ni
c J I
NC CN
P4
NC CN (CH3)3Si
-CHO
CHZCN (CH3)3Si M
Piperidine
NCCHz Si(CH3)3
~
NC CN OHC Si(CH3)3
(CH3)3S
CH
(CH3)3S1 M
PG
NC CN
M Si(CH3)3
C= HC M = Fe, Co, Ni
CN CN Si(CH3)3
NC CN
n
P5
Synthesis of TCNE-Based Magnetic Polymers
[0083] Tetracyanoethylene (TCNE) as a strong electron donating molecule
undergoes
numerous reactions and exists in structural motifs of a variety of organic or
inorganic
compounds. Of particular interests, TCNE was reported to react with electron-
rich acetylenes
to afford TCNE derivatives, which were considered to be formed by a ring-
opening reaction of
22
CA 02695856 2010-03-05
initially produced [2 + 2] cycloadducts. Such reaction mechanism paves a new
way to
synthesize TCNE-based electron donating monomers having phosphine groups,
which would
in turn react with metallocene monomers to give molecule-based magnetic
polymers.
[0084] Synthesis of TCNE-Based Electron Donating Monomers
PdC12(PPh3)2/CuI SiMe3
+ Me3Si-C-CH MeLi
THF/Diisopropylamine 1~2~ = SiMe3 THE
NC CN
PPh2
PPh2 NC CN I PPh2Cl TCNE I NC CN M = Fe, Co, Ni
1~2~ ~E:::: PPh2 Ph2P
NC CN
PPh2-TCNE-Mc
SiMe3 P(NEt2)2
MeLi (Et2N)2PC1 TCNE
SiMe3 THE = P(NEt2)2
NC CN
I P(NEt2)2
O I
NC CN M = Fe, Co, Ni
NC CN
(Et2N)2P I
NC CN
P(Net2)2-TCNE-BiMc
[0085] Both PPh2-TCNE-Mc and P(NEt2)2-TCNE-Mc possess a metallocene center,
which directly connects with two TCNE units and facilitates the strong
intramolecular
interactions between electron donating and electron accepting constituents.
The diethylamino
groups in P(NEt2)2-TCNE-Mc may make its reaction with TCNE much easier. The
flexible
side chains would reduce the steric hindrance. Due to its easy formation of
mixed-valence
23
CA 02695856 2010-03-05
Fe(II)-Fe(III) species and charge transfer complex, bimetallocenes were also
synthesized
according to the following reaction schemes:
I SiMe3
+ Me3Si-C-CH PdClz(PPh3)z/CuI 30 30 Cu
I THF/Diisopropylamine 140 oC
SiMe3 O = PPh
MeLi PPh2CI_
THE
Me3Si PPh2
NC CN
PPhz
TCNE NC CN NC CN M = Fe, Co, Ni
Phz
NC CN
SiMe3 P(NEt2.
MeLi (Et2N)PCI M
THE
Me3Si = -
(Et2N)z -
NC CN
P(NEtz)z
O
M=Fe,CoNi
TCNE NC CN NC CN
(Et2N)2
NC CN
P(NEt2)2-TCNE-BiMc
24
CA 02695856 2010-03-05
[0086] 2. Synthesis of Electron Donating Bimetallocene Monomers
[0087] 1,1'-diazidoferrocene is unstable above 50 C, and rather sensitive to
light under
ambient conditions. Therefore, a more stable diazido-monomer based on
bimetallocene was
synthesized, because the number of carbon is largely greater than that of
nitrogen and the
distance between two azido-groups has been dramatically enlarged.
Br C N3
NaN3, CuC M
O M Fe, Co, Ni
=
mrW
EtOHH2O
M M
Br-~ N3--<L;;;,
[0088] 3. Polymerization of TCNE-Based Magnetic Polymers
NC CN
I CD
PPh2N3
NC CN I + O M THF
I NC CN M
Ph2P I N3-~
NC CN
N
M
NC CN
Ph M
P_ N-ern
NC CN Ph ~/
M = Fe, Co, Ni
Ph NC CN
Ph
NC CN
P6
CA 02695856 2010-03-05
NC CN
P(NEt2)2 Q-N3
NC CN + M ,THF
NC CN M
(Et2N)2P N3-~
NC CN
O N
M
NC CN
NEt2 M
P_ N
NC CN NEt2 M = Fe, Co, Ni
NEt2 NC CN
P
NEt2
NC CN
P7
NC CN
O I PPh2 N3
I M
+ THF
NC CN NC CN
I N3-
Ph2
NC CN
O N
M
NC CN
Ph M
P N
I M = Fe, Co, Ni
Ph
NC CN NC CN
Ph
T P I
Ph NC CN
in
P8
26
CA 02695856 2010-03-05
NC CN
O I P(NEt2)2 N3
I M
+ THF
NC CN NC CN
M
I N3-~
(Et2N)2
NC CN
4N
M
NC CN O
NEt2 M
P-N-<jL;;I
NEt2
NC CN O NC CN M = Fe, Co, Ni
NEt2
p
NEt2 NC CN
n
P9
[0089] 4. Synthesis of TCNE-Based Magnetic Polymers via Post-Polymerization
Reaction
[0090] Considering the high reactivity of TCNE with ethynly group in the
presence of
strong electron donating groups such as amonio group, we synthesized three
additional TCNE-
based magnetic polymers by incorporating TCNE units either in the main chain
or in the side
chain. Specifically, we first synthesized metallocene-containing conjugated
polymers having
ethynyl groups and amino groups through carbon-carbon coupling reactions using
different
metal-ion containing catalyst systems. After that, these conjugated polymers
performed further
reaction with TCNE to afford the respective magnetic polymers.
27
CA 02695856 2010-03-05
[0091] (a) Main-Chain TCNE-Based Bimetallocene Magnetic Polymers
~SnBu 3 I2/CH2C12_ ~I
n-BuLi, TMEDA n-Bu3SnC_ o +
Hexane -78 C -SnBu 3 -78 C-
PdC12(PPh3)2, Cut, PPh3 _ Qo --C-C-SiMe3 Cu
Me3si-C-CH
THF/Diisopropylamine I DMF
~C-C-SiMe3 C-CH
K2CO3/MeOH, THE M
r.t., 10 h
Me3Si-C-C- HC-C~
M = Fe, Co, Ni
CH3 I
I2, H5I06/CHC13 - H3C \ CH3 KMnO4/H2O KMnO4, KOH H+ 30. H2O, H2SO4, AcOH _
Pyridine, reflux H2O
CH3
I I I
HOOC OCOOH SOCIZ_ CIOC OCOCI NaN3 Acetone, H2O, 0 C N3OC CONS
I I I
I
Benzene KOH/H20 HCI NaHCO3 _ H2N NH2 + C8H171 Na2CO3/DMF, THE
100 C, 24 h
I I I
(C$H17)ZN NH(C8H17)2 C8H171, NaH _ (C8H17)2N N(C8H17)2
15-Crown-5, THE
I I
28
CA 02695856 2010-03-05
O4 CEECH M Pd(PPh3)4, CuI
+ (C8H17)2N N(C8H17)2
M - THF/Diisopropylamine
HC-C--<~
N(C8H17)
CEC
M TONE
(C8H17)21`I
M
C- C--
NC CN N(C8H17)2
M I (C8H17)2N
NC CN NC CN
M M = Fe, Co, Ni
NC CN
P10
[0092] The conjugated bimetallocene polymer is obtained by Sonogashira cross-
coupling
reaction. The amino groups on the benzene ring will ensure the high reactivity
of ethynyl group
with TCNE, while the bimetallocene will facilitate both ethynyl groups in each
repeat unit to
react with TCNE.
H2N NH2 H2N NH2
1:~ KI/H2O2/H2SO4
CH3OH I
H2N - NH2 (C8H17)2N NH(C8H17)
+ C8H171 K2CO3THF/DMF + C81-1171
I / I
NaH/THF (C8H17)2N N(C8H17)2
15-Crown-5
I / I
29
CA 02695856 2010-03-05
O C-CH
(CBH17)2N N(C8H17)2 M
+
I ~ I M
HC- C-~
(C8H17)2N
CC-C N(C8H17)2
M
Pd(PPh3)4, CuI
THF/Diisopropylamine M
C- C
n
NC CN (CgH17)2N
/ \ N(C8H17)2
TCNE NC CN NC CN
M
M = Fe, Co, Ni
NC CN
n
P11
[0093] The unique feature of the polymer P11 is that the amino group lies in
the para-
position of the triple bond, which would give rise to a large increase in the
reactivity of the
triple bond with TCNE. Since P11 has amino groups in para- and ortho-positions
of the triple
bond in this polymer, it is quite possible that both triple bonds in each
repeat unit would react
with TCNE. Also, the meta-benzene unit in P11 would further improve the
solubility of the
polymer.
[0094] (b) Side-Chain TCNE-Based Magnetic Polymers
CA 02695856 2010-03-05
I /-\ NH2 + C4H9I Na2CO3/DMF, THF I /-\ N(C4H9)2 + (CH3)3Si-C-CH
100 C, 24 h
PdC12(PPh3)2, Cul, PPh3 K2CO3/MeOH, THF
THF, diisopropylamine (CH3)3Si-C-C-& N(C4H9)2 r.t., 10 h HC-C - N(C4H9)2
I
H5106, KI _ - PdC12(PPh3)2, CuI, PPh3,
Br Br Br Br + HC-Si(CH3)3
H2SO4, -30 C THF/Diisopropylamine
Br
-~-~
(CH3)3SiC-C C-CSi(CH3)3 + HC-=C N(C4H9)2 PdC12(PPh3)2, Cul, PPh3
THF, diisopropylamine
Br
PhN(C4H9)2 PhN(C4H9)2
iiC iiC
C C
(CH3)3SiC=C C-CSi(CH3)3 K2CO3 HC-C C-CH
THF/CH3OH -
C C
(C4H9)2NPh (C4H9)2NPh
31
CA 02695856 2010-03-05
PhN(C4H9)2
C
C
T I Pd(PPh3)4/CuI C=C
I THE/Diisopropylamine
C
C
(C4H9)2NPh
CN
NC \ PhN(C4H9)2
JCN
NC
TCNE
CHZCIZ CEC C-C~O
CN Fe
NC
(C4H9)2NPh \ CN
NC n
P12
[0095] The metallocene conjugated polymer is also achieved by Sonogashira
cross-
coupling reaction. In the chemical structure of this conjugated polymer, the
two ethynyl groups
in the side chain of each repeat unit are much easier to react with TCNE and
form a very strong
electron donating center, and consequently the two ethynyl groups in the main
chain would
become rather difficult to react with TCNE.
32
CA 02695856 2010-03-05
I I I
H3C CH3 NBS , BrH2C CH2Br P(OEt)g , (EtO)2OPH2C CH2PO(OEt)2
AIB N/Benzene Toluene
I I I
N(CBHn)2
0
C
2
C
+ HC=C aN(CBH,,)2 PdCI2(PPh3)2, CuI, PPh3
(EtO)2OPH2C CH2P0(OEt)2
THE/Di isopropy lam i ne
C
i,
C
0
(C8H 1 7)2N
N(8Hn)2
0
C
C
O-CHO t-BuOK -CH=CH
_ ~ -
+ T
-CHO THE CH=CH-~ C
C
0 n
(CgH17)2N
CN
NC PhN(C8Hn)2
CN
TCNE NC
CH2C12 - O}CH=CH
~M M = Fe, Co Ni
CH=CH--~ CN
NC
(C8HI7)2NPh CC NN
NC
n
P13
33
CA 02695856 2010-03-05
[0096] Since the chemical structure of P12 is very rigid, it has only limited
solubility in
solvents and relatively low molecular weight. Therefore, another magnetic
polymer P13 was
first polymerized by Horner-Wadsworth-Emmons olefination reaction of
dialdehydes and
bisphosphonates and then reacted with TCNE. The solubility of P13 would be
enhanced
considerably due to the use of the ethylene group, which has less rigidity
than the ethynyl
group, and the longer flexible side chains.
[0097] (c) Side-Chain TCNE-Based Magnetic Polymers with TCNE in the
Metallocene
Unit
CH2Br CH2PO(OEt)2
+ P(OEt)3 toluene
CH2Br CH2PO(OEt)2
0
CHO p-Toluenesulfonic acid t-BuLi (C4H9)3SnCl
CHO + HO(CH2)3OH M
CH2CI2 ether
0
Sn(C4H9)3
O~-CHO
M O 12 HCI 3-0 0 + HC-C N(CBHI7)2
CH2C12 THFIH2O, r. t. CHO
O~ I
Sn(C4H9)3
PhN(C8H17)2
C
CCH2PO(OEt)2
CHO
PdC12(PPh3)2, CUL PPh3 + t-BuOK
THF/Diisopropy1 pylamine
OHC THE
CC CH2PO(OEt)2
(C8H17)2NPh/
34
CA 02695856 2010-03-05
C PhN(C8H17)2
C
CH=CH /_\ CH=CH TCNE
C
C,
(C8H17)2NPh/
n
CN
NC PhN(C8H17)2
CN
NC
CH=CH&CH=CH
M
M= Fe, Co, Ni
CN
NC
\ CN
(C8H 17)2NPh
CN
-n
P14
[0098] In the chemical structure of metallocene conjugated polymer P14, which
is also
polymerized by Horner-Wadsworth-Emmons olefination reaction, the two ethynyl
groups in
the side chain are directly linked to metallocene unit, and thus form the
charge transfer
complexes in the side chain.
[0099] The synthesis procedures for a series of high-Tc molecule-based
magnetic
polymers are provided along with the presentation of representative properties
of the
synthesized magnetic polymers via electron spin resonance (ESR) spectrometry
and X-ray
diffraction (XRD). FIG. 23 gives an ESR spectrum of the molecule-based
magnetic polymer
P1. The ESR spectrum indicates the presence of spin-spin interactions between
the constituent
monomers that constitute the P1 magnetic polymer. As seen in FIG. 24a, XRD
pattern
(intensity versus two-theta (20) angle) for the molecule-based magnetic
polymer P1 is given.
The XRD pattern for P1 is clearly distinct from the XRD pattern for iron oxide
as shown in
FIG. 24b. In particular, the XRD pattern for P1 has no reflection peaks for
the values of 20
CA 02695856 2010-03-05
ranging from 30 to 70 degrees, whereas iron oxide has several reflection peaks
in the same
range of 20 values. Thus we can conclude that P1 is substantially devoid of
iron oxide.
[00100] As can be seen in FIGs. 23-25, the molecule-based magnetic polymer P1,
for
example, have the following features: (1) it exhibits the presence of spin-
spin interactions
between the constituent components within the polymer (FIG. 23), (2) it is
free of any
magnetic metallic particles and thus is homogeneous (FIG. 24a), and (3) it is
soluble in
common solvents, as shown in FIG. 25, offering good processability.
[00101] In one embodiment of the invention, the magnetic fluids (liquid
magnets), which
can be prepared from the molecule-based magnetic polymers P1-P14 are
intrinsically
homogeneous. Hence, these liquid magnets can replace conventional ferrofluids
or MR fluids,
which are suspensions of magnetic nanoparticles, currently found in the
marketplace.
[00102] Based upon the foregoing disclosure, and the examples thereof, it
should now be
apparent that the method of preparing molecule-based magnetic polymers and use
of these
polymers in preparing magnetic fluids described herein will carry out the
objects set forth
hereinabove. It is, therefore, to be understood that any variations evident
fall within the scope
of the claimed invention and thus, the selection of specific component
elements can be
determined without departing from the spirit of the invention herein disclosed
and described.
36
