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The porphyrin handbook - Kadish K.M.

Kadish K.M. The porphyrin handbook - Academic press, 2000. - 368 p.
Download (direct link): kadishsmishgulilard2000.djvu
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al. used the Heck coupling reaction to synthesize conjugated porphyrinic
polymers.1X7 A series of polymers (Figure 117) were generated with Mw
values of
5,000 to 46,000. The polymers were soluble in a range of organic solvents
and were cast as optical films onto glass slides. Their conductivities
were studied, showing a steady increase in current upon photo
irradiation.
Recent studies by Jones and coworkers have produced conjugated
porphyrin polymers with oligophenyleneviny-lene bridges.188189 Using the
Wittig reaction, as illustrated in Figure 118, a series of polymers were
synthesized and labeled PP1 through PP3. The molecular weights, as
determined by GPC, were inversely proportional to bridge length, ranging
from Mn = 6692 (PP3) to 12230 (PP1). To increase solubility of the
polymers in organic solvents, long
a
{0, 0,
0.25)
VaW
Nf '

V-
6-2'
Figure 100. Packing arrangement in [Cu(TPyP)-Cu]" 1 framework. Larger
circles represent copper ions. Solvent and noncoordinating anions omitted
for clarity. Reprinted with permission from Abrahams, B. F.; Hoskins, B.
F.; Michall, D. .; Robson, R. Nature 1994, 369, 727. (c) 1994 Me Millan
Publishers Ltd.
108
Chou et al.

Figure 101. (A) Packing arrangement in [Cu(TCNPP) Cu]"1 framework.
Separate frameworks are indicated by light and dark shading. Large
circles represent copper ions; (B) Schematic representation of extended
framework. Cu(ll) ions in center of porphyrin macrocycle represented by
small circles. Cu(l) ions coordinating between porphyrin molecules
indicated by large circles. Solvate and noncoordinating anions omitted
for clarity. Reprinted with permission from Abrahams, B. F.; Hoskins, B.
F.; Michall, D. .; Robson, R. Nature 1994, 369, 727. (c) 1994 Me Millan
Publishers Ltd.
41 / Porphyrin Materials Chemistry
30 00 Angstroms
Figure 102. Parallel polymeric porphyrin bands showing coordinate bonding
between tetrabidentate porphyrin carboxylate and calcium ions both as
space-filling and schematic models (top). In this schematic model,
intersection of cylinders represents the center of the porphyrin
macrocycle and corners represent calcium ions. Extended three-dimensional
structure showing interpenetration of porphyrin bands (bottom). Guest
pyridine molecules and coordinated water molecules have been omitted for
clarity.
alkoxy groups were appended (it Ihe bridges, per milling casting of
porphyrin films from toluene solution. Preliminary results showed that
the nondoped polymers had conductivities of less Ilian 10 1 'em
. Doping with
nitromethane solutions or anln (.Irons !eC'i; increased
conductivities to approximately 10 f' Q 'em !. The visible spectrum of
the doped polymer, which showed red shifting of the absorption bands
relative to the porphyrin monomer, was indicative of the narrowed HOMO-
LIJMO
gap.
109
i
110
Chou et al.
Figure 104. Crystal packing in Mn(ll) coordinative network of Mn(lll)
derivative of H2(TpCPP).
41 / Porphyrin Materials Chemistry
Figure 105. Crystal packing in H;)(DiC.arPP) molecular species showing
channels between poiphyrin columns. Solvent molecules omitted for
clarity.
c. Conductive Porphyrin-Linked Polymers and Porphyrin Arrays
Another approach taken toward the creation of porphyrin-containing
conductive polymers has been to incorporate porphyrins into the backbone
of traditional conductive polymers. This approach has been studied
extensively by Shimidzu and coworkers.1 ''"-m As shown in Figure I I1).
P(TPP)(CI)2 can react with thienyl or oligothienvl alcohols to generate
the corresponding polymer precursors. Electrochemical oxidation of the
thiophene-containing precursor gives the polymer. These types of polymers
have also been built two-dimensionally via electrochemical polymerization
of 5,10,15,20-oligothienyl-substituted porphyrins. The l-D polymers are
particularly interesting in that the conductivity is enhanced by
photoirradiation. The conductivities of poly-2 and poly-3 were 1.2 x 10
* ii 'em 1 and 5.1 '< It)*
Q 'em respectively, under dark conditions. When irradiated with photons
from a 500-W Xe lamp, conductivity enhancements of greater than threefold
were seen.
2. Ferroelectric Porphyrin Materials
Very little work has been done in the development of coordination
polymers as molecular based ferroelectric materials. Ferroelectric^ carry
a permanent, macroscopic electric dipole moment (i.e.. polarization) in
the absence of an electric Held. Furthermore, the polarization of
ferroelectric materials can be switched with the application of an
external electric field. Ivrroelecti ics have unusual electro-optical,
photorefractive and pyroelectric properties. They can be fabricated into
electronic oscillators, high frequency (liters, electroacoustic
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