in black and white
Main menu
Share a book About us Home
Biology Business Chemistry Computers Culture Economics Fiction Games Guide History Management Mathematical Medicine Mental Fitnes Physics Psychology Scince Sport Technics

The porphyrin handbook - Kadish K.M.

Kadish K.M. The porphyrin handbook - Academic press, 2000. - 368 p.
Download (direct link): kadishsmishgulilard2000.djvu
Previous << 1 .. 62 63 64 65 66 67 < 68 > 69 70 71 72 73 74 .. 240 >> Next

metalloporphyrins, the volumes of the coordinated ligands were counted as
pan of the porphyrin volume. h Total channel volume is defined as the sum
of void and solvate volume, in A'. Values in brackets refer to the
percentage of total channel volume in the unit eell.
41 / Porphyrin Materials Chemistry

V--N ,f H
N --/
Figure 85. 5,10,15,20-Tetrakis(2',6'-dihydroxyphenyl)porphyrin,
H2[T(2',6'-DHP)P], and 5,10,15,20-Tetrakis(3',5'-dihydroxyphenyl)
porphyrin, H2[T(B',5'-DHP)P].
Figure 86. Molecular packing diagrams of H2[T(3',5'-DHP)P]-5EtOAc
showing (a) channels between porphyrins columns; (b) channels
perpendicular to the columns.135
gallery height strongly indicated that the porphyrins were arranged
perpendicular to the LDH layers.
Tetra-anionic Mnnl(TSPP)-LDH was prepared by anion exchange.172 The
resulting LDH material contained 2.5 to
Figure 87. Molecular packing diagrams of H2[T(3',5'-DHP)P]-7C6H5CN: (A)
showing channels formed by one-dimensional corrugated sheets (light and
dark shading); (B) showing approximately perpendicular channels.135
4.5% of Mn-porphyrin; even after prolonged soaking in methanol and
water, the metalloporphyrin was not extracted. More recently, Besse and
coworkers reported the intercalation of carboxylate [H2(TpCPP)J and
sulfonate [H2(TSPP)] porphyrins in LDH systems by coprecipitation and
anionic exchange.173 Powder X-ray diffraction data and UV-visible
diffuse-reflectance absorption spectra of the intercalated LDH show
complete intercalation. Interlayer d-spacing increased from 18.5 A for
H2(ToCPP)-LDH to 22.9 A for H2(/?TSPP)-LDH and to 22.7 A for H2(TpCPP)-
LDH. Several orientations of the porphyrin molecules between the LDH were
proposed (Figure 114). The authors suggest that the interlayer
arrangement is determined by both the layer-charge density of the host
materials and the isomeric position of the anionic groups substituted on
the guest porphyrin molecules.
Binding of tetracationic porphyrins on layered antimony hydrogen
phosphate and zirconium hydrogen phosphate (a-ZrP) have been reported by
Thompson and coworkers.174 Both monolayer and bilayer guest structures
have been pre-
Chou et al.
Figure 88. (a) Two-dimensional layer from the crystal structure of
Zn[T(3',5'-DHP)P](THF)2 2THF-3CH2CI2; (b) Molecular packing diagram
showing interconnected layers. Porphyrins in dark and light shades
indicate two different layers. Hydrogen-bonding interactions are shown
with dotted lines. Noncoordinated solvates are omitted for clarity.135
pared with the heme guests adopting parallel or tilted orientation
relative to the host layers. The authors argue that the orientation
results from maximization of electrostatic and hydrogen-bonding
interactions between the host and the guest.
From the work just discussed it is clear that clay intercalation of
porphyrins can be done efficiently. The rapid development of materials
such as larger-pore pillared clays should lead to more intense
exploration of this area.
Studies in the areas of conductive polymers and ferroelectric materials
constitute a relatively small subset of porphyrin materials research.
Nonetheless, the versatility of porphyrins has allowed for some
interesting and useful results in these areas. We will examine the
variety of approaches toward the creation of porphyrin-based conductive
polymers and the potential applicability of porphyrinic polymers as
ferroelectric materials.
Figure 89. Molecular packing diagram of Mn[T(3',5'-DHP)P](THF)2,CI-2THF-
5C6H5CH3 showing two-dimensional sheets of porphyrin linked by unusual
square-planar Cl anions hydrogen bonding to four metalloporphyrins.
Spheres indicate bridging chloride ions. Solvate molecules and
coordinated THF ligands omitted for clarity.135
Figure 90. Space-filled diagram showing channels in Mn[T(3',5'-
DHP)P](THF)2-CI-2THF-5C6H5CH3. Solvate molecules and coordinated THF
ligands omitted for clarity.135
1. Conductive Porphyrin Polymers
Electrical conductivity of polymers continues to be one of the most
important research areas for materials science. The conductivity of
metals (typically 102 ~ 103 Q 'em - 1 at room temperature) is generally
higher than for semiconductors, but it is temperature dependence that
truly defines the difference: electrical conductivity of metallic
substances increases with decreasing temperature, while that of a
semiconductor decreases.175 The interest in superconduct-
41 / Porphyrin Materials Chemistry
Figure 91. Molecular packing diagram of H2[T(2'(6'-DHP)P] 4EtOAc
showing two-dimensional layered structure. Hydrogen-bonding interactions
between the hydroxyl groups are shown with dotted lines. Solvent
molecules are omitted for clarity.135
Figure 92. Molecular packing diagram of H2(T(2',6'-DHP)P) 4EtOAc
showing channels between the porphyrin layers. Solvent molecules are
Previous << 1 .. 62 63 64 65 66 67 < 68 > 69 70 71 72 73 74 .. 240 >> Next