Hydrogen-bonded porphyrinic solids: Supramolecular networks of octahydroxy porphyrins

Article abstract of DOI:10.1021/ja971093w

Symmetrically substituted octahydroxy polphyrins, tetrakis(3',5'-dihydroxyphenyl)porphyrin H₂T(3',5'-DHP)P, tetrakis(2',6'-dihydroxyphenyl)porphyrin H₂T(2',6'-DHP)P, and their Zn(II) and Mn(III) derivatives have been developed as building blocks for supramolecular hydrogen-bonded networks. The crystal structures of a series of these porphyrins exhibit unique structural features through assembly of porphyrin networks by means of directional hydrogen bonding. The position of the peripheral hydroxyl groups, the choice of metallo- or free base porphyrin, and the nature of the solvate (i.e., guest) dramatically influence structural features. A one-dimensional, columnar structure is found for H₂T(3',5'-DHP)P·5EtOAc. With benzonitrile as solvate, the structure of H₂T(3',5'-DHP)P·7C₆H₅CN changes substantially to a three-dimensional corrugated-sheet structure in order to accommodate a larger pore Size. When the hydroxyl substituents are simply changed from the m- to the o-phenyl positions, an essentially two-dimensional layered structure is formed for H₂T(2',6'-DHP)P·4EtOAc. Zn[T(2',6'-DHP)P](EtOAc)₂·2EtOAc has a two-dimensional layered structure, similar to that of its free base H₂T(2',6'-DHP)P interaction between the aryl rings of the adjacent layers. The crystal structures of both Zn[T(3',5'-DHP)P] and Mn[T(3',5'-DHP)P](Cl) exhibited three-dimensional hydrogen-bonding features. Zn[T(3',5'-DHP)P](THF)₂·2THF·3CH₂Cl₂ has a three-dimensional interconnected layered structure with metalloporphyrins arranged in a slipped stack orientation within the layers. In the structure of Mn[T(3',5'-DHP)P](THF)₂.Cl·2THF·5C₆H₅CH₃ a chloride anion dictates the three-dimensional packing by bridging four metalloporphyrin molecules through Cl···HO bonding interactions. In all of these structures, large solvate-filled channels are present with cross-sections as large as 42 A?². The pore volumes of these channels are exceptionally large: as much as 67% of the unit cell volume.

Full text of DOI:10.1021/ja971093w

8492
J. Am. Chem. Soc. 1997, 119, 8492-8502
Hydrogen-Bonded Porphyrinic Solids: Supramolecular
Networks of Octahydroxy Porphyrins
P. Bhyrappa, Scott R. Wilson, and Kenneth S. Suslick*
Contribution from the Department of Chemistry, UniVersity of Illinois at Urbana-Champaign,
601 South Goodwin AVenue, Urbana, Illinois 61801
ReceiVed April 7, 1997X
Abstract: Symmetrically substituted octahydroxy porphyrins, tetrakis(3′,5′-dihydroxyphenyl)porphyrin, H2T(3′,5′-
DHP)P, tetrakis(2′,6′-dihydroxyphenyl)porphyrin, H2T(2′,6′-DHP)P, and their Zn(II) and Mn(III) derivatives have
been developed as building blocks for supramolecular hydrogen-bonded networks. The crystal structures of a series
of these porphyrins exhibit unique structural features through assembly of porphyrin networks by means of directional
hydrogen bonding. The position of the peripheral hydroxyl groups, the choice of metallo- or free base porphyrin,
and the nature of the solvate (i.e., guest) dramatically influence structural features. A one-dimensional, columnar
structure is found for H2T(3′,5′-DHP)P‚5EtOAc. With benzonitrile as solvate, the structure of H2T(3′,5′-DHP)P‚7C6H5-
CN changes substantially to a three-dimensional corrugated-sheet structure in order to accommodate a larger pore
size. When the hydroxyl substituents are simply changed from the m- to the o-phenyl positions, an essentially
two-dimensional layered structure is formed for H2T(2′,6′-DHP)P‚4EtOAc. Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc
has a two-dimensional layered structure, similar to that of its free base H2T(2′,6′-DHP)P interaction between the aryl
rings of the adjacent layers. The crystal structures of both Zn[T(3′,5′-DHP)P] and Mn[T(3′,5′-DHP)P](Cl) exhibited
three-dimensional hydrogen-bonding features. Zn[T(3′,5′-DHP)P](THF)2‚2THF‚3CH2Cl2 has a three-dimensional
interconnected layered structure with metalloporphyrins arranged in a slipped stack orientation within the layers. In
the structure of Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2THF‚5C6H5CH3, a chloride anion dictates the three-dimensional packing
by bridging four metalloporphyrin molecules through Cl‚‚‚HO bonding interactions. In all of these structures, large
solvate-filled channels are present with cross-sections as large as 42 Å2. The pore volumes of these channels are
exceptionally large: as much as 67% of the unit cell volume.
Introduction
and co-workers5 have reported a wide range of clathrate-like
host/guest solid state structures of H2TPP and its metal
derivatives. meso-Tetraphenylporphyrins are the most widely
used systems due to their ease of synthesis and facile function-
alization.
In recent years there has been an increasing interest in
nanoporous molecular crystalline solids and their various
applications.1 Of special importance is the development of
molecular building blocks for the design and crystal engineering
of such materials. A wide variety of organic molecules have
been engineered for generating nanoporous crystalline materi-
als.1 Porphyrins and metalloporphyrins provide a relatively
unexplored class of such building blocks because of their large
size, ease of synthesis, excellent thermal stability, and diversity
of their coordination and catalytic chemistry. Furthermore,
porphyrins provide an extremely versatile platform on which
to build desired peripheral functionality with designed orienta-
tions. Such functionality can provide the intermolecular interac-
tions that control self-assembly both in solution and in the solid
state. There have been a few recent reports on the supramo-
lecular architectures of porphyrin solids with hydrogen-bonded2
and metal-organic coordination3 networks. In addition, the
extensive structural work that exists for porphyrins and metal-
loporphyrins4 provides a database for the systematic examination
of intermolecular interactions in the solid state. Notably, Strouse
X Abstract published in AdVance ACS Abstracts, August 15, 1997.
(1) Bein, T., Ed.; Supramolecular Architecture; ACS Symposium Series;
American Chemical Society: Washington, DC, 1992; Vol. 499, pp 88-
253. (b) Komarneni, S.; Smith, D. M.; Beck, J. S. Ed.; AdVances in Porous
Materials; Materials Research Society: Pittsburgh, PA, 1995. (c) Yaghi,
O. M.; Li, G.; Li, H. Nature 1995, 378, 703. (d) Yaghi, O. M.; Hailian, L.;
Groy, T. L. J. Am. Chem. Soc. 1996, 118, 9096 and references cited therein.
(e) Venkataraman, D.; Garner, G. B.; Lee, S.; Moore, J. S. J. Am. Chem.
Soc. 1996, 118, 9096.
(2) Goldberg, I.; Kruptitsky, H.; Stein, Z.; Hsiou, Y.; Strouse, C. E.
Supramol. Chem. 1995, 4, 203 and references cited therein.
(3) (a) Abrahams, B. F.; Hoskins, B. F.; Michall, D. M.; Robson, R.
Nature 1994, 369, 727. (b) Abrahams, B. F.; Hoskins, B. F.; Michall, D.
M.; Robson, R. J. Am. Chem. Soc. 1991, 113, 3606.
In order to more rationally control the structure of porphyrinic
solids, we prepared a family of symmetric octahydroxy-
substituted porphyrins and their metal complexes, wherein the
three-dimensional structure is determined by the directional
hydrogen bonding of hydroxyl groups. We report here the
synthesis of two octahydroxy porphyrins,6 H2T(3′,5′-DHP)P and
H2T(2′,6′-DHP)P, and their Zn(II) and Mn(III) derivatives
(Figure 1) as building blocks for the synthesis of hydrogen-
bonded crystalline solids, together with six X-ray structures
derived from these porphyrins; this paper is an extension of
our preliminary communication of the free base porphyrin
structures.6b Several structural architectures in the packing of
these porphyrins have been observed and are discussed below
in some detail. The use of hydroxy substitution, combined with
the rigidity and high symmetry of the porphyrinic building
blocks, leads to the formation of highly open structures with
large void volumes.
(5) Byrn, M. P.; Curtis, C. J.; Hsiou, Y.; Khan, S. I.; Sawin, P. I.; Tendick,
S. K.; Terzis, A.; Strouse, C. E. J. Am. Chem. Soc. 1993, 115, 9480 and
references cited therein. (b) Krupitsky, H.; Stein, S.; Goldberg, I. J. Inclusion
Phenom. Mol. Recognit. Chem. 1995, 20, 211. (c) Krupitsky, H.; Stein, S.;
Goldberg, I. Strouse, C. E. J. Inclusion Phenom. Mol. Recognit. Chem. 1994,
18, 177.
(6) (a) Abbreviations: T(2′,6′-DMP)P, 5,10,15,20-tetrakis(2′,6′-dimethoxy-
phenyl)porphyrinate(-2); T(2′,6′-DHP)P, 5,10,15,20-tetrakis(2′,6′-dihy-
droxyphenyl)porphyrinate(-2); T(3′,5′-DMP)P, 5,10,15,20-tetrakis(3′,5′-
dimethoxyphenyl)porphyrinate(-2); T(3′,5′-DHP)P, 5,10,15,20-tetrakis-
(3′,5′-dihydroxyphenyl)porphyrinate(-2); EtOAc, ethyl acetate; THF,
tetrahydrofuran. (b) Bhyrappa, P; Wilson, S. R.; Suslick, K. S. Supramol.
Chem. In press.
(4) Scheidt, W. R.; Lee, Y. J. Struct. Bond. (Berlin) 1987, 64, 1.
S0002-7863(97)01093-7 CCC: $14.00 © 1997 American Chemical Society

Hydrogen-Bonded Porphyrinic Solids
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8493
Figure 1. Chemical structures of octahydroxy porphyrins, H2T(3′,5′-
DHP)P and H2T(2′,6′-DHP)P, and their metal derivatives.
Experimental Section
Materials. Octamethoxy porphyrins, 5,10,15,20-tetrakis(2′,6′-
dimethoxyphenyl)porphyrin,7a H2T(2′,6′-DMP)P, and 5,10,15,20-tet-
rakis(3′,5′-dimethoxyphenyl)porphyrin,7b H2T(3′,5′-DMP)P, were syn-
thesized using reported procedures. 5,10,15,20-Tetrakis(3′,5′-dihy-
droxyphenyl)porphyrin, H2T(3′,5′-DHP)P, was prepared using literature
method.7 Demethylation of H2T(2′,6′-DMP)P was unsuccessful with
BBr3 and was carried out using pyridinium hydrochloride at 220 °C
under N2.8 Zinc complexes, Zn[T(2′,6′-DHP)P] and Zn[T(3′,5′-DHP)P],
were prepared by metallation in the usual fashion.9 Dichloromethane,
purchased from Fisher was distilled over CaH2 under nitrogen before
use. Ethyl acetate was purchased from Fisher and used as received.
Toluene obtained from Fisher was distilled over sodium under nitrogen
before use. Tetrahydrofuran was predried from 4 Å molecular sieves
and distilled from sodium/benzophenone under nitrogen before use.
n-Heptane and benzonitrile, C6H5CN, obtained from Aldrich were used
as received.
Synthesis of 5,10,15,20-tetrakis(2′,6′-dihydroxyphenyl)porphyrin,
H2T(2′,6′-DHP)P. Demethylation of H2T(2′,6′-DMP)P was carried out
using reported procedures8 with slight modifications. To a Schlenk
flask containing H2T(2′,6′-DMP)P (0.38 g, 0.5 mmol) was added
pyridinium hydrochloride (20.0 g, 0.17 mol). The reaction mixture
was stirred and refluxed (200-220 °C) under Ar for 2 h. At the end
of this period, the mixture was cooled to room temperature and poured
into water (500 mL). The porphyrin was extracted with ethyl acetate.
The organic layer was washed twice with hydrochloric acid (0.1 M)
followed by saturated aqueous NaHCO3 solution and dried over
anhydrous Na2SO4. The resulting solution was concentrated and
chromatographed on a silica gel column using 20% THF in ethyl acetate
as the eluent. The yield of the product was 0.25 g (75%). Anal. Calcd
for C44H30N4O8‚H2O: C, 69.47; H, 4.24; N, 7.36. Found: C, 69.70;
H, 4.25; N, 7.18. 1H NMR in CD3CN: -2.75 (s, 2H, imino-H), 7.2-
7.8 (12H, m, phenyl-H), and 8.85 (8H, s, pyrrole-H) ppm.
Synthesis of 5,10,15,20-Tetrakis(3′,5′-dihydroxyphenyl)porphi-
natomanganese(III) Chloride, Mn[T(3′,5′-DHP)P](Cl). This com-
plex was prepared using variant of reported procedure.10 To a DMF
(30 mL) solution containing (0.2 g, 0.25 mmol) H2T(3′,5′-DHP)P was
added anhydrous MnCl2 (0.5 g, 3.9 mmol), and the solution was
refluxed for a period of 6 h. At the end of this period, DMF was
removed under reduced pressure. The residue thus obtained was
redissolved in ethyl acetate and washed with distilled water to remove
excess MnCl2. The product was recrystallized from 1:1 mixture of
THF/CH2Cl2 and dried under vacuum at 100 °C for 12 h. The yield
of the product was found to be 0.12 g (65%). Anal. Calcd. for
C44H28N4O8MnCl: C, 63.61; H, 3.40; N, 6.75; Mn, 6.62; Cl, 4.21%.
Found: C, 63.10; H, 3.30; N, 6.65; Mn, 6.40; Cl, 4.30. UV-vis
absorption spectrum in THF, λmax: 375, 395, 479, 523, 584, and 623
Figure 2. Molecular packing diagram of H2T(3′,5′-DHP)P‚6EtOAc
showing one-dimensional columnar structure. Hydrogen-bonding in-
teractions between the hydroxyl groups are shown with dotted lines.
nm. Negative ion electrospray mass spectrum: calcd (m/e) for [M -
Cl]+, 795.67; found, 794.90.
Crystallization. Porphyrin crystals were grown by liquid diffusion
of a second solvent into a porphyrin solution. For H2T(3′,5′-
DHP)P‚5EtOAc, H2T(3′,5′-DHP)P‚7C6H5CN, H2T(2′,6′-DHP)P‚4EtOAc,
and Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc, crystals were grown by direct
diffusion of n-heptane into a EtOAc (or benzonitrile) porphyrin solution.
For Mn[T(3′,5′-DHP)](THF)2‚Cl‚2THF‚5C6H5CH3, toluene was allowed
to diffuse slowly over a period of roughly 3 days into a saturated
solution of Mn[T(3′,5′-DHP)P](Cl) in THF. Crystals of Zn[(T(3′,5′-
DHP)P](THF)2‚2THF‚3CH2Cl2 were grown by direct diffusion of CH2-
Cl2 into a saturated solution of Zn[T(3′,5′-DHP)P] in THF. All
crystallization procedures were carried out at room temperature. The
crystals employed in this study were found to lose solvates upon
removal from the mother liquor, and subsequent loss of crystallinity
occurred. Attempts to replace solvate into dried solids by vapor
diffusion resulted in partial resolvation (based on thermogravimetric
data) in some but not all cases.
X-ray Data Collection. The X-ray diffraction data were collected
on a automated Enraf-Nonius CAD-4 diffractometer. Single crystals
were covered with oil (Paratone-N, Exxon), mounted on to a thin glass
fiber, and then cooled to 198 K to prevent solvate loss. Porphyrin
crystals tend to lose crystallinity upon removal from mother liquor at
room temperature. Intensity data was collected by ω-2θ mode in the
range of 1.0-23° at 198 K. Three standard intensities were monitored
for every 90 min and showed 1.6, 0.8, 0.54, and 0.5% decay for
H2T(3′,5′-DHP)P‚5EtOAc, H2T(3′,5′-DHP)P‚7C6H5CN, Zn[T(3′,5′-
DHP)P](THF)2‚2THF‚3CH2Cl2, and Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2-
THF‚5C6H5CH3 crystals, respectively. No intensity decay was observed
for H2(2′,6′-DHP)P‚4EtOAc and Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc
crystals. No decay corrections were applied.
(7) (a) Tsuchida, E.; Komatsu, T.; Hasegava, E.; Nishide, H. J. Chem.
Soc., Dalton Trans. 1990, 2713. (b) Jin, R.-H.; Aida, T.; Inoue, S. J. Chem.
Soc., Chem. Commun. 1993, 1260.
(8) Momenteau, M.; Mispelter, J.; Loock, B.; Bisagni, E. J. Chem. Soc.,
Perkin Trans. 1 1983, 189.
(9) Dorough, G. D.; Miller, J. R.; Huennekens, F. M. J. Am. Chem. Soc.
1948, 70, 1808.
(10) Jones, R. D.; Summerville, D. A.; Basolo, F. J. Am. Chem. Soc.
1978, 100, 4416.
Crystal structure data for H2T(3′,5′-DHP)P‚5EtOAc: red prismatic
crystals; C64H70N4O18, M ) 1183.24, triclinic, P1h, a ) 7.245(2) Å,
b ) 14.727(3) Å, c ) 14.835(4) Å, a ) 90.18(2)° , â ) 92.90(2)°, γ
) 90.02(2)°, V ) 1580.8(7) Å3, Z ) 1. The structure was refined

8494 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bhyrappa et al.
Figure 3. Crystal packing modes showing close contact and a channel for H2T(3′,5′-DHP)P‚5EtOAc. Solvent molecules are not shown for clarity.
using full-matrix least-squares on Fo2 (data/restraints/parameters 4369:
336:391), converging to R1 ) 0.1138, wR2 ) 0.2801 (on 2588, I >
2σ(I) observed data). The solvate molecules were highly disordered.
restraints/parameters 5942:226:567), converging to R1 ) 0.0797, wR2
) 0.1742 (on 2568, I > 2σ(I) observed data).
Structure Analysis and Refinement. Structures were solved by
direct methods (SHELXS).11a In all cases, porphyrin macrocycle non-
H-atoms were deduced from an E-map. For all structures, one cycle
of isotropic least-squares refinement followed by an unweighted
difference Fourier synthesis revealed positions for ordered atoms. H
atoms and disordered solvate molecules were idealized. Successful
convergence of the full-matrix least-squares refinement on F2
(SHELXL)11b was indicated by the maximum shift/error for the cycle.
Final difference electron density maps for Zn[T(3′,5′-DHP)P](THF)2‚-
2THF‚3CH2Cl2 and Zn[T(2′,6′-DHP)P](EtOAc)2]‚2EtOAc structures
showed a residual density of 1.05 and 1.43 e Å-3 in the vicinity of
disordered solvate molecules, respectively. Final difference electron-
density maps were featureless. Molecular modeling of porphyrins and
solvent molecules were performed on a Silicon Graphics Indigo2
Extreme workstation using Cerius,2 Quanta 4.0, and CHARMm software
package.
Crystal structure data for H2T(3′,5′-DHP)P‚7C7H5N: purple plate-
like crystals; C93H65N11O8, M ) 1464.56, monoclinic, P21/m, a )
11.105(4) Å, b ) 25.744(7) Å, c ) 14.022(3) Å, â ) 108.09(2)°, V )
3811(2) Å3, Z ) 2. The structure was refined using full-matrix least-
2
squares on Fo (data/restraints/parameters 6106:0:548), converging to
R1 ) 0.0622, wR2 ) 0.1305 (on 2588, I > 2σ(I) observed data).
Crystal structure data for H2T(2′,6′-DHP)P‚4EtOAc: purple prismatic
crystals; C60H62N4O16, M ) 1095.14, triclinic, P1h, a ) 13.736(3) Å, b
) 14.032(3) Å, c ) 17.029(3) Å, R ) 93.77(3)°, â ) 110.92(3)°, γ )
111.81(3)°, V ) 2770.9(10) Å3, Z ) 2. The structure was refined using
full-matrix least-squares on Fo2 (data/restraints/parameters 8624:64:846),
converging to R1 ) 0.0457, wR2 ) 0.1129 (on 6260, I > 2σ(I) observed
data).
Crystal structure data for Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc: red
prismatic crystals; C60H60N4O16Zn, M ) 1158.49, triclinic, P1h, a )
10.599(3) Å, b ) 11.301(4) Å, c ) 12.535(6) Å, R ) 85.70(4)°, â )
70.19(4)°, γ ) 79.15(3)°, V ) 1387.2(9) Å3, Z ) 1. The structure
Results and Discussion
2
was refined using full-matrix least-squares on Fo (data/restraints/
In order to more rationally control the structure of porphyrinic
solids, we have examined a pair of symmetric polysubstituted
porphyrins, wherein the three-dimensional structure is deter-
mined by the directional hydrogen bonding of eight hydroxyl
groups per porphyrin. To this end, we have examined two meso-
tetraaryl porphyrins, with four dihydroxyphenyl groups either
m- or o-substituted: H2T(3′,5′-DHP)P and H2T(2′,6′-DHP)P,
and their Zn(II) and Mn(III) derivatives with several different
solvates (Figure 1). The characteristic solid state structural
features of these octahydroxy porphyrins are dictated by
parameters 3850:20:371), converging to R1 ) 0.0984, wR2 ) 0.2527
(on 2610, I > 2σ(I) observed data).
Crystal structure data for Zn[T(3′,5′-DHP)P](THF)2‚2THF‚3CH2Cl2:
purple, plate-like crystals; C63H66N4Cl6O12Zn, M ) 1349.27, triclinic,
P1h, a ) 10.212(3) Å, b ) 12.365(3) Å, c ) 14.628(3) Å, R ) 99.71-
(2)° , â ) 108.52(2)°, γ ) 107.49(2)°, V ) 1597.6(7) Å3, Z ) 1. The
2
structure was refined using full-matrix least-squares on Fo (data/
restraints/parameters 5585:255:528), converging to R1 ) 0.0679, wR2
) 0.1889 (on 4121, I > 2σ(I) observed data).
Crystal structure data for Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2-
THF‚5C6H5CH3: purple, tabular crystals; C95H100N4Cl MnO12, M )
1580.18, monoclinic, P21/n, a ) 13.937(4) Å, b ) 16.443(5) Å, c )
19.541(6) Å, R ) 90°, â ) 106.71(2)°, γ ) 90°, V ) 4289(2) Å3, Z )
2. The structure was refined using full-matrix least-squares on Fo2 (data/
(11) (a) Sheldrick, G. M. SHELXS-86. Acta Crystallogr. 1990, A46, 467.
(b) Sheldrick, G. M. SHELXL-93. Program for the Refinement of Crystal
Structures from Diffraction Data; University of Goettingen, Germany, 1993.

Hydrogen-Bonded Porphyrinic Solids
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8495
(a)
(b)
Figure 4. Molecular packing diagrams of H2T(3′,5′-DHP)P‚5EtOAc
(van der Waals spheres shown at 0.7 of atomic radii): (a) showing
channels of 6.5 Å by 6.5 Å, between the columns; (b) showing channels
of 3.4 Å × 3.4 Å running perpendicular to the columns. Solvent
molecules are not shown for clarity. Distances shown for the channels
exclude van der Waals radii of 3.6 Å.
directional hydrogen bonding. This can lead to one-dimensional
columnar structures, two-dimensional sheet structures, and three-
dimensional networks. The order of discussion below follows
the increasing dimensionality of these solid state structures. As
a consequence of the constraints that the hydrogen-bonding
networks impose, the solids of these complexes have very large
amounts of solvate molecules in the lattice relative to previously
known porphyrin crystals:2,5 in some cases, as many as seven
solvates per porphyrin, with lattice solvate volume occupying
as much as two-thirds of the total.
(A) Free Base Porphyrin Structures. To delineate the effect
of substituent position on the crystal packing and porosity of
the structure, diffraction quality crystals of H2T(3′,5′-DHP)P
and H2T(2′,6′-DHP)P were obtained with the same lattice guest,
ethyl acetate. The observed bond lengths and bond angles for
the porphyrin macrocycle are not significantly different from
that of the meso-tetraphenylporphyrin.20
Figure 5. Depicts the molecular packing of H2T(3′,5′-DHP)P‚7C6H5-
CN complex. Hydrogen bonds are shown in dotted lines. (a) Corrugated
two-dimensional layer of hydrogen-bonded porphyrins. (b) Intercon-
nections by hydrogen bonding between layers. The porphyrins in dark
and light shades indicate front and back, respectively.
H2T(3′,5′-DHP)P‚5EtOAc. As shown in Figure 2, H2T(3′,5′-
DHP)P‚5EtOAc shows an essentially one-dimensional columnar
structure and the unit cell has one porphyrin with five EtOAc
molecules. The structure is controlled by the presence of strong,
directional hydrogen bonding between the meso-(phenylhy-
droxyl) groups. The phenyl rings are roughly perpendicular to
the porphyrin plane with angles of 70-85°. To optimize
hydrogen-bonding interactions, the porphyrin macrocycles are
almost planar and are nearly eclipsed with respect to one another
within each of the columns. Hydrogen bonding exists only
between each porphyrin and its nearest neighbor above and
below within the column, with an interporphyrin plane separa-
tion of 7.0 Å and negligible π-π interactions between the
macrocycles. The average O‚‚‚O separation between hydrogen-
bonded OH groups was found to be 2.68 Å, indicative of strong
directional hydrogen bonding and comparable to previously
reported structures.2
As shown in Figure 3, the columns stack parallel to one
another, forming a porous network in H2T(3′,5′-DHP)P‚5EtOAc.
There is no hydrogen bonding between columns, instead the

8496 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bhyrappa et al.
perpendicular to each other with sizes of 5.5 Å × 6.0 Å (i.e.,
cross-sectional area 33 Å2) and 4.0 Å × 5.0 Å, respectively.
Porphyrin molecules are arranged in an offset fashion to favor
hydrogen-bonding interactions at the expense of π-π interac-
tions.
In the structure of H2T(3′,5′-DHP)P‚7C6H5CN, each porphy-
rin is hydrogen bonded to three closest neighbor porphyrins.
The center-to-center distance between the adjacent layers is
about 12.6 Å, and the vertical distance between nearest
hydrogen-bonded porphyrins is 7.4 Å. Porphyrins are arranged
in an offset fashion within the sheet to maximize hydrogen
bonding between the OH groups, with a mean porphyrin-
porphyrin vertical separation of 7.08 Å. Within the layer, the
average O‚‚‚O distance between the hydrogen-bonded OH
groups is 2.85 Å. The largest vertical separation between the
two nearest neighbors in a given sheet is 13.10 Å. The two
corrugated layers are held together by means of hydrogen
bonding (OH‚‚‚OH) with a mean O‚‚‚O distance of 2.73 Å.
Hydrogen bonding between the porphyrins is partially disrupted
by the benzonitrile due to hydrogen bonding from the porphyrin
hydroxyl groups to nitriles of the solvates with an average O‚‚‚N
distance of 2.85 Å. Two benzonitrile molecules are located
above the porphyrin plane with a mean plane separation of 3.60
Å. The closest separation between the neighboring porphyrin
phenyl rings is 3.44 Å.
H2T(2′,6′-DHP)P‚4EtOAc. When the position of the hy-
droxyl substituents is changed from the m- to the o- positions
of the phenyl rings, a substantial change in the structure
occurs: H2T(2′,6′-DHP)P‚4EtOAc has a two-dimensional lay-
ered structure, as shown in the molecular packing diagram in
Figure 7. The unit cell has two porphyrins, each with four ethyl
acetate molecules. The porphyrin rings are slightly ruffled and
show strong directional hydrogen bonding induced by the
peripheral hydroxyl groups. Each porphyrin has four hydrogen-
bonded nearest neighbors in an offset orientation. The average
hydrogen-bonding distance (O‚‚‚O) is 2.79 Å. In a given layer,
the vertical distance between the offset porphyrins is 7.0 Å.
The center-to-center distance between the adjacent layers is 11.8
Å, and no hydrogen bonding occurs between the porphyrinic
layers. This suggests a minimal interaction between the layers
which are held together by van der Waals forces.
Figure 6. Molecular packing diagrams of H2T(3′,5′-DHP)P‚7C6H5-
CN: (a) showing channels of 5.5 Å × 6.0 Å (molecules shown in
light and dark shades indicates different one-dimensional corrugated
sheets); (b) showing 4.0 Å × 5.0 Å wide channels running ap-
proximately perpendicular to the channels shown in Figure 6a
(molecules shown in dark and light shades indicate front and farther
away, respectively). Atoms are drawn at 70% of their VDW atomic
radii. Solvate molecules are not shown for clarity.
columns are held together by weak van der Waals forces. The
closest intercolumnar phenyl-phenyl ring separations are at 3.79
and 3.69 Å, which indicate only limited π-π interaction
between them. The center-to-center distance between the
adjacent porphyrins of the neighboring columns is 14.83 Å. Four
columns form a large solvate-filled channel of 6.5 Å × 6.5 Å
(van der Waals surface to van der Waals surface), i.e., a cross-
sectional area of 42 Å2 (Figure 4a). There are two smaller
channels (3.4 Å × 3.4 Å) running perpendicular to each other
and perpendicular to the columns, as shown in Figure 4b. The
solvent molecules show some disorder and are free of any
hydrogen-bonding interactions.
H2T(3′,5′-DHP)P‚7C6H5CN. For examination of the effect
of the solvate on the molecular packing in these systems, crystals
of H2T(3′,5′-DHP)P were grown from benzonitrile, a much
larger solvate molecule. The solid state structure of H2T(3′,5′-
DHP)P‚7C6H5CN is dramatically altered by the benzonitrile
(Figure 5). The structure has changed from a one-dimensional
columnar structure (for ethyl acetate) to a three-dimensional
corrugated slipped-stack structure, with a pore size matched to
the benzonitrile. Two corrugated sheets (Figure 5a) are
interconnected by a third, which forms the observed three-
dimensional structure. The unit cell contains 2 planar porphyrin
molecules and 14 benzonitrile solvate molecules. Molecular
packing diagrams (Figure 6) show two solvate-filled channels
There exists an interesting interaction between the layers in
H2T(2′,6′-DHP)P‚4EtOAc. meso-Aryl rings of the adjacent
layers are at a mismatched orientation with one aryl C-H
pointing into the middle of another aryl ring on a porphyrin in
the adjacent layer. The slightly short distance of 3.33 Å from
the aryl C-H to the adjacent porphyrin aryl-carbon indicates
there is weak C-H‚‚‚π interactions between the layers.12
A
channel of about 3.0 Å × 3.6 Å (van der Waals surface to van
der Waals surface) runs along the layers and is filled with ethyl
acetate molecules (Figure 8). Ethyl acetate molecules in the
lattice are hydrogen bonded through their carbonyl groups to
the hydroxyl groups of the porphyrins with an O‚‚‚O average
distance of 2.65 Å.
(B) Metalloporphyrin Structures. For examination of the
effects of metallation on the structures and porosity of these
octahydroxy porphyrins, Zn(II) and Mn(III) complexes were
prepared and crystallized. These both form axially ligated
complexes under crystallization conditions, which increases the
steric demands of the porphyrin building block. For Zn(II)
(12) (a) Steiner, T. J. Chem. Soc., Chem. Commun. 1995, 95. (b) Hunter,
R.; Haueisen, R. H.; Irving, A. Angew. Chem., Int. Ed. Engl. 1994, 33,
566. (c) Desiraju, G. R. Acc. Chem. Res. 1996, 29, 441.

Hydrogen-Bonded Porphyrinic Solids
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8497
Figure 7. Molecular packing diagram of H2T(2′,6′-DHP)P‚4EtOAc showing a two-dimensional layered structure. Hydrogen-bonding interactions
between the hydroxyl groups are shown with dotted lines. Solvent molecules are not shown for clarity.
Figure 9. ORTEP diagram of the metalloporphyrin unit in the crystal
structure of Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc
in Figure 9, the porphyrin ring is nearly planar in Zn[T(2′,6′-
DHP)P] while it is slightly ruffled in H2T(2′,6′-DHP)P. It can
be seen that both crystals have four ethyl acetates per porphyrin.
The ethyl acetate molecules are hydrogen bonded to hydroxyl
groups in H2T(2′,6′-DHP)P, whereas for the Zn(II) complex,
two ethyl acetate molecules are bonded to the metal center
(Figure 9), while the other two are hydrogen bonded to the OH
groups of the porphyrin. Axially ligated ethyl acetate molecules
are in a trans-orientation and are bonded through the carbonyl
oxygen of the ester with an average Zn-O distance of 2.532-
(3) Å. This rather long bond length may represent a crystal-
lographic average of twin disordered five-coordinate complexes
with the Zn atom out of the porphyrin plane closer to one ethyl
acetate and with the second (trans) ethyl acetate only very
loosely interacting. The large thermal parameters in the axial
direction of the Zn and of the coordinated carbonyl oxygen make
this a plausible explanation. Unfortunately, the Zn atom is at
a center of inversion in this structure, so it is not possible to be
more definitive. The average equatorial Zn-N distance is an
unexceptional 2.043(2) Å.
Figure 8. Molecular packing diagram of H2T(2′,6′-DHP)P‚4EtOAc
showing 3.0 Å × 3.6 Å wide channels along the layers. Space filling
is shown at 0.7 of VDW atomic radii, and solvent molecules are not
shown for clarity. Distances shown for the channels exclude van der
Waals radii of 3.6 Å. The porphyrins in dark and light shades indicate
that they are closer and further away, respectively.
metalloporphyrins, six-coordinate13 complexes are less common
than five-coordinate4,14 ones. Mn(III) on the other hand
generally forms six-coordinate complexes in the presence of
excess ligands; in addition, the Mn(III) have a counteranion to
place in the lattice as well. The observed bond lengths and
bond angles for the metalloporphyrin macrocycles are not
significantly different from those of similar metal complexes
of the meso-tetraphenylporphyrin.
Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc. Crystals of H2T-
(2′,6′-DHP)P and Zn[T(2′,6′-DHP)P](EtOAc)2 were prepared
with the same solvate (i.e., guest) to delineate the effect of axial
ligation on the crystal packing and structural porosity. As shown
(13) (a) Schauer, G. C.; Anderson, O. P.; Eaton, S. S.; Eaton, G. R. Inorg.
Chem. 1985, 24, 4082. (b) Bhyrappa, P.; Krishnan, V.; Nethaji, M. J. Chem.
Soc., Dalton Trans. 1993, 1901.
The molecular packing structure of Zn[T(2′,6′-DHP)P]-
(EtOAc)2‚2EtOAc exhibits a two-dimensional layered structure
(Figure 10) remarkably similar to that found in H2T(2′,6′-
(14) Collins, D. M.; Hoard, J. L. J. Am. Chem. Soc. 1970, 92, 3761.

8498 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bhyrappa et al.
Figure 10. Molecular packing diagram of two-dimensional layered structure of Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc; a single plane of hydrogen-
bonded porphyrin complexes is shown. The solvate (noncoordinated) molecules are not shown for clarity.
Figure 11. A perspective view of the Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc showing interlayer (C-Η‚‚‚π) interaction between layers. Coordinated
ethyl acetate molecules are not shown for clarity. Hydrogen-bonding interactions are shown with dotted lines. Molecules shown in dark and light
shades indicate front and farther away, respectively.
DHP)P‚4EtOAc. The two noncoordinated EtOAc molecules
are hydrogen bonded to the hydroxyl groups with an O‚‚‚O
distance of 2.620 Å. The weakly coordinated ethyl acetate
molecules help fill the solvated channel space. The porphyrins
interact through peripheral hydroxyl groups via strong direc-
tional hydrogen bonding and are arranged in an offset fashion
with an interporphyrin vertical separation of 6.91 Å. The
average hydrogen-bonding distance for O‚‚‚O (HO‚‚‚HO) is 2.75

Hydrogen-Bonded Porphyrinic Solids
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8499
Å. Each layer is separated by a center-to-center distance of
11.00 Å. No hydrogen bonding was observed between the
layers.
As seen with H2T(2′,6′-DHP)P‚4EtOAc, there exists an
unusual interaction between the hydrogen-bonded porphyrin
layers in Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc. meso-aryl rings
of the adjacent layers are at a mismatched orientation with one
aryl C-H pointing into the middle of another aryl ring on a
porphyrin in the adjacent layer (Figure 11). The short distance
of 2.71 Å from the aryl C-H to the adjacent porphyrin aryl-
carbon indicates there is some C-H‚‚‚π interactions between
the layers.12
Zn[T(3′,5′-DHP)P](THF)2‚2THF‚3CH2Cl2. Crystals were
not forthcoming from Zn[T(3′,5′-DHP)P] in ethyl acetate, but
Figure 12. ORTEP diagram of the metalloporphyrin unit in the crystal
structure of Zn[T(3′,5′-DHP)P](THF)2‚2THF‚3CH2Cl2.
Figure 13. (a) Two-dimensional layer from the crystal structure of Zn[T(3′,5′-DHP)P](THF)2‚2THF‚3CH2Cl2. Noncoordinated solvates are not
shown for clarity. (b) Molecular packing diagram of Zn[T(3′,5′-DHP)P](THF)2‚2THF‚3CH2Cl2 showing interconnected layers. Porphyrins in dark
and light shades indicate two different layers. Hydrogen-bonding interactions are shown with dotted lines. Noncoordinated solvates are not shown
for clarity.

8500 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bhyrappa et al.
[T(3′,5′-DHP)P](THF)2‚2THF‚3CH2Cl2 has one porphyrin and
seVen solvate molecules (including the ligated THF).
A
molecular packing diagram showing a two-dimensional layered
structure is shown in Figure 13a. Each porphyrin has four
nearest hydrogen-bonded porphyrin neighbors. The interplanar
separation between the hydrogen-bonded neighbors in a given
layer is 6.81 Å. Within each layer the overlapping porphyrins
are separated by 13.32 Å. The porphyrins are arranged in a
slipped-stack orientation within the layer to maximize hydrogen-
bonding interactions, with a mean O‚‚‚O separation of 2.72 Å.
The two noncoordinated THF molecules are hydrogen bonded
to the porphyrin OH groups. The (O‚‚‚O) separation is 2.62 Å
within the layers and 2.71 Å between the layers. Two layers
are interconnected to give a three-dimensional structure, as
shown in Figure 13b. The planes of the phenyl rings are offset
between the adjacent layer, separated by a distance of 5.0 Å,
and show negligible π-π interaction. The nearest neighbor in
the adjacent layer is offset by a vertical distance of 4.98 Å from
the porphyrin plane. In this complex, the adjacent layers are
held together by means of hydrogen-bonding interactions, while
Figure 14. ORTEP diagram of the metalloporphyrin unit in the crystal
structure of Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2THF‚5C6H5CH3.
were formed upon crystallization from THF. The porphyrin
ring is planar with a six-coordinate geometry at the Zn(II) center.
Two oxygen atoms of axial THF molecules are bonded to Zn-
(II) center with a Zn-O distance of 2.44(2) Å (Figure 12). The
average Zn-N distance in the equatorial plane is 2.045(3) Å.
A dramatic change in the crystal packing of H2T(3′,5′-DHP)P
arises with the inclusion of Zn(II) ion. The unit cell of Zn-
(a)
(c)
(b)
Figure 15. Molecular packing diagrams of Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2THF‚5C6H5CH3. The porphyrins in light and dark shades indicate farther
away and front, respectively. (a) Two-dimensional sheets of porphyrins (001 plane) linked by unusual square-planar Cl- anions hydrogen bonding
to four metalloporphyrins. Spheres indicate bridging chloride ions. Solvate molecules and coordinated THF ligands are not shown for clarity. (b)
A perpendicular view of the (100) plane showing interporphyrin hydrogen-bonding interactions. Spheres indicate bridging chloride ions. Solvate
molecules and coordinated THF ligands are not shown for clarity. (c) Space-filled diagram showing channels of 4.6 Å × 3.4 Å (0.7 of their VDW
atomic radii), viewed along the 100 plane (i.e., down the b axis). Noncoordinated solvates are not shown for clarity.

Hydrogen-Bonded Porphyrinic Solids
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8501
Table 1. Calculation of Channel Volumes for Various Porphyrin Complexes
unit cell
vol. (Å3)
porphyrin vol./
solvate vol./
void vol./
total channel vol./
unit cellb (Å3)
porphyrin complex
Z
unit cella (Å3)
590.8
unit cella (Å3)
unit cella (Å3)
H2TPPc
1
801.9
0
412.5
660
211
211
[26.3%]
960.2
[60.7%]
1537.9
[55.5%]
2569.4
[67.4%]
583.2
[42.0%]
841.7
[52.7%]
2676.7
[62.4%]
H2T(3′,5′-DHP)P‚5EtOAc
1
2
2
1
1
2
1581
620.8
1233.0
1241.6
804.1
547.7
877.9
1022
H2T(2′,6′-DHP)P‚4EtOAc
2770.9
3811
H2T(3′,5′-DHP)P‚7C6H5CN
1547
168
Zn[T(2′,6′-DHP)P](EtOAc)2‚2EtOAc
Zn[T(3′,5′-DHP)P](THF)2‚3CH2Cl2‚2THF
Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2THF‚5C6H5CH3
1387.2
1597.6
4289
415.2
514.8
1321.8
755.8
326.9
1355
1612.2
a Porphyrin and solvate van der Waals volumes were calculated using Quanta for each unit cell. Void volume is defined as the unit cell volume
minus the sum of the porphyrin volume and the solvate volume. For the metalloporphyrins, the volumes of the coordinated ligands were counted
as part of the porphyrin volume. b Total channel volume is defined as the sum of void and solvate volume, in Å3. Values in brackets refer to the
percentage of total channel volume in the unit cell. c Crystallographic data is taken from ref 20.
the porphyrin layers in the H2T(2′,6′-DHP)P‚4EtOAc crystal
lattice interact only with weaker van der Waals and C-H‚‚‚π
interactions.
distance between Mn(III) centers is 16.44 Å, while a 13.13 Å
separation is observed between two adjacent Mn(III) centers in
different planes.
Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2THF‚5C6H5CH3. Gener-
ally, Mn(III) porphyrin chloride derivatives retain Cl- as the
axial ligand, regardless of the solvent employed. They tend to
show both five- and six-coordination geometry in the solid state
depending on the crystallization solvent.4,15-19 For example,
even crystallization of MnTPP(Cl) from 1:1 benzene/pyridine
solution does not displace the coordinated Cl-, instead producing
a six-coordinate complex with pyridine occupying the sixth
coordination site.16
Surprisingly, for Mn[T(3′,5′-DHP)P]Cl, the Mn(III) porphyrin
is six-coordinate with two axially ligated THF molecules (Figure
14). The average equatorial Mn-N distance is 2.004(2) Å, and
the average axial Mn-O distance is 2.320(2) Å. A few six-
coordinate complexes derived from MnTPP(ClO4) have been
reported in the literature, including [MnTPP(CH3OH)2](ClO4),17
[MnTPP(DMF)2](ClO4),18 and [MnTPP(2,6-lutidine N-oxide)2]-
(ClO4).19
A chloride ion bridges four hydroxyl groups from four
different porphyrins in a square planar arrangement with an
average Cl‚‚‚O distance of 3.01 Å, as shown in Figure 15a,b.
This unusual mode of anion coordination in Mn[T(3′,5′-DHP)P]-
(THF)2‚Cl‚2THF‚5C6H5CH3 is probably due to lattice stabiliza-
tion by the hydrogen bonding between the Cl- and HO groups.
Packing diagrams of Mn[T(3′,5′-DHP)P](THF)2‚Cl‚2THF‚-
5C6H5CH3 are shown in Figure 15. In Figure 15a, one can see
the two-dimensional porphyrin layers held together by the
unusual square-planar Cl- anions, each hydrogen bonding to
four metalloporphyrin molecules. Figure 15b show that these
layers are themselves interconnected through hydrogen bonding
between metalloporphyrins of different layers, resulting in the
three-dimensional network structure. The largest distance
between the adjacent porphyrins within a layer is 10.27 Å, while
a shortest distance between the offset porphyrins is 5.14 Å. The
molecules are arranged alternatively in an offset fashion to give
interconnected layers. The distance between the aryl rings of
the adjacent porphyrins is greater than 4.69 Å, showing no π-π
interaction between the porphyrins. Within a given layer, the
A space-filled molecular packing diagram shown in Figure
15c reveals 4.6 Å × 3.4 Å channels. There is a very large
amount of solvate in the lattice. The five toluene molecules
show some disorder, whereas the two unligated THF solvates
are well ordered. The axially coordinated THF ligands partially
fill the remaining void volume.
Molecular Modeling. To rationalize the crystal packing and
the void space in these lattices, molecular modeling studies were
performed on these structures. Molecular van der Waals radii
of the solvate and the porphyrin or metalloporphyrin complex
were calculated from energy-minimized structures. The total
void volume of the unit cell was calculated by subtracting total
solvate and porphyrin volumes from crystallographic unit cell
volume and are summarized in Table 1. The porosity of these
structures is striking. Even though porphyrin structures have
been noted for high porosity, very few free base porphyrin
structures show more than three solvates per porphyrin:2,5
triclinic H2TPP, for example, has no solvate.20 As noted in
Table 1, for these hydrogen-bonding porphyrins, the total
channel volume is typically one-half to two-thirds of the total
unit cell.
There is no systematic difference in void space for H2T(2′,6′-
DHP)P versus H2T(3′,5′-DHP)P or their derivatives. Metal ions
do not appear to influence void volume significantly, and the
total channel volumes are comparable to the free base structures,
if one counts the coordinated solvate ligands.
Conclusions
A series of two tetrakis(dihydroxyphenyl)porphyrins and their
metal complexes have been explored as nanoporous supramo-
lecular hydrogen-bonded network solids. The crystal structures
for six such compounds have been determined. The self-
assembly of these porphyrin networks is dominated by direc-
tional hydrogen bonding and is largely independent of π-π
interactions. Profound structural differences arise by simple
permutation of phenyl substitution, solvate, and metal ion.
Examples of one-dimensional columnar, two-dimensional lay-
ered, and three-dimensional network structures have all been
found. In these structures, solvate-filled channels are observed
with cross-sectional areas as large as 42 Å2. The pore volumes
(15) (a) Cheng, H.; Scheidt, W. R. Acta. Crystallogr. 1996, C52, 361.
(b) Tulinsky, A.; Chen, B. M. L. J. Am. Chem. Soc. 1977, 99, 3647.
(16) Kirner, J. F.; Scheidt, W. R. Inorg. Chem. 1975, 14, 2081.
(17) Hatano, K.; Anzai, K.; Iitaka, Y. Bull. Chem. Soc. Jpn. 1983, 56,
422.
(18) Hill, C. L.; Williamson, M. M. Inorg. Chem. 1985, 24, 2836.
(19) Hill, C. L.; Williamson, M. M. Inorg. Chem. 1985, 24, 3024.
(20) Silvers, S. J.; Tulinsky, A. J. Am. Chem. Soc. 1967, 89, 3331.

8502 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bhyrappa et al.
of these channels are exceptionally large and can be as much
as two-thirds of the total unit cell volume.
metalloporphyrins to create heterogeneous catalysts for shape
selective oxidations.21
The present study demonstrates the effect of the directionality
of the porphyrin substituents and size of the solvate on the
supramolecular architectures of these molecules. We are
currently exploring the possibility of using these supramolecular
architectures in conjunction with the established reactivity of
Acknowledgment. We thank Teresa Prussak for technical
assistance in solving the crystal structures. This work was
supported by the National Institute of Health (HL 5R01-25934)
and in part by the DOE (DEFG0291ER45439).
(21) (a) Suslick, K. S. In ComprehensiVe Supramolecular Chemistry;
Bioinorganic Systems; Lehn, J. M., Ed.; Elsevier: London, 1996; Vol. 5,
p 141. (b) Suslick, K. S.; Cook, B. R.; Fox, M. M. J. Chem. Soc., Chem.
Commun. 1985, 580. (c) Cook, B. R.; Reinert, T. J.; Suslick, K. S. J. Am.
Chem. Soc. 1986, 108, 7281. (d) Suslick, K.; Cook, B. J. Chem. Soc., Chem.
Commun. 1987, 200. (e) Suslick, K. S.; Cook, B. R. Shape Selective
Oxidation as a Mechanistic Probe. In Inclusion Phenomena and Molecular
Recognition; Atwood, J. L., Ed.; Plenum Press: London, 1990; pp 209-
215.
Supporting Information Available: Tables of crystal-
lographic data including atomic positional, thermal parameters,
bond lengthes, and bond angles for all the six crystal structures
(46 pages). See any current masthead page for ordering and
Internet access instructions.
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