Self-assembly of porphyrin arrays via coordination to transition metal bisphosphine complexes and the unique spectral properties of the product metallacyclic ensembles

Article abstract of DOI:10.1021/ja9839825

Self-assembly of predesigned angular and linear dipyridylporphyrin modules with bisphosphine-coordinated Pd(II) and Pt(II) angular and linear modules leads to cyclic porphyrin arrays containing two or four units and ranging in size from 15 to 39 ?. Multinuclear NMR spectra indicate high symmetry for these macrocycles. Restriction in rotation of trans-DPyDPP groups around the axis defined by the terminal metalnitrogen bonds distorts the symmetry of the tetramers, but the rotation is unrestricted at elevated temperatures. Chiral metal triflates containing R(+)- or S(-)-BINAP phosphines promote formation of enantiomeric macrocycles with a puckered geometry. CD spectra of the chiral macrocycles reveal a strong exciton coupling between the porphyrin chromophores in the tetramers. Emission spectra reveal moderate fluorescence quenching of the dipyridylporphyrin fluorophores upon treatment with metal triflates and concomitant incorporation into the macrocycles.

Full text of DOI:10.1021/ja9839825

J. Am. Chem. Soc. 1999, 121, 2741-2752
2741
Self-Assembly of Porphyrin Arrays via Coordination to Transition
Metal Bisphosphine Complexes and the Unique Spectral Properties of
the Product Metallacyclic Ensembles
Jun Fan,† Jeffery A. Whiteford,† Bogdan Olenyuk,† Michael D. Levin,†
Peter J. Stang,*,† and Everly B. Fleischer‡
Contribution from the Departments of Chemistry, UniVersity of Utah, Salt Lake City, Utah 84112, and
UniVersity of California, IrVine, California 92697
ReceiVed NoVember 17, 1998
Abstract: Self-assembly of predesigned angular and linear dipyridylporphyrin modules with bisphosphine-
coordinated Pd(II) and Pt(II) angular and linear modules leads to cyclic porphyrin arrays containing two or
four units and ranging in size from 15 to 39 Å. Multinuclear NMR spectra indicate high symmetry for these
macrocycles. Restriction in rotation of trans-DPyDPP groups around the axis defined by the terminal metal-
nitrogen bonds distorts the symmetry of the tetramers, but the rotation is unrestricted at elevated temperatures.
Chiral metal triflates containing R(+)- or S(-)-BINAP phosphines promote formation of enantiomeric
macrocycles with a puckered geometry. CD spectra of the chiral macrocycles reveal a strong exciton coupling
between the porphyrin chromophores in the tetramers. Emission spectra reveal moderate fluorescence quenching
of the dipyridylporphyrin fluorophores upon treatment with metal triflates and concomitant incorporation into
the macrocycles.
Introduction
rosettes,13 dendrimers,14 and others.15 The porphyrin oligomers
have been synthesized by either covalent attachment of the
monomers3,4,7-9,10b,14 or methods of self-assembly.10a,c-13,15
Porphyrin arrays consisting of up to nine units have been
reported.11
Nevertheless, the challenge remains for the preparation of
new porphyrin-containing oligomers with well-defined structure
and properties, since the optimal molecular arrangement for
various applications has yet to be realized. Moreover, we have
found no reports of chiral porphyrin arrays with more than two
units.16 Preparation of the porphyrin arrays in high yields and
significant quantities is still problematic. One of the major
obstacles for porphyrin derivatives is low solubility, which
complicates scale-up and characterization of the products.1 In
A significant amount of practical insight has been gained and
correlated to natural chromophores by designing and comparing
light harvesting porphyrin arrays and aggregates to monopor-
phyrin systems.1 Various molecular devices based on oligo-
porphyrins have recently been engineered and prepared, such
as artificial photosynthetic systems,2 photoinduced picosecond
molecular switches,3 optoelectronic gates,4 fluorescence quench-
ing sensors,5 photonic wires,6 and cancer therapy agents.7 The
porphyrin array architectures reported to date include linear
chains,7,8 cyclic oligomers,9 squares,10 sheets and tapes,11 stars,12
† University of Utah.
‡ University of California, Irvine.
(1) For a comprehensive monograph, see: The Porphyrins; Dolphin, D.,
Ed.; Academic: New York, 1978.
(10) (a) Drain, C. M.; Lehn, J. M. J. Chem. Soc., Chem. Commun. 1994,
2313. (b) Wagner, R. W.; Seth J.; Yang, S. I.; Kim, D.; Bocian, D. F.;
Holten, D.; Lindsey, J. S. J. Org. Chem. 1998, 63, 5042. (c) Slone, R. V.;
Hupp, J. T. Inorg. Chem. 1997, 36, 5422.
(11) Drain, C. M.; Nifiatis, F.; Vasenko, A.; Batteas, J. D. Angew. Chem.,
Int. Ed. Engl. 1998, 37, 2344.
(12) Yuan, H.; Thomas, L.; Woo, L. K. Inorg. Chem. 1996, 35, 2808.
(13) Drain, C. M.; Russell, K. C.; Lehn, J.-M. Chem. Commun. 1996,
337.
(2) (a) Wasielewski, M. R. Chem. ReV. 1992, 92, 435. (b) Gust, D.;
Moore, T. A.; Moore, A. L. Acc. Chem. Res. 1993, 26, 198. (c) Harriman,
A.; Sauvage, J.-P. Chem. Soc. ReV. 1996, 41. (d) Van Patten, P. G.; Shreve,
A. P.; Lindsey, J. S.; Donohoe, R. J. J. Phys. Chem. B 1998, 102, 4209.
(3) Gosztola, D.; Niemczyk, M. P.; Wasielewski, M. R. J. Am. Chem.
Soc. 1998, 120, 5118.
(4) Wagner, R. W.; Lindsey, J. S.; Seth, J.; Palaniappan, V.; Bocian, D.
F. J. Am. Chem. Soc. 1996, 118, 3996.
(5) De Silva, A. P.; Gunaratne, H. Q. N.; Gunnlaugsson, T.; Huxley, A.
J. M.; McCoy, C. P.; Rademacher, J. T.; Rice, T. E. Chem. ReV. 1997, 97,
1515 and references therein.
(14) Xu, Z.; Moore, J. S. Acta Polym. 1994, 45, 83.
(15) (a) Alessio, E.; Macchi, M.; Heath, S.; Marzilli, L. G. Inorg. Chem.
1997, 36, 5614. (b) Alessio, E.; Macchi, M.; Heath, S.; Marzilli, L. G. J.
Chem. Soc., Chem. Commun. 1996, 1411. (c) Kobuke, Y.; Miyaji, H. Bull.
Chem. Soc. Jpn. 1996, 69, 3563. (d) Stibrany, R. T.; Vasudevan, J.; Knapp,
S.; Potenza, J. A.; Emge, T.; Schugar, H. J. J. Am. Chem. Soc. 1996, 118,
3980. (e) Tamiaki, H.; Miyatake, T.; Tanikaga, R.; Holzwarth, A. R.;
Schaffner, K. Angew. Chem., Int. Ed. Engl. 1996, 35, 772. (f) Amabilino,
D. B.; Dietrich-Bucheker, C. O.; Sauvage, J.-P. J. Am. Chem. Soc. 1996,
118, 3285. (g) Rao, T. A.; Maiya, B. G. J. Chem. Soc., Chem. Commun.
1995, 939. (h) Anderson, S.; Anderson, H. L.; Sanders, J. K. M. Acc. Chem.
Res. 1993, 26, 469.
(16) For examples of chiral self-assembled macrocycles see: (a) Mu¨ller,
C.; Whiteford, J. A.; Stang, P. J. J. Am. Chem. Soc. 1998, 120, 9827. (b)
Stang, P. J.; Olenyuk, B. Angew. Chem., Int. Ed. Engl. 1996, 35, 732. (c)
Olenyuk, B.; Whiteford, J. A.; Stang, P. J. J. Am. Chem. Soc. 1996, 118,
8221.
(6) Wagner, R. W.; Lindsey, J. S. J. Am. Chem. Soc. 1994, 116, 9759.
(7) (a) Sousa, C.; Maziere, C.; Maziere, J. C. Cancer Lett. 1998, 128,
177. (b) deVree, W. J. A.; Essers, M. C.; Sluiter, W. Cancer Res. 1997,
57, 2555. (c) Jasat, A.; Dolphin, D. Chem. ReV. 1997, 97, 2267.
(8) (a) Taylor, P. N.; Wylie, A. P.; Huuskonen, J.; Anderson, H. L.
Angew. Chem., Int. Ed. Engl. 1998, 37, 986. (b) Nishino, N.; Wagner, R.
W.; Lindsey, J. S. J. Org. Chem. 1996, 61, 7534. (c) Wagner, R. W.;
Johnson, T. E.; Lindsey, J. S. J. Am. Chem. Soc. 1996, 118, 11166. (d)
Osuka, A.; Tanabe, N.; Zhang, R. P.; Maruyama, K. Chem. Lett. 1993, 9,
1505. (e) Hammel, D.; Erk, P.; Schuler, B.; Heinze, J.; Mu¨llen, K. AdV.
Mater. 1992, 4, 737.
(9) (a) Vidal-Ferran, A.; Clyde-Watson, Z.; Bampos, N.; Sanders, J. K.
M. J. Org. Chem. 1997, 62, 240. (b) Anderson, S.; Anderson, H. L.; Sanders,
J. K. M. J. Chem. Soc., Perkin Trans. 1 1995, 2255.
10.1021/ja9839825 CCC: $18.00 © 1999 American Chemical Society
Published on Web 03/11/1999

2742 J. Am. Chem. Soc., Vol. 121, No. 12, 1999
Fan et al.
Table 1. Size of Various Porphyrin Tetramers Based on MM2
Scheme 1
Calculations
building modules
corresponding
macrocycles
linear
angular
diagonal (Å)
side (Å)
none
4L1
4L2
2A1 + 2A2
4A2
4A1
20-23, 29, 30
12-19, 26-28
24, 25
15
29
39
12
20
24
Scheme 2
this paper, we describe the preparation of well-defined, highly
soluble, readily available, macrocyclic arrays of two or four
pyridyl-substituted porphyrins by self-assembly with bisphos-
phine-coordinated transition metal triflates.17 We have synthe-
sized achiral and chiral cyclic arrays and studied their structure
and properties by NMR, UV, emission, and CD spectroscopic
techniques.
Results and Discussion
Design of Macrocycles. The self-assembly of rigid macro-
cycles requires well-defined, geometrically templated, building
block precursors.18 Specifically, the assembly of square-shaped
arrays requires four preprogrammed, 90° angular modules,
which may be supplemented by four linear modules. Di(4′-
pyridyl)porphyrins substituted in positions 5 and 10 or 5 and
15 (1-6) can serve as the angular or linear building blocks,
respectively. Square-shaped arrays of three types have been
prepared based on the di(4′-pyridyl)porphyrins (Scheme 1). In
the smaller macrocycles two 5,10-di(4′-pyridyl)porphyrins (1,
2, modules A1) alternate with two transition metal-based angular
units A2 (7-10). 5,15-Di(4′-pyridyl)porphyrins (3-6) are used
as the linear modules L1 spanning four angular units A2. Finally,
four porphyrin-containing angular blocks A1 have been used to
connect four platinum-terminated linear modules L2. Both free
base porphyrin (1, 3, and 5) and zinc porphyrin derivatives (2,
4, and 6) are employed as the modules A1 and L1. Bistriflates
of 1,3-bis(diphenylphosphino)propane (dppp), 2,2′-bis(diphenyl-
phosphino)-1,1′-binaphthyl (BINAP), dpppPd(II) (7), dpppPt(II)
(8), and R(+)-, S(-)-BINAP-Pd(II) (9 and 10) have been used
as precursors for the angular units A2, and 1,4-bis-[trans-Pt-
(PEt3)2(OTf)]benzene (11) has been used as the precursor for
the linear units L2. The geometrical parameters of the molecular
squares, as evaluated by molecular modeling (modified MM2),19
are listed in Table 1.
Synthesis and General Properties of Macrocycles. Achiral
cyclic tetramers 12-19 were obtained by reacting bistriflates
of dpppPd(II) or dpppPt(II) (7 and 8) with 5,15-di(4′-pyridyl)-
10,20-diphenylporphyrin (trans-DPyDPP) (3), 5,15-di(4′-pyr-
idyl)-3,7,13,17-tetramethyl-2,8,12,18-tetrahexylporphyrin (trans-
DPyTTP) (5), and their zinc-containing analogues 4 and 6
(Scheme 2). The triflates 7 and 8 were also reacted with 5,10-
di(4′-pyridyl)-15,20-diphenylporphyrin (cis-DPyDPP) (1) and
cis-ZnDPyDPP (2) to yield the smaller macrocycles 20-23
(Scheme 3). Larger macrocycles 24 and 25 resulted from the
reaction between the angular porphyrin precursors 1 and 2 and
1,4-bis[trans-Pt(PEt3)2(OTf)]benzene (11, Scheme 4). The chiral
macrocycles 26 and 27 were formed in good yields by the
reaction of trans-DPyDPP (3) with pure R (+)- or S (-)-
BINAP-Pd(II) bistriflates 9 and 10 (Scheme 5). trans-ZnD-
PyDPP (4) yielded the tetramer 28 upon reaction with 9.
Reaction of cis-DPyDPP (1) with the triflates 9 and 10 gave
access to the chiral dimer macrocycles 29 and 30, respectively
(Scheme 6).
(17) For a preliminary communication see: Stang, P. J.; Fan, J.; Olenyuk,
B. J. Chem. Soc., Chem. Commun. 1997, 1453.
(18) (a) Olenyuk, B.; Fechtenko¨tter, A.; Stang, P. J. J. Chem. Soc., Dalton
Trans. 1998, 1707. (b) Stang, P. J.; Olenyuk, B. Acc. Chem. Res. 1997, 30,
502 and references therein. (c) Fujita, M. J. Synth. Org. Chem., Jpn. 1996,
54, 953 and references therein.
(19) (a) MM2 single point calculations and geometry optimization was
performed with CS Chem3D Pro, Version 3.5.1, CambridgeSoft Corporation,
875 Massachusetts Avenue, Cambridge, MA 02139. (b) ESFF potential set
geometry optimization was performed with INSIGHT II (97.0) and Discover
3, BIOSYM. The dielectric constant was set to 8.0.

Self-Assembly of Porphyrin Arrays
J. Am. Chem. Soc., Vol. 121, No. 12, 1999 2743
Scheme 3
Scheme 5
1
R-pyridyl protons in the H NMR spectra, while the metal-
containing reagent has a distinctive signal for the bisphosphine
ligands in the proton-decoupled 31P NMR spectra. Excess of
either reagent can be quenched with the other reagent without
significant effect on the yield. When the correct stoichiometry
is achieved, the corresponding signals of the starting materials
disappear. The formation of the respective macrocycle is
complete when the line width of the 31P{1H} NMR signal
reaches its minimum.
Scheme 4
Dichloromethane is the preferred solvent in most cases, but
acetone or mixtures of chloroform and methanol are required
for the zinc-containing porphyrins 2, 4, and 6 because of low
solubility in dichloromethane. Longer reaction times and higher
temperatures are usually needed for the completion of the
reactions involving zinc-containing porphyrin derivatives, and
somewhat lower isolated yields are observed in these reactions.
Formation of the dimer macrocycles 20-23 proceeds faster than
that of the tetramer macrocycles. The purple-red microcrystalline
macrocycles precipitate out of the reaction mixture upon addition
of diethyl ether. Analytically pure samples are obtained by
redissolving the assemblies in the original solvent and recrystal-
lizing them upon slow infusion of diethyl ether.
Interestingly, all macrocycles are more soluble than the
precursor porphyrins alone. Presumably, the positive charge of
the macrocycles and the arrangement of the phosphine ligands
is such that they project out of the plane defined by the corners
of the macrocycles, and prevent intermolecular stacking. This
makes the crystal packing less thermodynamically favorable,
and, thus, increases the solubility of the macrocycles. In this
respect, the bisphosphine-coordinated Pd(II) and Pt(II) angular
modules have solubility advantages over the analogous neutral
transition metal chlorides used previously.10a,11 The higher
solubility of the charged porphyrin oligomers allows one to carry
out self-assembly on a preparative scale at a higher concentration
without precipitation of the intermediates.
Since both reagents in these reactions contain variable
amounts of water, it is necessary to monitor the stoichiometry
of the reagents by NMR while preparing these assemblies. The
pyridyl-containing reagent has a characteristic signal for the

2744 J. Am. Chem. Soc., Vol. 121, No. 12, 1999
Fan et al.
Scheme 6
Figure 1. Assignment of the aromatic region of the 1H NMR spectrum
of tetramer 13, 5.5 × 10-3 M in acetone-d6 at ambient temperature.
The tetramers are stable below 240 °C, while the dimers
decompose when heated above 350 °C. The decomposition
temperature of the Pt-based macrocycles is 30-40 °C higher
than those of their Pd-based analogues. Additionally, the
macrocycles are somewhat hydroscopic in the solid state and
light sensitive in solution.
These spectroscopic data are in accord with the results of
molecular modeling of the structure of tetramers 12-15 and
with studies of restricted rotation in pyridine-transition metal
complexes.21 At the optimized geometries (modified MM2)19
for the tetramers, the pyridyl groups are perpendicular to the
coordination plane of the metals and the plane of the porphyrin
rings. This forces the porphyrin rings to be nearly coplanar with
each other resulting in a planar macrocycle. Rotation around
the metal-nitrogen bonds and the bonds between the pyridyl
and porphyrin moieties is slow at ambient temperature on the
NMR time scale, and this causes splitting of the signals and/or
broadening of the lines in the spectra.16c The line widths and
the splitting patterns vary with solvent, temperature, and the
coordinated metal. In less polar solvents (e.g. chloroform as
compared to acetone) the signals due to the pyridyl-bound
R-protons and the phenyl-bound dppp protons are broader, and
the splitting between the signals of the porphyrin-bound protons
is larger. This splitting is reduced at elevated temperatures. In
the dpppPd-based tetramer 12, the upfield signals, attributed to
the phenyl-bound protons of the trans-DPyDPP moiety (Hph and
NMR Spectra
trans-Dipyridylporphyrin Tetramers. The macrocycles 12-
15 have complex, but similar 1H NMR spectra. The assignment
of the aromatic region of the 1H NMR spectrum of 13 in
1
acetone-d6 (Figure 1) was based on a H-1H COSY NMR
spectrum and by comparison with the spectra of other dppp
chelated macrocycles. The doublets at δ 9.7 and 8.4 ppm are
due to the R- and â-protons of the pyridyl moieties. The signals
of the R-protons in 12-15 are significantly shifted downfield
compared to those in the parent porphyrin due to coordination
of the pyridyl group to a metal.10a,c,12 The four signals between
δ 8.1 and 9.1 ppm are attributed to the porphyrin-bound protons
(Hp and Hp′). The number of these signals is twice as large as
the number of the corresponding signals in the parent trans-
DPyDPP (3). The doubling of the number of signals is caused
by the orientation of the porphyrin rings in the macrocycle such
that half of the protons (Hp′) are located inside of the macrocycle,
while the other half (Hp) are located outside of the macrocycle.
The intense signals at δ 8.3 and 7.8 ppm are assigned to the
phenyl-bound protons of the dppp groups (HL). Finally, the four
signals at δ 8.3,20 8.0, 7.0, and 6.1 ppm are due to the protons
attached to the phenyl groups in positions 10 and 20 on the
porphyrin rings (Hph and Hph′). As in the case of the signals of
the porphyrin-bound protons, the large number of signals from
the phenyl-bound Hph and Hph′ is due to inequivalent phenyl
groups located inside and outside of the macrocycle, respec-
tively.
Hph′), coalesce around 60 °C in CDCl3 solution. For the dpppPt-
based tetramer 13 the effect of temperature is less pronounced,
and the coalescence cannot be reached below the boiling point
of CDCl3 at ambient pressure. Restriction in rotation around
the metal-nitrogen bonds is relaxed at elevated temperature
and in more polar solvents. The fact that the ligands rotate faster
in the Pd-based macrocycles compared to the Pt-based analogues
is in accord with the previous studies of such rotation.21
The 31P{1H} NMR spectra of each of the tetramers 12 and
14 consist of one singlet at ambient conditions. The 31P{1H}
NMR spectra of tetramers 13 and 15 are similar to those of 12
and 14, except that they contain platinum satellites due to the
195Pt-31P spin-spin coupling. Compared to the 31P{1H} NMR
1
(20) This signal overlaps in the 1D H NMR spectrum with a signal of
(21) (a) Fuss, M.; Siehl, H.-U.; Olenyuk, B.; Stang, P. Organometallics
1999, 18, in press. (b) Stang, P. J.; Olenyuk, B.; Arif, A. M. Organometallics
1995, 14, 5281.
dppp phenyl-bound protons. It has been assigned based on the 1H-1H COSY
NMR spectrum of 13.

Self-Assembly of Porphyrin Arrays
J. Am. Chem. Soc., Vol. 121, No. 12, 1999 2745
signals are presumably due to one or more other conformers.
Analysis of the possible mutual arrangements of the porphyrin
modules in the tetramers (Figure 3) shows that only two
conformers possess the required symmetry to give the experi-
mentally observed 31P{1H} NMR spectrum. A dome-shaped
structure I, where the four transition metals define the plane, is
in the C4 symmetry point group (Figure 3a) while the puckered
configuration II is defined as D2 (Figure 3b). In the latter
structure the porphyrin rings are oriented such that two C2
symmetry axes are passing through four meso carbon atoms of
the opposite side rings. Each structure contains four equivalent
bisphosphine ligands, with a pair of inequivalent phosphorus
nuclei at each metal center. Molecular modeling (modified MM2
and ESFF)19 suggests that structure II has a lower energy than
structure I. Furthermore, no local minimum has been found for
a structure with C4 symmetry. Geometry optimization (ESFF)
yielded several local minima (e.g, III, Figure 3c) with structures
similar to II. All these structures have the same puckered
geometry but differ in the relative orientation of the porphyrin
rings, which are con- or disrotated by about 30° around the Pd-
Pd axis. This relieves some strain from steric interaction between
the porphyrin-bound phenyl groups. Apparently, structure II is
the average of the less symmetric structures with local minima,
which is in agreement with the 31P NMR data. Furthermore,
the puckered structure is also favored by the BINAP-coordinated
metal corners since they prefer the pyridyl ligand planes with
a dihedral angle less than 90°.
Interestingly, the coalescence of the signals in the 31P NMR
spectra of the BINAP-containing tetramer 26 occurs at a much
higher temperature than that of the analogous dppp-containing
tetramer 13. Assuming the puckered structure II for the tetramer
26, the difference in the coalescence temperatures can be
explained by a difference in the mechanism by which the
macrocycles 13 and 26 increase their symmetry, or by a different
barrier to puckering in the corresponding macrocycles.
cis-Dipyridylporphyrin Dimers and Tetramers. The spectra
of the cis-DPyDPP dimers 20-23 and tetramers 24 and 25 are
similar to those of the trans-DPyDPP tetramers 12-15. The
signals in the 1H NMR spectra of the dimers 20-23 are narrower
compared to those of 12-15, presumably due to the lack of
conformational changes at ambient temperature on the NMR
time scale. The 1H NMR spectra of the tetramers 24 and 25 are
simpler than those of the dppp-containing macrocycles since
they do not contain the signals from the dppp phenyl groups.
The signals due to the pyridyl-bound protons in 24 and 25 are
shifted upfield compared to those in the other macrocycles.
The 31P{1H} NMR spectra of the macrocycles 20-23 consist
of single signals, which indicates that all the phosphorus nuclei
are equivalent. The signals are shifted upfield by ca. 15 ppm
compared to those of the starting bistriflates 7 and 8 as a result
of a strong coordination of the pyridyl groups to the transition
metals. The 31P{1H} NMR spectra of the macrocycles 24 and
25 consist of a singlet with two symmetrical satellites. The
singlet is shifted upfield by 4 ppm compared to that of the
starting bistriflate. The 19F NMR spectrum of every individual
macrocycle consists of one narrow singlet at around δ -77 ppm,
which is characteristic for an uncoordinated triflate anion.23
Figure 2. 31P{1H} NMR spectra of the tetramer 26 in a CD3NO2
solution at various temperatures.
signals of the bistriflates 7 and 8, the tetramer signals are shifted
upfield by ∼10 ppm, indicative of the coordination of the
nitrogen lone pair to the transition metal.22 The singlet in the
spectrum of 13 splits into two below 0 °C in CDCl3. The
splitting of the signal is most likely due to the slow intercon-
version of conformers with inequivalent phosphorus nuclei. The
conformers may be formed in two ways. If all four metal corners
are in one plane, the conformers will differ by the mutual
orientation of the porphyrin moieties with their parts inside and
outside of the macrocycle above or below the plane. If the
geometry of the cyclic tetramers is puckered, the conformers
will differ by the relative arrangement of the porphyrin cores
to the puckering angle. In the former case, the coalescence of
the 31P{1H} NMR signals in the tetramers corresponds to the
unfreezing of the restricted rotation of the porphyrin modules
so that they can turn around the coplanar arrangement, but still
cannot rotate freely around the axis defined by the metals. In
the latter case, coalescence of the signal suggests unfreezing of
the puckering motion in the macrocycles.
The 31P{1H} NMR spectra of the chiral phosphine containing
tetramers 26, 27, and 28 consist of two signals. The major signal
has an AB pattern, caused by the spin-spin coupling of two
inequivalent 31P nuclei coordinated to the same metal. A less
intense broad signal appears close to the center of the AB pattern
of the major signal. In the case of the macrocycle 26, these two
signals collapse into one sharp singlet at ca. 60 °C in a CD3NO2
solution (Figure 2). The changes are reversible upon cooling.
This observation allows the assignment of the AB pattern to
the most favorable macrocycle conformer, while the minor
Mass Spectrometry
Fast atom bombardment mass spectrometry (FABMS) analy-
sis of 20 and 21 gave M - OTf peaks of m/z 2716.5 and m/z
2895.8, respectively, with +1 charge states (i.e., separation of
(22) Stang, P. J.; Cao, D. H.; Saito, S.; Arif, A. M. J. Am. Chem. Soc.
1995, 117, 6273.
(23) Lawrance, G. A. Chem. ReV. 1986, 86, 17.

2746 J. Am. Chem. Soc., Vol. 121, No. 12, 1999
Fan et al.
Figure 3. (a) Structure I: Only meso-carbons of porphyrins and Pd atoms are shown. (b) Structure II: Only meso-carbons of porphyrins and Pd
atoms are shown. (c) Structure III: Only meso-carbons of porphyrins and Pd atoms are shown.
peaks by 1 m/z unit) resulting from a loss of one triflate from
a total of four. Also indicative of the proposed molecule were
the isotopic distribution patterns which were very close to the
calculated compositions of the species. The calculated and
experimental isotopic distribution patterns of the platinum
analogue 21 are shown in Figure 4. Although this technique
has been successful in producing evidence for the smaller
macrocycles 20 and 21 and several other examples,24 the upper
molecular weight limit is approximately 4000-5000 amu.
Alternatively, electrospray mass spectrometry (ESMS) has been
successful in identifying the composition of larger aggregates
and assemblies (5000-10000).25 Application of this technique
to macrocycle 16 gave similar results to previously reported
examples studied by ESMS. The observation of the +4 species
(1525.3 m/z) resulting from the loss of four triflate counterions
(from a total of eight) and the isotopic distribution consistent
with the theoretical isotopic envelope confirmed the composition
of macrocycle 16.
Absorption and Emission Spectra
The maxima of the Soret and Q-bands, characteristic for the
porphyrin chromophores,26 are red-shifted by 8-12 nm in the
macrocycles 12-30 as compared to those of the starting
porphyrins. This shift is more pronounced for the Pt-containing
macrocycles. Analogous but smaller shifts have been reported
for Pt(II)- and Pd(II)-coordinated monopyridyl porphyrin deriva-
tives.12
Figure 4. Experimental (top) and calculated (bottom) isotopic distribu-
The Soret bands of the macrocycles 12-30 are broader
tion pattern of (M-OTf)+ for 21.
compared to those of the starting porphyrins 1-6, which may
be attributed to an intramolecular exciton coupling between the
porphyrin chromophores in the macrocycles. The extinction
coefficient per porphyrin unit decreases upon formation of
almost every macrocycle. The only exception is trans-ZnDPy-
DPP (4). Its absorption in solution is depressed (ꢀ 79 000 mol-1
× cm-1 at λ 420 nm) compared to other similar porphyrins (ꢀ
ca. 350 000 mol-1 × cm-1), presumably due to an extensive
intermolecular coordination of the pyridyl groups to the zinc
(24) Whiteford, J. A.; Rachlin, E. M.; Stang, P. J. Angew. Chem., Int.
Ed. Engl. 1996, 35, 2524. mass spec ref 4000-5000 mw limit.
(25) Manna, J.; Kuehl, C. J.; Whiteford, J. A.; Stang, P. J.; Muddiman,
D. C.; Hofstadler, S. A.; Smith, R. D. J. Am. Chem. Soc. 1997, 119, 11611.
mass spec ref 5000-10000 mw limit.
(26) Gouterman, M. In The Porphyrins. Vol. 3, Physical Chemistry, Part
A; Dolphin, D., Ed.; Academic: New York, 1978.

Self-Assembly of Porphyrin Arrays
J. Am. Chem. Soc., Vol. 121, No. 12, 1999 2747
Figure 5. Absorption spectra of reaction mixtures of cis-DPyDPP (1)
and dpppPd(OTf)2 (7), 5 × 10-6 M solution in CH2Cl2 at ambient
temperature.
atoms.27 The molar absorptions of the trans-ZnDPyDPP-
containing macrocycles 13 and 15, however, are comparable
to those of the similar macrocycles 12, 14, and 16-30. Thus,
we observe a significant increase in the extinction coefficient
per porphyrin unit upon incorporation of trans-ZnDPyDPP in
the macrocycles 13 and 15.
An interesting observation is that the porphyrins incorporated
in the macrocycles do not possess a shoulder to their Soret band
due to the B(0-1) transition.26 The only exceptions are the
macrocycles 26 and 27 with the BINAP-Pd(II) corners. If an
excess of the metal-containing reagent is present in the reaction
mixture, a distinct shoulder to the Soret band of a porphyrin at
longer wavelengths (usually ca. 460 nm) is observed (Figure
5).
A steady decrease in fluorescence is observed upon titration
of trans-DPyDPP or cis-DPyDPP solutions with solutions of
dppp-metal triflates in CH2Cl2. An overall 30-60% drop in
fluorescence of the porphyrins is observed upon formation of
the macrocycles. The fluorescence of the macrocycles is
suppressed even further upon addition of excess of the dppp-
metal triflates. The decrease in fluorescence is more pronounced
upon addition of dpppPt(II) than dpppPd(II) triflate. This
observation is in accord with an assumption that the heavy-
atom effect is the major contributor to the fluorescence
quenching.28
Figure 6. CD and UV-vis spectra of the tetramer 26 (solid line) and
27 (dashed line), 1.1 × 10-6 M solution in CH2Cl2 at ambient
temperature.
extinction coefficient of the porphyrin chromophores provides
for a very strong exciton coupling in the macrocycles.33
However, even taking into account the short interchromophore
distances of ca. 14 Å between the adjacent porphyrin cores and
ca. 21 Å between the porphyrin cores opposite one another,
the observed magnitude of the splitting may be explained only
by a cooperative interaction between several porphyrin chro-
mophores.
Three types of coupling interactions may exist between the
four porphyrin chromophores in 26 and 27: (a) four “adjacent”
porphyrin couplings (pairs of porphyrins attached to the same
transition metal corner), (b) two “opposing” porphyrin couplings
(porphyrins on opposing sides of the macrocycle), and (c) a
combination of a and b. Examination of structure II reveals
that both the “adjacent” and the “opposing” pairs of porphyrin
chromophores are in the same chiral environment of the BINAP
ligands. This is in accord with the signs of the first and the
second Cotton effects observed in the CD spectrum for the Soret
band of the macrocycles 26 and 27, as well as with the large
magnitude of the splitting due to mutual cooperativity. The
macrocycles 26 and 27 are enantiomers, hence their CD spectra
are mirror images of each other.
No circular dichroism is observed for the Soret band of the
zinc-containing tetramer 28 presumably because of the high
symmetry (D4h) of the zinc porphyrin chromophore.26 Circular
dichroism (ꢀ 300 at λ 420 nm) without chiral exciton coupling
is observed for the Soret band of the macrocycles 29 and 30.
This fact suggests that the two porphyrin cores are coplanar,
and the consequent coplanarity of the transition moments of
CD Spectra of Macrocycles Containing Chiral
Bisphosphines
A striking feature of the CD spectra of the tetramers 26 and
27 is the bisignate curve (positive and negative components)
between 400 and 450 nm (Figure 6). It is probably due to exciton
coupling between two or more porphyrin chromophores of the
macrocycle.29 The apparent Davydov splitting29,30 is 10 nm. The
amplitude of the splitting is quite impressive: ∆ꢀ ) 1800 L ×
mol-1 × cm-1. This amplitude is inversely proportional to the
square of the interchromophore distance31 and proportional to
the square of the extinction coefficients.32 An extremely high
(27) (a) Hunter, C. A.; Hyde, R. K. Angew. Chem., Int. Ed. Engl. 1996,
35, 1936. (b) Fleischer, E. B.; Shachter, A. M. Inorg. Chem. 1991, 30,
3763.
(28) Klessinger, M.; Michl, J. Excited States and Photochemistry of
Organic Molecules; VCH: New York, 1995.
(29) Harada, N.; Nakanishi, K. Circular Dichroic Spectroscopy; Uni-
versity Science Books: Mill Valley, CA, 1983.
(30) (a) Harada, N.; Nakanishi, K. Acc. Chem. Res. 1972, 5, 257. (b)
Davydov, A. S. Theory of Molecular Excitons McGraw-Hill: New York,
1962.
(31) Harada, N.; Chen, S.-M.; Nakanishi, K. J. Am. Chem. Soc. 1975,
97, 5345.
(33) Matile, S.; Berova, N.; Nakanishi, K.; Fleischhauer, J.; Woody, R.
(32) Heyn, M. P. J. Phys. Chem. 1975, 79, 2424.
W. J. Am. Chem. Soc. 1996, 118, 5198.

2748 J. Am. Chem. Soc., Vol. 121, No. 12, 1999
Fan et al.
the chromophores prevents the coupling from being observed.29
The dimers 29 and 30 are enantiomers and also give antipodal
Cotton effects, respectively.
Materials. Commercial reagents were ACS reagent grade or higher
and were used without further purification. Methylene chloride was
purified according to literature procedure34 and distilled over CaH2.
Diethyl ether was purified according to literature procedure34 and
distilled over Na/benzophenone. Methylene chloride and chloroform
used for spectroscopic measurements were spectrophotometric grade.
3,3′-Dihexyl-4,4′-dimethyl-2,2′-dipyrrylmethane,35 cis-DPyDPP (1),27b
trans-DPyDPP (3),27b dpppPd(OTf)2 (7),22 dpppPt(OTf)2 (8),22 Pd(R(+)-
BINAP)(OTf)2 (9),16c Pd(S(-)-BINAP)(OTf)2 (10),16c and 1,4-bis(trans-
Pt(PEt3)2(OTf))benzene (11)25 were prepared according to published
procedures.
cis-ZnDPyDPP (2). To a stirred solution of 100.0 mg (0.16 mmol)
of 1 in a 70 mL of mixture of CHCl3 and MeOH (3:1) was added 356
mg (1.6 mmol) of Zn(OAc)2. The mixture was stirred and refluxed in
the dark for 20 h. The solvent was removed in vacuo. The residue was
washed with MeOH (3 × 20 mL). The product was dried in vacuo.
Yield: 79 mg (73%). Mp > 400 °C dec. 1H NMR (300 MHz, CDCl3)
δ 8.90 (s, 2H, H-17 and H-18), 8.76 (d, J ) 3.9 Hz, 2H, H-2 and
H-13), 8.15 (m, 6H, H-3, H-12, and Ph Ho), 7.98 (s, 2H, H-7 and H-8),
7.73 (m, 6H, Ph Hm, Hp), 7.17 (br, s, 4H, py Hâ), 2.45 (s, 4H, py HR).
13C{1H} NMR (75 MHz, CDCl3) δ 150.9 (s), 150.4 (s), 148.7 (s), 148.1
(s), 143.0 (s), 134.7 (s), 132.9 (s), 132.7 (s), 130.8 (s), 130.6 (s), 129.1
(m), 127.8 (s), 126.7 (s), 122.5 (s). UV-vis (CHCl3) λmax (ꢀ) [nm (cm-1
M-1)] 422 (537 000), 552 (17 000), 600 (7000). MS (CI) m/z 679.2
(100, M+). Anal. Calcd for C42H26N6Zn‚H2O: C, 72.26; H, 4.04; N,
12.04. Found: C, 71.79; H, 3.92; N, 11.85.
Conclusions
Macrocyclic assemblies, containing two or four porphyrin
units, are readily obtained on a preparative scale via self-
assembly with use of Pd(II)- or Pt(II)-containing auxiliary
modules. The bisphosphine ligands coordinated to transition
metals provide for an enhanced solubility of the macrocycles.
The porphyrin cores are not coplanar when used as parts of the
linear modules in the tetramers 12-19. The barrier to rotation
of the trans-DPyDPP moiety around the axis defined by the
two metal-nitrogen bonds in the nonchiral tetramers depends
on the type of transition metal used in the assembly and on the
solvent. Two stages of unfreezing of the conformational motion
are distinguished by NMR spectroscopy: initially the macro-
cycles adopt a coplanar arrangement, and at a high temperature
the full rotation of the rings becomes fast on the NMR time
scale. Chiral macrocycles are formed upon employment of the
BINAP-Pd(II) angular building block. The chiral tetramers have
a puckered structure of D2 symmetry at ambient temperature.
The porphyrin chromophores in the enantiomeric dimers 29 and
30 and the enantiomeric tetramers 26 and 27 show strong
circular dichroism around 420 nm. Cooperative coupling of four
excitons in the tetramers 26 and 27 leads to Davydov splitting
with a very high amplitude. The high solubility and ease of
synthesis of self-assembled porphyrin macrocycles, based on
Pt(II) and Pd(II) phosphine bistriflates, provides tetramers that
are excellent ensembles for the study of porphyrin exciton
coupling interactions and induced circular dichroism (ICD).
trans-ZnDPyDPP (4). To a stirred solution of 30.0 mg (0.049 mmol)
of 3 in a 40 mL mixture of CHCl3 and MeOH (3:1) was added 106.6
mg (0.49 mmol) of Zn(OAc)2. The mixture was stirred and refluxed in
the dark for 10 h. The solvent was removed in vacuo. The residue was
washed with MeOH (3 × 20 mL). The product was dried in vacuo.
1
Yield: 34 mg (100%). Mp 360-362 °C dec. H NMR (300 MHz,
CDCl3) δ 8.70 (d, J ) 3.9 Hz), 8.08 (m), 7.70 (m), 7.20 (br, s, 4H, py
Hâ), 2.13 (s, 4H, py HR). 13C{1H} NMR (75 MHz, CDCl3) δ 152.2 (s),
150.5(s), 148.5 (s), 144.3 (m), 143.0 (s), 139.1 (s), 134.6 (6), 132.7
(s), 130.7 (s), 129.1 (s), 127.7 (s), 126.6 (s), 121.8 (s), 120.9 (s), 118.5
(s), 118.1 (s), 116.3 (m). UV-vis (CHCl3) λmax (ꢀ) [nm (cm-1 M-1)]
418 (76 000), 548 (7000), 614 (4000).
Experimental Section
General Methods. All reactions were conducted under a dry nitrogen
atmosphere following Schlenk techniques, although the products may
be handled in air. IR spectra were recorded on a Mattson Polaris FT-
IR spectrometer. UV-vis spectra were obtained with use of a Hewlett-
Packard 8452A UV-vis spectrophotometer. Circular dichroism (CD)
spectra were recorded on an Aviv 62ADS CD spectrometer. Optical
rotations were measured on a Perkin-Elmer 241MC polarimeter. NMR
spectra were recorded on a Varian Unity-300, Varian XL-300, or Varian
VXR-500 spectrometer. The 1H NMR spectra were recorded at 300 or
500 MHz, and chemical shifts are reported relative to internal TMS δ
0.0 ppm or to the signal of a residual protonated solvent: CDHCl2 δ
5.32 ppm, CHCl3 δ 7.27 ppm, or (CD3)CO(CD2H) δ 2.05 ppm. The
13C{1H} NMR spectra were recorded at 75 or 125 MHz, and chemical
shifts are reported relative to CD2Cl2 δ 54.00 ppm or CDCl3 δ 77.23
ppm. The 19F NMR spectra were recorded at 282 MHz and chemical
shifts are reported relative to external CFCl3 δ 0.0 ppm. The 31P{1H}
NMR spectra were recorded at 121 or 202 MHz, and chemical shifts
are reported relative to external 85% aqueous H3PO4 δ 0.0 ppm. The
signals in 1H NMR due to water are omitted. Elemental analyses were
performed by Atlantic Microlab Inc., Norcross, GA. Melting points
were obtained with a Mel-Temp capillary melting point apparatus and
were not corrected. Mass spectra of 20 and 21 were obtained with a
Finnigan MAT 95 mass spectrometer with a Finnigan MAT ICIS II
operating system under positive fast atom bombardment (FAB)
conditions at 20 keV. 3-Nitrobenzyl alcohol was used as a matrix in
CHCl3 as a solvent, and polypropylene glycol and cesium iodide were
used as a reference for peak matching. Larger macrocycle (>5000 amu)
16 was analyzed with a Micromass Quatro II with ionization performed
under electrospray conditions (flow rate 7.7 µL/min; capillary voltage
3.0 kV; cone 27 V; Extractor 12 V). About 15 individual scans were
averaged for the mass spectrum. The calibration of the mass range 100-
3000 amu was done with a 1:1 mixture of a 2-propanol-water solution
of NaI (2 µg/µL) and CsI (0.01 µg/µL). Samples were prepared as 10
pg/µL solutions in acetone just prior to the analysis.
trans-DPyTTP (5). A solution of 380 mg (1.11 mmol) of 3,3′-
dihexyl-4,4′-dimethyl-2,2′-dipyrrylmethane, 120 mg (1.11 mmol) of
4-pyridinecarboxaldehyde, and 56.8 mg (0.3 mmol) of p-toluenesulfonic
acid in 14 mL of methanol was stirred for 6 h in the dark at ambient
temperature and for 16 h at 0 °C. Then, 531 mg (2.34 mmol) of 2,3-
dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was added and the
mixture was stirred in the dark for an additional 4 h. The precipitate
was filtered and washed with methanol. The filtrate was evaporated
and the residue was treated with a 10% aqueous solution of NaOH,
then with water. The black solid was dissolved in CH2Cl2 and filtered
through a short pad of silica gel and further purified by column
chromatography with a mixture of CH2Cl2 and ethyl acetate (3:1) as
eluent. Yield: 50 mg (12%). Mp 250-252 °C dec. 1H NMR (300 MHz,
CD2Cl2, TMS) δ 10.28 (s, 2H, H-10 and H-20), 9.05 (d, J ) 5.7 Hz,
4H, py HR), 8.09 (d, J ) 6.0 Hz, 4H, py Hâ), 3.99 (t, J ) 7.8 Hz, 8H,
porph-CH2-(CH2)4CH3), 2.53 (s, 12H, porph-CH3), 2.19 (m, 8H, porph-
CH2CH2-(CH2)2CH3), 1.74 (m, 8H, porph-(CH2)2CH2-(CH2)2CH3), 1.48
(m, 8H, porph-(CH2)3CH2-CH2CH3), 1.38 (m, 8H, porph-(CH2)4CH2-
CH3), 0.91 (t, J ) 7.2 Hz, 12H, porph-(CH2)5CH3), -2.42 (s, 2H, NH).
13C{1H} NMR (75 MHz, CD2Cl2, TMS) δ 150.8 (s, py Cγ), 149.2 (s,
py CR), 144.3 (s, porph C4), 144.2 (s, porph C1), 141.8 (s, porph C3),
135.6 (s, porph C2), 128.5 (s, py Câ), 114.8 (s, porph C5-py), 97.7 (s,
C10), 33.6 (s, porph-CH2), 32.2 (s, porph-CH3), 30.2 (s, hexyl CH2),
27.0 (s, hexyl CH2), 23.0 (s, hexyl CH2), 15.2 (s, hexyl CH2), 14.4 (s,
hexyl CH3). IR (neat) 2930, 2854, 1590, 1462, 1286, 1129, 1068, 960,
759 cm-1. UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1 M-1)] 292 (493 000),
406 (180 4000), 508 (186 000), 540 (87 000), 574 (87 000), 628
(36 000). MS (CI) m/z 857 (M+, 100).
trans-ZnDPyTTP (6). To a stirred solution of 20.0 mg (0.023 mmol)
of 5 in a 40 mL of mixture of CHCl3 and MeOH (3:1) was added 51.2
(34) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory
Chemicals; Pergamon Press: Oxford, 1988.
(35) Bao, Z.; Chen, Y.; Yu, L. Macromolecules 1994, 27, 4629.

Self-Assembly of Porphyrin Arrays
J. Am. Chem. Soc., Vol. 121, No. 12, 1999 2749
mg (0.23 mmol) of Zn(OAc)2. The mixture was stirred and refluxed in
the dark for 3 h. The solvent was removed in vacuo. The residue was
washed with MeOH (3 × 20 mL). The product was dried in vacuo.
Yield: 17 mg (79%). Mp 284-286 °C dec. 1H NMR (300 MHz,
CDCl3) δ 9.99 (s, 2H, H-10 and H-20), 3.81 (t, J ) 5.0 Hz, 8H, porph-
CH2-(CH2)4CH3), 2.04 (m, 8H, porph-CH2CH2-(CH2)3CH3), 1.66 (br,
s, 20H, porph-CH3 and porph-(CH2)2CH2-(CH2)2CH3), 1.44 (m, 8H,
porph-(CH2)3CH2-CH2CH3), 1.34 (m, 8H, porph-(CH2)4CH2-CH3), 0.86
(t, J ) 6.9 Hz, 12H, porph-(CH2)5CH3). 13C{1H} NMR (75 MHz,
CDCl3, TMS) δ 152.7 (s, py Cγ), 146.5 (s, py CR), 146.1 (s, porph C4),
143.9 (s, porph C1), 136.4 (s, porph C3), 136.3 (s, porph C2), 127.8 (s,
py Câ), 114.9 (s, porph C5-py), 97.9 (s, C10), 33.6 (s, porph-CH2), 32.2
(s, porph-CH3), 30.3 (s, hexyl CH2), 27.0 (s, hexyl CH2), 23.0 (s, hexyl
CH2), 15.3 (s, hexyl CH2), 14.4 (s, hexyl CH3). IR (neat) 2924, 1609,
1458, 1261, 1069 cm-1. UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1 M-1)]
412 (342 000), 540 (20 000), 576 (11 000). MS (CI) m/z 919 (M+, 100).
[Pd(dppp)(trans-DPyDPP)]4[OTf]8 (12). To a solution of 10.0 mg
(0.012 mmol) of dpppPd(OTf)2, 7, in 5 mL of a 3:1 mixture of CHCl3
and CH3OH was added 7.5 mg (0.012 mmol) of porphyrin 3, and the
resulting solution was stirred at room temperature for 1 h. The solvent
was reduced in volume to 1 mL in vacuo and ether was added resulting
in the formation of a dark-red solid, which was collected, washed with
ether, and dried in vacuo. Yield 16.4 mg (94%). Mp 304-306 °C dec.
1H NMR (300 MHz, CDCl3) δ 9.62 (s, 16H, py HR), 8.93 (br, s, 8H,
outer pyrrol Hâ), 8.33 (m, 16H, pyrrol Hâ), 8.12 (m, 36 H, py Hâ, porph
outer Ph Ho,p, pyrrol Hâ), 7.68(m, 32H, PhP Ho), 7.65 (m, 56H, porph
outer Ph Hm, PhP Hm,p), 6.98 (br, s, 8H, porph inner Ph Ho), 6.04 (br,
s, 12H, porph inner Ph Hm,p), 3.50 (m, 16H, PhP-CH2), 2.56 (m, 8H,
PhP-CH2CH2), -3.04 (s, 8H, NH). 13C{1H} NMR (125 MHz, CDCl3)
δ 153.7 (s, py Cγ), 149.3 (s, py CR), 143.3 (s), 141.1 (s), 134.8 (s, py
Câ), 133.7 (m), 132.9 (s), 132.0 (s), 130.2 (s), 126.8 (s), 125.4 (m),
121.3 (q, J ) 318 Hz, CF3SO3), 114.8 (s, porph C-5 and C-15), 95.0
(s, porph C-10 and C-20), 29.9 (PhP CH2), 18.3 (s, PhPCH2CH2).
31P{1H} NMR (121 MHz, CDCl3, H3PO4) δ 3.9 (s). 19F NMR (282
MHz, CDCl3, CFCl3) δ -79.6 (s). UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1
M-1)] 268 (151 000), 422 (918 000), 520 (77 000), 556 (52 000), 594
(29 000), 650 (35 000). Anal. Calcd for C284H216N24P8O24S8F24Pd4‚
8H2O: C, 58.02; H, 3.98; N, 5.72; S, 4.36. Found: C, 57.72; H, 3.92;
N, 5.63; S, 4.48.
[Pt(dppp)(trans-DPyDPP)]4[OTf]8 (13). A solution of 10.0 mg
(0.011 mmol) of dpppPt(OTf)2, 8, in 5 mL of acetone was treated with
6.8 mg (0.011 mmol) of porphyrin 3 and the resulting solution was
stirred at 40 °C for 4 h. The solvent was reduced in volume to 0.5 mL
followed by addition of diethyl ether. The brown precipitate was
collected, washed with ether, and dried in vacuo. Yield: 14.0 mg (83%).
Mp 330-332 °C dec. 1H NMR (500 MHz, acetone-d6) δ 9.70 (d, J )
4.5 Hz, 16H, py HR), 9.10 (s, 8H, outer pyrrol Hâ), 8.68 (s, 8H, outer
pyrrol Hâ), 8.47 (s, 8H, inner pyrrol Hâ), 8.39 (m, 24H, porph outer
Ph Ho, py Hâ), 8.30 (m, 32H, PhP Ho), 8.11 (s, 8H, inner pyrrol Hâ),
7.90 (m, 12H, porph outer Ph Hm,p), 7.75 (m, 48H, PhP Hm,p), 7.03 (s,
8H, porph inner Ph Hï), 6.12 (s, 12H, porph inner Ph Hm,p), 3.78 (s,
16H, PhP-CH2), 2.59 (m, 8H, PhP-CH2CH2), -3.03 (s, 8H, NH).
13C{1H} NMR (125 MHz, CDCl3) δ 154.3 (s, py Cγ), 149.4 (s, py CR),
141.9 (s), 134.7 (m), 133.8 (m), 132.9 (s), 132.5 (s), 130.1 (s), 127.3
(m), 121.3 (q, J ) 320 Hz, CF3SO3), 114.5 (s), 99.7 (s), 29.9 (PhP
CH2), 18.4 (s, PhPCH2CH2). 31P{1H} NMR (202 MHz, acetone-d6,
H3PO4) δ -9.9 (JPt-P ) 3060 Hz). 19F NMR (282 MHz, CDCl3, CFCl3)
δ -78.9 (s). UV-vis (CHCl3) λmax (ꢀ) [nm (cm-1 M-1)] 426
(1 000 000), 518 (52 000), 558 (36 000), 592 (18 000), 652 (18 000).
Anal. Calcd for C284H216N24P8O24S8F24Pt4‚8H2O: C, 54.72; H, 3.75;
N, 5.39; S, 4.11. Found: C, 54.47; H, 3.67; N, 5.14; S, 3.91.
(br, s, 8H, porph inner Ph Ho), 5.95 (br, s, 12H, porph inner Ph Hm,p),
3.58 (s, 16H, PhP-CH2), 2.43 (m, 8H, PhP-CH2CH2). 13C{1H} NMR
(125 MHz, CDCl3/CD3OD) δ 154.3 (s), 149.4 (s), 141.9 (s), 134.7 (m),
133.8 (m), 132.9 (s), 132.5 (s), 130.1 (s), 127.3 (m), 121.3 (q, J ) 320
Hz, CF3SO3), 114.5 (s), 99.7 (s), 29.9 (s), 18.4 (s). 31P{1H} NMR (121
MHz, CDCl3/CD3OD, H3PO4) δ 4.8 (s). 19F NMR (282 MHz, CDCl3/
CD3OD, CFCl3) δ -79.5 (s). UV-vis (CHCl3) λmax (ꢀ) [nm (cm-1
M-1)] 429 (813 000), 557 (48 000), 608 (27 000).
[Pt(dppp)(trans-ZnDPyDPP)]4[OTf]8 (15). A solution of 7.5 mg
(0.011 mmol) of 4 and 10.0 mg (0.011 mmol) of dpppPt(OTf)2, 8 in
10 mL of a 3:1 mixture of CHCl3 and CH3OH was stirred at room
temperature for 5 days. The solvent was reduced in volume, followed
by addition of diethyl ether. The brown solid was collected, washed
with ether, and dried in vacuo. Yield: 14.4 mg (82%). Mp 310-315
1
°C dec. H NMR (300 MHz, CDCl3/CD3OD) δ 9.41 (br, s, 8H, outer
pyrrol Hâ), 9.33 (s, 16H, py HR), 8.76-8.64 (m, 8H, outer pyrrol Hâ),
8.25 (m, 16H, inner pyrrol Hâ), 8.02-7.86 (m, 28H, porph outer Ph
Ho,p, py Hâ), 7.66-7.38 (m, 88H, porph outer Ph Hm, PhP Ho,m,p), 6.90
(br, s, 8H, porph inner Ph Ho), 5.95 (br, s, 12H, porph inner Ph Hm,p),
3.58 (16H, PhP-CH2), 2.43 (m, 8H, PhP-CH2CH2). 13C{1H} NMR (125
MHz, CDCl3/CD3OD) δ 154.3 (s), 149.4 (s), 141.9 (s), 134.7 (m), 133.8
(m), 132.9 (s), 132.5 (s), 130.1 (s), 127.3 (m), 121.3 (q, J ) 320 Hz,
CF3SO3), 114.5 (s), 99.7 (s), 29.9 (s), 18.4 (s). 31P{1H} NMR (121
MHz, CDCl3/CD3OD, H3PO4) δ -7.8 (JPt-P ) 3043 Hz). 19F NMR
(282 MHz, CDCl3/CD3OD, CFCl3) δ -74.5 (s). UV-vis (CHCl3) λmax
(ꢀ) [nm (cm-1 M-1)] 433 (1 040 000), 560 (58 000), 608 (39 000).
[Pd(dppp)(trans-DPyTTP)]4[OTf]8 (16). To a solution of 15.0 mg
(0.017 mmol) of porphyrin 5 in 10 mL of CH2Cl2 was added 14.0 mg
(0.017 mmol) of dpppPd(OTf)2, 7, and the resulting solution was stirred
at room temperature for 1 h. The solvent vas reduced in volume to 1
mL in vacuo and pentane was added resulting in the formation of a
dark-red solid, which was collected, washed with pentane, and dried
1
in vacuo. Yield 28.0 mg (96%). Mp 248-250 °C dec. H NMR (300
MHz, CD2Cl2, TMS) δ 10.29 (s, 4H, porph H-20), 9.77 (s, 4H, porph
H-10), 9.55 (d, J ) 5.1 Hz, 16H, py HR), 8.15-8.10 (m, 48H, py Hâ,
PhP Ho), 7.75-7.64 (m, 48H, PhP Ho+Hp), 3.99 (m, 16H, outer hexyl
(CH2)(CH2)4CH3), 3.27 (m, 16H, PhP-CH2), 2.86 (m, 16H, inner hexyl
(CH2)(CH2)4CH3), 2.51 (m, 8H, PhP-CH2CH2), 2.22 (m, 16H, outer
hexyl CH2(CH2)(CH2)3CH3), 2.06 (m, 48H, porph-CH3), 1.80 (m, 16H,
outer hexyl (CH2)2(CH2)(CH2)2CH3), 1.58 (m, 16H, outer hexyl (CH2)3-
(CH2)CH2CH3), 1.45 (m, 16H, outer hexyl (CH2)4CH2CH3), 1.15 (m,
16H, inner hexyl CH2(CH2)(CH2)3CH3), 0.97 (m, 24H, outer hexyl
CH3), 0.12 (m, 16H, inner hexyl (CH2)2(CH2)(CH2)2CH3), -0.08 (m,
16H, inner hexyl (CH2)3(CH2)CH2CH3), -0.25 (m, 16H, inner hexyl
(CH2)4CH2CH3), -0.51 (m, 24H, inner hexyl CH3), -2.38 (s, 8H, NH).
13C{1H} NMR (75 MHz, CD2Cl2, TMS) δ 154.5 (s, py Cγ), 151.1 (s,
py CR), 145.3 (s, porph C1), 145.2 (s, porph C9), 144.2 (s, porph C4,
C6), 142.2 (s, porph C3, C7), 135.5 (s, porph C2), 134.7 (s, porph C8),
134.2 (s, py Câ), 133.4 (s, PhP Co), 131.8 (s, PhP Cp), 130.8 (s, PhP
Cm), 125.7 (m, PhP Cipso), 119.6 (q, J ) 319 Hz, CF3SO3), 113.0 (s,
porph C5), 98.8 (s, porph C20), 98.4 (s, porph C10), 33.8 (s, outer hexyl
CH2(CH2)4CH3), 32.6 (s, porph outer CH3), 31.1 (s, inner hexyl
CH2(CH2)4CH3), 30.6 (s, porph inner CH3), 29.2, 27.2 (all s, outer
hexyl), 26.4, 25.1, 24.9, 23.4 (all s, outer and inner hexyls), 22.0 (m,
PhP CH2), 19.0 (s, PhPCH2CH2), 17.8, 17.1, 14.5, 13.1 (all s, inner
hexyl). 31P{1H} NMR (121 MHz, CD2Cl2, H3PO4) δ 6.4 (s). 19F NMR
(282 MHz, CD2Cl2, CFCl3) δ -76.1 (s). IR (neat) 2926, 2863, 1608,
1438, 1252, 1155, 1030, 747 cm-1. UV-vis (CH2Cl2) λmax (ꢀ) [nm
(cm-1 M-1)] 276 (574 000), 414 (634 000), 510 (67 000), 546 (39 000),
580 (36 000), 632 (20 000). Anal. Calcd for C348H408N24P8O24S8F24-
Pd4‚5H2O: C, 61.59; H, 6.21; N, 4.96; S, 3.77. Found: C, 61.29; H,
6.11; N, 4.97; S, 3.74. MS (ES) m/z 1525.3 (M - 4OTf)4+ calcd 1525.8.
[Pt(dppp)(trans-DPyTTP)]4[OTf]8 (17). A solution of 9.5 mg
(0.011 mmol) of porphyrin 5 in 10 mL of CH2Cl2 was treated with
10.0 mg (0.011 mmol) of dpppPt(OTf)2, 8, and stirred at room
temperature for 4 days. The solvent was reduced in volume to 0.5 mL
followed by addition of diethyl ether. The brown precipitate was
collected, washed with ether, and dried in vacuo. Yield: 16.5 mg (85%).
Mp 290-292 °C dec. 1H NMR (300 MHz, CD2Cl2, TMS) δ 10.28 (s,
4H, porph H-20), 9.77 (s, 4H, porph H-10), 9.65 (d, J ) 4.2 Hz, 16H,
py HR), 8.17-8.12 (m, 48H, py Hâ, PhP Ho), 7.75 (t, J ) 6.9 Hz, 32H,
[Pd(dppp)(trans-ZnDPyDPP)]4[OTf]8 (14). To a solution of 8.6
mg (0.013 mmol) of 4 in 5 mL of CHCl3 was added 10.3 mg (0.013
mmol) of dpppPd(OTf)2, 7, and the solution was stirred at room
temperature for 1 h. The solvent was reduced in volume to 0.5 mL in
vacuo. Diethyl ether was then added and the dark-purple precipitate
was filtered and dried in vacuo. Yield: 14.8 mg (78%). Mp 280-285
1
°C dec. H NMR (300 MHz, CDCl3/CD3OD) δ 9.41 (br, s, 8H, outer
pyrrol Hâ), 9.33 (s, 16H, py HR), 8.76-8.64 (m, 8H, outer pyrrol Hâ),
8.25 (m, 16H, inner pyrrol Hâ), 8.02-7.86 (m, 28H, porph outer Ph
Ho,p, py Hâ), 7.66-7.38 (m, 88H, porph outer Ph Hm, PhP Ho,m,p), 6.90

2750 J. Am. Chem. Soc., Vol. 121, No. 12, 1999
Fan et al.
PhP Hm), 7.67 (t, J ) 7.5 Hz, 16H, PhP Hp), 3.99 (m, 16H, outer hexyl
(CH2)(CH2)4CH3), 3.33 (m, 16H, PhP-CH2), 2.84 (m, 16H, inner hexyl
(CH2)(CH2)4CH3), 2.46 (m, 8H, PhP-CH2CH2), 2.22 (m, 16H, outer
hexyl CH2(CH2)(CH2)3CH3), 2.07 (s, 24H, porph outer CH3), 2.00 (s,
24H, porph inner CH3), 1.80 (m, 16H, outer hexyl (CH2)2(CH2)(CH2)2-
CH3), 1.56 (m, 16H, outer hexyl (CH2)3(CH2)CH2CH3), 1.46 (m, 16H,
outer hexyl (CH2)4CH2CH3), 1.13 (m, 16H, inner hexyl CH2(CH2)(CH2)3-
CH3), 0.97 (m, 24H, outer hexyl CH3), 0.12 (m, 16H, inner hexyl
(CH2)2(CH2)(CH2)2CH3), -0.08 (m, 16H, inner hexyl (CH2)3(CH2)CH2-
CH3), -0.24 (m, 16H, inner hexyl (CH2)4CH2CH3), -0.52 (m, 24H,
inner hexyl CH3), -2.36 (s, 8H, NH). 13C{1H} NMR (75 MHz, CD2Cl2,
TMS) δ 155.2 (s, py Cγ), 151.1 (s, py CR), 145.6 (s, porph C1), 145.4
(s, porph C9), 144.1 (s, porph C4, C6), 142.4 (s, porph C3), 142.2 (s,
porph C7), 135.4 (s, porph C2), 134.6 (s, porph C8), 134.3 (s, py Câ),
133.6 (s, PhP Co), 132.5 (s, PhP Cp), 130.7 (s, PhP Cm), 124.9 (m, PhP
9.70 (d, J ) 5.4 Hz, 16H, py HR), 8.18 (m, 48Η, py Hâ, PhP Ho), 7.78
(t, J ) 7.2 Hz, 32H, PhP Hm), 7.65 (t, J ) 7.2 Hz, 16H, PhP Hp), 3.96
(m, 16H, outer hexyl (CH2)(CH2)4CH3), 3.36 (m, 16H, PhP-CH2), 2.84
(m, 16H, inner hexyl (CH2)(CH2)4CH3), 2.50 (m, 8H, PhP-CH2CH2),
2.19 (m, 16H, outer hexyl CH2(CH2)(CH2)3CH3), 2.06 (s, 24H, outer
porph-CH3), 1.97 (s, 24H, inner porph-CH3), 1.78 (m, 16H, outer hexyl
(CH2)2(CH2)(CH2)2CH3), 1.57 (m, 16H, outer hexyl (CH2)3(CH2)CH2-
CH3), 1.46 (m, 16H, outer hexyl (CH2)4CH2CH3), 1.02 (m, 16H, inner
hexyl CH2(CH2)(CH2)3CH3), 1.00 (m, 24H, outer hexyl CH3), 0.00 (m,
16H, inner hexyl (CH2)2(CH2)(CH2)2CH3), -0.21 (m, 32H, inner hexyl
(CH2)3CH2CH2CH3), -0.50 (m, 24H, inner hexyl CH3). 13C{1H} NMR
(125 MHz, CDCl3, TMS) δ 156.5 (s, py Cγ), 150.7 (s, py CR), 147.0
(s, porph C1, C9), 146.2 (s, porph C4, C6), 145.5 (s, porph C3), 145.0
(s, porph C7), 136.5 (s, porph C2), 136.0 (s, porph C8), 134.0 (s, py
Câ), 133.2 (s, PhP Co), 132.4 (s, PhP Cp), 130.5 (s, PhP Cm), 124.6 (t,
J ) 34.9 Hz, PhP Cipso), 121.4 (q, J ) 318 Hz, CF3SO3), 113.7 (s,
porph C5), 99.3 (s, porph C20), 98.8 (s, porph C10), 33.5 (s, outer hexyl
CH2(CH2)4CH3), 32.2 (s, porph outer CH3), 32.1 (s, inner hexyl
CH2(CH2)4CH3), 30.6 (s, porph inner CH3), 30.3, 28.8 (all s, outer
hexyl), 27.0, 25.9, 24.8, 23.0 (all s, outer + inner hexyls), 21.6 (m,
PhP CH2), 18.7 (s, PhPCH2CH2), 18.3, 18.0, 14.4, 13.0 (all s, inner
hexyl). 31P{1H} NMR (121 MHz, CD2Cl2, H3PO4) δ -14.1 (s, 195Pt
satellites, JPt-P ) 3086 Hz). 19F NMR (282 MHz, CD2Cl2, CFCl3) δ
-75.9 (s). IR (neat) 2963, 2927, 2884, 1608, 1439, 1291, 1151, 1031,
699 cm-1. UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1 M-1)] 350 (81 000),
420 (492 000), 546 (48 000), 584 (34 000). Anal. Calcd for C348H400N24P8-
O24S8F24Pt4Zn4‚8H2O: C, 56.11; H, 5.63; N, 4.51; S, 3.44. Found: C,
55.91; H, 5.77; N, 4.44; S, 3.50.
Cipso), 121.8 (q, J ) 320 Hz, CF3SO3), 112.7 (s, porph C5), 99.0 (s,
porph C20), 98.5 (s, porph C10), 33.8 (s, outer hexyl CH2(CH2)4CH3),
32.6 (s, porph outer CH3), 31.1 (s, inner hexyl CH2(CH2)4CH3), 30.6
(s, porph inner CH3), 29.1, 27.2 (all s, outer hexyl), 26.3, 24.7, 23.3,
23.1 (all s, outer + inner hexyls), 21.9 (m, PhP CH2), 18.9 (s,
PhPCH2CH2), 17.9, 17.1, 14.5, 13.1 (all s, inner hexyl). 31P{1H} NMR
(121 MHz, CD2Cl2, H3PO4) δ -16.0 (195Pt satellites, JPt-P ) 3101 Hz).
19F NMR (282 MHz, CD2Cl2, CFCl3) δ -76.5 (s). IR (neat) 2927, 2871,
1610, 1437, 1279, 1254, 1155, 1029, 748 cm-1. UV-vis (CH2Cl2) λmax
(ꢀ) [nm (cm-1 M-1)] 416 (174 000), 512 (17 000), 548 (10 000), 578
(9000), 632 (5000). Anal. Calcd for C348H408N24P8O24S8F24Pt4‚7H2O:
C, 58.22; H, 5.93; N, 4.69; S, 3.57. Found: C, 57.99; H, 5.74; N, 4.62;
S, 3.50.
[Pd(dppp)(trans-ZnDPyTTP)]4[OTf]8 (18). To a solution of 4.0
mg (0.0043 mmol) of 6 in 5 mL of CHCl3 was added 3.5 mg (0.0043
mmol) of dpppPd(OTf)2, 7, and the solution was stirred at room
temperature for 1 h. The solvent was reduced in volume to 0.5 mL in
vacuo. Diethyl ether was then added and the dark-purple precipitate
was filtered and dried in vacuo. Yield: 7.4 mg (98%). Mp 224-226
[Pd(dppp)(cis-DPyDPP)]2[OTf]4 (20). To a solution of 10.0 mg
(0.012 mmol) of dpppPd(OTf)2, 7, in 2 mL of a 3:1 mixture of CHCl3
and CH3OH was added 7.5 mg (0.012 mmol) of porphyrin 1 and the
resulting solution was stirred at room temperature for 1 h. The solvent
was reduced in volume to 1 mL in vacuo and ether was added resulting
in the formation of a dark-red solid, which was collected, washed with
ether, and dried in vacuo. Yield 16.3 mg (93%). Mp 338-340 °C dec.
1H NMR (500 MHz, CDCl3) δ 9.83 (d, J ) 6.0 Hz, 8H, py HR), 8.92
(d, J ) 4.5 Hz, 4H, porph H-2 and H-13), 8.86 (s, 4H, porph H-17 and
H-18), 8.58 (s, 4Η, porph H-7 and H-8), 8.33 (d, J ) 4.5 Hz, 4H,
porph H-3 and H-12), 8.23-8.17 (m, 16H, py Hâ, porph-Ph Ho), 8.07
(m, 16H, PhP Ho), 7.82 (m, 12H, porph-Ph Hm + Hp), 7.66 (m, 16H,
PhP Hm), 7.51 (m, 8H, PhP Hp), 3.49 (m, 8H, PhP-CH2), 2.53 (m, 4H,
PhP-CH2CH2), -3.00 (s, 4H, NH). 13C{1H} NMR (125 MHz, CDCl3)
δ 153.3 (s, py Cγ), 149.3 (s, py CR), 141.6 (s, porph C17,18), 134.9 (s,
py Câ), 133.7 (s), 132.9 (s), 130.2 (s), 128.4 (s), 127.1 (s), 125.7 (m),
122.7 (s), 121.3 (q, J ) 318 Hz, CF3SO3), 114.7 (s), 29.9 (PhP CH2),
18.3 (s, PhPCH2CH2). 31P{1H} NMR (202 MHz, CDCl3, H3PO4) δ 4.4
(s). 19F NMR (282 MHz, CDCl3, CFCl3) δ -79.4 (s). UV-vis (CHCl3)
λmax (ꢀ) [nm (cm-1 M-1)] 268 (72 000), 422 (485 000), 520 (33 000),
556 (17 000), 592 (12 000), 650 (6000). Anal. Calcd for C142H108N12P4-
O12S4F12Pd2‚5H2O: C, 57.67; H, 4.02; N, 5.68; S, 4.34. Found: C,
57.51; H, 3.99; N, 5.40; S, 4.37. MS (FAB) m/z 2716.5 (M - OTf)+
calcd 2717.4.
1
°C dec. H NMR (500 MHz, CD2Cl2, TMS) δ 10.26 (s, 4H, porph
H-20), 9.69 (s, 4H, porph H-10), 9.54 (d, J ) 5.0 Hz, 16H, py HR),
8.17-8.15 (m, 48Η, py Hâ, PhP Ho), 7.75 (t, J ) 7.3 Hz, 32H, PhP
Hm), 7.69 (t, J ) 7.5 Hz, 16H, PhP Hp), 3.99 (m, 16H, outer hexyl
(CH2)(CH2)4CH3), 3.25 (m, 16H, PhP-CH2), 2.74 (m, 16H, inner hexyl
(CH2)(CH2)4CH3), 2.51 (m, 8H, PhP-CH2CH2), 2.22 (m, 16H, outer
hexyl CH2(CH2)(CH2)3CH3), 2.08 (s, 24H, outer porph-CH3), 1.97 (s,
24H, inner porph-CH3), 1.81 (m, 16H, outer hexyl (CH2)2(CH2)(CH2)2-
CH3), 1.59 (m, 16H, outer hexyl (CH2)3(CH2)CH2CH3), 1.47 (m, 16H,
outer hexyl (CH2)4CH2CH3), 1.28 (m, 16H, inner hexyl CH2(CH2)(CH2)3-
CH3), 0.98 (m, 24H, outer hexyl CH3), -0.02 (m, 16H, inner hexyl
(CH2)2(CH2)(CH2)2CH3), -0.19 (m, 16H, inner hexyl (CH2)3(CH2)CH2-
CH3), -0.28 (m, 16H, inner hexyl (CH2)4CH2CH3), -0.55 (m, 24H,
inner hexyl CH3). 13C{1H} NMR (125 MHz, CD2Cl2, TMS) δ 156.1
(s, py Cγ), 151.1 (s, py CR), 147.3 (s, porph C1, C9), 146.7 (s, porph
C4, C6), 145.6 (s, porph C3), 145.4 (s, porph C7), 137.2 (s, porph C2),
136.7 (s, porph C8), 134.3 (s, py Câ), 133.5 (s, PhP Co), 132.2 (s, PhP
Cp), 130.9 (s, PhP Cm), 125.8 (t, J ) 26.6 Hz, PhP Cipso), 121.8 (q, J
) 320 Hz, CF3SO3), 114.7 (s, porph C5), 99.4 (s, porph C20), 99.0 (s,
porph C10), 33.8 (s, outer hexyl CH2(CH2)4CH3), 32.5 (s, porph outer
CH3), 30.9 (s, inner hexyl CH2(CH2)4CH3), 30.6 (s, porph inner CH3),
30.3, 29.2 (all s, outer hexyl), 27.2, 26.2, 25.2, 23.4 (all s, outer +
inner hexyls), 22.0 (m, PhPCH2), 19.0 (s, PhPCH2CH2), 18.5, 18.2,
14.5, 13.1 (all s, inner hexyl). 31P{1H} NMR (121 MHz, CD2Cl2, H3PO4)
δ 9.0 (s). 19F NMR (282 MHz, CD2Cl2, CFCl3) δ -74.7 (s). IR (neat)
3107, 2925, 1606, 1436, 1260, 1101, 1029, 801 cm-1. UV-vis (CH2Cl2)
λmax (ꢀ) [nm (cm-1 M-1)] 348 (51 000), 414 (397 000), 542 (35 000),
582 (29 000). Anal. Calcd for C348H400N24P8O24S8F24Pd4Zn4‚15H2O: C,
57.89; H, 6.00; N, 4.66; S, 3.55. Found: C, 57.66; H, 5.80; N, 4.83; S,
3.49.
[Pt(dppp)(cis-DPyDPP)]2[OTf]4 (21). A solution of 7.3 mg (0.0081
mmol) of dpppPt(OTf)2, 8, in 2 mL of a 3:1 mixture of CHCl3 and
CH3OH was treated with 5.0 mg (0.0081 mmol) of porphyrin 1 and
stirred at room temperature for 2 days. The solvent was reduced in
volume to 0.5 mL followed by addition of diethyl ether. The brown
precipitate was collected, washed with ether, and dried in vacuo.
Yield: 9.0 mg (73%). Mp 383-385 °C dec. 1H NMR (300 MHz,
CDCl3) δ 9.88 (d, J ) 4.2 Hz, 8H, py HR), 8.92 (d, J ) 4.8 Hz, 4H,
porph H-2 and H-13), 8.85 (s, 4H, porph H-17 and H-18), 8.57 (s, 4Η,
porph H-7 and H-8), 8.31 (d, J ) 4.8 Hz, 4H, porph H-3 and H-12),
8.21(m, 16H, py Hâ, porph-Ph Ho), 8.09 (m, 16H, PhP Ho), 7.82 (m,
12H, porph-Ph Hm + Hp), 7.66 (m, 16H, PhP Hm), 7.49 (m, 8H, PhP
Hp), 3.57 (8H, PhP-CH2), 2.49 (m, 4H, PhP-CH2CH2), -2.99 (s, 4H,
NH). 13C{1H} NMR (125 MHz, CDCl3) δ 153.8 (s, py Cγ), 149.4 (s,
py CR), 141.5 (s, porph C17,18), 134.9 (s), 134.7 (s), 133.7 (s), 133.5 (s,
py Câ), 133.0 (s), 130.1 (s), 128.4 (s), 127.1 (s), 125.0 (m), 123.0 (s),
121.3 (q, J ) 320 Hz, CF3SO3), 114.4 (s), 29.9 (PhP CH2), 18.4 (s,
PhPCH2CH2). 31P{1H} NMR (121 MHz, CDCl3, H3PO4) δ -16.9 (s,
195Pt satellites, JPt-P ) 3069 Hz). 19F NMR (282 MHz, CDCl3,
[Pt(dppp)(trans-ZnDPyTTP)]4[OTf]8 (19). A solution of 16.0 mg
(0.017 mmol) of 6 and 15.7 mg (0.017 mmol) of dpppPt(OTf)2, 8, in
5 mL of CHCl3 was stirred at room temperature for 5 days. The solvent
was reduced in volume, followed by addition of diethyl ether. The
brown solid was collected, washed with ether, and dried in vacuo.
1
Yield: 25.4 mg (80%). Mp 260-262 °C dec. H NMR (500 MHz,
CD2Cl2, TMS) δ 10.22 (s, 4H, porph H-20), 9.98 (s, 4H, porph H-10),

Self-Assembly of Porphyrin Arrays
J. Am. Chem. Soc., Vol. 121, No. 12, 1999 2751
CFCl3) δ -79.4 (s). UV-vis (CHCl3) λmax (ꢀ) [nm (cm-1 M-1)] 422
(453 000), 520 (30 000), 556 (15 000), 594 (10 000), 650 (5000). Anal.
Calcd for C142H108N12P4O12S4F12Pt2‚6H2O: C, 54.10; H, 3.84; N, 5.33;
S, 4.07. Found: C, 54.03; H, 3.68; N, 5.15; S, 4.03. MS (FAB) m/z
2895.8 (M - OTf)+ calcd 2895.6.
(30 000), 650 (25 000). Anal. Calcd for C296H368N24P16O24S8F24Pt8: C,
47.95; H, 5.00; N, 4.53; S, 3.46. Found: C, 48.02; H, 5.11; N, 4.39; S,
3.26.
Cyclotetrakis[(cis-ZnDPyDPP)[1,4-bis(trans-Pt(PEt3)2(OTf))-
benzene]] (25). To a solution of 10.0 mg (0.0081 mmol) of 1,4-bis-
(trans-Pt(PEt3)2(OTf))benzene, 11, in 2 mL of CH2Cl2 was added 5.5
mg (0.0081 mmol) of compound 2. The resulting solution was stirred
at 40 °C for 10 h. The solvent was reduced in volume to 0.5 mL in
vacuo. Diethyl ether was then added and the dark-red precipitate was
filtered and dried in vacuo. Yield: 13.2 mg (85%). Mp 262-264 °C
[Pd(dppp)(cis-ZnDPyDPP)]2[OTf]4 (22). A solution of 8.3 mg
(0.012 mmol) of 2 in 3 mL of CHCl3 was added to 10.0 mg (0.012
mmol) of dpppPd(OTf)2, 7, in 5 mL of a 3:1 mixture of CHCl3 and
CH3OH. The resulting solution was stirred at room temperature for 1
h. The solvent was reduced in volume to 0.5 mL in vacuo. Diethyl
ether was then added and the dark-purple precipitate was filtered and
dried in vacuo. Yield: 17.1 mg (93%). Mp 320-325 °C dec. 1H NMR
(300 MHz, CDCl3/CD3OD) δ 9.52 (d, J ) 4.5 Hz, 8H, py HR), 8.83
(d, J ) 4.8 Hz, 4H, porph H-2 and H-13), 8.77 (s, 4H, porph H-17 and
H-18), 8.56 (s, 4Η, porph H-7 and H-8), 8.22 (d, J ) 4.8 Hz, 4H,
porph H-3 and H-12), 8.11-8.05 (m, 16H, py Hâ, porph-Ph Ho), 7.94
(m, 16H, PhP Ho), 7.69 (m, 12H, porph-Ph Hm + Hp), 7.55 (m, 16H,
PhP Hm), 7.45 (m, 8H, PhP Hp), 3.32 (8H, PhP-CH2), 2.41 (m, 4H,
PhP-CH2CH2). 13C{1H} NMR (125 MHz, CDCl3) δ 154.4 (s), 150.7
(d, J ) 31 Hz), 148.6 (s), 148.4 (s), 142.9 (s), 134.8 (s), 132.8 (m),
131.0 (d, J ) 21 Hz), 130.0 (s), 129.3 (s), 127.8 (s), 126.7 (s), 125.3
(m), 123.0 (s), 120.6 (q, J ) 320 Hz, CF3SO3), 115.3 (s), 29.9 (PhP
CH2), 18.1 (s, PhPCH2CH2). 31P{1H} NMR (121 MHz, CDCl3/CD3OD,
H3PO4) δ 5.0 (s). 19F NMR (282 MHz, CDCl3, CFCl3) δ -79.3 (s).
UV-vis (CHCl3) λmax (ꢀ) [nm (cm-1 M-1)] 264 (74 000), 318 (51 000),
430 (469 000), 562 (40 000), 604 (18 000). Anal. Calcd for C142H104N12P4-
O12S4F12Pd2Zn2‚6H2O: C, 54.98; H, 3.77; N, 5.42; S, 4.13. Found: C,
54.91; H, 3.77; N, 5.21; S, 3.76.
[Pt(dppp)(cis-ZnDPyDPP)]2[OTf]4 (23). A solution of 5.1 mg
(0.0075 mmol) of 2 in 1 mL of CHCl3 was added to 6.8 mg (0.0075
mmol) of dpppPt(OTf)2, 8, in 2 mL of a 3:1 mixture of CHCl3 and
CH3OH. The resulting solution was stirred at room temperature for 1
day. The solvent was reduced in volume to 0.5 mL in vacuo. Diethyl
ether was then added and the dark-purple precipitate was filtered and
dried in vacuo. Yield: 9.7 mg (82%). Mp 353-355 °C dec. 1H NMR
(500 MHz, CDCl3/CD3OD) δ 9.55 (br, s, 8H, py HR), 8.84 (d, J ) 4.5
Hz, 4H, porph H-2 and H-13), 8.78 (s, 4H, porph H-17 and H-18),
8.58 (s, 4Η, porph H-7 and H-8), 8.21 (d, J ) 4.5 Hz, 4H, porph H-3
and H-12), 8.10 (m, 16H, py Hâ, porph-Ph Ho), 7.96 (m, 16H, PhP
Ho), 7.68 (m, 12H, porph-Ph Hm + Hp), 7.56 (m, 16H, PhP Hm), 7.45
(m, 8H, PhP Hp), 3.50 (8H, PhP-CH2), 2.37 (m, 4H, PhP-CH2CH2).
13C{1H} NMR (125 MHz, CDCl3/CD3OD) δ 155.7 (s, py Cγ), 151.0
(s, py CR), 150.3 (s), 148.3 (s), 147.9 (s), 142.7 (s), 134.7 (s), 133.5
(s), 133.0 (m), 132.7 (s), 130.8 (s), 130.0 (s), 127.8 (s), 126.6 (s), 124.8
(m), 123.3 (s), 121.0 (q, J ) 320 Hz, CF3SO3), 114.4 (s), 29.8 (PhP
CH2), 18.2 (s, PhPCH2CH2). 31P{1H} NMR (121 MHz, CDCl3/CD3OD,
H3PO4) δ -16.7 (s, 195Pt satellites, JPt-P ) 3025 Hz). 19F NMR (282
MHz, CDCl3, CFCl3) δ -79.4 (s). UV-vis (CHCl3) λmax (ꢀ) [nm (cm-1
M-1)] 318 (14 000), 434 (186 000), 562 (15 000), 604 (6000). Anal.
Calcd for C142H104N12P4O12S4F12Pt2Zn2‚6H2O C, 52.01; H, 3.57; N, 5.13;
S, 3.91. Found: C, 51.75; H, 3.67; N, 4.89; S, 3.54.
Cyclotetrakis[(cis-DPyDPP)[1,4-bis(trans-Pt(PEt3)2(OTf))-
benzene]] (24). To a solution of 10.0 mg (0.0081 mmol) of 1,4-bis-
(trans-Pt(PEt3)2(OTf))benzene, 11, in 2 mL of CH2Cl2 was added 5.0
mg (0.0081 mmol) compound 1. The resulting solution was stirred at
room temperature for 1 h. The solvent was reduced in volume to 0.5
mL in vacuo. Diethyl ether was then added and the dark-purple
precipitate was filtered and dried in vacuo. Yield: 14.3 mg (95%).
Mp 220-225 °C dec. 1H NMR (500 MHz, CD2Cl2) δ 9.22 (s, 16H, py
HR), 9.10 (s, 8H, porph H-2 and H-13), 9.04 (s, 8H, porph H-17 and
H-18), 8.98 (s, 8Η, porph H-7 and H-8), 8.78 (s, 8H, porph H-3 and
H-12), 8.64 (s, 16H, py Hâ), 8.27 (m, 16H, porph-Ph Ho), 7.85 (m,
24H, porph-Ph Hm + Hp), 7.31 (m, 16H, PhPt Ho), 1.71 (m, 96H, PCH2-
CH3), 1.39 (m, 144H, PCH2CH3), -2.77 (s, 8H, NH). 13C{1H} NMR
(125 MHz, CD2Cl2) δ 154.1 (s, py Cγ), 151.1 (s, py CR), 141.9 (s),
137.3 (s), 135.2 (s), 133.7 (s), 131.3 (m), 128.8 (s), 127.5 (s), 125.5
(s), 123.4 (s), 121.7 (q, J ) 319 Hz, CF3SO3), 114.9 (s), 13.4 (PCH2-
CH3), 8.3 (s, PCH2CH3). 31P{1H} NMR (121 MHz, CD2Cl2, H3PO4) δ
17.4 (JPt-P ) 2721 Hz). 19F NMR (282 MHz, CD2Cl2, CFCl3) δ -73.5
(s). UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1 M-1)] 298 (84 000), 372
(113 000), 424 (1 258 000), 518 (82 000), 556 48 000), 594
1
dec. H NMR (300 MHz, CD2Cl2) δ 9.07 (m, 24H, py HR, porph H-2
and H-13), 8.97 (s, 8H, porph H-17 and H-18), 8.93 (d, J ) 4.8 Hz,
8H, porph H-7 and H-8), 8.80 (d, J ) 4.2 Hz, 8Η, porph H-3 and
H-12), 8.62 (m, 16H, py Hâ), 8.27 (m, 16H, porph-Ph Ho), 7.81 (m,
24H, porph-Ph Hm + Hp), 7.29 (m, 16H, PhPt Ho), 1.70 (m, 96H, PCH2-
CH3), 1.39 (m, 144H, PCH2CH3). 13C{1H} NMR (125 MHz, CD2Cl2)
δ 156.2 (s), 151.6 (s), 151.0 (s), 150.2 (s), 149.0 (s), 148.7 (s), 143.2
(s), 137.3 (s), 135.1 (s), 133.9 (s), 133.5 (s), 133.2 (s), 131.6 (s), 130.4
(m), 128.1 (s), 127.0 (s), 125.6 (s), 123.7 (s), 120.6 (q, J ) 319 Hz,
CF3SO3), 115.1 (s), 13.4 (PCH2CH3), 8.3 (s, PCH2CH3). 31P{1H} NMR
(121 MHz, CD2Cl2, H3PO4) δ 17.4 (JPt-P ) 2732 Hz). 19F NMR (282
MHz, CD2Cl2, CFCl3) δ -74.3 (s). UV-vis (CH2Cl2) λmax (ꢀ) [nm
(cm-1 M-1)] 314 (90 000), 432 (1 068 000), 560 (82 000), 602 (31 000).
Anal. Calcd for C296H360N24P16O24S8F24Pt8Zn4‚20H2O: C, 44.28; H,
5.02; N, 4.19; S, 3.19. Found: C, 44.16; H, 4.78; N, 3.89; S, 3.39.
Cyclotetrakis[[cis-Pd(R(+)-BINAP)(OTf)2](trans-DPyDPP)] (26).
To a solution of 10.0 mg (0.0097 mmol) of Pd(R(+)-BINAP)(OTf)2,
9, in 5 mL of CH2Cl2 was added 6.0 mg (0.0097 mmol) of
trans-DPyDPP, 3. The resulting solution was stirred at room temperature
for 20 min and was reduced in volume to 0.5 mL in vacuo. Diethyl
ether was then added and the dark brown precipitate was filtered and
dried in vacuo. Yield: 14.1 mg (88%). Mp 268-270 °C dec. [R]D
+500° (c 3.6 × 10-5 M, CH2Cl2, 20 °C). CD (CH2Cl2) λ (∆ꢀ) [nm (L
mol-1 cm-1)] 251 (+416.7), 276 (-20.8), 332 (+166.7), 351 (-104.2),
422 (-975.0), 432 (+833.3). 1H NMR (300 MHz, CD2Cl2) δ 9.34 (s,
8H, py HR), 9.18 (s, 8H, py HR), 8.94 (d, J ) 4.2 Hz, 4H), 8.84 (s,
4H), 8.63 (m, 8H), 8.39-8.16 (m, 40H), 8.10 (s, 4H), 8.02 (d, J ) 8.4
Hz, 16H), 7.90 (m, 24H), 7.80 (m, 24H), 7.68 (d, J ) 6.0 Hz, 8H),
7.52 (m, 24H), 7.36 (m, 4H), 7.14 (m, 32H), 6.59 (d, J ) 8.4 Hz,
16H), 6.18 (m, 8H), -3.24 (s, 4H, NH), -3.33 (s, 4H, NH). 13C{1H}
NMR (125 MHz, CD2Cl2) δ 154.2 (d, J ) 27 Hz), 150.5 (m), 142.1
(s), 141.6 (s), 140.7 (m), 137.4 (m), 136.2 (s), 135.5 (s), 135.0 (d, J )
28 Hz), 133.8 (s), 133.0 (s), 132.3 (s), 131.8 (m), 131.4 (s), 130.9 (s),
130.0 (s), 129.4 (s), 129.0 (s), 128.1 (m), 127.8 (m), 127.6 (s), 127.2
(s), 126.1 (m), 125.2 (s), 124.7 (s), 121.9 (d, J ) 34 Hz), 121.7 (q, J
) 339 Hz, CF3SO3), 119.6 (s), 119.1 (s), 115.2 (d, J ) 49 Hz). 31P{1H}
NMR (121 MHz, CD2Cl2, H3PO4) δ 24.5 (AB, J ) 18 Hz), 25.0 (AB,
J ) 18 Hz). 19F NMR (282 MHz, CD2Cl2, CFCl3) δ -77.6 (s). UV-
vis (CH2Cl2) λmax (ꢀ) [nm (cm-1 M-1)] 290 (246 000), 422 (1 641 000),
518 (100 000), 556 (63 000), 592(31 000), 648 (33 000). Anal. Calcd
for C352H240N24P8O24S8F24Pd4‚8H2O: C, 62.92; H, 3.84; N, 5.00; S,
3.82. Found: C, 62.76; H, 3.93; N, 5.06; S, 3.81.
Cyclotetrakis[[cis-Pd(S(-)-BINAP)(OTf)2](trans-DPyDPP)] (27).
To a solution of 10.0 mg (0.0097 mmol) of Pd(S(-)-BINAP)(OTf)2,
10, in 5 mL of CH2Cl2 was added 6.0 mg (0.0097 mmol) of trans-
DPyDPP, 3. The resulting solution was stirred at room temperature
for 20 min and was reduced in volume to 0.5 mL in vacuo. Diethyl
ether was then added and the dark brown precipitate was filtered and
dried in vacuo. Yield: 15.1 mg (94%). Mp 268-270 °C dec. [R]D
-474° (c 2.8 × 10-5 M, CH2Cl2, 20 °C). CD (CH2Cl2) λ (∆ꢀ) [nm (L
mol-1 cm-1)] 251 (-387.5), 276 (+93.8), 332 (-125.0), 351 (+120.8),
422 (+843.8), 432 (-645.8). UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1
M-1)] 292 (232 000), 422 (1 647 000), 518 (94 000), 554 (57 000), 592
(26 000), 648 (28 000). 1H, 31P, 13C, and 19F NMR spectra of 27 were
found to be identical with those of 26. Anal. Calcd for C352H240N24P8-
O24S8F24Pd4‚8H2O: C, 62.92; H, 3.84; N, 5.00; S, 3.82. Found: C,
62.76; H, 3.93; N, 5.06; S, 3.81.
Cyclotetrakis[[cis-Pd(R(+)-BINAP)(OTf)2](trans-ZnDPyDPP)] (28).
To a solution of 7.6 mg (0.0074 mmol) of Pd(R(+)-BINAP)(OTf)2, 9,
in 5 mL of CHCl3 was added 5.0 mg (0.0074 mmol) of trans-

2752 J. Am. Chem. Soc., Vol. 121, No. 12, 1999
Fan et al.
ZnDPyDPP, 4, in a 3:1 mixture of chloroform and methanol. The
resulting solution was stirred at room temperature for 40 min and was
reduced in volume to 0.5 mL in vacuo. Diethyl ether was then added
and the dark brown precipitate was filtered and dried in vacuo. Yield:
10.1 mg (80%). Mp 298-300 °C dec. CD (CH2Cl2) λ (∆ꢀ) [nm (L
mol-1 cm-1)], 233 (-300.5), 253 (+333.8), 286 (-115.0), 325 (+89.8),
(s), 130.9 (s), 130.1 (s), 129.3 (s), 129.0 (s), 128.6 (s), 128.3 (s), 127.7
(d, J ) 11 Hz), 127.4 (s), 125.8 (s), 125.3 (m), 124.7 (s), 122.9 (s),
121.5 (q, J ) 319 Hz, CF3SO3), 119.7 (s), 119.2 (m), 114.9 (s). 31P-
{1H} NMR (121 MHz, CD2Cl2, H3PO4) δ 27.3 (s). 19F NMR (282 MHz,
CD2Cl2) δ -73.6 (s). UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1 M-1)],
292 (95 000), 424 (642 000), 520 (39 000), 556 (20 000), 592(13 000),
648 (6000) nm. Anal. Calcd for C176H120N12P4O12S4F12Pd2‚8H2O: C,
61.59; H, 3.99; N, 4.90; S, 3.74. Found: C, 61.35; H, 3.76; N, 4.57; S,
3.79.
1
339 (+23.8), 368 (+84.5). H NMR (300 MHz, CD2Cl2) δ 9.34 (s,
8H, py HR), 9.18 (s, 8H, py HR), 8.94 (d, J ) 4.2 Hz, 4H), 8.83 (s,
4H), 8.59 (m, 8H), 8.38-8.16 (m, 40H), 8.09 (s, 4H), 8.02 (d, J ) 8.4
Hz, 16H), 7.90 (m, 24Η), 7.80 (m, 24H), 7.68 (d, J ) 6.0 Hz, 8H),
7.52 (m, 24H), 7.36 (m, 4H), 7.14 (m, 32H), 6.59 (d, J ) 8.4 Hz,
16H), 6.17 (m, 8H). 31P{1H} NMR (121 MHz, CD2Cl2, H3PO4) δ 25.8
(AB, J ) 18 Hz), 26.2 (AB, J ) 18 Hz). 19F NMR (282 MHz, CD2Cl2,
CFCl3) δ -77.7 (s). UV-vis (CH2Cl2/CH3OH) λmax (ꢀ) [nm (cm-1
M-1)] 402 (180 000), 424 (1 740 000), 556 (94 000), 555 (34 000).
Cyclobis[[cis-Pd(R(+)-BINAP)(OTf)2](cis-DPyDPP)] (29). To a
solution of 16.6 mg (0.016 mmol) of Pd(R(+)-BINAP)(OTf)2, 9, in 10
mL of CH2Cl2 was added 10.0 mg (0.016 mmol) of cis-DPyDPP, 1.
The resulting solution was stirred at room temperature for 20 min and
was reduced in volume to 0.5 mL in vacuo. Diethyl ether was then
added and the dark brown precipitate was filtered and dried in vacuo.
Yield: 23.5 mg (88%). Mp 278-280 °C dec. [R]D +1090° (c 3.6 ×
10-5 M, CH2Cl2, 20 °C). CD (CH2Cl2) λ (∆ꢀ) [nm (L mol-1 cm-1)]
250 (+122.4), 276 (-65.3), 332 (+49.0), 351 (-62.0), 422 (+293.9).
1H NMR (300 MHz, CD2Cl2) δ 9.64 (d, J ) 4.8 Hz, 4H, py HR), 9.58
(d, J ) 4.8 Hz, 4H, py HR), 8.89 (s, 12H), 8.40 (m, 8H), 8.25-8.07
(m, 20H), 7.99-7.91 (m, 8H), 7.82-7.74 (m, 24H), 7.51 (q, J ) 7.5
Hz, 12Η), 7.32 (s, 4H), 7.13 (q, J ) 7.8 Hz, 12H), 6.60 (d, J ) 9.0
Hz, 8H), -2.96 (s, 4H, NH). 13C{1H} NMR (125 MHz, CD2Cl2) δ
154.2 (s), 151.1 (s), 150.1 (s), 142.0 (s), 140.8 (s), 136.0 (s), 135.4 (d,
J ) 12 Hz), 135.1 (s), 133.8 (s), 133.4 (s), 132.7 (s), 132.5 (s), 132.3
Cyclobis[[cis-Pd(S(-)-BINAP)(OTf)2](cis-DPyDPP)] (30). To a
solution of 16.6 mg (0.016 mmol) Pd(S(-)-BINAP)(OTf)2, 10, in 10
mL of CH2Cl2 was added 10.0 mg (0.016 mmol) of cis-DPyDPP, 1.
The resulting solution was stirred at room temperature for 20 min and
was reduced in volume to 0.5 mL in vacuo. Diethyl ether was then
added and the dark brown precipitate was filtered and dried in vacuo.
Yield: 24.9 mg (94%). Mp 278-280 °C dec. [R]D -1160° (c 5.4 ×
10-5 M, CH2Cl2, 20 °C). CD (CH2Cl2) λ (∆ꢀ) [nm (L mol-1 cm-1)],
250 (-81.6), 276 (+63.7), 332 (-40.8), 351 (+57.1), 422 (-302.0).
UV-vis (CH2Cl2) λmax (ꢀ) [nm (cm-1 M-1)], 288 (100 000), 424
1
(638 000), 518 (42 000), 554 (21 000), 590(15 000), 646 (7000). H,
31P, 13C, and 19F NMR spectra of 30 were found to be identical with
those of 29. Anal. Calcd for C176H120N12P4O12S4F12Pd2‚8H2O: C, 61.59;
H, 3.99; N, 4.90; S, 3.74. Found: C, 61.35; H, 3.76; N, 4.57; S, 3.79.
Acknowledgment. Dedicated to Professor Allen J. Bard on
the occasion of his 65th birthday. We thank the National Science
Foundation (CHE-9529093) and the National Institute of Health
(5R01GM57052) for financial support.
JA9839825