Construction of functionalized metallosupramolecular tetragonal prisms via multicomponent coordination-driven self-assembly

Article abstract of DOI:10.1021/ic2002157

A new approach for the construction of functionalized metallosupramolecular tetragonal prisms via multicomponent, coordination-driven, template-free self-assembly is described. The combination of tetra-(4-pyridylphenyl)ethylene, a 90° Pt(II) acceptor, and

Full text of DOI:10.1021/ic2002157

ARTICLE
pubs.acs.org/IC
Construction of Functionalized Metallosupramolecular Tetragonal
Prisms via Multicomponent Coordination-Driven Self-Assembly
Ming Wang, Yao-Rong Zheng, Timothy R. Cook, and Peter J. Stang*
Department of Chemistry, University of Utah, 315 South 1400 East Salt Lake City, Utah 84112, United States
S Supporting Information
b
ABSTRACT: A new approach for the construction of functio-
nalized metallosupramolecular tetragonal prisms via multicom-
ponent, coordination-driven, template-free self-assembly is
described. The combination of tetra-(4-pyridylphenyl)ethylene,
a 90° Pt(II) acceptor, and ditopic bipyridine or carboxylate
ligands functionalized with hydroxyl or amine groups, hydro-
phobic alkyl chains, or electrochemically active ferrocene, yields a suite of seven self-assembled tetragonal prisms under mild
1
conditions. These three-dimensional metallosupramolecules were characterized by multinuclear NMR (31P and H) and mass
spectrometry. Their shapes and sizes were established using Merck Molecular Force Field (MMFF) simulations. In addition, their
approximate sizes were further supported by pulsed-field-gradient spinꢀecho (PGSE) NMR experiments.
’ INTRODUCTION
supramolecular structures has emerged.8ꢀ12 For example, by
employing sterically demanding tectons in the presence of
aromatic templates, Fujita et al. have designed multicomponent
self-assembled trigonal prisms which are competent for hostꢀ
guest chemistry.9 Severin et al. have described the preparation of
macrocycles and cages based on metalꢀligand interactions and
reversible covalent reactions.10 Stoddart et al. have developed
multicomponent self-assemblies of Borromean rings using com-
plementary imine bond formation and metalꢀligand coordina-
tion.11 We have previously demonstrated that discrete metallo-
supramolecular macrocycles and tetragonal prisms can be ob-
tained by controlling the size, shape, and ratio of the multiple
subunits used in self-assembly.12 More recently, we and others
have found that three-component systems composed of square
planar platinum(II) or palladium(II) centers, pyridine, and anionic
carboxylate donors can self-assemble into multicomponent su-
pramolecular rectangles and prisms with high efficiency.13 The
isolation of discrete self-assemblies without deleterious side
product formation was ascribed to the favorable energetics
associated with heteroligated Pt or Pd centers containing one
carboxylate and one pyridine ligand. Despite these emerging
strategies, which allow the use of multiple building blocks,
reports of multicomponent coordination-driven self-assemblies
using functionalized tectons are rare. The attachment of specific
chemical functionalities to metallosupramolecules is necessary to
enable applications in supramolecular catalysis, chemical sensing,
and hostꢀguest chemistry, therefore motivating the develop-
ment of novel routes to functionalized aseemblies.6
Multicomponent self-assembly is a ubiquitous phenomenon
in biological systems. Nature has demonstrated an extraordinary
ability to assemble two-dimensional (2-D) and three-dimen-
sional (3-D) supramolecular nanoarchitectures from multiple
subunits to effect biological functions.1 For example, the capsids
of Tomato Bushy Stunt Virus are assembled from three protein
subunits and serve the role of nucleic acid storage.2 Apoferritin is
a globular protein composed of 24 components to store and keep
intracellular iron in a soluble and nontoxic form.3 One strategy to
mimic biological processes and to develop new biomimetic
materials is the synthesis of functionalized supramolecular nano-
scale structures with well-defined shapes and sizes, accessible
through efficient and predictable multicomponent self-
assembly.4
In the past two decades, coordination-driven self-assembly has
emerged as a powerful tool to construct abiological structures,
enabling an efficient route which parallels natural pathways. The
rational design of discrete polygons and polyhedra has been
achieved by utilizing molecular subunits encoded with specific
chemical and geometric information.5 In addition, by conjugat-
ing chemical functionalities to individual building blocks prior to
self-assembly, functionalized supramolecular nanoarchitectures
with predetermined sizes and shapes can be realized.6 Despite the
efficiency of preparing abiological structures via coordination-
driven self-assembly, most reports are limited to a single metal
acceptor and a single, electron-rich donor.5,6 The self-assembly of
three or more components is plagued with the formation of
entropically favored, disordered oligomers, and/or dynamic
mixtures.7 Therefore, efficient methods to self-assemble discrete
supramolecular structures with controllable size and shapes from
more than two distinct tectons remain underdeveloped.
We report herein the formation and characterization of 3-D
tetragonal prisms arising from template-free, multicomponent
coordination-driven self-assembly. As shown in Scheme 1, the
Recently, an interest in multicomponent coordination-driven
self-assembly with an emphasis on constructing discrete
Received: January 31, 2011
Published: June 02, 2011
r
2011 American Chemical Society
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Scheme 1. Multicomponent Coordination-Driven Self-Assembly of Functionalized Tetragonal Prismatic Cages
signals in both the 31P{1H} and 1H NMR spectra of 4a support
the formation of single, symmetric reaction product. The 31P-
{1H} NMR spectrum of 4a displays two doublets, occurring at
δ = 0.85 ppm and 0.78 ppm (2JPꢀP = 20.2 Hz) as well as the
expected 195Pt satellites (Figure 1, A). These doublets are shifted
upfield (Δδ = ∼ 4.2 ppm) relative to the singlet of the Pt starting
material, 2. The two doublets of 4a indicate that the platinum
centers each possess two distinct phosphorus environments and
that all the Pt centers are themselves symmetry related. These
observations are consistent with the assigned tetragonal prismatic
structure of 4a, as each platinum binds to both 1 and 3a, breaking
the symmetry of the phosphines.12b,14 The 1H NMR spectrum of
4a displays sharp, clean signals for the pyridine protons, which
exhibit typicaldownfieldshifts relative to free pyridine (Δδpy-R-H
=
0.20ꢀ0.30 ppm, Δδpy-β-H = 0.40ꢀ0.50 ppm) associated with a
loss of electron density upon binding (Figure 1B). Further
support of the tetragonal prismatic structure of 4a is given by
ESI-MS. As shown in Figure 2, peaks centered at 1845.4, 1446.5,
Figure 1. 31P{1H} NMR spectrum (A) and partial 1H NMR spectrum
(B; 300 MHz, 298 K) of 4a recorded in acetonitrile-d3.
1180.6, 848.3, and 515.8, corresponding to [M ꢀ 4OTf]4þ
,
combination of tetra-(4-pyridylphenyl)ethylene (1),12b cis-
(PEt3)2PtII(OTf)2 (2), and functionalized ditopic bipyridine or
carboxylate ligands (3aꢀ3g) in a ratio of 2:8:4 results in the
formation of functionalized tetragonal prisms (4aꢀ4g). Prisms 4
were characterized by multinuclear NMR and electron-spray
ionization mass spectrometry (ESI-MS), supporting their as-
signed structures. Also, pulsed-field-gradient spin-echo (PGSE)
NMR measurements and computational simulations were em-
ployed to predict the shapes and approximate sizes of the prisms.
[M ꢀ 5OTf]5þ, [M ꢀ 6OTf]6þ, [M ꢀ 8OTf]8þ, and [M ꢀ
12OTf]12þ, for 4a, were observed. Furthermore, the peak arising
from [M ꢀ 4OTf]4þ was isotopically resolved and agreed well
with its calculated theoretical distribution.
Functionalized tetragonal prisms 4bꢀ4e were prepared based
on a recently reported strategy for the multicomponent self-
assembly of 2-D and 3-D metallosupramolecules using a 90°
Pt(II) acceptor with carboxylate and pyridine donors.13 The
general route involves mixing the tetratopic pyridine donor, 1,
PtII acceptor, 2, and functionalized isophthalate derivatives
(amino (3b), nitro (3c), n-propanyl (3d), or 3-ferrocenylpropa-
nyl (3e)) in a 2:8:4 ratio in acetone/water (v:v = 8:1). In a typical
synthesis, the solution is stirred for 4 h at 65 °C, after which the
solvent is removed in vacuo and the resulting residue redissolved
in neat nitromethane-d3, followed by an additional 4 h of stirring
at 65 °C. This route yielded prisms 4bꢀ4e in solution. 31P{1H}
’ RESULTS AND DISCUSSION
Tetragonal prism 4a was prepared by mixing 1, 2, and ditopic
1,2-di(4-pyridyl)glycol (3a) in a 2:8:4 ratio in acetone/nitro-
methane (v:v = 2:1). After 12 h of stirring at room temperature,
the reaction mixture appeared yellow. The well-defined NMR
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Figure 2. Full ESI-MS spectrum and isotopic resolved peak of [M ꢀ 4OTf]4þ (calculated: red; experimental: blue) for tetragonal prism 4a.
1
and H NMR multinuclear analyses of the reaction mixtures
indicated the formation of single, discrete self-assemblies with
high symmetry. For example, the 31P{1H} NMR spectrum of 4b
displays two doublets with approximately equal intensities at δ =
6.95 and 1.01 ppm (2JPꢀP = 21.9 Hz; Figure 3, A). The presence
of doublets indicates distinct phosphorus environments, which
would arise from the heteroligated platinum centers containing
both pyridine and carboxylate ligands.12,13 The doublet observed
at 6.95 ppm is ascribed to the phosphines trans to carboxylates
and displays a small shift relative to the resonance found in 2. The
doublet at 1.01 ppm is assigned to the phosphorus atoms trans to
the pyridine ligands and is shifted nearly 6.5 ppm relative to that
of 2. Similarly to 4b, self-assemblies 4cꢀ4e display two doublets
with approximately equal intensities in their 31P{1H} NMR
Figure 3. 31P{1H} NMR spectrum (A) and partial 1H NMR spectrum
(B; 300 MHz, 298 K) of 4c recorded in nitromethane-d3.
spectra, as shown in the Supporting Information, Figures
S1ꢀS3. In the 1H NMR spectra of 4bꢀ4e, sharp signals
corresponding to the coordinated pyridines were identified
around δ = 7.73 and 8.66 ppm, with small downfield shifts
1
conditions as for 4bꢀ4e. 31P{1H} and H NMR multinuclear
relative to those of 1 (Δδpy-R-H = 0.20ꢀ0.30 ppm, Δδpy-β-H
=
analyses of the reaction mixtures indicated the formation of
single, discrete self-assemblies with high symmetry. The 31P{1H}
NMR spectra of 4f and 4g display four doublets with approxi-
mately equal intensities, corresponding to two sets of coupled
0.30ꢀ0.40 ppm; Figure 3B and Supporting Information, Figures
S1ꢀS3). The sharp signals in both the 31P{1H} and the 1H NMR
spectra support the exclusive formation of single, functionalized
tetragonal prisms as products, ruling out other possible assem-
blies and oligomers. ESI-MS provides further evidence for the
tetragonal prismatic structures of 4bꢀ4e. As shown in Figure 4,
peaks centered at 2063.5, 1510.6, 1178.6, and 680.7, correspond-
ing to [M ꢀ 3OTf]3þ, [M ꢀ 4OTf]4þ, [M ꢀ 5OTf]5þ, and
[M ꢀ 8OTf]8þ, for 4b, were observed. Similarly to 4b, the ESI-
MS spectra of 4cꢀ4e display well-defined peaks arising from
tetragonal prismatic structures, as shown in the Supporting
Information, Figures S4ꢀS6. All the peaks of [M ꢀ 3OTf]3þ
of 4bꢀ4e are isotopically resolved and in good agreement with
their calculated theoretical distributions (Figure 4 and Support-
ing Information, Figures S4ꢀS6).
phosphorus atoms, at δ = 6.79, 6.12, 1.28, and 1.21 ppm (2JPꢀP
=
21.4 Hz; Figure 5) for 4f, 6.80, 6.10, 1.28, and 1.21 ppm for 4g
(2JPꢀP = 21.4 Hz; Supporting Information, Figure S7). The
presence of four doublets indicates distinct phosphorus environ-
ments, which is indicative of heteroligated coordination of
pyridine and asymmetric carboxylate to each platinum center.
The two doublets observed between 6.5 and 7.2 ppm are ascribed
to the phosphines trans to carboxylates and display small shifts
relative to 2. Because the functionalized carboxylate linkers are
asymmetric, two distinct Pt environments exist in these prisms
and therefore two different phosphine environments trans to
carboxylates are present. The other two doublets between 1.28
and 1.21 ppm are assigned to the phosphorus atoms trans to the
pyridine ligands and are shifted nearly 6.5 ppm relative to 2. The
distinct phosphine environments trans to the pyridines also
result from the asymmetry of the carboxylate linkers, which
To further demonstrate the construction of functionalized
metallosupramolecules via the multicomponent self-assembly
introduced above, asymmetric terephthalate ligands functiona-
lized with n-hexyl (3f) and 6-ferrocenylhexyl (3g) were self-
assembled with the tetratopic pyridine donor (1) and a PtII
acceptor (2) to afford tetragonal prisms under similar synthetic
1
breaks the symmetry of the Pt centers.13,14 In the H NMR
spectra of 4f and 4g, sharp signals corresponding to the
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Figure 4. Full ESI-MS spectrum and isotopic resolved peak of [M ꢀ 3OTf]3þ(calculated: red; experimental: blue) for tetragonal prism 4b.
’ CONCLUSION
We report here a facile route to functionalized metallosupra-
molecular tetragonal prisms via multicomponent, coordination-
driven, template-free self-assembly. Functionalities were intro-
duced onto 3-D nanostructures by utilizing premodified building
blocks prior to self-assembly. The methodology developed in this
paper extends the emerging strategy of simple, multicomponent
self-assembly to allow the integration of specific functionalities
onto supramolecules. As such, this chemistry is an important step
in designing functional nanoscale architectures which can mimic
natural systems.
Figure 5. 31P{1H} NMR spectrum (A) and partial 1H NMR spectrum
’ EXPERIMENTAL SECTION
(B; 300 MHz, 298 K) of 4f recorded in acetone-d6.
General Details. Ligands 3d16 and 3f17 were prepared according to
reported procedures. Deuterated solvents were purchased from Cam-
bridge Isotope Laboratory (Andover, MA). NMR spectra were recorded
on a Varian Unity 300 MHz spectrometer. 1H NMR chemical shifts are
reported relative to residual proteo solvent signals, and 31P{1H} NMR
chemical shifts are referenced to an external unlocked sample of 85%
H3PO4 (δ 0.0). Mass spectra for the self-assemblies were recorded on a
Micromass Quattro II triple-quadrupole mass spectrometer using
electrospray ionization with a MassLynx operating system. Molecular
modeling of tetragonal prisms was performed using the program
Maestro v 8.0.110 with MMFF methods. Platinum was modeled using
the force field of carbon restrained to have a planar geometry and typical
platinumꢀnitrogen, platinumꢀoxygen, and platinumꢀphosphorus
bond lengths. For the models of 4e and 4g, ferrocenes were replaced
with cyclopentadiene groups.
Synthesis of 3e. Dimethyl-5-hydroxyisophthalate (450.0 mg, 2.1
mmol) and potassium carbonate (0.8 g, 5.8 mmol) weremixedin20.0 mL
of anhydrous dimethylformamide (DMF) and stirred for 1 h under an
atmosphere of nitrogen. A solution of 3-bromopropanylferrocene18 (0.65 g,
2.1 mmol) in 1.0 mL of DMF was then added dropwise. The resulting
solution was stirred at 60 °C for 24 h, quenched with water, and
extracted with ethyl acetate (3 ꢁ 20 mL). The combined organic phases
were dried with anhydrous sodium sulfate, and the solvent was removed
in vacuo. The residue was purified by flash chromatography on silica gel
(eluent: hexane/dichloromethane, v:v = 1:10) to afford dimethyl-3-
ferrocenylpropanyloxyisophthalate as a reddish oil which was used, as
isolated, in future steps. Yield: 43%. 1H NMR (CDCl3, 300 MHz,
298 K): δ = 8.27 (m, 1H, Ar-H), 7.76 (m, 2H, Ar-H), 4.05ꢀ4.15 (m,
11H, Fc and OCH2), 3.95 (s, 6H, COOCH3), 2.54 (m, 2H, CH2CH3),
2.02 (t, 2H, 6.0 Hz, CH3).
coordinated pyridines were identified around δ = 7.73 and 8.66
ppm with small downfield shifts relative to 1 (Δδpy-R-H
=
0.20ꢀ0.30 ppm, Δδpy-β-H = 0.30ꢀ0.40 ppm; Figure 5, and
Supporting Information, Figure S7). ESI-MS also provides
further evidence for the tetragonal prismatic structures of 4f
and 4g. As shown in Figure 6 and Supporting Information, Figure
S8, peaks corresponding to [M ꢀ 3OTf]3þ, [M ꢀ 4OTf]4þ
,
[Mꢀ 5OTf]5þ, [Mꢀ 6OTf]6þ,and[Mꢀ 8OTf]8þ were observed
for 4f and 4g. In addition, the peaks of [M ꢀ 3OTf]3þ are
isotopically resolved and in good agreement with their calculated
theoretical distributions. The clean and well-defined signals in
both the NMR and the MS spectra support the exclusive
formation of functionalized tetragonal prisms as products.15
As attempts to grow single crystals of 4 suitable for X-ray
crystallography have so far been unsuccessful, molecular force
field simulations and PGSE NMR experiments were used to gain
further structural information about 4. Molecular dynamic
simulations using the Merck Molecular Force Fields (MMFFs)
were applied to independently equilibrate cages 4aꢀ4g, followed
by energy minimizations of the resulting structures to full
convergence. As shown in Figure 7 and Supporting Information,
Figure S9, the computed structures of 4 are well-defined tetra-
gonal prisms with diameters between 2.30 and 2.70 nm, which
are comparable to the sizes determined by PGSE NMR measure-
ments (4a: 2.32 ( 0.06 nm; 4b: 2.48 ( 0.04 nm; 4c: 2.84 (
0.12 nm; 4d: 2.12 ( 0.04 nm; 4e: 2.26 ( 0.02 nm; 4f: 2.21 (
0.11 nm; 4g: 2.43 ( 0.19 nm).
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Figure 6. Full ESI-MS spectrum and isotopic resolved peak of [M ꢀ 3OTf]3þ(calculated: blue; experimental: red) for tetragonal prism 4f.
To a solution of dimethyl-6-ferrocenylhexyloxyterephthalate, 0.47 g
(1.0 mmol) in 5.0 mL of methanol, was added 5.0 mL of aqueous NaOH
(0.36 g, 9.0 mmol). The mixture was refluxed for 5 h, and the solvent
removed under reduced pressure. The resulting aqueous solution was
acidified with HCl to afford a yellow precipitate, 6-ferrocenehexylox-
yterephthalic acid. Yield: 82%. 1H NMR (DMSO-d6, 300 MHz, 298 K):
δ = 7.54 (d, 1H, Ar-H, 8.4 Hz), 7.55 (d, 1H, Ar-H, 8.4 Hz), 7.52 (s, 1H,
Ar-H), 4.03ꢀ4.10 (m, 11H, Fc and OCH2), 1.35ꢀ2.28 (m, 11H, alkyl
1
chain); H NMR (DMSO-d6, 5 MHz, 298 K): 168.1, 167.5, 157.6,
135.2, 126.8, 121.6, 114.1, 89.8, 69.1, 68.9, 68.6, 67.6, 31.4, 29.8, 29.3,
29.2, 25.8.
The corresponding sodium salt, 3g, was isolated by neutralization of
Figure 7. Molecular models of tetragonal prisms 4a (A), 4b (B), and
4f (C).
6-ferrocenehexyloxyterephthalic acid (102.2 mg) with 2 equiv of sodium
bicarbonate (38.2 mg) in 3.0 mL of aqueous solution and subsequent
precipitation with acetone to give a yellow solid.
To a solution of dimethyl-3-ferrocenylpropanyloxyisophthalate,
0.50 g (1.1 mmol) in 5.0 mL of methanol, was added 5.0 mL of aqueous
Self-Assembly of Tetragonal Prism 4a. Tetra-(4-pyridylphe-
nyl)ethylene 1 (1.04 mg, 1.62 μmol), (PEt3)2Pt(OTf)2 (2) (4.72 mg,
6.49 μmol), and dipyridine ligand 3a (0.70 mg, 3.24 μmol) were mixed
in 0.9 mL of acetone/nitromethane (v:v = 2:1) and then stirred for 12 h
at room temperature. After removing the solvent in vacuo, the resulting
residue was washed with dichloromethane three times to afford 4a as
yellow solid. Yield: 41%. 31P{1H} NMR (acetonitrile-d3, 121.4 MHz)
δ = 0.85 (d, 2JPꢀP = 20.2 Hz, 195Pt satellites,1JPtꢀP: 3082.3 Hz), 0.78 (d,
2JPꢀP = 20.2 Hz, 195Pt satellites,1JPtꢀP: 3080.2 Hz); 1H NMR
(acetonitrile-d3, 300 MHz, 298 K): δ = 8.67 (m, 16H, HR-Py for donor
1), 8.67 (m, 16H, HR-Py for donor 3a),7.75 (m, 16H, Hβ-Py for donor
1), 7.58 (m, 16H, Hβ-Py for donor 3a), 7.20ꢀ7.54 (d, 32H, ArꢀH, 8.4
Hz), 4.19 (m, 8H, CHꢀOH), 3.90 (m, 8H, CHꢀOH), 1.84 (m, 96H,
F48N16O56P16Pt8S16): m/z: 1845.6.2 [M ꢀ 4OTf]4þ; 1446.9 [M ꢀ
5OTf]5þ. Anal. Calcd for C252H352F48N16O56P16Pt8S16: C, 37.92; H,
4.44; N, 2.81; Found: C, 37.47; H, 4.50; N, 2.83.
General Procedure for the Self-Assembly of Tetragonal
Prisms 4bꢀ4g Using Functionalized Phthalate Ligands.
Tetra-(4-pyridylphenyl)ethylene 1, (PEt3)2Pt(OTf)2 2, and phthalate
derivatives 3bꢀ3g were mixed in 0.9 mL of acetone/H2O (v:v = 8:1).
The mixtures were stirred at 65 °C for 4 h, at which time the solvents
were removed and the residues redissolved in nitromethane-d6, followed
by a further 4 h of stirring at 65 °C. Tetragonal prisms 4bꢀ4g were
isolable as solids recrystallized from acetone/diethyl ether.
NaOH (0.20 g, 5.0 mmol). The mixture was refluxed for 5 h, and the
solvent removed under reduced pressure. The resulting aqueous solu-
tion was acidified with HCl to afford a yellow precipitate, 3-ferrocene-
propanyloxyisophthalic acid. Yield: 82%. 1H NMR (DMSO-d6, 300
MHz, 298 K): δ = 8.08 (s, 1H, Ar-H), 7.65 (m, 2H, Ar-H), 4.05ꢀ4.13
(m, 11H, Fc and OCH2), 2.47 (m, 2H, CH2CH3), 1.99 (t, 3H, 6.1 Hz,
CH3); 13C NMR (DMSO-d6, 75 MHz, 298 K): 167.4, 159.6, 133.6,
123.0, 119.7, 89.7, 69.0, 68.4, 67.6, 30.3, 26.1.
The corresponding sodium salt, 3e, was isolated by neutralization of
3-ferrocenepropanyloxyisophthalic acid (111.3 mg) with 2 equiv of
sodium bicarbonate (45.8 mg) in 3.0 mL of aqueous solution and
subsequent precipitation with acetone to give a yellow solid.
Synthesis of 3g. Dimethyl-2-hydroxyterephthalate (630.0 mg, 3.0
mmol) and potassium carbonate (0.9 g, 6.9 mmol) were mixed in
20.0 mL of anhydrous DMF and stirred for 3 h under an atmosphere of
nitrogen. A solution of 6-bromohexylferrocene19 (1.24 g, 3.6 mmol) in
1.0 mL of DMF was then added dropwise. The resulting solution was
stirred at 60 °C for 2 days, quenched with water and extracted with ethyl
acetate (3 ꢁ 20 mL). The combined organic phases were dried with
anhydrous sodium sulfate, and the solvent was removed in vacuo. The
residue was purified by flash chromatography on silica gel (eluent:
hexane/dichloromethane, v:v = 2:3) to afford dimethyl-6-ferrocenyl-
hexyloxy-terephthalate as a reddish oil which was used, as isolated, in
future steps. Yield: 43%. 1H NMR (CDCl3, 300 MHz, 298 K): δ = 7.78
(d, 1H, Ar-H, 8.4 Hz), 7.63 (d, 1H, Ar-H, 8.4 Hz), 7.61 (s, 1H, Ar-H),
4.00ꢀ4.15 (m, 11H, Fc and OCH2), 3.94, 3.91 (s, 6H, COOCH3),
1.40ꢀ2.35 (m, 11H, alkyl chain).
PCH2CH3), 1.23(m, 144H, PCH2CH3); MS (ESI) for 4a (C252H352
-
Synthesis and Characterization of 4b. Reaction scale: tetra-
topic ligand (1) (0.94 mg, 1.47 μmol), (PEt3)2Pt(OTf)2 (2) (4.28 mg,
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5.87 μmol), and 5-aminoisophthalate (3b) (0.66 mg, 2.94 μmol). Yield:
Synthesis and Characterization of 4g. Reaction scale: tetra-
topic ligand (1) (0.63 mg, 0.98 μmol), (PEt3)2Pt(OTf)2 (2) (2.87 mg,
3.93 μmol), and 2-(6-Ferrocenylhexyl)terephthalate (3g) (0.97 mg, 1.97
μmol). Yield: 86%. 31P{1H} NMR (acetone-d6, 121.4 MHz) δ = 6.80 (d,
82%. 31P{1H} NMR (nitromethane-d3, 121.4 MHz) δ = 6.95 (d, 2JPꢀP
=
2
21.6 Hz, 195Pt satellites,1JPtꢀP: = 3220.7 Hz), 1.01 (d, JPꢀP = 21.5 Hz,
195Pt satellites,1JPtꢀP: = 3428.3 Hz); H NMR (nitromethane-d3, 300
1
MHz, 298 K): δ = 8.79 (m, 16H, HR-Py for donor 1), 7.78 (m, 16H, Hβ-Py
for donor 1, ArꢀH), 7.56 (m, 16H, ArꢀH), 7.34(m, 4H, ArꢀH), 7.30 (m,
16H, ArꢀH), 7.24 (m, 8H, ArꢀH), 1.98 (m, 96H, PCH2CH3), 1.31 (m,
144H, PCH2CH3); MS (ESI) for 4b (C225H324F15N12O31P16Pt8S5):
m/z: 2063.2 [M ꢀ 3OTf]3þ. Anal. Calcd for C228H324F24N12O40P16-
Pt8S8: C, 41.23; H, 4.62; N, 2.53; Found: C, 40.52; H, 4.76; N, 2.51.
Synthesis and Characterization of 4c. Reaction scale: tetra-
topic ligand (1) (1.00 mg, 1.56 μmol), (PEt3)2Pt(OTf)2 (2) (4.55 mg,
6.24 μmol), and 5-nitroisophthalate (3c) (0.80 mg, 3.12 μmol). Yield:
2JPꢀP = 21.9 Hz, 195Pt satellites,1JPtꢀP: = 3215.9 Hz), 6.10 (d, 2JPꢀP
=
21.9 Hz, 195Pt satellites,1JPtꢀP: = 3208.6.9 Hz), 1.28 (d, 2JPꢀP = 21.9 Hz,
2
195Pt satellites,1JPtꢀP: = 3419.3 Hz), 1.21(d, JPꢀP = 21.9 Hz, 195Pt
satellites,1JPtꢀP: = 3410.3 Hz); 1H NMR (acetone-d6, 300 MHz, 298 K):
δ = 8.91 (m, 16H, HR-Py for donor 1),7.93 (m, 16H, Hβ-Py for donor 1),
7.27ꢀ7.72 (m, 16H, ArꢀH), 7.23 (d, 4H, 9.0 Hz), 7.20 (s, 4H, ArꢀH),
6.97 (d, 4H, 9.0 Hz), 4.05ꢀ4.10 (m, 45H, ferrocene), 3.89 (t, 8H, OCH2,
5.4 Hz), 2.12 (m, 40H, alkyl), 1.99 (m, 96H,PCH2CH3), 1.32 (m, 144H,
PCH2CH3); MS (ESI) for 4g (C292H400F24Fe4N8O44P16Pt8S8): m/z:
2422.8[M ꢀ 3OTf]3þ. Anal. Calcd for C292H400F24Fe4N8O44P16Pt8S8:
C, 45.44; H, 5.22; N, 1.45; Found: C, 44.71; H, 5.02; N, 1.44.
74%. 31P{1H} NMR(nitromethane-d3, 121.4 MHz) δ = 6.71 (d, 2JPꢀP
=
21.7 Hz, 195Pt satellites,1JPtꢀP: = 3203.7 Hz), 1.35 (d, 2JPꢀP = 21.6 Hz,
1
195Pt satellites,1JPtꢀP: = 3512.3 Hz); H NMR (nitromethane-d3, 300
MHz, 298 K): δ = 8.82 (m, 16H, HR-Py for donor 1), 8.83 (m, 8H,
ArꢀH), 8.36 (m, 4H, ArꢀH), 7.79 (m, 16H, Hβ-Py for donor 1), 7.54 (m,
16H, ArꢀH), 7.26 (m, 16H, ArꢀH), 1.99(m, 96H,PCH2CH3), 1.31(m,
144H, PCH2CH3); MS (ESI) for 4c (C252H316F15N12O39P16Pt8S5): m/
z: 2104.5 [M ꢀ 3OTf]3þ. Anal. Calcd for C228H316F24N12O48P16Pt8S8:
C, 40.5; H, 4.71; N, 2.49; Found: C, 39.60; H, 4.51; N, 2.42.
’ ASSOCIATED CONTENT
Supporting Information. 31P {1H} and H NMR spec-
1
S
b
1
tra, ESI-MS spectra; molecular modeling of 4cꢀ4e, 4 g. H
NMR, 13C NMR spectra of 3f and 3g. This material is available
free of charge via the Internet at http://pubs.acs.org.
Synthesis and Characterization of 4d. Reaction scale: tetra-
topic ligand (1) (0.93 mg, 1.45 μmol), (PEt3)2Pt(OTf)2 (2) (4.25 mg,
5.80 μmol), and 5-(3-propanyl)isophthalate (3d) (0.78 mg, 2.90 μmol).
Yield: 86%. 31P{1H} NMR (acetonitrile-d3, 121.4 MHz) δ = 6.71 (d,
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: stang@chem.utah.edu.
2JPꢀP = 21.7 Hz, 195Pt satellites,1JPtꢀP: = 3192.7 Hz), 1.17 (d, 2JPꢀP
=
21.6 Hz, 195Pt satellites,1JPtꢀP: = 3448.9 Hz); 1H NMR (acetonitrile-d3,
300 MHz, 298 K): δ = 8.67 (m, 16H, HR-Py for donor 1),7.70 (m, 16H,
’ ACKNOWLEDGMENT
H
β-Py for donor 1), 7.52 (m, 16H, ArꢀH), 7.39 (d, 8H, ArꢀH), 7.20 (s,
P.J.S. thanks the NIH (Grant GM-057052) for financial
support. This paper is dedicated to Professor Michael Hanack
on the occasion of his 80th birthday.
16H, ArꢀH), 3.92 (t, 8H, OCH2, 5.4 Hz), 2.12 (m, 8H, alkyl), 1.79 (m,
96H,PCH2CH3), 1.18 (m, 144H, PCH2CH3); 1.01 (t, 12H, CH3, 7.4
Hz); MS (ESI) for 4d (C237H344F15N8O35P16Pt8S5): m/z: 2121.8[M ꢀ
3OTf]3þ. Anal. Calcd for C272H356F24N12O68P16Pt8S8: C, 42.30; H,
5.09; N, 1.64; Found: C, 41.84; H, 4.93; N, 1.68.
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Synthesis and Characterization of 4e. Reaction scale: tetra-
topic ligand (1) (0.94 mg, 1.47 μmol), (PEt3)2Pt(OTf)2 (2) (4.29 mg,
5.88 μmol), and 5-(3-Ferrocenylpropanyl)isophthalate (3e) (1.33 mg,
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6.72 (d, 2JPꢀP = 21.6 Hz, 195Pt satellites,1JPtꢀP: = 3202.7 Hz), 1.19 (d,
2JPꢀP = 21.6 Hz, 195Pt satellites,1JPtꢀP: = 3431.9 Hz); 1H NMR
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4.05 (t, 8H, OCH2, 5.4 Hz), 2.54 (m, 8H, CH2-Fc); 1.89 (m, 104H,
PCH2CH3, OCH2CH2CH2Fc), 1.15 (m, 144H, PCH2CH3); MS (ESI)
for 4e (C277H376F15Fe4N8O35P16Pt8S5): m/z: 2366.9[M ꢀ 3OTf]3þ
.
Anal. Calcd for C280H376F24Fe4N8O44P16Pt8S8: C, 44.54; H, 5.02; N,
1.48; Found: C, 43.71; H, 4.92; N, 1.48.
Synthesis and Characterization of 4f. Reaction scale: tetra-
topic ligand (1) (1.03 mg, 1.61 μmol), (PEt3)2Pt(OTf)2 (2) (4.61 mg,
6.44 μmol), and 2-(6-hexyl)terephthalate (3f) (1.00 mg, 3.22 μmol).
Yield: 74%. 31P{1H} NMR(acetone-d6, 121.4 MHz) δ = 6.79 (d, 2JPꢀP
=
21.9 Hz, 195Pt satellites,1JPtꢀP: = 3228.1 Hz), 6.12 (d, 2JPꢀP = 21.9 Hz,
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2
195Pt satellites,1JPtꢀP: = 3221.9 Hz), 1.28 (d, JPꢀP = 21.9 Hz, 195Pt
2
satellites,1JPtꢀP: = 3439.3 Hz), 1.21 (d, JPꢀP = 21.9 Hz, 195Pt
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