A Pd8 Tetrafacial Molecular Barrel as Carrier for Water Insoluble Fluorophore

Article abstract of DOI:10.1021/jacs.5b08008

A new carbazole-based tetraimidazole ligand 1,3,6,8-tetra(1H-imidazol-1-yl)-9-methyl-9H-carbazole (L) has been synthesized. The unsymmetrical nature of L as well as the rotational freedom of imidazole donor moieties around C-N bond make it a special building unit, which upon treatment with cis-(tmeda)Pd(NO₃)₂ produced an unprecedented single linkage-isomeric Pd₈ tetrafacial molecular nanobarrel (PSMBR-1) [tmeda = N,N,N′,N′-tetramethylethane-1,2-diamine]. Unlike closed architectures, open barrel architecture of water-soluble PSMBR-1 makes it an ideal host for some water insoluble polyaromatic hydrocarbons in aqueous medium; one such inclusion complex coronenePSMBR-1 was characterized by X-ray diffraction study. Moreover, the potential application of PSMBR-1 as carrier in aqueous medium for the transportation of water insoluble fluorophore (perylene) for live cell imaging is explored.

Full text of DOI:10.1021/jacs.5b08008

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Communication
A Pd8 Tetrafacial Molecular Barrel as Carrier for Water Insoluble Fluorophore
Bijan Roy, aloke kumar ghosh, Shubhi Srivastava, Patrick D’ Silva, and Partha Sarathi Mukherjee
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.5b08008 • Publication Date (Web): 04 Sep 2015
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Journal of the American Chemical Society
A Pd8 Tetrafacial Molecular Barrel as Carrier for Water Insolu-
ble Fluorophore
Bijan Roy,a Aloke Kumar Ghosh,a‡ Shubhi Srivastava,b‡ Patrick D’ Silva,b Partha Sarathi
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Mukherjeea*
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aDepartment of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560012, India. Fax: 91-80-
2360-1552; Tel; 91-80-2293-3352.
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bDepartment of Biochemistry, Indian Institute of Science, Bangalore-560012.
Supporting Information Placeholder
cal or barrel shaped architectures are very much promising
ABSTRACT: A new carbazole based tetraimidazole ligand
as they possess windows similar to their cavity size. Moreo-
ver, release of guests is also expected to be easy through the
open window. Even in biology, barrel shaped protein struc-
tures, viz. beta-barrels have immense importance in the dif-
fusion process of small molecules and ions through cell
membranes.10 However, the synthesis of discrete barrel
shaped architectures by metal-ligand self-assembly remains
very challenging and scarcely reported in the literature.11
1,3,6,8-tetra(1H-imidazol-1-yl)-9-methyl-9H-carbazole (L) has
been synthesized. The unsymmetrical nature of L as well as
the rotational freedom of imidazole donor moieties around
C-N bond make it a special building unit, which upon treat-
ment with cis-(tmeda)Pd((NO3)2 produced an unprecedent-
ed single linkage-isomeric Pd8 tetrafacial molecular nanobar-
rel (PSMBR-1) [tmeda = N,N,N’,N’-tetramethylethane-1,2-
diamine]. Unlike closed architectures, open barrel architec-
ture of water soluble PSMBR-1 makes it an ideal host for
some water insoluble polyaromatic hydrocarbons (PAHs) in
aqueous medium; one of such inclusion complexes coro-
nene⊂PSMBR-1 was characterized by X-ray diffraction study.
Moreover, the potential application of PSMBR-1 as carrier in
aqueous medium for the transportation of water insoluble
fluorophore (perylene) for live cell imaging is explored.
Scheme 1: Schematic representation of the expected
cube and the synthesis of molecular barrel PSMBR-1.
Metal-ligand coordination driven self-assembly has
evolved as a powerful approach to achieve discrete nanome-
ter sized molecular architectures.1 After the successful syn-
thesis of the famous ‘molecular square’ in 1990 via this ap-
proach, the next two decades have seen a tremendous
growth in this field with the introduction of numerous fasci-
nating two-dimensional (2D) and three-dimensional (3D)
architectures of diverse shapes, sizes and functionality.2
While, the ‘Molecular library’ suggested by Stang et al have
made it easy to design precursors for a desired architecture,
the concept of ‘Ship in a bottle’ and ‘Molecular flask’ by Fu-
jita et al have illustrated their multifaceted applications in
guest encapsulation, catalysis, peptide binding etc.3-7 Sym-
metrical ligands have been extensively used due to the ease
of convergence in discrete closed-shell architecture.8 In this
context, the use of an non-symmetrical multitopic donor
(number of donor sites ≥ 3) remains largely neglected due to
the possibility of formation of multiple conformational iso-
mers upon diverse orientation of the donors around the met-
al centers (Figure S1). However, in principle, such non-
symmetrical multidentate donors can yield unprecedented
structural features which otherwise are not expected on the
basis of the ‘Molecular library’ concept.
Herein, we report the template free synthesis of an
unprecedented water soluble tetrafacial molecular barrel
PSMBR-1 via the self-assembly of a new asymmetric tetraim-
idazole donor L with 90° acceptor cis-Pd(tmeda)(NO3)2 (M)
(Scheme 1). Such a self-assembly reaction may also lead to
the expected closed cubic architecture M12L6 and numerous
linkage isomeric structures due to the different connectivity
of the two ‘pairs’ of dissimilar imidazole units in the ligand L.
Despite of such several possibilities, formation of a single
linkage isomeric tetrafacial barrel in the present case is very
surprising (Figure S1). The barrel has hydrophobic pocket
surrounded by the four conjugated aromatic walls (L). The
newly engineered molecular barrel with integrated hydro-
phobic pocket and water soluble nature has shown to be
suitable for the encapsulation of water insoluble aromatic
hydrocarbons in aqueous medium.12 Moreover, the potential
of this open barrel as carrier for the transportation of water
insoluble perylene into HeLa cell in aqueous medium for live
cell imaging without alteration of cell morphology has been
explored.
L was synthesized in good yield from the N-methyl
tetrabromo derivative of carbazole (2) by standard copper (I)
catalyzed C-N coupling reaction as shown in Scheme 2. It
was fully characterized by elemental analysis, multinuclear
NMR spectroscopy, COSY, NOESY, ESI- MS spectrometry,
and its solid state structure was elucidated by single crystal
X-ray diffraction analysis (Figure 1).
Most of the reported 3D discrete architectures of
Pd(II)/Pt(II) have closed structures. Due to their closed-shell
topology, they possess comparatively smaller windows with
respect to their internal cavity size, which in turn restricts
bigger guest molecules to go inside.9 In this respect, cylindri-
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Scheme 2: Synthetic strategy for the donor L.
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Figure 2. 1H NMR spectra of PSMBR-1. Only aromatic region
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The imidazoles at C3 and C12 are found to reside se-
verely out of the carbazole plane compared to the rests due
to steric repulsion with the N-methyl group, as is reflected
is shown for the sake of clarity. The peaks were assigned with
the help of the 1H-1H COSY spectra (Figure S10) as well as the
single crystal X-ray structure of the coronene⊂PSMBR-1
complex (Figure 3).
from the torsional angles (ϕC2-C3-N2-C16 = -62.8°; ϕC13-C12-N8-C25
=
53.6°; ϕC4-C5-N4-C19 = -16.9° and ϕC9-C10-N6-N22 = 26.2°). Though
the imidazoles at C3 and C12 as well as at C5 and C10 look
different in terms of their orientations in the solid state, the
Unfortunately, several attempts to obtain diffrac-
tion quality single crystals of PSMBR-1 remained unsuccess-
ful. However, the coronene encapsulated PSMBR-1 was suc-
cessfully crystallized by diffusion of acetone vapour into
aqueous solution of the encapsulated complex. Single crystal
X-ray diffraction analysis unambiguously established the
open tetrafacial barrel architecture of the assembly (Figure
3). The inclusion complex (coronene ⊂ PSMBR-1) was crys-
tallized in triclinic space group P-1 where the asymmetric
unit contains only one molecule. The four panel-like ligands
are connected together in head-to-head fashion by eight
Pd(II) acceptors which furnishes the square barrel topology.
The dimension of the cavity is found to be 11.7×11.4×10.5 Å3
and the farthest methyl groups associated with the diagonal
metal centres are ~25 Å apart from each other (Figure 3),
which is quite close to the hydrodynamic radius of PSMBR-1
as obtained from the DOSY experiment. All the four N-
methyl groups of the ligands are found to be tilted inwards
the cavity. The crystal structure also showed that the oppo-
site ligand panels of the centrosymmetric molecular barrel
are identical, however, different from the adjacent ones
1
differences remain untraced in the H NMR spectra due to
their rapid rotation with respect to the NMR time scale (Fig-
ure S4).
Figure 1. Ball and stick representation of the crystal structure
of L. Hydrogen atoms are omitted for clarity.
Overnight heating of a clear solution of L and cis-
(tmeda)Pd(NO3)2 (M) in DMSO at 80° C in 1:2 molar ratio
resulted a clear brown solution which upon treatment with
excess ethyl acetate yielded PSMBR-1 as off white precipitate
in quantitative yield. The product is completely soluble in
1
which clearly explains the origin of fourteen peaks in the H
NMR spectra of PSMBR-1. Interestingly, though the distanc-
es between the opposite walls of the cavity are differ by ~2.7
Å (Figure S26), the two coronene molecules are found to be
comfortably aligning within the smaller gap. The coronene-
coronene shortest distance is 3.90 Å while they are 3.72 Å
apart from the walls.
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water which is known as the ‘solvent of nature’. H NMR
spectra in D2O showed the presence of fourteen peaks be-
tween 9.0-7.3 ppm (Figure 2), which could be due to different
orientation of the imidazole moieties around metal centers
or the formation of mixture of products. Diffusion ordered
NMR spectroscopy (DOSY, DMSO-d6), however, corroborat-
ed the formation of a single product with hydrodynamic ra-
PAHs and their derivatives are generally π-electron
rich and possess attractive luminescence properties and
hence found immense importance in optoelectronics and dye
industries.13 But, their poor solubility in water limits their use
in aqueous medium. To judge the efficiency of the newly
engineered molecular barrel as a host for PAHs and their
derivatives in aqueous medium, naphthalene, anthracene,
pyrene, perylene and perylene tetracarboxylic acid dianhy-
dride (PTCDA) along with the coronene were selected as
analytes, which are mostly insoluble in water.14 To our great
delight, all the guests molecules were found to be efficiently
encapsulated by PSMBR-1 upon overnight stirring at room
temperature in water and the inclusion of guests was con-
1
dius of ~ 11.8 Å (Figure S11). Variable temperature H NMR
spectra in DMSO-d6 showed no permanent change in the
peak positions or any deformation upon heating up to 125° C,
strictly advocated the stability of PSMBR-1 in a wide range of
temperature in solution (Figure S12). The composition of the
assembly was precisely determined by ESI-MS spectrometry
-
of the PF6 analogue of PSMBR-1. The presence of several
prominent peaks at m/z = 1815.51, 1325.38 and 1031.31 with
isotopic distribution patterns corresponding to [PSMBR-1-
- +3
- +4
- +5
3PF6 ] , [PSMBR-1-4PF6 ] and [PSMBR-1-5PF6 ] charge
fragments respectively, confirmed the formation of a M8L4
species (Figures S13-14). Though the formation of tetrafacial
barrel was quite evident from the NMR and ESI-MS analyses,
1
firmed by H NMR, UV-Vis and fluorescence studies. Encap-
sulations caused significant changes in peak positions in the
aromatic region as observed in the 1H NMR spectra for all the
encapsulated complexes except PTCDA (Figures S15-S20),
attributed due to
1
the H NMR spectra was inconclusive about the exact orien-
tation of the imidazole moieties around metal centers in the
assembly.
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Figure 5. Aqueous solutions of PSMBR-1, perylene ⊂
PSMBR-1 and PTCDA ⊂ PSMBR-1 complexes under (a)
normal light and (b) UV light and their corresponding (c)
absorption and (d) emission spectra.
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Figure 3. Crystal structure of coronene ⊂ PSMBR-1. Guest
molecules are represented in space filled model. Colour
codes: green = carbon, blue = nitrogen. Hydrogen atoms,
counter anions and solvent molecules are omitted for clarity.
from simple organic dyes to metal-ligand complexes.16 How-
ever, special attention is still required to overcome the com-
mon problems such as solubility, aggregation induced
quenching, pH sensitivity etc. Our target in that context is:
can we use simple organic fluorophores such as PAHs as cell
imaging agents by delivering them inside cell via water solu-
ble host like PSMBR-1? To answer this question, HeLa cells
were incubated with a 25 µM solution of perylene⊂PSMBR-1
complex for a period of 30 minutes. Perylene⊂PSMBR-1
complex readily internalizes inside the cells without causing
toxicity. Microscopy images of the treated cells show brilliant
blue emission from the cytoplasm without alteration of cell
morphology (Figure 6). In a control experiment, no fluores-
cence was detected upon treatment of the cells with perylene
itself due to the lack of solubility. The successful membrane
penetration of the inclusion complex could be attributed to
the presence of 32 lipophilic methyl groups associated with
the palladium acceptors.
the strong π-π interaction of the guest molecules with the
walls of the cavity. Moreover, the encapsulated guests mole-
cules showed new set of peaks in the range of 7-5 ppm, which
were significantly shielded due to the ring current effect in-
side cavity. Remarkable visual colour changes of the aqueous
solutions were observed from pale yellow to intense yellow
and red in case of perylene and PTCDA respectively (Figure
5) upon encapsulation, which was also reflected in their UV-
Vis spectra with the presence of additional bands assigned to
the guest molecules. In addition, the inclusion complexes of
anthracene, perylene and PTCDA showed characteristic lu-
minescence of the guest molecules respectively (Figure 5) in
aqueous medium. The stoichiometry of the host-guest com-
plexes could not be determined by conventional spectroscop-
ic titrations due to the poor aqueous solubility of the ana-
lytes. NMR study was also not much helpful for this purpose
1
because of broadened H NMR peaks as a result of tumbling
motion of the guests inside the cavity. Albeit, the successful
single crystal X-ray diffraction analysis of the coro-
nene⊂PSMBR-1 inclusion complex unambiguously con-
firmed the host-guest stoichiometry to be 1:2.
Figure 6. Microscopy images show blue emission from the
cytoplasm of HeLa cells after the incubation with aqueous
solution of perylene⊂PSMBR-1 complex (b, c). Perylene
alone is not able to go inside the cell and hence no fluores-
cence was observed (a).
In conclusion, we report here the selective for-
mation of a single linkage isomeric unprecedented tetrafacial
nanobarrel employing a new nonsymmetric tetraimidazole
ligand with 90⁰ Pd(II) ditopic acceptor. Despite of the possi-
bility of expected closed cubic structure as well as several
linkage isomeric barrels due to different connectivity of the
nonsymmetric tetratopic donor, the formation of a single
isomeric tetrafacial barrel in the present case is remarkable.
The water soluble nature in combination with the presence
of hydrophobic pocket make it a novel host for the encapsu-
lation of water insoluble PAHs, as evident from spectroscopic
studies including X-ray analysis of coronene⊂PSMBR-1
Figure 4. Aromatic region of the 1H NMR spectra of perylene
⊂ PSMBR-1 inclusion complex. Star marked peaks corre-
spond to the encapsulated perylene molecules.
Live cell imaging has become an indispensable method for
diagnostics as well as biological studies in order to track dy-
namics and functions of various cellular processes. The fore-
most important factors associated with a cell imaging fluoro-
phore are membrane permeability, cell viability, solubility
and stability.15 Various probes have been developed for this
purpose
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chi, K. J. Am. Chem. Soc. 2000, 122, 6311. (f) Ramsay, W. J.; Szczypin´
complex. Moreover, the preliminary investigation has
demonstrated the PdII molecular barrel (PSMBR-1) to be a
ski, F. T.; Weissman, H.; Ronson, T. K.; Smulders, M. M. J.;
Rybtchinski, B.; Nitschke, J. R. Angew. Chem., Int. Ed. 2015, 54, 5636.
(g) Furrer, M. A.; Schmitt, F.; Wiederkehr, M.; Juillerat-Jeanneret, L.;
Therrien, B. Dalton Trans. 2012, 41, 7201.
(4) (a) Mahata, K.; Frischmann, P. D.; Wurthner, F. J. Am. Chem.
Soc. 2013, 135, 15656. (b) Mal, P.; Breiner, B.; Rissanen, K.; Nitschke, J.
R. Science 2009, 324, 1697.
(5) (a) Simón, C. G.-; Doria, R. G.-; Raoufmoghaddam, S.; Parella, T.;
Costas, M.; Ribas, X.; Reek, J. N. H. J. Am. Chem. Soc. 2015, 137, 2680.
(b) Yoshizawa, M.; Tamura, M.; Fujita, M. Science, 2006, 312, 251.
(6) (a) Samanta, D.; Mukherjee, P. S. Chem. Commun. 2014, 50, 1595.
(b) Samanta, D.; Mukherjee, P. S. Chem. Eur. J. 2014, 20, 5649.
(7) (a) Sato, S.; Yoshimasa, Y.; Fujita, D.; Utsumi, M. Y.-; Yamagu-
chi, T.; Kato, K.; Fujita, M. Angew. Chem., Int. ed. 2015, 54, 8435. (b)
Kikuchi, T.; Sato, S.; Fujita, D.; Fujita, M. Chem. Sci., 2014, 5, 3257.
(8) (a) Stang, P. J.; Olenyuk, B. Acc. Chem. Res. 1997, 30, 502. (b)
Cook, T. R.; Vajpayee, V.; Lee, M. H.; Stang, P. J.; Chi, K.-W. Acc.
Chem. Res. 2013, 46, 2464. (c) Cook, T. R.; Stang, P. J. Chem. Rev.
2015, 115, 7001.
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potential carrier to transport water insoluble perylene mole-
cules inside the live cell in aqueous medium in order to use
as a cell imaging probe. The “proof of concept” of transporta-
tion of water insoluble analyte to live cells using a water sol-
uble carrier has huge impact to explore the scope of using a
wide range of water insoluble dye molecules for live cell im-
aging as well as in drug delivery.
9
ASSOCIATED CONTENT
Supporting Information
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Supporting information contains experimental procedures
and characterization data (NMR, ESI MS, UV/Vis spectra) for
L, PSMBR-1 and encapsulated complexes along with cell
imaging protocol.
(9) (a) MacGillivray, L. R.; Atwood, J. L. Angew. Chem., Int. Ed. 1999,
38, 1018. (b) Bruns, C. J.; Fujita, D.; Hoshino, M.; Sato, S.; Stoddart, J.
F.; Fujita, M. J. Am. Chem. Soc. 2014, 136, 12027. (b) Samanta, D.;
Mukherjee, P. S. Chem. Eur. J. 2014, 20, 12483. (c) Sun, B.; Wang, M.;
Lou, Z.; Huang, M.; Xu, C.; Li, X.; Chen, L.-J.; Yu, Y.; Davis, G. L.; Xu,
B.; Yang, H.-B.; Li, X. J. Am. Chem. Soc. 2015, 137, 1556.
(10) (a) Bishop, R. E. Biochimica et Biophysica Acta 2008, 1778, 1881.
(b) Yamashita, D.; Sugawara, T.; Takeshita, M.; Kaneko, J.; Kamio, Y.;
Tanaka, I.; Tanaka, Y.; Yao, M. Nature Commun. 2014, 5, 4857.
(11) (a) Yamanoi, Y.; Sakamoto, Y.; Kusukawa, T.; Fujita, M.; Sakamo-
to, S.; Yamaguchi, K. J. Am. Chem. Soc. 2001, 123, 980. (b) Goeb, S.;
Bivaud, S.; Croué, V.; Vajpayee, V.; Allain, M.; Sallé, M. Materials
2014, 7, 611. (c) Nakamura, T.; Ube, H.; Miyake, R.; Shionoya, M. J.
Am. Chem. Soc. 2013, 135, 18790. (d) Bar, A. K.; Chakrabarty, R.; Mo-
stafa, G.; Mukherjee, P. S. Angew. Chem., Int. Ed. 2008, 27, 316. (e)
Riddell, I. A.; Hristova, Y. R.; Clegg, J. K.; Wood, C. S.; Breiner, B.;
Nitschke, J. R. J. Am. Chem. Soc. 2013, 135, 2723.
(12) (a) Hof, F.; Craig, S. L.; Nuckolls, C.; Rebek, Jr., J. Angew. Chem.,
Int. Ed. 2002, 41, 1488. (b) Dsouza, R. N.; Pischel, U.; Nau, W. M.
Chem. Rev. 2011, 111, 7941. (c) Schmuck, C. Angew. Chem., Int. Ed.
2007, 46, 5830.
(13) (a) Weil, T.; Vosch, T.; Hofkens, J.; Peneva, K.; Müllen, K. Angew.
Chem., Int. Ed. 2010, 49, 9068. (b) Faulkner, E. B.; Schwartz, R. J.;
Greene, M. Perylene Pigments Wiley-VCH Verlag GmbH & Co. KGaA,
Weinheim, 2009. (c) Yang, J.; Yan, D.; Jones, T. S. Chem. Rev. 2015,
115, 5570. (d) Zang, L.; Che, Y.; Moore, J. S. Acc. Chem. Res. 2008, 41,
1596.
(14) (a) Li, K.; Zhang, L.-Y.; Yan, C.; Wei, S.-C.; Pan, M.; Zhang, L.; Su,
C.-Y. J. Am. Chem. Soc. 2014, 136, 4456. (b) Bivaud, S.; Goeb, S.;
Croué, V.; Dron, P. I.; Sallé, A., M. J. Am. Chem. Soc. 2013, 135, 10018.
(15) (a) Herschman, H. R. Science 2003, 302. (b) He, Y.; Su, Y.; Yang,
X.; Kang, Z.; Xu, T.; Zhang, R.; Fan, C.; Lee, S.-T. J. Am. Chem. Soc.
2009, 131, 4434. (c) Tan, T. T. T.; Khaw, C.; Ng, M. M. L. Microscopy:
Science, Technology, Applications and Education A. Méndez-Vilas and
J. Díaz (Eds.).
(16) (a) Yuan, L.; Lin, W.; Zheng, K.; He, L.; Huang, W. Chem. Soc.
Rev. 2013, 42, 622. (b) Wolfbeis, O. S. Chem. Soc. Rev. 2015, 44, 4743.
(c) Mishra, A.; Ravikumar, S.; Song, Y. H.; Prabhu, N. S.; Kim, H.;
Hong, S. H.; Cheon, S.; Nohe, J.; Chi, K.-W. Dalton Trans. 2014, 43,
6032. (d) Schmitt, F.; Freudenreich, J.; Barry, N. P. E.; Juillerat-
Jeanneret, L.; Süss-Fink, G.; Therrien, B. J. Am. Chem. Soc. 2012, 134,
754.
AUTHOR INFORMATION
Corresponding Author
*psm@ipc.iisc.ernet.in
Author Contributions
‡These authors contributed equally.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT
The authors sincerely acknowledge CSIR-India and DST-
INSPIRE program for financial support. PSM and PDS thank
the DST, New Delhi for financial support as Swarnajayanti
fellowship. AKG is grateful to UGC (New Delhi) for Dr. D. S.
Kothari Postdoctoral fellowship.
REFERENCES
(1) (a) Lehn, J. M. Proc. Natl. Acad. Sci. U. S. A. 2002, 99, 4763. (b)
Fujita, M.; Tominaga M.; Hori, A.; Therrien, B. Acc. Chem. Res. 2005,
38, 371. (c) Ronson, T. K.; Zarra, S.; Black, S. P.; Nitschke, J. R. Chem.
Commun. 2013, 49, 2476. (d) Mukherjee, S.; Mukherjee, P. S. Chem.
Commun. 2014, 50, 2239. (e) Leininger, S.; Olenyuk, B.; Stang, P. J.
Chem. Rev. 2000, 100, 853.
(2) (a) Fujita, M.; Yazaki, J.; Ogura, K. J. Am. Chem. Soc. 1990, 112,
5645. (b) Pirondini, L.; Bertolini, F.; Cantadori, B.; Ugozzoli, F.;
Massera, C.; Dalcanale, E. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 4911.
(c) Beissel, T.; Powers, R. E.; Raymond, K. N. Angew. Chem., Int. Ed.
Engl. 1996, 35, 1084. (d) Bolliger, J. L.; Belenguer, A. M.; Nitschke, J.
R. Angew. Chem., Int. Ed. 2013, 52, 7958. (e) Seidel, S. R.; Stang, P. J.
Acc. Chem. Res. 2002, 35, 972. (f) Bhat, I. A.; Samanta, D.; Mukherjee,
P. S. J. Am. Chem. Soc. 2015, 137, 9497. (g) Xu, L.; Wang, Y.-X.; Chen,
L.-J.; Yang, H.-B. Chem. Soc. Rev., 2015, 44, 2148. (h) Saha, M. L.;
Mittal, N.; Batsb, J. W.; Schmittel, M. Chem. Commun. 2014, 50,
12189. (j) Soria, J. F.; Fernandez, A.; Pineda, E. M.; Varey, S. A.; Ad-
ams, R. W.; Tuna, F.; Timco, G. A.; Muryn, C. A.; Winpenny, R. E. P.
J. Am. Chem. Soc. 2015, 37, 7644.
(3) (a) Chakrabarty, R.; Mukherjee, P. S.; Stang, P. J. Chem. Rev. 2011,
111, 6810. (b) Kusukawa, T.; Fujita, M. J. Am. Chem. Soc. 1999, 121,
1397. (c) Ibukuro, F.; Kusukawa, T.; Fujita, M. J. Am. Chem. Soc. 1998,
120, 8561. (d) Aoyagi, M.; Biradha, K.; Fujita, M. J. Am. Chem. Soc.
1999, 121, 7457. (e) Yoshizawa, M.; Kusukawa, T.; Fujita, M.; Yamagu-
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