Dibenzoarsacrowns: an experimental and computational study on the coordination behaviors

Article abstract of DOI:10.1039/d0cc07191a

Dibenzoarsacrowns have been synthesized as a novel class of heteroatom-fused crown ethers. The dibenzoarsacrowns can size-selectively capture alkali metal cations, and the arsenic atoms chemoselectively coordinated to gold(i) chloride (AuCl) due to the soft Lewis acid-base interaction. It is notable that the AuCl complex of 21-dibenzoarsacrown-7 further encapsulated Na⁺with the enhanced association constant from bare 21-dibenzoarsacrown-7. The positive allosteric effect was studied computationally.

Full text of DOI:10.1039/d0cc07191a

Showcasing research from Professor Naka and Imoto’s
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Engineering, Kyoto Institute of Technology, Kyoto, Japan
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Dibenzoarsacrowns: an experimental and computational
study on the coordination behaviors
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Dibenzoarsacrowns have been developed as a novel class of
host molecules. The arsenic atom preferentially coordinates
to gold(I) chloride to enhance the association constant for
binding sodium cation at the ethylene oxide loop.
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Dibenzoarsacrowns: an experimental and
computational study on the coordination
behaviors†
Cite this: Chem. Commun., 2021,
7, 2013
5
Received 30th October 2020,
Accepted 23rd December 2020
a
a
b
ac
Akifumi Sumida, Ryosuke Kobayashi, Takashi Yumura,
Hiroaki Imoto* and
ac
Kensuke Naka
*
DOI: 10.1039/d0cc07191a
rsc.li/chemcomm
0
Dibenzoarsacrowns have been synthesized as a novel class of respectively. As pioneering work in this field, 2,2 -bipyridine
heteroatom-fused crown ethers. The dibenzoarsacrowns can size- containing crown ethers (Fig. 1a) drastically affected the affinity
selectively capture alkali metal cations, and the arsenic atoms of the ether ring to alkali metal or ammonium cations by
0
4
chemoselectively coordinated to gold(I) chloride (AuCl) due to the coordination of the 2,2 -bipyridine unit to transition metals.
soft Lewis acid–base interaction. It is notable that the AuCl complex Phosphine-tethered azacrown (Fig. 1b) can bind a cation to
+
of 21-dibenzoarsacrown-7 further encapsulated Na with the change conformation around the transition metal coordinated
5
enhanced association constant from bare 21-dibenzoarsacrown-7. by the phosphine moiety. Catalytic functions due to the
The positive allosteric effect was studied computationally.
transition metal can be altered in response to the guest inclu-
6
sion to the crown ring.
7
,8
Crown ethers have played central roles in supramolecular
In this context, phosphacrown,
in which some oxygen
1
,2
chemistry.
Pedersen’s discovery of 18-dibenzocrown-6 in atoms of a crown ether are substituted by phosphorus, would
1
967 is an important point of departure from conventional be a suitable motif to attain cation-induced conformational
1
naturally-occurring host molecules. Since the artificial inclu- change around the transition metal center based on a simple
sion space can be precisely designed according to the purpose, structure. Actually, a part of the authors previously reported
highly functional crown ethers have been developed to date. platinum(II) dichloride and palladium(II) dichloride complexes
8
a,b
Among the functionalities, inclusion-driven conformational with diphosphacrowns (Fig. 1c).
However, phosphacrown
switching of crown rings has attracted considerable attention architectures forming bimetallic complex of transition and
as a mimic of enzymes with allosteric regulation; the first alkali metals are limited to examples featuring the metallo-
9
binding event transforms the ring conformation to promote the crown motif shown in Fig. 1d. A serious drawback to study
3
–5
second.
For allosterically-cooperative crown ethers, a mole- phosphacrown is air-sensitivity of the trivalent phosphorus
cular design is required to selectively recognize the first and
second guest molecule at separate sites. Pnictogen-fused crown
ethers are beneficial for selective guest binding because pnicto-
gen atom and ether ring are soft and hard Lewis bases,
a
Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology,
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
E-mail: himoto@kit.ac.jp, kenaka@kit.ac.jp
b
Faculty of Material Science and Technology, Kyoto Institute of Technology,
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
c
Materials Innovation Lab, Kyoto Institute of Technology, Goshokaido-cho,
Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
†
Electronic supplementary information (ESI) available: Experimental details,
X-ray crystallography, NMR spectra, and results of computational calculations.
Supplementary crystallographic data: no. 2034462 (1), 2034457 (2), 2034459
(
bis(o-anisyl)phenylarsine) 2034458 (4-Li), 2034460 (4-Na), 2034463 (4-K),
034461 (4-Rb), 2034880 ([AuCl(1)]), 2034881 ([AuCl(2)]), 2034455 ([AuCl(4)]),
0
2
Fig. 1 Heteroatom-fused crown ethers: (a) 2,2 -bipyridine-containing
and 2034456 ([AuCl(4-Na)]). For ESI and crystallographic data in CIF or other
crown ether, (b) phosphine ligand-tethered azacrown, (c) diphospha-
crown, (d) metalla-phosphacrown, and (e) dibenzoarsacrown (this work).
electronic format see DOI: 10.1039/d0cc07191a
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atom; diphosphacrowns should be handled under inert gas phenyl groups of the arsenic atoms were substituted to exocyclic
8
after deprotection of the phosphorus atoms. An alternative direction because of the steric repulsion against the ring, and thus
element for coordination site is desired for practical use. guest molecules can access to the cavity of the arsacrowns. The
Herein, we focused on arsenic because the trivalent arsenic lengths between coordination sites (As and O atoms) and their
1
0
atom has remarkably higher air-stability than phosphorus.
centroids were 1.91–2.13 Å (1) and 2.37–2.91 Å (2). Considering the
14
There is no report on arsacrowns despite their promising van der Waals radii of arsenic (1.85 Å) and oxygen (1.52 Å), there
air-stability, probably due to a lack of synthetic methodologies are vacant spaces in the crown rings.
for organoarsenic compounds. Recently, we have been working
on practical synthesis of organoarsenic compounds. In this hexafluorophosphate (PF ) salts. The association behaviors of
The alkali metal coordination chemistry was explored with
1
1
6
work, we designed dibenzoarsacrowns, in which a triphenylarsine 1–4 with alkali metal cations were evaluated by the chemical
1
unit is introduced (Fig. 1e). Gold(I) chloride (AuCl) and alkali shifts of the H-NMR spectra. A 1 : 1 mixed solvent of deuterated
metal cations were coordinated to arsenic and oxygen atoms, chloroform (CDCl ) and acetonitrile (CD CN) was used because
3
3
respectively. Eventually, drastic conformational change has been the former and the latter were good solvents for the arsacrowns
attained in the bimetallic system. and alkali metal cations, respectively, in reference to the
The synthesis of arsacrowns are shown in Scheme 1. A diethyl previous literature on phosphacrowns. The Job plots sug-
ether (Et O) solution of PhAsI was added to o-lithiated gested that 1–4 formed 1 : 1 complexes with alkali metal cations
8
d
2
2
12
phenyoxytetrahydropyran. After deprotection of the tetrahydro- when significant changes of the chemical shifts were observed
pyranyl group under acidic conditions, Williamson ether synthesis (Fig. S20–S28, ESI†). The association constants were estimated
1
with oligo(ethylene glycol) ditosylates was carried out in the by H-NMR titration (Fig. S29–S46, ESI†) and summarized in
+
presence of metal carbonates to give 12-dibenzoarsacrown-4 (1), Table 1. Arsacrowns 2, 3, and 4 had the highest affinities to Na ,
+
+
1
2
5-dibenzoarsacrown-5 (2), 18-dibenzoarsacrown-6 (3), and Na , and K , respectively, and arsacrown 1 showed quite low
+
1-dibenzoarsacrown-7 (4). NMR spectroscopy and high-resolution affinity to even Li . The association tendency of the arsacrowns
mass analysis revealed the successful synthesis of the target is different from conventional crown ethers; 15-crown-5,
+
+
+
arsacrowns.
18-crown-6, 21-crown-7 strongly bind Na , K , and Cs ,
1
5
Single crystals of 1 and 2 suitable for X-ray diffraction analysis respectively. This is probably because the rigid benzo linkers
were grown due to the relatively rigid structures (Fig. 2). The arsenic prohibited induced-fit of the host cavity. The complex struc-
+
+
+
+
atoms adopted trigonal pyramidal geometries. Considering that the tures of 4 with alkali metal cations Li , Na , K , and Rb were
13
average C–As–C bond angle of bis(o-anisyl)phenylarsine is 98.91, analyzed by X-ray crystallography (for detail, see ESI†). It was
the endocyclic C–As–C bond angle of 1 (94.7(1)1) was narrowed by confirmed that the ethylene oxide loops and the arsenic atoms
the relatively small size of the ring. On the other hand, that of interacted to the included alkali cations. The oxygen atoms of
2
(99.08(8)1) was similar to the average C–As–C bond angle of bis- the phenoxy moieties more weakly coordinated to the cations
(o-anisyl)phenylarsine, meaning that the 15 membered-ring is of when compared with those of the ethylene oxide loops, indicating
sufficient size to circumvent the strain due to ring structure. The that the rigid benzo linkers inhibited the induced-fit for the cation
guests.
Our interest then shifted to complexation of arsacrowns 1–4
with a transition metal. Herein we selected gold(I) chloride
(AuCl) because simple mono-coordination structures can be
constructed. Complexes [AuCl(arsacrown)] (arsacrown = 1–4)
were synthesized by mixing 1–4 with AuCl (Scheme 2a). The
(1 and 2), structures of [AuCl(1)], [AuCl(2)], and [AuCl(4)] were success-
fully analyzed by X-ray crystallography. It was revealed that only
the arsenic atoms coordinated to the Au(I) cations due to the
soft Lewis acid–base interactions (Scheme 2b). In addition, the
Scheme 1 Synthesis of arsacrowns 1–4. M
2 3 2 3
CO : Na CO
K
2
CO (3), Cs CO (4).
3
2
3
Table 1 Association constants for the 1 : 1 complexations of arsacrowns
a
1
–4 with alkali metal cations.
b
ꢀ1
Log K (DG1/kJ mol
)
+
+
+
+
+
Li
Na
K
Rb
Cs
c
c
c
c
c
c
c
1
2
3
4
—
—
—
—
—
—
—
—
—
—
—
c
c
c
2.04 (ꢀ11.5)
c
2.85 (ꢀ16.0) 3.15 (ꢀ17.7) 2.00 (ꢀ11.3)
2.70 (ꢀ15.2) 3.20 (ꢀ18.1) 4.27 (ꢀ24.0) 3.95 (ꢀ22.3) 3.46 (ꢀ19.5)
Fig. 2 ORTEP of (a) 1 and (b) 2. Thermal ellipsoids are drawn at the 50%
probability level. Hydrogen atoms are omitted for clarity. Blue dots indicate
centroids for all the As and O atoms in the ring. The lengths between the
centroids and atoms (Å) and C–As–C bond angle (1) are displayed.
a
b
1
Estimated by H-NMR titration in CDCl
Standard free energy change. Data not obtained because of negligible
3
/CD
3
CN (v/v = 1/1) at 25 1C.
c
changes of the chemical shifts.
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[
AuCl(4-Na)], we initially assumed that the positive allosteric effect
is attributed to the Cl–Na interaction. To check this hypothesis, the
structures of [AuCl(4-Na)] and 4-Na were optimized (Fig. S49, ESI†).
+
The binding energies due to electrostatic interactions between Na
and negatively charged oxygen atoms of the crown in [AuCl(4-Na)]
ꢀ
1
and 4-Na were estimated to be 100.4 kcal mol
1
and
01.1 kcal mol , respectively. Even when considering the
solvation of acetonitrile (MeCN) to [AuCl(4-Na)] and 4-Na
Fig. S49, ESI†), their binding energies did not change signifi-
ꢀ
1
Scheme 2 (a) Complexation of 1–4 with AuCl, and (b) ORTEP of
(
[
AuCl(4)]. Thermal ellipsoids are drawn at the 50% probability level.
ꢀ1
ꢀ1
cantly (95.1 kcal mol and 90.7 kcal mol , respectively).
These results cannot support the experimental findings,
indicating that the Cl–Na interaction had a negligible effect
on the enhancement of the binding constant.
Hydrogen atoms were omitted for clarity.
phenyl groups of the arsenic atoms were still substituted to the
exocyclic direction likely to the bare arsacrowns 1–4. Therefore,
free ethylene oxide loops can be utilized for further complexa-
tion, unlike known platinum(II) dihalide complexes with dipho-
sphacrowns, in which sufficient size of cavity was lost by
conformational change by the coordination.
We thus tried many combinations of [AuCl(arsacrowns)] and
alkali metal cations to analyze the complexation structure by
Instead of the initial assumption, we considered as another
assumption that processes for the complexation of Na to the
host molecules in the presence of MeCN solvents played pivotal
roles here. As initial states, [AuCl(4)] and 4 attached by a MeCN
molecule ([AuCl(4-MeCN)] and 4-MeCN, respectively) were opti-
mized as shown in Fig. 4a-i and b-i. In [AuCl(4-MeCN)] and
+
8
a
4
-MeCN, positively charged hydrogens of MeCN interacted to
negatively charged oxygen atoms of 4. In the case of [AuCl
X-ray crystallography. Finally, the structure of the complex of
+
+
(
4-MeCN)], the Na insertion can preferentially proceed in an
[
(
AuCl(4)] with Na ([AuCl(4-Na)]) was successfully analyzed
ꢀ
1
+
exothermic manner (66.6 kcal mol ) to obtain [AuCl(4-MeCN-Na)],
as shown in Fig. 4a-ii. This exothermic insertion is due to cation-p
interactions in addition to the aforementioned electrostatic inter-
Fig. 3). As expected, the Na was encapsulated by the ethylene
+
oxide loop. Interestingly, the Na interacted to the chloride
ligand in addition to the oxygen atoms. On the other hand,
negligible change from [AuCl(4)] was observed for the coordi-
+
actions. Note that the Na insertion to [AuCl(4-MeCN)] occurs,
+
keeping the MeCN solvation whose nitrogen location was changed.
nation structures around the Au(I). The insertion of the Na did
not affected the bond lengths of the Au–Cl ([AuCl(4)]: 2.282(2) Å,
[AuCl(4-Na)]: 2.278(1) Å) and Au–As ([AuCl(4)]: 2.329(1) Å,
[
(
AuCl(4-Na)]: 2.329(1) Å), and the bond angle of the Cl–Au–As
[AuCl(4)]: 175.81(4)1, [AuCl(4-Na)]: 178.40(3)1). The Na -captured
+
ethylene oxide loop approached the fixed triphenylarsine–AuCl
complex moiety through the formation of the Na–Cl interaction,
resulting in the drastic conformational change in the crown ring.
1
The H-NMR titration revealed that the association constant for
+
the 1 : 1 complex of [AuCl(4)] with Na (log K = 3.90) was signifi-
+
cantly higher than that of 4 and Na (log K = 3.20), implying minor
positive allosteric regulation. To understand this phenomenon, the
+
complexation behavior between [AuCl(4)] and Na was investigated
16
by dispersion-corrected DFT calculations (B3LYP-D2). On the
basis of the X-ray crystallography, suggesting the Cl–Na bond in
Fig. 4 Optimized structures for (a-i) [AuCl(4-MeCN)] and (b-i) 4-MeCN,
where one attached MeCN is involved, on the basis of B3LYP-D2/SDD+6-31G**
calculations. Optimized structures for (a-ii) [AuCl(4-MeCN-Na)] and (b-ii)
4-MeCN-Na. Black, red, purple, cyan, and yellow balls represent carbon, oxygen,
arsenic, nitrogen, and sodium atoms, respectively.
Fig. 3 ORTEP of [AuCl(4-Na)]: (a) side few, (b) top view. Thermal ellipsoids
are drawn at the 50% probability level. Hydrogen atoms and PF
omitted for clarity. Bond lengths and angles (bare) are displayed.
6
are
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On the other hand, 4-MeCN does not have a site suitable for
15359–15367; (c) L. K. S. von Krbek, D. A. Roberts, B. S. Pilgrim,
C. A. Schalley and J. R. Nitschke, Angew. Chem., Int. Ed., 2018, 43,
+
trapping a Na cation to form 4-MeCN-Na. In fact, the optimization
14121–14124; (d) A. Ravi, R. S. Krishnarao, T. A. Shumilova,
+
of an initial structure where the Na binds into a nitrogen atom
V. N. Khrustalev, T. R u¨ ffer, H. Lang and E. A. Kataev, Org. Lett.,
2018, 20, 6211–6214.
in 4-MeCN (the separation: 2.4 Å) resulted in the structure for
4
5
(a) J. Rebek, S. E. Trend, R. V. Wattley and S. Chakravorti, J. Am.
Chem. Soc., 1979, 101, 4333–4337; (b) J. Rebek and R. V. Wattley,
J. Am. Chem. Soc., 1980, 102, 4853–4854; (c) J. Rebek and L. Marshall,
J. Am. Chem. Soc., 1983, 105, 6668–6670; (d) F. Gavina, S. V. Luis,
A. M. Costero, M. I. Burguete and J. Rebek, J. Am. Chem. Soc., 1988,
4
-MeCN-Na in Fig. 4b-ii, equivalent to that in Fig. S49a-ii (ESI†).
To generate the structure for 4-MeCN-Na (Fig. 4b-ii) from 4-MeCN
+
(Fig. 4b-i) and Na , desolvation of the MeCN from 4-MeCN is
necessary to allow negatively charged oxygen atoms to capture
the Na cation. After encapsulation of Na into 4, the MeCN is again
solvated to the captured the Na , resulting in the optimized 4-Na
solvated by MeCN. This complicated process can proceed, only
when MeCN can be desolvated from 4-MeCN by overcoming
the binding energy between 4 and MeCN, calculated to be
110, 7140–7143.
+
+
(a) M. R. Kita and A. J. M. M. Miller, J. Am. Chem. Soc., 2014, 136,
14519–14529; (b) J. Grajeda, M. R. Kita, L. C. Gregor, P. S. White and
A. J. M. Miller, Organometallics, 2016, 35, 306–316; (c) L. C. Gregor,
J. Grajeda, M. R. Kita, P. S. White, A. J. Vetter and A. J. M. Miller,
Organometallics, 2016, 35, 3074–3086; (d) A. M. Camp, M. R. Kita,
J. Grajeda, P. S. White, D. A. Dickie and A. J. M. Miller, Inorg. Chem.,
2017, 56, 11141–11150; (e) J. B. Smith, S. H. Kerr, P. S. White and
A. J. M. Miller, Organometallics, 2017, 36, 3094–3103; ( f ) M. R. Kita
and A. J. M. Miller, Angew. Chem., Int. Ed., 2017, 56, 5498–5502.
+
ꢀ1
12.7 kcal mol . Therefore, the experimental findings on the
positive allosteric effect can be qualitatively understood from the
DFT calculations. While MeCN was fully encapsulated in 4 via
induced-fit, the flexibility of ethylene oxide chain was reduced
by the coordination to AuCl in [AuCl(4-MeCN)], resulting in less
structural change after the Na insertion where MeCN rotates 901
in a counterclockwise fashion (Fig. 4a-i and a-ii).
In the present study, 12-dibenzoarsacrown-4, 15-dibenzo-
arsacrown-5, 18-dibenzocrown-6, and 21-dibenzoarsacrown-7 were
synthesized as the first examples of arsacrowns. It has been
demonstrated that the arsenic and oxygen atoms can effectively
interact with soft and hard metals, respectively. Bimetallic complex
6 C. Yoo, H. M. Dodge and A. J. M. Miller, Chem. Commun., 2019,
5, 5047.
7
5
(a) L. W. Wei, A. Bell, S. Warner, I. D. Williams and S. J. Lippard,
J. Am. Chem. Soc., 1986, 108, 8302–8303; (b) L. W. Wei, A. Bell,
K. H. Ahn, M. M. Holl, S. Warner, I. D. Williams and S. J. Lippard,
Inorg. Chem., 1990, 29, 825–837; (c) P. Pongr ´a cz, H. Szentj ´o bi,
T. T o´ th, P. Huszthy and L. Koll ´a r, Mol. Catal., 2017, 439, 128–133;
+
(
d) H. Szab ´o -Szentj ´o bi, I. Majoros, A. M ´a rton, I. Leveles,
B. G. V ´e rtessy, M. D ´e k ´a ny, T. T ´o th and P. Huszthy, Synthesis, 2020,
870–2882.
(a) Y. Morisaki, H. Imoto, K. Tsurui and Y. Chujo, Org. Lett., 2009,
1, 2241–2244; (b) Y. Morisaki, H. Imoto, K. Hirano, T. Hayashi and
2
8
9
1
Y. Chujo, J. Org. Chem., 2011, 76, 1795–1803; (c) Y. Morisaki, R. Kato
and Y. Chujo, J. Org. Chem., 2013, 78, 2769–2774; (d) Y. Morisaki,
R. Kato and Y. Chujo, ChemistryOpen, 2016, 5, 325–330.
(a) J. Powell, A. Kuksis, C. J. May, P. E. Meindl and S. J. Smith,
Organometallics, 1989, 8, 2933–2941; (b) Y. Li, B. Ma, Y. He, F. Zhang
and Q. H. Fan, Chem. – Asian J., 2010, 5, 2454–2458; (c) I. Mon,
D. A. Jose and A. Vidal-Ferran, Chem. – Eur. J., 2013, 19, 2720–2725;
6
of 21-dibenzoarsacrown-7 with gold(I) chloride and NaPF caused
drastic conformational change from the monometallic complexes.
The metal-coordination-driven transformation will lead to enzyme-
mimic catalytic systems with allosteric regulation. We are now
investigating the synthesis of more diverse arsacrown derivatives,
and development of bimetallic catalytic reactions. The results will be
reported in future publications.
(
d) L. Rovira, M. Vaquero and A. Vidal-Ferran, J. Org. Chem., 2015,
80, 10397–10403; (e) L. Rovira, H. Fern ´a ndez-P ´e rez and A. Vidal-
Ferran, Organometallics, 2016, 35, 528–533; ( f ) M. Vaquero and
A. Vidal-Ferran, Chem. Commun., 2016, 52, 11038–11051.
This work was supported by JSPS KAKENHI, grant Number
1
0 W. Levaso and G. Reid, Comprehensive Coordination Chemistry II, ed.
J. A. McCleverty and T. J. Meyer, Elsevier Science, Amsterdam,
The Netherlands, 2004, vol. 1, ch. 1.16, pp. 377–389.
19H04577 (Coordination Asymmetry) and 20H02812 (Grant-in-
Aid for Scientific Research (B)) to HI.
1
1
1
1
1 For reviews, see: (a) H. Imoto, Polym. J., 2018, 50, 837–846;
(
b) H. Imoto and K. Naka, Chem. – Eur. J., 2019, 25, 1883–1894.
2 T. Kato, S. Tanaka and K. Naka, Chem. Lett., 2015, 44,
476–1478.
3 H. Imoto, C. Yamazawa, S. Tanaka, T. Kato and K. Naka, Chem. Lett.,
017, 46, 821–823.
4 A. Bondi, J. Phys. Chem., 1964, 68, 441–451.
Conflicts of interest
1
There are no conflicts to declare.
2
Notes and references
1
(a) C. J. Pedersen, J. Am. Chem. Soc., 1967, 89, 2495–2496;
b) C. J. Pedersen, J. Am. Chem. Soc., 1967, 89, 7017–7036.
For reviews, see: (a) C. J. Pedersen, Angew. Chem., Int. Ed. Engl., 1988,
(
2
2
1
7, 1021–1027; (b) J. S. Bradshaw and R. M. Izatt, Acc. Chem. Res.,
997, 30, 338–345; (c) G. W. Gokel, W. M. Leevy and M. E. Weber,
Chem. Rev., 2004, 104, 2723–2750; (d) Z. Liu, S. K. M. Nalluri and
J. F. Stoddart, Chem. Soc. Rev., 2017, 46, 2459–2478; (e) J. L. Atwood,
Comprehensive Supramolecular Chemistry II, ed. G. W. Gokel,
S. Negin and R. Cantwell, Elsevier, Amsterdam, 2017, pp. 3–48.
For recent papers, see: (a) L. K. S. von Krbek, A. J. Achazi,
M. Solleder, M. Weber, B. Paulus and C. A. Schalley, Chem. – Eur.
J., 2016, 22, 15475–15484; (b) L. Moreira, J. Calbo, J. Arag ´o ,
B. M. Illescas, I. Nierengarten, B. Delavaux-Nicot, E. Ort ´ı ,
N. Mart ´ı n and J.-F. Nierengarten, J. Am. Chem. Soc., 2016, 138,
3
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