Lower-Rim-Modified Calix[4]arene-Pyrrolotetrathiafulvalene Molecular Tweezers

Article abstract of DOI:10.1002/ejoc.202100676

An approach for the lower rim modification of the calix[4]arene-based molecular tweezes with monopyrrolo-tetrathiafulvalene (MPTTF) arms attached to the upper rim of calixarenes is described. First, calixarene-MPTTF conjugates with free hydroxyl on the lower rim are synthesized using the Ullmann reaction, then hydroxyl groups are substituted by propargyl groups, which can be used for further modification by the click reaction. The new calixarene-TTF derivatives displayed reversible redox processes, as well as demonstrated binding affinity for electron-deficient molecular guests such as tetracyanoquinodimethane. The described synthetic approach will be used for the modular synthesis of molecular receptors tailored for specific applications.

Full text of DOI:10.1002/ejoc.202100676

European Journal of Organic Chemistry
Accepted Article
Accepted Article
Title: Lower-rim Modified Calix[4]arene−Pyrrolotetrathiafulvalene
Molecular Tweezers
Authors: Dirk Schlüter, Kai R. Korsching, and Vladimir A. Azov
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.202100676
Link to VoR: https://doi.org/10.1002/ejoc.202100676
01/2020

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Lower-rim Modified Calix[4]arene−Pyrrolotetrathiafulvalene Molecular
Tweezers
In memoriam of Professor François Diederich
Dirk Schlüter,[a] Kai R. Korsching,[b] Vladimir A. Azov*[c]
[a] Dirk Schlüter, Department of Chemistry, University of Bremen, Leobener Str. NW 2C,
28359 Bremen, Germany. ORCID: 0000-0002-4996-8501
[b] Kai R. Korsching, Molecular Sensory Systems, Center of Advanced European Studies
and Research, 53175 Bonn, Germany.
[c] Prof. Dr. Vladimir A. Azov, Department of Chemistry, University of the Free State, P.O.
Box 339, 9300 Bloemfontein, South Africa. ORCID: 0000-0002-2340-2198
E-mail: azovv@ufs.ac.za
1
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Abstract: We describe an approach to the lower rim modification of the calix[4]arene-based
molecular tweezes with monopyrrolo-tetrathiafulvalene (MPTTF) arms attached to the upper
rim of calixarenes. First, calixarene-MPTTF conjugates with free hydroxyl on the lower rim
are synthesized using the Ullmann reaction, then hydroxyl groups are substituted by
propargyl groups, which can be used for further modification by the click reaction. The new
calixarene-TTF derivatives displayed reversible redox processes, as well as demonstrated
binding affinity for electron-deficient molecular guests such as tetracyanoquinodimethane.
The described synthetic approach will be used for the modular synthesis of molecular
receptors tailored for specific applications.
2
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Introduction
Tetrathiafulvalenes[1] (TTFs) gained their popularity as building blocks in supramolecular
and materials chemistry[2] due to their excellent electron-donating properties and the ability of
reversible one-electron oxidations, forming first a stable radical cation and subsequently a
dication. This way it is possible to reversibly shut down the electron-donating ability of TTF
units and, thus, control the properties of a molecular or supramolecular system.[3] Redox and
donating properties of TTFs can be effectively tuned by the extension of their conjugated
system, leading to the so-called extended tetrathiafulvalenes[4] (ex-TTF); pyrrolo-
tetrathiafulvalenes[5] serve as an example of such extended TTF systems with improved
electron-donating capability.
Despite high affinity to electron-deficient substances, application of TTFs for the
construction of molecular receptors has been initially overlooked, but in the last two decades
several successful receptor architectures have been developed.[6] TTF-calix[4]pyrrole
receptors, originating from a collaboration between the Sessler and Jeppensen groups,
represent a so-far unique example of TTF-based molecular receptors comprising four
monopyrollo-tetrathiafulvalene (MPTTF) units serving as molecular recognition centers.[7]
Moreover, due to the possibility of switching the calix[4]pyrrole cores between their alternate
and cone conformations, it proved possible to employ these electron-rich receptors for the
binding of two different substrate classes, namely 1) planar electron-deficient aromatic
molecules and 2) more spacious spherical fullerenes. Upon proper modification, this class of
receptors could be employed to create, for example, supramolecular copolymers via the self-
assembly of TTF-calix[4]pyrrole receptors with complementary monomers[8] and molecular
sensors for nitro aromatics,[9] paving the way towards their practical applications. Rigid
glycoluril-based bis-TTF molecular architectures designed in the group of Chiu[10] and
Hudhomme[11] constitute two examples of the so called molecular tweezers,[12] non-cyclic
molecular receptors with open cavities, both possessing two TTF arms. These receptors
have demonstrated high affinity to a number of planar electron-deficient molecular guests.
Screening of possible TTF-based molecular receptor structures[13] led us to a potent guest
binder[14] that consists of a bis-anti-substituted calix[4]arene[15] bowl with directly attached
monopyrollo-tetrathiafulvalene (MPTTF) groups 1a-c (Figure 1). These calixarene-based
receptors with the architecture of molecular tweezers were prepared using a direct Cu(I)-
catalyzed N-arylation, an Ullmann-type coupling reaction,[16] that involved reaction of
brominated calixarene backbones with non-substituted as well as substituted (R = H, SPr,
Me)
MPTTFs.
Addition
of
planar
electron-deficient
guests,
such
as
tetracyanoquinodimethane (TCNQ) or 2,5,7-trinitro-9-dicyanomethylenefluorene (TNF), to a
receptor solution leads to formation of deeply-colored charge-transfer complexes, easily
3
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
visible to the naked eye. The binding constants reached as high as 2105 M-1 in CH2Cl2 for
Me-substituted TTF derivative[17] 1c.
Figure 1. Previously synthesized calixarene-MPTTF 1a-c and lower rim-modified calixarene-MPTTF
tweezers 2-5 prepared in this work.
In contrast to the TTF-based receptors developed by other groups, bis-MPTTF-
calix[4]arene molecular tweezers are constructed using modular principle and are rich in
sites that allow for flexible structural modification. The calix[4]arene backbone can be
substituted both on the lower rim (where the hydroxyl groups are) and upper rim. Whereas
the use of different MPTTF derivatives influences the binding efficiency of the receptors,
variation of the substituents on the lower calixarene rim can be employed to improve
solubility in polar solvents, create systems that allow surface immobilization, as well as to
attach electron-deficient moieties leading to self-complementary structures.
Results and Discussion
Using model aromatic derivatives, it has been demonstrated that the Cu(I)-catalyzed
Ullmann coupling is tolerant to the presence of substituents of different nature on the
aromatic components, including non-protected hydroxyl groups.[18] In the current study we
performed the synthesis of the calixarene-MPTTF molecular tweezers with the free hydroxyl
groups 2 and 3, propargylated derivative 4, and its click reaction product 5 (Figure 1).
Though receptor 1c with Me-substituted MPTTF has demonstrated the highest binding
efficiency, we have selected PrS-substituted MPTTF 6 as a building block in this model study
because of the ease of its preparation and high stability. Two oppositely brominated
calixarene backbones with unprotected HO-groups being either on the brominated or non-
brominated phenyl rings, compounds 7 and 8 (Scheme 1), were chosen as calix[4]arene
scaffolds (See Schemes S1 and S2 in SI for details on the preparation of building blocks 6, 7
4
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
and 8). Of the last two, calixarene derivative 7 is accessible more readily than 8, therefore, it
was the one preferentially used in our further experiments.
The Cu(I) catalyzed N-arylation of MPTTF 6 with 7 and 8 was carried out using our
previously established reaction conditions with minor modifications: we increased the amount
of CuI to 0.5 eq. to each aromatic bromide group, as well as lengthened the reaction time to
72 h. It allowed us to isolate the target MPTTF-calixarene conjugates 2 and 3 with yields of
68% and 74%, respectively, thus demonstrating that non-protected aromatic HO-groups do
not hinder the Ullmann coupling reaction.
Scheme 1. Synthesis of the calixarene-MPTTF molecular tweezers 2 and 3. DACH = trans-1,2-
diaminocyclohexane.
Calix[4]arene derivatives 2 and 3 with only two bulky propyl groups on the lower rim are
not fixed in the cone conformation, since the phenyl rings with non-substituted HO-groups
can freely thread through the calix[4]arene ring. Therefore, the consequent alkylation can
lead to formation of an isomeric mixture, in which partial cone and 1,3-alternate conformers
can be admixed to the target cone conformer. In addition, it was reported that calix[4]arene
derivatives with four propynyl groups on the lower rim may display unexpectedly fast
conformational interconversion.[19] Thus, we first tried the alkylation reaction with propargyl
bromide with the more easily accessible calixarene derivative 7 and were satisfied to isolate
the alkylated product 9 exclusively in the cone conformation in 83% yield (Scheme 2). No
conformational interconversion of the calix[4]arene backbone was observed under ambient
conditions. We then tested compound 9 in the Cu(I) catalyzed N-arylation with MPTTF 6 and
were surprised to discover the formation of 2 with 52% yield, which meant the quantitative
cleavage of the propargyl groups from the aromatic ring. Complete removal of propargyl
groups was also observed in several test experiments with model aromatic compounds,
which implies possible use of the propargyl group as a protective group for phenols and shall
constitute a separate detailed study.
5
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Scheme 2. Synthesis of the upper-rim calixarene-MPTTF molecular tweezers 5 using the click
chemistry N-arylation approach. DACH trans-1,2-diaminocyclohexane, TBTA
tris(benzyltriazolylmethyl)amine.
-
=
=
Model click reaction of 9 with dodecylazide in DMF using tetrakis(acetonitrile)copper(I)
hexafluorophosphate / tris(benzyltriazolylmethyl)amine (TBTA) mixture as a catalyst at 60 °C
for 24 h afforded the target product 10 with 62% yield. Compound 10 was then subjected to a
copper-catalyzed N-arylation reaction with MPTTF 6 under previously described conditions,
and we obtained the target product 5 with 61% yield. This result demonstrated that the 1,2,3-
triazole moiety formed in the click reaction is stable under Ullmann reaction conditions.
Though this synthetic pathway to 5 succeeded, it is by no means considered to be functional,
since it does not allow modular preparation of the modified receptors.
Therefore, we obtained compound 5 via an alternative route (Scheme 3). First, two free
hydroxyl groups of MPTTF-calix[4]arene conjugate 2 were propargylated affording compound
4 in 74% yield. Similar to the propargylation of 7, compound 4 was obtained exclusively in
the cone conformation. Afterwards 4 was subjected to the click reaction conditions with
dodecylazide, yielding molecular tweezers 5 in 68% yield. Thus, we have demonstrated that
(i) conjugate 2 can serve as a precursor to MPTTF-calix[4]arene molecular tweezers with
different substituents on the calixarene lower rim and (ii) propargylated derivative 4 can be
modified using the click reaction with various substituents bearing an azide group, which
makes compound 4 another universal precursor in the synthesis of modified MPTTF-
calix[4]arene receptors. In future, functionalities attached to the lower rim can be used, for
example, for solubilization of the receptors in aqueous media[20] or for their attachment onto
surfaces e.g. for sensing applications.[21]
6
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Scheme 3. Synthesis of the upper-rim calixarene-MPTTF molecular tweezers 10 using the alkylation
of 2 - click chemistry approach.
Electrochemical properties of new bis-MPTTF molecular tweezers have been investigated
by means of cyclic voltammetry (CV) in dichloromethane/Bu4NClO4 solution (Figure 2). All
compounds demonstrated two quasi-reversible TTF-centered oxidation processes, the first
one leading to the TTF radical cation and the second affording the dication, which is typical
for TTF derivatives. Still, there was significant difference in the form of the first oxidation
wave between the derivatives 2 and 3 with a pair of free hydroxyls on the lower rim and
compounds 5 and 1a, which possess four substituents on the lower rim. Whereas 2 and 3
showed sharp oxidation waves both in cathodic and anodic scans and a relatively small
interval between the cathodic and anodic peak potentials (Table 1), the first oxidation wave
for compounds 5 and 1a was broadened with a small kink visible in cathodic and anodic
scans, and the interval between the cathodic and anodic peak potentials was found to be
substantially larger. Such broadening effect is commonly explained by the formation of
mixed-valence tetrathiafulvalene dimers (TTF2)+• in the partially oxidized state, which is
stabilized by intramolecular charge-transfer interactions between the proximal TTF and TTF+•
moieties,[22] and it was commonly observed by us in our bis-TTF molecular systems.[13,14,17]
Such behavior of derivatives 2 and 3, which is different from what we observed on all other
our bis-TTF systems, implies that TTF moieties in 2 and 3 cannot easily come into spatial
proximity with each other.
7
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Figure 2. Cyclic voltammograms of the new compounds 2, 3 and 5, as well as of the original receptor
1a for comparison. C = 110-3 M, 0.1 M Bu4NClO4 in CH2Cl2, plotted vs. SCE.
Table 1. Electrochemical data of calixarene-MPTTF molecular tweezers.a
Compound
Epcox1 (V)
0.43
Epaox1 (V)
0.18
Epcox1-Epaox1 (V)
E1/2ox1 (V)
0.31
E1/2ox2 (V)
0.91
1a
5a
2
0.25
0.17
0.11
0.09
0.44
0.27
0.35
0.92
0.49
0.38
0.44
0.83
3
0.47
0.38
0.43
0.86
a Data were obtained using a one-compartment cell in CH2Cl2/0.1 M Bu4NClO4, Pt as the working and counter
electrodes and a non-aqueous Ag/Ag+ reference electrode; scan rate 100 mV/s. Values given at room
temperature vs. SCE; the Fc/Fc+ couple (0.480 V vs. SCE) was used as an internal reference.
Epcox1 and Epaox1 are cathodic and anodic peak potentials of the first oxidation wave, respectively.
Though the molecular tweezers with PrS-substituted MPTTF moieties could not be
expected to be strong binders of electron deficient molecular guests, such as TCNQ, we
decided to perform comparative testing of binding efficiency of the new compounds 2, 3 and
5 with the original receptor 1a. From our previous experience, intensity of the charge transfer
(CT) bands of the TCNQ complex with bis-TTF molecular tweezers provides a good
correlation with its binding affinity to TCNQ, and we could estimate the binding efficiency of
the modified receptors. Thus, we have measured UV/Vis spectra of equimolar 1:1 mixtures of
TCNQ with the receptors 1a, 2, 3 and 5 in CH2Cl2 at 210-3 M concentration (Figure 3). We
found that the intensity of CT bands for the TCNQ complex of 5 was comparable, though ca.
20 % lower than for the complex of 1a. This result indicates that two bulky 1,2,3-triazole
moieties on the lower rim, formed via click reaction, do not significantly alter the binding
efficiency of such receptor architecture. On another hand, the intensity of CT bands for the
8
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
TCNQ complexes of 2 and 3 was found to be extremely small. It implies significantly lower
binding efficiency, since the intensity of the charge transfer bands for the complexes between
the same types of hosts and substrates is expected to be roughly proportional to the
concentration of the complex in the solution.
Figure 3. UV/Vis spectra of the charge transfer bands for the complexes of calixarene derivatives 1a,
2, 3 and 5. CH2Cl2, CHost = CTCNQ = 210-3 M.
Much lower efficiency of derivatives 2 and 3 as TCNQ binders implied that two MPTTF
moieties cannot adopt the alignment necessary for stacking of a guest molecule in between
them, thus confirming the similar indications from the CV experiments. Considerations
coming from our knowledge of conformational behavior of calix[4]arene backbones can
rationalize such molecular behavior. Calix[4]arene scaffolds with four substituted hydroxyl
groups on the lower rim prefer to adopt the pinched cone conformation,[23] in which two
opposite aromatic rings are almost parallel, and the two others are widely open. Therefore,
calixarene-MPTTF molecular tweezers with four substituted hydroxyl groups can readily
adopt the guest-binding conformation with two quasi-parallel MPTTF units with a suitable gap
in between.[14] On another hand, calix[4]arene scaffolds possessing two opposite pairs of
protected and non-protected hydroxyl groups on the lower rim adopt a more symmetric vase-
shaped conformation due to the stabilizing effect of H-bonds on the lower rim.[24] In this
conformation all aromatic rings are positioned symmetrically at an angle to the axis going
through the center of the calixarene, thus preventing their upper rim substituents to come into
a close proximity with each other.
Conclusions
To sum up, we have demonstrated that the Ullmann reaction can be effectively used for
the coupling of MPTTFs with the upper rim Br-substituted calix[4]arenes that have free
hydroxyl groups on the lower rim. Afterwards, the free hydroxyl groups of the MPTTF-
calix[4]arene conjugates can be substituted by other residues, such as propargyl groups
9
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
used in this study, affording the calixarene derivative fixed in the desired cone conformation.
Further modification of the terminal alkynes on the lower rim of calixarenes can be performed
using the click reaction. The new calixarene-MPTTF derivatives displayed reversible redox
processes, whereas the product of the click reaction 5 showed high binding affinity to the
electron-deficient TCNQ molecular guest. Moreover, we have discovered that the conditions
of the copper-catalyzed Ullmann coupling lead to quantitative removal of the phenolic
propargyl groups, which may open the possibility to use them as protection for aromatic
hydroxyl groups.
In future, we plan to use the described synthetic approach for the modular synthesis of
molecular receptors tailored for specific applications: employing a modular assembly
methodology and taking advantage of several available calix[4]arene and tetrathiafulvalene
building blocks with various substitution patterns, we will assemble molecular receptors
tailored for particular applications in the fields of sensorics and functional materials.
Experimental Section
General. Monopyrrolo-tetrathiafulvalene 6[25] and calixarene derivatives 5,17-dibromo-26,28-
di-(1-propoxy)calix[4]arene 7[26] and 5,17-dibromo-25,27-di-(1-propoxy)calix[4]arene 8[27]
were prepared as previously reported with minor modifications in synthetic procedures.
Commercial reagent grade chemicals and solvents, including dry dioxane (extra dry, over
molecular sieves) were used without further purification. All reactions were carried out under
an atmosphere of dry N2. Chemical shifts () are reported in parts per million (ppm) relative to
TMS, the residual solvent signals were used as reference: CDCl3 (7.26 ppm for 1H, 77.0 ppm
1
1
for 13C) or CD2Cl2 (5.32 ppm for H, 53.8 ppm for 13C). H NMR coupling constants (J) are
reported in Hertz (Hz) and multiplicity is indicated as follows: s (singlet), d (doublet), t (triplet),
q (quartet), sext (sextet). Routine MS spectra were measured on a Bruker Esquire-LC ion
trap spectrometer (ESI+ mode). High resolution MS spectra (HRMS) were measured on a
Thermo Fisher Scientific LTQ Orbitrap spectrometer (ESI+ mode). UV/Vis measurements
were performed in a 1 cm path length quartz optical cell. Melting points were determined
using a capillary melting point apparatus and are uncorrected. Rf values were determined
using 0.2 mm silica gel 60 F-254 aluminum TLC sheets with F-254 fluorescent indicator,
visualized under 254 nm UV light. Flash chromatography (FC) was carried out using 230–
440 mesh (particle size 36–70 m) silica gel.
Cyclic voltammetry. Cyclic voltammetry (CV) was performed using a computer controlled
HEKA PG390 potentiostat in a three-electrode single-compartment cell (2.5 mL) with a
platinum disk working electrode (diameter of 1.5 mm) and a platinum wire used as counter
electrode. A non-aqueous Ag/Ag+ secondary electrode (0.1 M TPAP + 0.01 M AgNO3 in
10
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
MeCN) was used as the reference electrode. CV samples were dissolved to a concentration
of 110-3 M in dry degassed CH2Cl2 containing 0.1 M Bu4NClO4 (TBAP) as supporting
ox
electrolyte. Ferrocene was used as an electrochemical reference[28] with the potential E1/2
=
0.48 V vs. saturated calomel electrode (SCE) for the Fc/Fc+ couple in TBAP/CH2Cl2.[29] A CV
scan of 110-3 M ferrocene solution was taken after each CV measurement for calibration
purposes; the values of oxidation potentials were referenced to the Fc/Fc+ couple and
recalculated and reported vs. SCE.
11,23-Bis({2-[bis(propylsulfanyl)-2H-1,3-dithiol-2-yliden]-2H,5H-[1,3]dithiolo[4,5-
c]pyrrol-5-yl})-26,28-dipropoxypentacyclo-[19.3.1.13,7.19,13.115,19]octacosa-
1(25),3,5,7(28),9(27),10,12,1 5(26),16,18,21,23-dodecan-25,27-diol (2). A heavy walled
Schlenk tube with a wide bore Teflon screw stopcock was charged with 54.5 mg (0.08 mmol,
1.0 eq.) calix[4]arene derivative 7, 15.6 mg (0.08 mmol, 1.0 eq.) CuI, 138 mg (0.65 mmol,
8.0 eq.) K3PO4, 80.0 mg (0.20 mmol, 2.5 eq.) MPTTF 6, 15 µL (0.12 mmol, 1.5 eq.)
1,2-diaminocyclohexane under inert nitrogen atmosphere, and then absolute dioxane (5 mL)
was added via syringe. The reaction mixture was degassed by three freeze-pump-thaw
cycles, the vessel filled with nitrogen and the reaction mixture was stirred at 110 °C for 72 h.
After removal of the solvent under reduced pressure the residue was dissolved in a small
amount of CH2Cl2 and filtered through a plug of silica. Flash chromatography
(CH2Cl2/cyclohexane, 1:1) of the yellow-brownish, oily residue afforded product 2 as
crystalline bright yellow-orange solid. Yield: 77.9 mg (0.06 mmol, 74 %). Rf = 0.46
1
(CH2Cl2/cyclohexane, 1:1); m.p. 145–148 °C; H NMR (360 MHz, CD2Cl2): δ = 8.57 (s, 2H;
OH), 7.05 (s, 4H; HAr), 7.03 (d, 3JH,H=7.6 Hz, 4H; HAr), 6.85 (t, 3JH,H=7.6 Hz, 2H; HAr), 6.76 (s,
4H; Hpyrrole), 4.34 (d, 2JH,H=13.0 Hz, 4H; CAr-CHax-CAr), 4.01 (t, 3JH,H=6.3 Hz, 4H; O-CH2), 3.43
2
3
(d, JH,H=13.0 Hz, 4H; CAr-CHeq-CAr), 2.81 (t, JH,H=7.2 Hz, 8H; S-CH2), 2.09 (sext,
3
3JH,H=6.7 Hz, 4H; O-CH2-CH2), 1.66 (sext, JH,H=7.3 Hz, 8H; S-CH2-CH2), 1.34 (t,
3
3JH,H=7.5 Hz, 6H; O-(CH2)2-CH3), 1.01 ppm (t, JH,H=7.4 Hz, 12H; S-(CH2)2-CH3); 13C NMR
(90 MHz, CD2Cl2): δ = 152.44, 152.26, 133.38, 132.90, 129.64, 129.11, 127.90, 125.64,
121.79, 120.82, 112.14, 78.98, 38.54, 31.63, 23.85, 23.51, 13.25, 11.08 ppm; UV/Vis
(CH2Cl2): λmax (ε) = 320 (57800); 303 nm (61300 mol−1dm3cm−1); MS (ESI, CH2Cl2/MeOH
1:10): m/z (%): 1325 (4) [M+K]+, 1309 (29) [M+Na]+, 1286 (100) [M]+, 935 (6) [M-
C14H16NS6+K]+, 919 (54) [M-C14H16NS6+Na]+, 896 (37) [M-C14H16NS6]+; HRMS (ESI): m/z
calcd for C62H66N2O4S12+: 1286.16656 [M]+; found: 1286.16731; CV (vs Ag/Ag+, CH2Cl2):
E1/2ox1 = 0.43, E1/2ox2 = 0.86 V.
5,17-Bis({2-[bis(propylsulfanyl)-2H-1,3-dithiol-2-yliden]-2H,5H-[1,3]dithiolo[4,5-
c]pyrrol 5-yl})-26,28-dipropoxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-
1(25),3,5,7(28),9(27),10,12,15(26),16,18,21,23-dodecan-25,27-diol (3). A heavy walled
Schlenk tube with a wide bore Teflon screw stopcock was charged with 67.0 mg (0.10 mmol,
11
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
1.0 eq.) calix[4]arene derivative 8,19.2 mg (0.10 mmol, 1.0 eq.) CuI, 170.8 mg (0.80 mmol,
8.0 eq.) K3PO4, 98.4 mg (0.25 mmol, 2.5 eq.) MPTTF 6, 18.2 µL (0.15 mmol, 1.5 eq.)
1,2-diaminocyclohexane under inert nitrogen atmosphere, and then absolute dioxane (5 mL)
was added via syringe. The reaction mixture was degassed by three freeze-pump-thaw
cycles, the reaction vessel filled with nitrogen and the reaction mixture was stirred at 110 °C
for 72 h. After removal of the solvent under reduced pressure the residue was dissolved in a
small amount of CH2Cl2 and filtered through a plug of silica. Flash chromatography
(CH2Cl2/cyclohexane, 1:1) of the brownish, oily residue afforded product 3 as crystalline
bright yellow-orange solid. Yield: 87.5 mg (0.07 mmol, 68 %).
Rf = 0.35
1
(CH2Cl2/cyclohexane, 1:1); m.p. 145–148 °C; H NMR (360 MHz, CD2Cl2): δ = 8.27 (s, 2H;
OH), 7.07 (d, 3JH,H=7.6 Hz, 4H; HAr), 6.93 (s, 4H; HAr), 6.65 (t, 3JH,H=7.6 Hz, 2H; HAr), 6.65 (s,
4H; Hpyrrole), 4.34 (d, 2JH,H=13.0 Hz, 4H; CAr-CHax-CAr), 4.01 (t, 3JH,H=6.1 Hz, 4H; O-CH2), 3.44
2
3
(d, JH,H=13.0 Hz, 4H; CAr-CHeq-CAr), 2.79 (t, JH,H=7.4 Hz, 8H; S-CH2), 2.09 (sext,
3
3JH,H=7.0 Hz, 4H; O-CH2-CH2), 1.63 (sext, JH,H=7.2 Hz, 8H; S-CH2-CH2), 1.34 (t,
3
3JH,H=7.4 Hz, 6H; S-(CH2)2-CH3), 1.00 ppm (t, JH,H=7.4 Hz, 12H; O-(CH2)2-CH3); 13C NMR
(90 MHz, CD2Cl2): δ = 153.78, 150.71, 137.37, 135.53, 129.21, 128.86, 127.86, 127.51,
121.60, 121.45, 119.86, 119.59, 111.60, 79.08, 38.53, 31.81, 23.85, 23.49, 13.24, 11.07
ppm; UV/Vis (CH2Cl2): λmax (ε) = 330 (79100), 292 nm (71200 mol−1dm3cm−1); MS (ESI,
CH2Cl2/MeOH 1:10): m/z (%): 1325 (5) [M+K]+, 1309 (16) [M+Na]+, 1286 (100) [M]+, 919 (5)
[M-C14H16NS6+Na]+; HRMS (ESI): m/z calcd for C62H66N2O4S12+: 1286.16656 [M]+; found:
1286.16762; CV (vs Ag/Ag+, CH2Cl2): E1/2ox1 = 0.44, E1/2ox2 = 0.83 V.
5,17-bis({2-[(2E)-bis(propylsulfanyl)-2H-1,3-dithiol-2-ylidene]-2H,5H-[1,3]dithiolo[4,5-
c]pyrrol-5-yl})-26,28-bis(prop-2-yn-1-yloxy)pentacyclo[19.3.1.1³,⁷.1⁹,¹³.1¹⁵,¹⁹]octacosa-
1(25),3,5,7(28),9(27),10,12,15(26),16,18,21,23-dodecaene-25,27-diol (4).
Under inert
nitrogen atmosphere, 130 mg (0.10 mmol, 1.0 eq.) of calix[4]arene derivative 2 were placed
into a Schlenk tube and dissolved in absolute DMF (4 mL). Afterwards 79 µL (0.71 mmol,
7.0 eq.) of propargyl bromide and 30 mg (1.25 mmol, 12.4 eq.) of NaH, which had been freed
of paraffin oil by washing with n-pentane, were added to the reaction vessel, and the reaction
mixture was stirred at 60 °C for 42 h. After removal of the solvent under vacuum, the residue
was dissolved in CH2Cl2 (20 mL) and washed with water (310 mL). The aqueous phase was
extracted with CH2Cl2 (310 mL), and the combined organic phases were filtered through a
dry cotton plug. After removal of the solvent under reduced pressure the residue was
dissolved in a small amount of eluent (n-hexane/CH2Cl2, 1:1), filtered through a plug of silica
and crystallized upon evaporation of the solvent. Trituration of the crystals with n-pentane
afforded pure 4 as yellow crystalline solid. Additional purification can be performed by flash
chromatography (CH2Cl2/cyclohexane, gradient 1:3  1:2). Yield: 102.6 mg (0.08 mmol,
74 %). Rf = 0.45 (CH2Cl2/cyclohexane, 1:3); m.p. 191–196 °C; 1H NMR (600 MHz, CDCl3): δ
12
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
= 7.05 (s, 4H; TTF-HAr), 6.88 (s, 4H; Hpyrrole), 6.34-6.37 (m, 2H; HAr), 6.29 (d, 4H, 2JH,H=7.6 Hz;
4
2
HAr), 4.96 (d, JH,H=2.4 Hz, 4H; O-CH2-C≡C-H), 4.57 (d, JH,H=13.4 Hz, 4H; CAr-CHax-CAr),
3
2
3.72 (t, JH,H=6.9 Hz, 4H; O-CH2), 3.20 (d, JH,H=13.5 Hz, 4H; CAr-CHeq-CAr), 2.82 (t,
3JH,H=7.2 Hz, 8H; S-CH2), 2.43 (t, 4JH,H=2.4 Hz, 2H; C≡C-H), 1.94 (sext, 3J H,H=7.3 Hz, 4H; O-
3
3
CH2-CH2), 1.68 (sext, JH,H=7.3 Hz, 8H; S-CH2-CH2), 1.10 (t, JH,H=7.4 Hz, 6H; O-(CH2)2-
3
CH3)), 1.03 ppm (t, JH,H=7.3 Hz, 12H; S-(CH2)2-CH3); 13C-NMR (150 MHz, CDCl3): δ =
155.53, 153.37, 138.91, 135.60, 132.52, 127.69, 127.50, 122.50, 121.63, 120.09, 119.20,
111.38, 111.07, 80.24, 75.24, 60.19, 38.22, 31.44, 23.54, 23.14, 13.16, 10.83 ppm; UV/Vis
(CH2Cl2): λmax (ε) = 330 nm (60100 mol−1dm3cm−1); MS (ESI, CH2Cl2/MeOH 1:10): m/z (%):
+
1362 (100) [M]+, 973 (6) [M-C14H16NS6]+; HRMS (ESI): m/z calcd for C68H70N2O4S12
:
1362.19786 [M]+; found: 1362.19887.
4-({[11,23-bis({2-[bis(propylsulfanyl)-2H-1,3-dithiol-2-ylidene]-2H,5H-[1,3]dithiolo[4,5-
c]pyrrol-5-yl})-27-[(1-dodecyl-1H-1,2,3-triazol-4-yl)methoxy]-26,28-
dipropoxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-
1(25),3,5,7(28),9(27),10,12,15(26),16,18,21,23-dodecan-25-yl]oxy}methyl)-1-dodecyl-1H-
1,2,3-triazol (5). Method 1: A Schlenk tube was charged with 15.0 mg (0.011 mmol,
1.0 eq.) calix[4]arene derivative 4, 2.14 mg (0.004 mmol, 0.4 eq.) TBTA, 1.64 mg
(0.004 mmol, 0.4 eq.) tetrakis(acetonitrile)copper(I) hexafluorophosphate and 27.0 mg
(0.140 mmol, 4.0 eq.) dodecyl azide under inert nitrogen atmosphere, and then absolute
DMF (1.5 mL) was added via syringe. The reaction mixture was degassed by three freeze-
pump-thaw cycles, the vessel filled with nitrogen and the reaction mixture was stirred at
60 °C for 23 h. Evaporation of the solvent under high vacuum afforded product 5 as
brownish, amorphous solid. The product was purified by flash chromatography
(CH2Cl2/EtOAc, 9:1) to yield product 5 as yellow amorphous solid. Yield: 13.4 mg
(0,0075 mmol, 68 %). Method 2: A heavy walled Schlenk tube with a wide bore Teflon
screw stopcock was charged with 63.8 mg calix[4]arene 10 (0.05 mmol, 1.0 eq.), 10.4 mg
CuI (0.05 mmol, 1.0 eq.), 93.0 mg K3PO4 (0.44 mmol, 8.0 eq.), 53.6 mg TTF 8 (0.14 mmol,
2.5 eq.), 15.0 µL 1,2-diaminocyclohexane (0.12 mmol, 1.5 eq.) under an inert nitrogen
atmosphere, and then absolute dioxane (5 mL) was added via syringe. The reaction mixture
was degassed by three freeze-pump-thaw cycles, the reaction vessel filled with nitrogen, and
the reaction mixture was stirred at 110 °C for 72 h. After removal of the solvent under
reduced pressure the residue was dissolved in a mixture of CH2Cl2/MeOH (9:1) and filtered
through a plug of silica gel. Flash column chromatography (CH2Cl2/EtOAc, 9:1) of the yellow-
brownish residue afforded product 5 as yellow amorphous solid. Yield: 59.8 mg (0.03 mmol,
1
61 %). Rf = 0.57 (CH2Cl2/EtOAc, 9:1); m.p. 163–166 °C; H NMR (360 MHz, CDCl3):
δ = 7.55 (s, 2H; Htriazole), 6.67-6.65 (m, 6H; HAr), 6.49 (bs, 4H; HAr), 6.35 (s, 4H; Hpyrrole), 5.15
3
2
(s, 4H; O-CH2-Ctriazole), 4.35 (t, J=7.2 Hz, 4H; Ntriazole-CH2-CH2), 4.33 (d, JH,H=13.3 Hz, 4H;
13
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
3
3
CAr-CHax-CAr), 3.77 (t, J=7.9 Hz, 4H; O-CH2-CH2), 3.05 (d, JH,H=13.3 Hz, 4H; CAr-CHeq-CAr),
3
2.8 (t, JH,H=7.4 Hz, 8H; S-CH2-CH2), 1.93–1.84 (m, 4H; N-CH2-CH2), 1.78 (sext,
3JH,H=7.7 Hz, 4H, O-CH2-CH2), 1.67 (sext, 3JH,H=7.3 Hz, 8H, S-CH2-CH2), 1.35–1.21 (m, 36H;
N-(CH2)2-(CH2)9-CH3), 1.01 (t, 3JH,H=7.2 Hz, 12H; S-(CH2)2-CH3), 0.88 (t, 3JH,H=6.7 Hz, 6H; N-
3
(CH2)11-CH3), 0.84 ppm (t, JH,H=7.4 Hz, 6H; O-(CH2)2-CH3); 13C NMR (90 MHz, CDCl3):
δ = 156.55, 143.98, 136.68, 134.46, 128.36, 127.43, 123.14, 122.51, 121.58, 119.88, 67.11,
50.25, 38.21, 31.88, 31.34, 30.44, 29.59, 29.53, 29.41, 29.31, 29.01, 26.46, 23.13, 22.95,
22.65, 14.09, 13.19, 10.16 ppm; UV/Vis (CH2Cl2): λmax (ε) = 325 (45600), 318 nm (45700
mol−1dm3cm−1); MS (ESI, CH2Cl2/MeOH 1:10): m/z (%): 1823 (3) [M+K]+, 1807 (43) [M+Na]+,
1784 (100) [M]+; HRMS (ESI+): m/z calcd for C92H120N8O4S122+: 892.30452 [M]2+; found:
892.30424; CV (vs Ag/Ag+, CH2Cl2): E1/2ox1 = 0.35, E1/2ox2 = 0.92 V.
5,17-dibromo-26,28-bis(prop-2-yn-1-yloxy)-25,27-
dipropoxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-
1(25),3,5,7(28),9(27),10,12,15(26),16,18,21,23-dodecan (9). A Schlenk tube was charged
with 250.0 mg (0.375 mmol, 1.0 eq.) calix[4]arene derivative 7 and absolute DMF (25 mL),
then 92 µL propargyl bromide (1.22 mmol, 3.25 eq.) and 23.40 mg (0.98 mmol, 2.6 eq.)
sodium hydride, which had been freed of paraffin oil by washing with n-pentane before, were
added to the reaction mixture, which was then stirred at 60 °C for 20 h under inert nitrogen
atmosphere. After removal of the solvent under vacuum the residue was dissolved in CH2Cl2
(100 mL) and washed with water (340 mL). The aqueous phase was extracted with CH2Cl2
(340 mL) and the combined organic phases were filtered through a dry cotton plug.
Removal of the solvent under reduced pressure and flash column chromatography
(CH2Cl2/cyclohexane, 1:3) afforded compound 9 as a colorless solid. Yield: 229.9 mg
(0.31 mmol, 83 %). Rf = 0.33 (CH2Cl2/cyclohexane, 1:3); m.p. 227–230 °C; 1H NMR
4
(360 MHz, CDCl3): δ = 7.33–7.26 (m, 4H; HAr), 6.37-6.22 (m, 6H; HAr), 4.95 (d, JH,H=2.4 Hz,
2
3
4H; O-CH2-C≡C-H), 4.49 (d, JH,H=13.4 Hz, 4H; CAr-CHax-CAr), 3.68 (t, JH,H=6.9 Hz, 4H; O-
CH2), 3.15 (d, 2JH,H=13.6 Hz, 4H; CAr-CHeq-CAr), 2.41 (t, 4JH,H=2.4 Hz, 2H; C≡C-H), 1.92 (sext,
3
3JH,H=7.2 Hz, 4H; O-CH2-CH2), 1.09 ppm (t, JH,H=7.4 Hz, 6H; CH3); 13C NMR (90 MHz,
CDCl3): δ = 155.32, 154.40, 139.85, 132.25, 131.25, 127.76, 122.50, 115.86, 80.13, 75.28,
59.87, 31.09, 23.54, 10.85 ppm; MS (ESI, CH2Cl2/MeOH 1:10): m/z (%): 779 (3) [M+K]+, 763
(100) [M+Na]+, 724 (3) [M-C3H3+Na]+, 684 (6) [M-Br+Na]+. HRMS (ESI+): m/z calcd for
C40H38Br2O4Na+: 763.10390 [M]+; found: 763.10291.
4-[({11,23-dibromo-27-[(1-dodecyl-1H-1,2,3-triazol-4-yl)methoxy]-26,28-
dipropoxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-
1(25),3,5,7(28),9(27),10,12,15(26),16,18,21,23-dodecan-25-yl}oxy)methyl]-1-dodecyl-1H-
1,2,3-triazol (10). A Schlenk tube was charged with 51.0 mg (0.07 mmol, 1.0 eq.)
calix[4]arene derivative 9, 14.6 mg (0.03 mmol, 0.4 eq.) TBTA, 10.2 mg (0.03 mmol, 0.4 eq.)
14
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
tetrakis(acetonitrile)copper(I) hexafluorophosphate, 58.1 mg (0.27 mmol, 4.0 eq.) dodecyl
azide under inert nitrogen atmosphere, and then absolute DMF (5 mL) was added via
syringe. The reaction mixture was degassed by three freeze-pump-thaw cycles the vessel
filled with nitrogen and the reaction mixture was stirred at 60 °C for 24 h. After removal of the
solvent under vacuum the residue was dissolved in a mixture of CH2Cl2/EtOAc (9:1) and
filtered through a plug of silica. Flash chromatography (CH2Cl2/MeOH, 19:1) of the oily
residue afforded product 10 as light brownish, amorphous solid. Yield: 49.3 mg (0.04 mmol,
62 %). Rf = 0.59 (CH2Cl2/MeOH, 19:1); 1H NMR (200 MHz, CDCl3): δ = 7.56 (bs, 2H; Htriazole),
3
6.99 (s, 4H; HAr), 6.49–6.31 (m, 6H; HAr), 5.29 (s, 4H; O-CH2-Ctriazole), 4.34 (t, JH,H=7.2 Hz,
4H; Ntriazole-CH2-CH2), 4.18 (d, 2JH,H=13.4 Hz, 4H; CAr-CHax-CAr), 3.66 (t, JH,H=7.5 Hz, 4H; O-
3
2
CH2-CH2), 3.01 (d, JH,H =13.6 Hz, 4H; CAr-CHeq-CAr), 1.93–1.81 (m, 4H; N-CH2-CH2), 1.75
3
(sext, JH,H=7.4 Hz, 4H; O-CH2-CH2), 1.36–1.17 (m, 36H; N-(CH2)2-(CH2)9-CH3), 0.90 (t,
3
3JH,H=7.4 Hz, 6H; N-(CH2)11-CH3), 0.87 ppm (t, JH,H=6.6 Hz, 6H; O-(CH2)2-CH3); 13C NMR
(50 MHz, CDCl3): δ = 155.73, 154.61, 143.96, 138.58, 133.14, 131.09, 128.00, 123.51,
122.44, 115.29, 66.35, 50.23, 31.86, 31.05, 30.40, 29.57, 29.41, 29.30, 29.01, 26.42, 23.02,
22.64, 14.08, 10.35 ppm; MS (ESI, CH2Cl2/MeOH 1:10): m/z (%): 1201 (5) [M+K]+, 1185
(100) [M+Na]+, 1162 (3) [M]+; HRMS (ESI): m/z calcd for C64H88Br2N6O4Na+: 1185.51362
[M]+; found: 1185.51260.
Acknowledgements
We are grateful to Dr. T. Dülcks, Ms. D. Kemken and Dr. Uli Papke for their help with the MS
characterization and to Dr. Linette Twigge for her help with the NMR characterization of the
new compounds.
Conflict of interest
The authors declare no conflict of interests.
Keywords: Click chemistry  Calixarenes  Molecular receptors  Tetrathiafulvalenes 
Ullmann coupling
References
[1]
a) G. Schukat, E. Fanghänel, Sulfur Rep. 1996, 18, 1–278; b) J. L. Segura, N. Martín,
Angew. Chemie Int. Ed. 2001, 40, 1372–1409, c) G. Schukat, E. Fanghänel, Sulfur
Rep. 2003, 24, 1–190.
[2]
a) T. Jørgensen, T. K. Hansen, J. Becher, Chem. Soc. Rev. 1994, 23, 41–51; b) M. R.
15
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Bryce, W. Devonport, L. M. Goldenberg, C. Wang, Chem. Commun. 1998, 945–951;
c) M. B. Nielsen, C. Lomholt, J. Becher, Chem. Soc. Rev. 2000, 29, 153–164; d) M. R.
Bryce, J. Mater. Chem. 2000, 10, 589–598; e) P. Batail, Special issue on molecular
conductors, Chem. Rev. 2004, 104, 4887–4890; f) N. Martín, Chem. Commun. 2013,
49, 7025–7027, g) P. J. Skabara, M. Sallé, Thematic series „Tetrathiafulvalene
chemistry”, Beilstein J. Org. Chem. 2015, 11, 1528–1529; h) J. J. Bergkamp, S.
Decurtins, S. X. Liu, Chem. Soc. Rev. 2015, 44, 863–874; i) R. Pfattner, S. T.
Bromley, C. Rovira, M. Mas-Torrent, Adv. Funct. Mater. 2016, 26, 2256–2275; j) A.
Jana, S. Bähring, M. Ishida, S. Goeb, D. Canevet, M. Sallé, J. O. Jeppesen, J. L.
Sessler, Chem. Soc. Rev. 2018, 47, 5614–5645.
[3]
a) D. Canevet, M. Sallé, G. Zhang, D. Zhang, D. Zhu, Chem. Commun. 2009, 2245–
2269; b) V. Balzani, A. Credi, B. Ferrer, S. Silvi, M. Venturi, in Top. Curr. Chem.,
Springer, Berlin, Heidelberg, 2005, pp. 1–27; c) H. V. Schröder, C. A. Schalley,
Beilstein J. Org. Chem. 2018, 14, 2163–2185.
[4]
[5]
a) F. G. Brunetti, J. L. López, C. Atienza, N. Martín, J. Mater. Chem. 2012, 22, 4188–
4205; b) O. Hammerich, M. B. Nielsen, J. Mater. Chem. C 2019, 7, 2809–2822.
a) J. O. Jeppesen, J. Becher, Eur. J. Org. Chem. 2003, 2003, 3245–3266; b) J. O.
Jeppesen, K. Takimiya, F. Jensen, T. Brimert, K. Nielsen, N. Thorup, J. Becher, J.
Org. Chem. 2000, 65, 5794–5805.
[6]
[7]
V. A. Azov, Tetrahedron Lett. 2016, 57, 5416–5425.
a) A. Jana, M. Ishida, J. S. Park, S. Bähring, J. O. Jeppesen, J. L. Sessler, Chem.
Rev. 2017, 117, 2641–2710; b) J. S. Park, J. L. Sessler, Acc. Chem. Res. 2018, 51,
2400–2410; c) S. Bähring, H. D. Root, J. L. Sessler, J. O. Jeppesen, Org. Biomol.
Chem. 2019, 17, 2594–2613.
[8]
[9]
a) D. S. Kim, J. Chang, S. Leem, J. S. Park, P. Thordarson, J. L. Sessler, J. Am.
Chem. Soc. 2015, 137, 16038–16042; b) S. Bähring, L. Martín-Gomis, G. Olsen, K. A.
Nielsen, D. S. Kim, T. Duedal, Á. Sastre-Santos, J. O. Jeppesen, J. L. Sessler, Chem.
- Eur. J. 2016, 22, 1958–1967.
a) J. S. Park, F. Le Derf, C. M. Bejger, V. M. Lynch, J. L. Sessler, K. A. Nielsen, C.
Johnsen, J. O. Jeppesen, Chem. - Eur. J. 2010, 16, 848–854; b) E. H. Witlicki, S.
Bähring, C. Johnsen, M. V. Solano, K. A. Nielsen, D. W. Silverstein, C. W. Marlatt, L.
Jensen, J. O. Jeppesen, A. H. Flood, Chem. Commun. 2017, 53, 10918–10921.
[10] a) K. W. Cheng, C. C. Lai, P. T. Chiang, S. H. Chiu, Chem. Commun. 2006, 2854–
2856; b) P.-T. Chiang, P.-N. Cheng, C.-F. Lin, Y.-H. Liu, C.-C. Lai, S.-M. Peng, S.-H.
Chiu, Chem. - Eur. J. 2006, 12, 865–876.
[11] a) Y. Cotelle, M. Allain, S. Legoupy, P. Hudhomme, Org. Lett. 2014, 16, 2590–2593;
16
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
b) M. Hardouin-Lerouge, Y. Cotelle, S. Legoupy, P. Hudhomme, New J. Chem. 2014,
38, 5341–5348.
[12] a) F. G. Klärner, T. Schrader, Acc. Chem. Res. 2013, 46, 967–978; b) M. Hardouin-
Lerouge, P. Hudhomme, M. Sallé, Chem. Soc. Rev. 2011, 40, 30–43; c) S. C.
Zimmerman, Beilstein J. Org. Chem. 2016, 12, 125–138.
[13] a) V. A. Azov, R. Gómez, J. Stelten, Tetrahedron 2008, 64, 1909–1917; b) M.
Skibiński, R. Gómez, E. Lork, V. A. Azov, Tetrahedron 2009, 65, 10348–10354; c) M.
H. Düker, R. Gómez, C. M. L. Vande Velde, V. A. Azov, Tetrahedron Lett. 2011, 52,
2881–2884; d) M.-L. L. Watat, T. Dülcks, D. Kemken, V. A. Azov, Tetrahedron Lett.
2014, 55, 741–744.
[14] M. H. Düker, H. Schäfer, M. Zeller, V. A. Azov, J. Org. Chem. 2013, 78, 4905–4912.
[15] C. D. Gutsche, Calixarenes. An Introduction, 2nd Edition, Royal Society of Chemistry,
Cambridge, 2008.
[16] F. Monnier, M. Taillefer, Angew. Chemie Int. Ed. 2009, 48, 6954–6971.
[17] K. R. Korsching, H. Schäfer, J. Schönborn, A. Nimthong-Roldán, M. Zeller, V. A. Azov,
RSC Adv. 2015, 5, 82633–82637.
[18] a) V. A. Azov, D. Janott, D. Schlüter, M. Zeller, Beilstein J. Org. Chem. 2015, 11, 860–
868; b) L. J. O’Driscoll, S. S. Andersen, M. V. Solano, D. Bendixen, M. Jensen, T.
Duedal, J. Lycoops, C. Van Der Pol, R. E. Sørensen, K. R. Larsen, K. Myntman, C.
Henriksen, S. W. Hansen, J. O. Jeppesen, Beilstein J. Org. Chem. 2015, 11, 1112–
1122.
[19] S. E. Matthews, S. Cecioni, J. E. O’Brien, C. J. MacDonald, D. L. Hughes, G. A.
Jones, S. H. Ashworth, S. Vidal, Chem. Eur. J. 2018, 24, 4436–4444.
[20] a) E. A. Kataev, C. Müller, Tetrahedron 2014, 70, 137–167; b) L. Escobar, P.
Ballester, Chem. Rev. 2021, 121, 2445–2514.
[21] a) K. Saha, S. S. Agasti, C. Kim, X. Li, V. M. Rotello, Chem. Rev. 2012, 112, 2739–
2779; b) H. J. Kim, M. H. Lee, L. Mutihac, J. Vicens, J. S. Kim, Chem. Soc. Rev. 2012,
41, 1173–1190.
[22] a) P.-T. Chiang, N.-C. Chen, C.-C. Lai, S.-H. Chiu, Chem. Eur. J. 2008, 14, 6546–
6552; b) J. Lyskawa, M. Sallé, J. Y. Balandier, F. Le Derf, E. Levillain, M. Allain, P.
Viel, S. Palacin, Chem. Commun. 2006, 2233–2235; c) P. Blanchard, N. Svenstrup, J.
Becher, Chem. Commun. 1996, 615–616; d) J. M. Spruell, A. Coskun, D. C. Friedman,
R. S. Forgan, A. A. Sarjeant, A. Trabolsi, A. C. Fahrenbach, G. Barin, W. F. Paxton, S.
K. Dey, M. A. Olson, D. Benítez, E. Tkatchouk, M. T. Colvin, R. Carmielli, S. T.
Caldwell, G. M. Rosair, S. G. Hewage, F. Duclairoir, J. L. Seymour, A. M. Z. Slawin,
W. A. Goddard III, M. R. Wasielewski, G. Cooke, J. F. Stoddart, Nat. Chem. 2010, 2,
17
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
870–879.
[23] a) M. Conner, S. L. Regen, V. Janout, J. Am. Chem. Soc. 1991, 113, 9670–9671; b) A.
Soi, W. Bauer, H. Mauser, C. Moll, F. Hampel, A. Hirsch, J. Chem. Soc. Perkin Trans.
2 1998, 1471–1478.
[24] I. Vatsouro, V. Rudzevich, V. Böhmer, Org. Lett. 2007, 9, 1375–1377.
[25] J. A. Hansen, J. Becher, J. O. Jeppesen, E. Levillain, M. B. Nielsen, B. M. Petersen, J.
C. Petersen, Y. Şahin, J. Mater. Chem. 2004, 14, 179–184.
[26] A. Dondoni, C. Ghiglione, A. Marra, M. Scoponi, J. Org. Chem. 1998, 63, 9535–9539.
[27] O. Hudecek, P. Curinova, J. Budka, P. Lhoták, Tetrahedron 2011, 67, 5213–5218.
[28] a) G. Gritzner, J. Kuta, Pure Appl. Chem. 1984, 56, 461–466; b) V. V. Pavlishchuk, A.
W. Addison, Inorganica Chim. Acta 2000, 298, 97–102; c) N. G. Connelly, W. E.
Geiger, Chem. Rev. 1996, 96, 877–910.
[29] S. V. Rosokha, J. K. Kochi, J. Am. Chem. Soc. 2007, 129, 3683–3697.
18
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202100676
European Journal of Organic Chemistry
Graphical abstract
Calix[4]arene-tetrathiafulvalene molecular tweezers modified on the lower rim were
synthesized using Ullman coupling – click reaction sequence.
19
This article is protected by copyright. All rights reserved.