Self-assembly of nanosized aggregates based on the photoswitchable p-tert-butyl thiacalix[4]arene derivative and Fe III, Cu II, and AgI cations

Article abstract of DOI:10.1007/s11172-009-0015-5

New p-tert-butyl thiacalix[4]arene tetrasubstituted at the lower rim and containing the azobenzene fragments in the 1,3-alternate configuration was synthesized. Its receptor properties with respect to d-metal cations (Fe ³⁺, Cu²⁺, Ag⁺) were studied using UV spectroscopy and dynamic light scattering (DLS). The ability of p-tert-butyl thiacalix[4]arene to molecular recognition of silver cations was estimated by UV spectroscopy. The aggregation of these systems was studied by the dynamic light scattering method.

Full text of DOI:10.1007/s11172-009-0015-5

Russian Chemical Bulletin, International Edition, Vol. 58, No. 1, pp. 101—107, January, 2009
101
Selfꢀassembly of nanosized aggregates based on the photoswitchable
pꢀtertꢀbutyl thiacalix[4]arene derivative and FeIII, CuII, and AgI cations*
E. A. Yushkova, E. N. Zaikov, I. I. Stoikov, and I. S. Antipin
A. M. Butlerov Chemical Institute at the Kazan State University,
18 ul. Kremlevskaya, 420008 Kazan, Russian Federation.
Fax: +7 (843) 231 5416. Eꢀmail: ivan.stoikov@mail.ru
New pꢀtertꢀbutyl thiacalix[4]arene tetrasubstituted at the lower rim and containing the
azobenzene fragments in the 1,3ꢀalternate configuration was synthesized. Its receptor properꢀ
ties with respect to dꢀmetal cations (Fe3+, Cu2+, Ag+) were studied using UV spectroscopy
and dynamic light scattering (DLS). The ability of pꢀtertꢀbutyl thiacalix[4]arene to molecular
recognition of silver cations was estimated by UV spectroscopy. The aggregation of these
systems was studied by the dynamic light scattering method.
Key words: selfꢀassembly, thiacalix[4]arenes, molecular recognition, dynamic light scattering
(DLS), silver cations, photoswitchers.
of the deuterated solvent (CDCl3, δ (CHCl3) 7.26). IR spectra
The study of conformationally controllable molecules
is highlighted in foldamer research, which aims at creatꢀ
ing synthetic analogues of biopolymers that can change
the size, shape, and spatial arrangement of functional
groups under external effects (light, pH).1 Similar synꢀ
thetic receptors, which exist in at least two different forms
and are reversibly transformed by external effects from one
state into another, can be used for storage and processing
of information and for the development of molecular
switchers, viz., ''intellectual'' materials, on the basis of these
receptors.
were measured on a Vector 22 FTꢀIHR spectrometer (Bruker) in
the interval of the wave numbers from 400 to 4000 cm–1
;
resolution 1 cm–1, accumulation 64 scans, detection time 16 s,
suspensions in Nujol. Mass spectra (ESI) were obtained on a
Bruker Esquire MS mass spectrometer. Elemental analysis of
crystalline samples was carried out on a Perkin—Elmer 2400
Series II instrument. Melting points of substances were determined
on a Boetius heating stage. Purity of compounds was monitored
1
by boiling and melting points and H NMR spectra. The purity
of substances and the reaction course were monitored by thin
layer chromatography on Silica G plates, 200 µm, UV 254. The
TLC plates were visualized using UVꢀirradiation with λ = 254 nm.
Electronic spectra were recorded on a Perkin—Elmer Lambdaꢀ35
spectrometer, the transmission layer thickness being 1 cm.
Nꢀ[(Е)ꢀ4´ꢀ(Phenyldiazenyl)phenyl]ꢀ2ꢀbromoacetamide.
Bromoacetyl bromide (3.98 mL, 45.63 mmol) was added
dropwise with stirring for 30 min to 4ꢀaminoazobenzene (10.00 g,
50.70 mmol, pure grade, ZAO Vekton) in benzene (500 mL).
The reaction mixture was stirred on reflux for 24 h. After
the mixture was cooled, the precipitate was filtered off and
recrystallized from EtOH. The yield of the product (orange
powder) was 10.46 g (72%), m.p. 168—169 °C. Found (%):
C, 52.72; H, 3.69; N, 13.25. C14H12BrN3O. Calculated (%):
C, 52.85; H, 3.80; N, 13.21. 1H NMR, δ: 3.78 (s, 2 H, OCH2CO);
7.23—7.34 (m, 3 H, Ar(2)H); 7.59 (d, 2 H, Ar(1)H, J = 8.8 Hz);
7.62—7.74 (m, 2 H, Ar(2)H); 7.69 (d, 2 H, Ar(1)H, J = 8.8 Hz);
9.97 (s, 1 H, NH). IR, ν/cm–1: 3260 (NH); 1660 (C=O).
5,11,17,23ꢀTetraꢀtertꢀbutylꢀ2,8,14,20ꢀtetrathiacalix[4]ꢀ
areneꢀ25,26,27,28ꢀtetraol (1), 5,11,17,23ꢀtetraꢀtertꢀbutylꢀ
25,26,27,28ꢀtetrakis(ethoxycarbonylmethoxy)ꢀ2,8,14,20ꢀtetraꢀ
thiacalix[4]arene (2), and 5,11,17,23ꢀtetraꢀtertꢀbutylꢀ25,26,
27,28ꢀtetrakis(carboxymethoxy)ꢀ2,8,14,20ꢀtetrathiacalix[4]ꢀ
arene (3) were synthesized according to earlier described
procedures.4—6
Presently, calix[4]arene is widely used as a molecular
platform for design of similar molecular structures.2,3 Advanꢀ
tages of this compound are in a possibility of its modification by
the introduction of various functional groups at both the lower
(hydroxy groups) and upper rims of the macrocycle (reꢀ
placement of the tertꢀbutyl group by other fragments) and
a possibility to vary the cavity size (for example, due to
the introduction of sulfur atoms into the macrocycle).
In this work, we studied routes of the synthesis of pꢀtertꢀ
butyl calix[4]arene tetrasubstituted at the lower rim and
containing azobenzene fragments in the 1,3ꢀalternate conꢀ
figuration and examined the ability of the synthesized
compound to interact with dꢀmetal cations (Fe3+, Cu2+
Ag+) by the dynamic light scattering method.
,
Experimental
1H NMR spectra were recorded on a Varian XLꢀ300 spectroꢀ
meter at a working frequency of 300.0 MHz at 25 °C. Chemical
shifts were determined relative to the signals of residual protons
* Dedicated to Academician A. I. Konovalov on his 75th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 101—107, January, 2009.
1066ꢀ5285/09/5801ꢀ0101 © 2009 Springer Science+Business Media, Inc.

102
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Yushkova et al.
5,11,17,23ꢀTetraꢀtertꢀbutylꢀ25,26,27,28ꢀtetrakis[2ꢀoxoꢀ
D/N 95ꢀ0021ꢀ10) at the wavelengths 365 and 254 nm. The
error of the dynamic light scattering method for particle size
determination is less than 2%. More than three independent
experiments were carried out for each system during the
determination of the hydrodynamic particle size. The tꢀStudent
criterion was used in statistical processing.
2ꢀ{4ꢀ[(E)ꢀ2ꢀphenylꢀ1ꢀdiazenyl]anilino}ethoxy]ꢀ2,8,14,20ꢀtetraꢀ
thiacalix[4]arene 1,3ꢀalternate (4). A mixture of pꢀtertꢀbutyl
thiacalix[4]arene 1 (1.00 g, 1.39 mmol), Nꢀ[(Е)ꢀ4´ꢀ(phenylꢀ
diazenyl)phenyl]ꢀ2ꢀbromoacetamide (3.54 g, 11.12 mmol),
cesium carbonate (3.62 g, 11.12 mmol), and acetone (60 mL)
was refluxed for 12 h. The solvent was distilled off in vacuo. The
residue was dissolved in CHCl3 (40 mL) and washed with a 2 M
HCl solution (40 mL). The organic phase was dried with Na2SO4,
and the solvent was removed in vacuo. The product was isolated
by recrystallization from an acetonitrile—chloroform mixture.
An orange powder was obtained in a yield of 1.05 g (45%),
m.p. 300—301 °C. Found (%): C, 69.40; H, 5.53; N, 9.57.
C96H92N12O8S4. Calculated (%): C, 69.04; H, 5.55; N, 10.06.
1H NMR, δ: 0.73 (s, 36 H, But); 4.94 (s, 8 H, OCH2CO);
7.45—7.58 (m, 12 H, Ar(2)H); 7.54 (s, 8 H, ArH); 7.76 (d, 8 H,
Ar(1)H, J = 8.8 Hz); 7.91—8.00 (m, 8 H, Ar(2)H); 7.99 (d, 8 H,
Ar(1)H, J = 8.8 Hz); 8.72 (s, 4 H, NH). IR, ν/cm–1: 3389 (NH
nonassociated); 3289 (NH associated); 1706 (C=O). MS, m/z
(Irel (%)): 1691.6 [М + Na]+ (100).
Determination of the stability constant and stoichiometry of
the complex by UV titration.7 A 5•10–6 М solution of silver
nitrate (0.03, 0.05, 0.08, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70,
0.80, 0.90, 1.00, 1.10, and 1.20 mL) was added to a solution of
receptor 4. The volume was brought to 5 mL with dichloroꢀ
methane, while the concentration of pꢀtertꢀbutyl thiacalix[4]ꢀ
arene tetrasubstituted with the azobenzene fragments
(3•10–6 mol L–1) remained constant. Then the UV spectra of
the obtained solutions were recorded. Three independent
experiments were carried out for each series. The tꢀStudent
criterion was used in statistical data processing.
Results and Discussion
Two possible approaches to the synthesis of pꢀtertꢀ
butyl thiacalix[4]arenes tetrasubstituted at the lower rim
in different configurations are described in literature
(Scheme 1). The first approach is the primary preparation
according to published procedures8 of tetraethers based
on pꢀtertꢀbutyl thiacalix[4]arene 1 in the configurations
cone, partial cone, and 1,3ꢀalternate followed by the
functionalization of the substituents at the lower rim of
the macrocycle by various fragments.
In the second approach, the oneꢀstep synthesis of the
tetrasubstituted products in various configurations is carꢀ
ried out by the direct alkylation of the hydroxy groups at
the lower rim of thiacalix[4]arene with alkyl halides bearꢀ
ing the carbonyl groups in the presence of alkaline metal
carbonates.9—11 This case, as the formation of tetraethers
based on pꢀtertꢀbutyl thiacalix[4]arene 1, is characterized
by the template effect of the cation.12
The study of aggregation of the stereoisomers of pꢀtertꢀ
butyl thiacalix[4]arenes tetrasubstituted at the lower rim
and containing the secondary amide group showed that for
the cone configuration aggregates are formed upon complex
formation predominantly as dimers.13 However, 1,3ꢀalterꢀ
nate turned out to be more interesting conformer for the
formation of nanosized structure for the creation of photoꢀ
switchable aggregates. In the case of creation of extended
photoswitchable aggregates based on the stereoisomer,
their size can change upon irradiation. Therefore, we chose
the azobenzene moiety as a photoswitchable fragment.
Primarily to study the first synthetic approach, we
synthesized tetraester based on pꢀtertꢀbutyl thiacalix[4]ꢀ
arene 2 in the 1,3ꢀalternate configuration.5 Hydrolysis of
compound 2 in the presence of LiOH in a THF—H2O
system afforded tetraacid 3 based on pꢀtertꢀbutyl thiaꢀ
calix[4]arene (Scheme 2).6 Then we studied the reaction
of acid chloride, which was obtained by the interaction of
acid 3 with thionyl chloride, with 4ꢀaminoazobenzene
in dichloromethane in the presence of triethylamine.13
It turned out that a poorly separable mixture of the partial
acylation products is formed.
Determination of the stoichiometry by the isomolar series
method. To determine the composition of the complex by the
isomolar series method, we prepared several solutions in which
the ratio of concentrations of silver nitrate and pꢀtertꢀbutyl thiaꢀ
calix[4]arene 4 tetrasubstituted with the azobenzene fragments
ranged from 13 : 2 to 2 : 13. The initial concentration of both
the substrate and receptor was 5•10–6 mol L–1. The absorbance
of the complex (Ac) at the wavelength 347.6 nm was determined
as the difference between the absorbance of the measured
solutions (A0) and solutions of pure pꢀtertꢀbutyl thiacalix[4]arene
with a specified concentration (AH). The maximum in the plot
of (A0 – AH) vs G/(H + G) (G is silver nitrate) indicates the
composition of the complex.
Dynamic light scattering method.7 Particle sizes were deterꢀ
mined on a Zetasizer Nano ZS instrument. The results were
processed using the DTS (Dispersion Technology Software 4.20)
program. The experimental conditions are as follows: solvent
CH2Cl2 (HPLC), temperature 2—30 °C, wavelength of a
He—Ne laser 633 nm, and power 4 MW. Solutions of the systems
under study were prepared by the dissolution of weighed samples
of dꢀmetal nitrates (2.32•10–4 mol L–1) in a 5•10–6 М solutions
(10 mL) of pꢀtertꢀbutyl thiacalix[4]arene 4 containing the
azobenzene groups in CH2Cl2 (HPLC), then the solutions
were stirred for 3 h, and the measurement was carried out.
When determining the particle size in the system containing
pꢀtertꢀbutyl thiacalix[4]arene 4 and AgNO3 (chemical pure),
Cu(NO3)2•3H2O (chemical pure), or Fe(NO3)3•9H2O (chemical
pure), the configuration of this macrocycle was transformed
from the transꢀ into cisꢀform due to the irradiation of the
samples with the UV lamp (UVGLꢀ25; Compact UV Lamp;
To accomplish the second approach, we studied the
reaction of pꢀtertꢀbutyl thiacalix[4]arene 1 with Nꢀ[(Е)ꢀ
4´ꢀ(phenyldiazenyl)phenyl]ꢀ2ꢀbromoacetamide in the
presence of cesium carbonate in acetone. Tetrasubstituted
product 4 in the 1,3ꢀalternate conformation was isolated
in a yield of 45%.

Photoswitchable thiacalixarenes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 1, January, 2009
103
Scheme 1
Cone
Partial cone
1,3ꢀAlternate
Cone
Partial cone
1,3ꢀAlternate
The ability of pꢀtertꢀbutyl thiacalix[4]arene 4 containꢀ
ing the azobenzene fragments in the 1,3ꢀalternate conꢀ
figuration to change its conformation under UV irradiaꢀ
tion at 365 nm due to the trans—cisꢀisomerization of the
photoswitchable fragments was studied by electronic specꢀ
troscopy. It was found that the spectrum of the transꢀform
of the compound exhibited several absorption band
near 230 nm, which is characteristic of the macrocyclic
ring of pꢀtertꢀbutyl thiacalix[4]arene,14 and at λ = 350
and 450 nm corresponding to the π—π* and n—π*
electron transitions of the azobenzene fragments (Fig. 1).
pꢀtertꢀButyl thiacalix[4]arene 4 is transformed from

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Yushkova et al.
Scheme 2
R =
i. 1) SOCl2; 2) H2NR, NEt3, CH2Cl2.
450 nm noticeably increases. In addition, substantial
changes occur at 200—300 nm, for example, an additional
chargeꢀtransfer band appears at 257 nm (see Fig. 1). This
process is reversible, because already 3 h after macrocycle
4 returns completely to the initial state with the transꢀ
configuration.
the transꢀ into cisꢀform under UV irradiation at
365 nm for 20 min. In this case, the chargeꢀtransfer
band at 350 nm disappears and the absorption intensity at
A
0.6
It was shown by spectrophotometry that the hyperꢀ
chromic effect was observed upon the interaction of
macrocycle 4 in the transꢀform with silver nitrate in
dichloromethane (Fig. 2). For the quantitative estimation
of complex formation, we determined the stability conꢀ
stant logKst = 4.73 and the 1 : 1 stoichiometry of the
formed complexes cation—pꢀtertꢀbutyl thiacalix[4]arene
4 by UV titration with the variation of the substrate conꢀ
centration (Fig. 3). The changes in the absorbance A were
detected at the wavelength corresponding to the maximum
absorption in the chargeꢀtransfer region (λmax = 235.9 nm),
because no substantial changes were observed in the specꢀ
tra at the wavelengths 350 and 450 nm. The 1 : 1 substrate
0.5
1
0.4
0.3
0.2
2
0.1
220 260 300 340 380 420 460 500 λ/nm
Fig. 1. UV spectra (5•10–6 mol L–1, 1ꢀcm cell) of pꢀtertꢀbutyl
thiacalix[4]arene 4 in the transꢀ (1) and cisꢀforms (2) in dichloroꢀ
methane.

Photoswitchable thiacalixarenes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 1, January, 2009
105
Table 1. Dependence of the aggregate size (hydrodynamic diameters of peak 2, 3 mean intensity — d2, d3, nm),
peak 2, 3 area intensity (S2, S3, %)*, and the polydispersity index (PDI) on the ratio of the reactants:
pꢀtertꢀbutyl thiacalix[4]arene 4 (H) and silver nitrate (G)
Ratio
G/H
Isomer
d2/S2
d3/S3
PDI
5•10–7/5•10–6
5•10–6/5•10–6
5•10–5/5•10–6
5•10–4/5•10–6
trans
cis
trans
cis
trans
cis
trans
cis
—
—
152.3 112.6/100
257.3 67.6/100
3015.0 1334.2/7.1 13.1
0.90 0.32
0.89 0.07
0.28 0.11
0.34 0.24
0.34 0.17
0.70 0.32
0.20 0.06
0.15 0.03
63.2 11.9/92.9 13.1
63.6 6.9/100
41.4 3.7/75.2 16.9
42.6 8.5/61.8 42.9
41.7 2.8/100
60.6 2.7/100
—
289.3 205.3/24.8 16.9
185.3 126.2/38.2 42.9
—
—
* The d1 and S1 values were not determined.
to receptor ratio was also confirmed by the isomolar series
method (Fig. 4).
It was found by the dynamic light scattering studies of
the systems containing pꢀtertꢀbutyl thiacalix[4]arene 4
tetrasubstituted by the azobenzene fragments that this
macrocycle existing in both the transꢀ and cisꢀconfiguraꢀ
tions was incapable of selfꢀassociation to form nanoscaled
aggregates. Similar experiments for silver, copper, and
iron nitrates also showed the absence of any particles in
the range from 0.6 to 6000 nm. However, the introducꢀ
tion of silver nitrate into the system containing pꢀtertꢀ
butyl thiacalix[4]arene 4 resulted in the formation of suꢀ
pramolecular associates under the conditions analogous
to UV titration (Table 1). The change in the cation to
pꢀtertꢀbutyl thiacalix[4]arene ratio exerts an effect on both
the shape of the UV spectra and the size of formed parꢀ
ticles (see Table 1). It should be mentioned that the tranꢀ
sition from the transꢀ to cisꢀisomer of compound 4 in the
presence of inorganic salts occurs irreversibly.
A
0.7
0.6
0.5
0.4
0.3
0.2
0.1
It was shown by dynamic light scattering that supraꢀ
molecular aggregates, whose size changed with an increase
in the silver nitrate concentration, were formed during
UV titration. In these nanoscaled particles the cation to
220 260
300
340 380 420
460 500 λ/nm
Fig. 2. UV spectra (3•10–6 mol L–1, 1ꢀcm cell) of pꢀtertꢀ
butyl thiacalix[4]arene 4 in the transꢀform and its 1 : 1 comꢀ
plexes with silver nitrate at different substrate concentrations
(3•10–7—1.2•10–5 mol L–1) in dichloromethane.
A0 – AH
log[AgnL+] – log[L]
0.018
0.016
0.014
0.012
0.010
0.008
6.6
6.4
6.2
6.0
5.8
5.6
5.4
5.2
5.0
0.3
0.4
0.5
0.6
G/(G + H)
4.8
Fig. 4. Job plot for the complex formation of pꢀtertꢀbutyl thiaꢀ
calix[4]arene (H) 4 and silver nitrate (G); A0 is the observed
optical absorption; AH is the absorbance of solutions of pure
pꢀtertꢀbutyl thiacalix[4]arene 4 with the specified concentration.
0.2 0.4 0.6 0.8 1.0 1.2 1.4 log[Ag+]
Fig. 3. Plot of log[AgnL+] – log[L] vs log[Ag+]; y = kx + b,
y = 1.06602x + 4.73495.

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Yushkova et al.
Table 2. Temperature dependence of the aggregate size (hydrodynamic diameters of peak 1, 2 mean intensity —
d1, d2, nm), peak 1, 2 area intensity (S1, S2, %)* and the polydispersity index (PDI) of the pꢀtertꢀbutyl
thiacalix[4]arene 4 (H)—silver nitrate (G) (1 : 1) system
T/°C
Isomer
d1/S1
d2/S2
PDI
2*
trans
cis
trans
cis
trans
cis
trans
cis
trans
cis
trans
cis
trans
cis
—
65.8 4.1/99.6 0.7
66.5 1.5/93.9 1.6
64.8 7.5/97.7 3.9
68.1 0.9/93.9 1.9
65.9 4.4/97.0 3.5
68.9 1.6/100
71.9 1.9/100
65.8 16.6/100
64.7 6.8/100
0.24 0.02
0.24 0.02
0.24 0.01
0.24 0.003
0.24 0.02
0.20 0.01
0.24 0.01
0.19 0.18
0.21 0.07
0.20 0.05
0.08 0.01
0.10 0.03
0.09 0.02
0.17 0.02
9.7 1.5/6.1 1.6
11.1 3.2/2.3 3.9
10.2 2.1/6.1 1.9
10.3 4.5/3.0 3.5
5
10
15
20
25
30
—
—
—
—
—
—
—
—
—
64.6 7.5/100
54.7 2.1/100
52.9 1.4/100
53.7 3.3/100
50.1 1.9/100
* The d3/S3 values are 5360.0 127.1/0.4 0.7, and they were not determined at other temperatures.
tra and the ability of the cisꢀ and transꢀisomers of pꢀtertꢀ
butyl thiacalix[4]arene 4 to form nanoscaled aggregates.
The addition of copper nitrate to the system, as in the
case with the silver cations, induces changes in the UV
spectra due to the interaction of this substrate with the
macrocycle (Fig. 5). However, no supramolecular selfꢀ
associates are formed under these conditions. The abꢀ
sence of nanosized aggregates was established under UV
irradiation with the wavelength 365 nm, which is related
to the fact that the transꢀconfiguration of macrocycle 4
cannot change (see Fig. 5). The transformation of pꢀtertꢀ
butyl thiacalix[4]arene 4 from the transꢀ into cisꢀform in
the presence of copper nitrate can take place upon irraꢀ
diation with the wavelength 254 nm. Under these condiꢀ
tions, pꢀtertꢀbutyl thiacalix[4]arene 4 only in the cisꢀform
can form supramolecular associates with copper nitrate
(Table 3). Substantial changes in the sizes of the particles
formed by two isomers of macrocycle 4 are observed in
the presence of iron nitrate, and the aggregates 62.5 nm
in size correspond to the transꢀisomer, whereas the cisꢀ
isomer is characterized by a size of 146.1 nm.
However, unlike the system containing silver nitrate
along with pꢀtertꢀbutyl thiacalix[4]arene 4, the size of
supramolecular associates depends on the wavelength
of the UV radiation (see Table 3). The UV spectrum of
the system consisting of compound 4 and iron nitrate and
subjected to the radiation with λ = 254 nm is similar to
that of the cisꢀisomer, whereas in the case of silver nitrate
the spectrum is similar to that of the transꢀform (see Fig. 5).
Thus, both the size of supramolecular aggregates and
the ability of photoswitchable thiacalix[4]arene 4 to change
its shape on going from the transꢀ to cisꢀisomer can be
purposefully controlled by raising the concentration of
metal cations, varying their nature, or changing the UV
radiation wavelength (254 or 365 nm).
pꢀtertꢀbutyl thiacalix[4]arene ratio determined by the
methods of UV titration and isomolar series is 1 : 1. The
linear dependence (see Fig. 3) demonstrates that the
cation to pꢀtertꢀbutyl thiacalix[4]arene ratio remains
constant for the aggregates with different sizes. The values
of mean hydrodynamic diameters, i.e., sizes of solvated
particles that exist in the Brownian motion state, polydisꢀ
persity indices (estimation of the distribution width for
the system), and surface areas of the maxima (estimation
of the distribution width in intensity units for one type of
particles) are given in Table 1. The obtained data indicate
that the substantial difference in the hydrodynamic diamꢀ
eters between the aggregates formed by the cisꢀ and
transꢀisomers of pꢀtertꢀbutyl thiacalix[4]arene 4 and silver
cations is observed when the substrate concentration is
5•10–7 and 5•10–4 mol L–1, respectively. However, for
the system with the cation to pꢀtertꢀbutyl thiacalix[4]arene
4 ratio equal to 1 : 10 the polydispersity index is 0.9, which
indicates that the associates are unstable under these
conditions. Raising the concentration the silver cations,
one can control the size of the supramolecular aggregates
formed by two photoswitchable cisꢀ and transꢀisomers
of pꢀtertꢀbutyl calix[4]arene. It was also shown that, on
going from the transꢀ to cisꢀisomer, the temperature
change from 2 to 30 °C exerts no effect on the size of
aggregates consisting of pꢀtertꢀbutyl thiacalix[4]arene 4
molecules and silver cations (Table 2). However, it turned
out that the aggregates formed by pꢀtertꢀbutyl thiacalixꢀ
[4]arene tetrasubstituted by the azobenzene fragments
with the silver cations exhibit the general dependence
of decreasing the hydrodynamic particle size from 65 to
50 nm with the temperature increase from 20 to 30 °C
(see Table 2).
It is interesting that the change in the substrate nature
substantially affects both the shape of the electronic specꢀ

Photoswitchable thiacalixarenes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 1, January, 2009
107
Table 3. Size of aggregates (hydrodynamic diameter of peak 1, 2 mean intensity — d1, d2, nm) and peak 1, 2 area
intensity (S1, S2, %) for associates of pꢀtertꢀbutyl thiacalix[4]arene 4 (5•10–6 mol L–1) in the 1,3ꢀalternate configuraꢀ
tion with cations of various metals (5•10–4 mol L–1), polydispersity index (PDI)
Cation
Fe3+
Isomer
λ/nm
d1/S1
d2/S2
PDI
trans
cis
—
65.2 10.8/100
146.1 48.8/89.7 11.3
125.7 21.0/94.6 4.0
—
—
0.90 0.11
0.27 0.06
0.19 0.05
—
365
254
—
365
254
—
4705.0 647.6/12.1 11.3
4770.0 578.9/5.4 4.0
Cu2+
Ag+
trans
cis
—
—
—
—
187.9 59.9/85.6 13.5
41.7 2.8/100
60.6 2.7/100
61.1 5.4/100
3730.0 535.8/14.4 13.5
0.34 0.16
0.20 0.06
0.15 0.03
0.16 0.02
trans
cis
—
—
—
365
254
A
A
A
This work was financially supported by the Russian
a
Foundation for Basic Research (Project Nos 06ꢀ03ꢀ32160,
08ꢀ03ꢀ90403ꢀUkr, and 08ꢀ03ꢀ91106ꢀAFGIR), the Proꢀ
gram of Cooperative Grants CRDF (RUC1ꢀ2910ꢀKAꢀ
07), and the Joined Program of the CRDF and the Minisꢀ
try of Science and Education of the Russian Federation
''Fundamental Research and Higher Education'' (Grant
RECꢀ007, BP2M07).
0.6
0.5
0.4
0.3
0.2
0.1
transꢀIsomer
cisꢀIsomer (365 nm)
transꢀIsomer
(254 nm)
References
260 300 340 380 420 460 500 540 λ/nm
1. S. H. Gellman, Acc. Chem. Res., 1998, 31, 173.
2. C. D. Gutsche, J. F. Stoddart, Calixarenes. Monographs in
Supramolecular Chemistry, RSC, London, 1989, р. 236.
3. C. D. Gutsche, Calixarenes Revisited. Monographs in Supraꢀ
molecular Chemistry, RSC, London, 1998, p. 233.
4. H. Kumagai, M. Hasegawa, S. Miyanari, Y. Sugawa, Y. Sato,
T. Hori, S. Ueda, H. Kamiyama, S. Miyano, Tetrahedron
Lett., 1997, 22, 3971.
0.7
0.6
0.5
0.4
0.3
0.2
0.1
b
transꢀIsomer
5. N. Iki, F. Narumi, T. Fujimoto, N. Morohashi, S. Miyano,
J. Chem. Soc., Perkin Trans. 2, 1998, 2745.
cisꢀIsomer (365 nm)
transꢀIsomer
(254 nm)
6. I. I. Stoikov, V. A. Smolentsev, I. S. Antipin, W. D. Habicher,
M. Gruner, A. I. Konovalov, Mendeleev Commun., 2006, 16, 294.
7. K. Hirose, J. Inc. Phen. Mac. Chem., 2001, 39, 193.
8. N. Iki, F. Narumi, T. Fujimoto, N. Morohashi, S. Miyano,
J. Chem. Soc., Perkin Trans. 2, 1998, 2745.
9. L. I. Gafiullina, I. S. Vershinina, I. I. Stoikov, I. S. Antipin,
A. I. Konovalov, J. Struct. Chem., 2005, 46, 25.
10. I. I. Stoikov, O. A. Omran, S. E. Solovieva, S. K. Latypov,
K. M. Enikeev, A. T. Gubaidullin, I. S. Antipin, A. I.
Konovalov, Tetrahedron, 2003, 59, 1469.
260 300 340 380 420 460 500 540 λ/nm
1.0
0.8
0.6
0.4
0.2
c
transꢀIsomer
cisꢀIsomer (365 nm)
11. N. Morohashi, H. Katagiri, N. Iki, Y. Yamane, C. Kabuto,
T. Hattori, S. Miyano, J. Org. Chem., 2003, 68, 2324.
12. J. Vicens, J. Harrowfield, Calixarenes in the Nanoworld,
Springer, Dordrecht, 2007, р. 135.
cisꢀIsomer
(254 nm)
13. I. I. Stoikov, E. A. Yushkova, A. Yu. Zhukov, I. Zharov, I. S.
Antipin, A. I. Konovalov, Tetrahedron, 2008, 64, 7112.
14. C. D. Gutsche, Calixarenes, Royal Society of Chemistry,
Sheffield, 1989, р. 222.
260 300 340 380 420 460 500 540 λ/nm
Fig. 5. UV spectra (5•10–6 mol L–1, 1ꢀcm cell) of pꢀtertꢀbutyl
thiacalix[4]arene 4 in the cisꢀ and transꢀforms in the presence of
silver (a), copper (b), and iron (c) nitrate in dichloromethane
(wavelengths of the UV lamp at with the systems were irradiated
are given in parentheses).
Received November 25, 2008;
in revised form December 25, 2008