Self-organization of crown-containing hetarylphenylethenes, phthalic acid, and potassium cations into supramolecular assemblies

Article abstract of DOI:10.1007/s11172-011-0047-5

Multicomponent molecular assemblies of 15-crown-5-containing 4-styrylpyridine with phthalic acid in the presence of potassium perchlorate were studied. The structure of the obtained complicated assemblies was determined by ¹H and ¹³C NMR spectroscopy, UV spectroscopy, and X-ray analysis. The composition of the supramolecular complexes was established by spectrophotometric titration, and the stability constants were calculated. The quantum yields of fluorescence for the ligand and its complexes of various nature were determined.

Full text of DOI:10.1007/s11172-011-0047-5

Russian Chemical Bulletin, International Edition, Vol. 60, No. 2, pp. 280—294, February, 2011
280
Selfꢀorganization of crownꢀcontaining hetarylphenylethenes, phthalic acid,
and potassium cations into supramolecular assemblies
Yu. V. Fedorov,a E. Yu. Chernikova,a A. S. Peregudov,a N. E. Shepel´,a
E. N. Gulakova,a L. G. Kuz´mina,b and O. A. Fedorovaa
aA. N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (495) 135 5085. Eꢀmail: fedorov@ineos.ac.ru
bN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
31 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (495) 954 1279
Multicomponent molecular assemblies of 15ꢀcrownꢀ5ꢀcontaining 4ꢀstyrylpyridine with
phthalic acid in the presence of potassium perchlorate were studied. The structure of the
obtained complicated assemblies was determined by 1H and 13C NMR spectroscopy, UV specꢀ
troscopy, and Xꢀray analysis. The composition of the supramolecular complexes was estabꢀ
lished by spectrophotometric titration, and the stability constants were calculated. The quanꢀ
tum yields of fluorescence for the ligand and its complexes of various nature were determined.
Key words: crown ethers, 4ꢀstyrylpyridine, potassium perchlorate, phthalic acid, compꢀ
lexation, spectrophotometry.
Development of supramolecular assemblies of organic
ic acid. The nitrogen atom of the heterocyclic residue of
hetarylphenylethenes can form bonds with the carboxyl
group of carboxylic acids. It was assumed that dicarboxylic
acids can bind two molecules of hetarylphenylethenes due
to coordination with their heterocyclic pyridine residues.
In the case of crownꢀcontaining hetarylphenylethenes, for
example, ligand 1, the presence in solution of large catꢀ
ions of alkaline or alkalineꢀearth metals can favor an addiꢀ
tional coordination of metal to the crown ether fragment
due to sandwich complexation.12 Potassium cation was
chosen as a metal cation. Hetarylphenylethene 2 containꢀ
ing two methoxy groups instead of the crown ether fragꢀ
ment was used for comparative analyses.
molecules is a modern direction of investigation in physiꢀ
cal organic chemistry having both fundamental and
applied aspects. Understanding of laws determining the
dependence of the manifested properties on the architecꢀ
ture of a supramolecular assembly makes it possible to
produce new systems and materials using modern apꢀ
proaches.
As known, ligands synthesized from hetarylphenylꢀ
ethene derivatives are widely used for synthesis of supramoꢀ
lecular assemblies.1—3 In the present study, we investigatꢀ
ed the properties of 4ꢀstyrylpyridine containing the macroꢀ
cyclic moiety of 15ꢀcrownꢀ5. The construction of multiꢀ
component molecular systems is based on the ability of
the nitrogen atom of the heterocyclic compound to form
strong coordination bonds with metal cations due to a lone
electron pair and to form hydrogen bonds with carboxyl
groups of other organic molecules. It is assumed that similar
ligands and related supramolecular assemblies can be used
to determine concentrations of heavy metals, in chemical
analysis, in modeling of biological systems,4 in medicine
for the development of drugs against HIV,5 as selective
fluorescent labels that can be included into the DNA strucꢀ
ture,6 for the construction of molecular devices with good
luminescence characteristics7,8 and materials for photonꢀ
ics, optoelectronics,9 and electrochemical analysis.10,11
In this work we present the results of studying the forꢀ
mation of supramolecular assemblies based on hetarylꢀ
phenylethene 1 and 2, potassium perchlorate, and phthalꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 274—287, February, 2011.
1066ꢀ5285/11/6002ꢀ280 © 2011 Springer Science+Business Media, Inc.

Supramolecular assemblies of some crowns
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
281
(С(7)), 144.94 (С(4)), 149.14 (С(12)), 149.78 (С(11)), 150.14
(С(2), С(6)).
The structure, stoichiometry, and stability of the comꢀ
plexes formed were studied using a combination of physiꢀ
cochemical methods including 1H and 13С NMR spectroꢀ
scopy, UV spectroscopy, ESI (electrospray ionization at
atmospheric pressure) mass spectrometry, and Xꢀray difꢀ
fraction analysis.
Ligand 1 in the presence of 0.5 equiv. KClO4. Ligand 1 (2.2 mg,
0.006 mmol) and KClO4 (0.4 mg, 0.003 mmol) were dissolved in
CD3CN (0.6 mL) under red light. 1H NMR, δ: 3.67—3.68 (m, 4 Н,
H(18), H(19)); 3.76—3.78 (m, 8 Н, H(16), H(17), H(20), H(21));
3.95—3.97 (m, 2 H, H(22)); 4.02—4.04 (m, 2 H, H(15)); 6.82
(d, 1 Н, Н(13), J = 8.4 Hz); 6.98 (s, 1 Н, Н(10)); 6.98 (d, 1 Н, Н(7),
J = 16.3 Hz); 7.12 (d, 1 H, Н(14), J = 9.7 Hz); 7.32 (d, 1 Н,
Н(8), J = 16.3 Hz); 7.36 (d, 2 Н, Н(3), Н(5), J = 5.7 Hz); 8.47
(d, 2 Н, Н(2), Н(6), J = 5.3 Hz). 13C NMR, δ: 67.16—67.33
(С(15), С(16), С(21), С(22)), 67.84, 67.87 (С(18), С(19)), 68.67,
68.72 (С(17), С(20)), 110.95 (С(10)), 112.97 (С(13)), 120.53
(С(3), С(5)), 121.46 (С(14)), 124.32 (С(8)), 130.10 (С(9)),
132.51 (С(7)), 144.74 (С(4)), 147.85 (С(12)), 148.38 (С(11)),
150.06 (С(2), С(6)).
Experimental
Potassium perchlorate was dried in vacuo at 230 °C. The
syntheses of 4ꢀ[2ꢀ(6,7,9,10,12,13,15,16ꢀoctahydroꢀ5,8,11,14,17ꢀ
pentaoxabenzocyclopentadecenꢀ2ꢀyl)vinyl]pyridine (1) and
4ꢀ[2ꢀ(3,4ꢀdimethoxyphenyl)vinyl]pyridine (2) have been deꢀ
scribed earlier.13 Preparation of solutions and all studies were
carried out under red light.
Acetonitrile (special purity grade, sort 1, KRIOKhROM)
was used for spectrophotometry. Electronic absorption spectra
were recorded on a SpecordꢀM40 spectrophotometer (Carl Zeiss
Jena) connected with a computer. Control of the spectroꢀ
photometer, data collection, and simplest computer processing
of spectra were performed by the SPECORD standard program
(version 2.0, Etalon). Fluorescence emission spectra were obꢀ
tained on a Shimadzu RFꢀ5301 PC fluorimeter connected with
a computer. Control of the spectrofluorimeter and data collecꢀ
tion were performed using the Hyper RF 1.57 program.
1H and 13С NMR spectra were recorded on an Avance 600
spectrometer (Bruker) in acetonitrileꢀd3 at frequencies of 600.22
and 150.93 MHz, respectively. Chemical shifts were determined
relative to residual signals of the solvent (CD3CN) and recalꢀ
culated to the internal standard (Me4Si). The gsꢀHMQC,
gsꢀHMBS, and gsꢀCOSY 2D procedures with pulse field gradiꢀ
ents were used for signal assignment in NMR spectra. The phaseꢀ
sensitive gsꢀNOESY or gsꢀROESY 2D procedures were used for
structural assignments.
Mass spectra (ESI) were detected in the mode of full mass
scanning of positive ions on a Finnigan LCQ Advantage tandem
dynamic mass spectrometer (USA) equipped with a mass anaꢀ
lyzer with an octapole ionic trap, an MS Surveyor pump, a Surꢀ
veyor autosampler, a SchmidlinꢀLab nitrogen generator (Gerꢀ
many), and a system of data collection and processing using the
X Calibur program, version 1.3 (Finnigan). The temperature of
the transfer capillary was 150 °C, and the field strength between
the needle and the counter electrode was 4.5 kV. Samples with
10–4 mol L–1 concentration in a MeCN solution were introꢀ
duced into the ion source with direct inlet with a low rate of
50 μL min–1 through a Reodyne injector with a loop of 20 μL.
1H and 13C NMR spectra of ligands 1 and 2 and their comꢀ
plexes with potassium perchlorate and phthalic acid (H2A). Ligand 1.
Ligand 1 (2.2 mg, 0.006 mmol) was dissolved in CD3CN
(0.6 mL) under red light. 1H NMR, δ: 3.60—3.62 (m, 4 Н, H(18),
H(19)); 3.63—3.65 (m, 4 Н, H(17), H(20)); 3.78—3.82 (m, 4 Н,
H(16), H(21)); 4.07—4.09 (m, 2 H, H(15)), 4.11—4.14 (m, 2 H,
H(22)); 6.91 (d, 1 Н, Н(13), J = 8.3 Hz); 7.03 (d, 1 Н, Н(7),
J = 16.3 Hz); 7.11 (dd, 1 H, Н(14), J = 8.4 Hz, J = 2.0 Hz); 7.20
(d, 1 Н, Н(10), J = 2.1 Hz); 7.35 (d, 1 Н, Н(8), J = 16.3 Hz);
7.41 (d, 2 Н, Н(3), Н(5), J = 6.4 Hz); 8.49 (d, 2 Н, Н(2), Н(6),
J = 6.2 Hz). 13C NMR, δ: 68.54 (С(15)), 68.68 (С(22)), 68.95
(С(16)), 69.05 (С(21)), 69.87, 69.92 (С(18), С(19)), 70.56, 70.57
(С(17), С(20)), 111.44 (С(10)), 113.42 (С(13)), 120.54 (С(3),
С(5)), 121.21 (С(14)), 123.94 (С(8)), 129.70 (С(9)), 132.80
Ligand 1 in the presence of 5 equiv. KClO4. Ligand 1 (2.2 mg,
0.006 mmol) and KClO4 (4.2 mg, 0.03 mmol) were dissolved in
CD3CN (0.6 mL) under red light. 1H NMR, δ: 3.71—3.72 (m, 4 Н,
H(18), H(19)); 3.79—3.77 (m, 4 Н, H(17), H(20)); 3.84—3.88
(m, 4 Н, H(16), H(21)); 4.21—4.22 (m, 2 H, H(15)); 4.24—4.25
(m, 2 H, H(22)); 7.03 (d, 1 Н, Н(13), J = 8.3 Hz); 7.12 (d, 1 Н,
Н(7), J = 16.4 Hz); 7.24 (d, 1 H, Н(14), J = 8.3 Hz); 7.29
(s, 1 Н, Н(10)); 7.44 (d, 1 Н, Н(8), J = 16.4 Hz); 7.49 (d, 2 Н,
Н(3), Н(5), J = 6.1 Hz); 8.57 (d, 2 Н, Н(2), Н(6), J = 6.1 Hz).
Ligand 1 in the presence of 0.5 equiv. H2A. Ligand 1 (4.4 mg,
0.012 mmol) and phthalic acid (1 mg, 0.006 mmol) were disꢀ
solved in CD3CN (0.6 mL) under red light. 1H NMR, δ: 3.69—3.70
(m, 4 Н, 2 H(18), H(19)); 3.71—3.73 (m, 4 Н, 2 H(17), H(22));
3.84—3.86 (m, 4 Н, H(16), H(21)); 4.10—4.12 (m, 2 H, H(22));
4.13—4.14 (m, 2 H, H(15)); 6.91 (d, 1 Н, Н(13), J = 8.8 Hz);
7.16 (s, 1 Н, Н(10)); 7.06 (d, 1 Н, Н(7), J = 16.3 Hz); 7.16 (d, 1 H,
Н(14), J = 5.7 Hz); 7.60—7.59 (m, 2 Н, Н(4´), Н(5´)); 7.47
(d, 1 Н, Н(8), J = 16.3 Hz); 7.61 (d, 2 Н, Н(3), Н(5), J = 6.2 Hz);
8.23—8.22 (m, 2 Н, Н(3´), Н(6´)); 8.57 (d, 2 Н, Н(2), Н(6),
J = 6.2 Hz). 13C NMR, δ: 68.31, 68.40 (С(15), С(22)), 68.89,
69.02 (С(16), С(21)), 69.64, 69.78 (С(18), С(19)), 70.26, 70.41
(С(17), С(20)), 111.34 (С(10)), 113.05 (С(13)), 121.50 (С(3),
С(5)), 122.06 (С(14)), 122.47 (С(8)), 128.99 (С(9)), 130.85
(С(4´), С(5´)), 132.01 (С(3´), С(6´)), 134.15 (C(1´), C(2´)),
136.63 (С(7)), 145.60 (С(2), С(6)), 148.89 (С(12)), 149.78
(С(4)), 150.32 (С(11)), 167.57 (COOH).
Ligand 1 in the presence of 1 equiv. H2A. Ligand 1 (4.4 mg,
0.012 mmol) and phthalic acid (2 mg, 0.012 mmol) was disꢀ
solved in CD3CN (0.6 mL) under red light. 1H NMR, δ:
3.66—3.72 (m, 8 Н, H(17), H(18), H(19), H(20)); 3.82—3.84
(m, 4 Н, H(16), H(21)); 4.03—4.05 (m, 2 H, H(22)); 4.09—4.12
(m, 2 H, H(15)); 6.86 (d, 1 Н, Н(13), J = 8.8 Hz); 7.08 (d, 1 Н,
Н(10), J = 1.6 Hz); 7.01 (d, 1 Н, Н(7), J = 16.2 Hz); 7.13 (dd, 1 H,
Н(14), J = 8.3 Hz, J = 1.9 Hz); 7.54—7.59 (m, 2 Н, Н(4´),
Н(5´)); 7.47 (d, 1 Н, Н(8), J = 16.5 Hz); 7.65 (d, 2 Н, Н(3),
Н(5), J = 6.4 Hz); 8.06—8.09 (m, 2 Н, Н(3´), Н(6´)); 8.55 (d, 2 Н,
Н(2), Н(6), J = 6.4 Hz). 13C NMR, δ: 68.27, 68.34 (С(15),
С(22)), 68.86, 68.99 (С(16), С(21)), 69.58, 69.74 (С(18), С(19)),
70.20, 70.37 (С(17), С(20)), 111.32 (С(10)), 113.00 (С(13)),
121.70 (С(3), С(5)), 122.18 (С(14)), 122.26 (С(8)), 128.85
(С(9)), 130.92 (С(4´), С(5´)), 131.45 (С(3´), С(6´)), 133.77
(C(1´), C(2´)), 137.44 (С(7)), 144.70 (С(2), С(6)), 148.85
(С(12)), 150.43 (С(4)), 150.79 (С(11)), 169.26 (COOH).
Ligand 1 in the presence of 0.5 equiv. H2A and 0.5 equiv.
KClO4. Ligand 1 (4.4 mg, 0.012 mmol), phthalic acid (1 mg,

282
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Fedorov et al.
0.006 mmol), and KClO4 (0.8 mg, 0.006 mmol) were dissolved
in CD3CN (0.6 mL) under red light. 1H NMR, δ: 3.68—3.69
(m, 4 Н, H(18), H(19)); 3.76—3.80 (m, 8 Н, H(16), H(17), H(20),
H(21)); 3.92—3.93 (m, 2 H, H(22)); 4.09—4.10 (m, 2 H, H(15));
6.88 (d, 1 Н, Н(13), J = 7.9 Hz); 6.95 (s, 1 Н, Н(10)); 6.99 (d, 1 Н,
Н(7), J = 16.7 Hz); 7.17 (dd, 1 H, Н(14), J = 8.4 Hz, J = 1.3 Hz);
7.41 (d, 1 Н, Н(8), J = 16.3 Hz); 7.49 (d, 2 Н, Н(3), Н(5),
J = 6.2 Hz); 7.61—7.62 (m, 2 Н, Н(4´), Н(5´)); 8.09—8.11
(m, 2 Н, Н(3´), Н(6´)); 8.44 (d, 2 Н, Н(2), Н(6), J = 5.7 Hz).
13C NMR, δ: 67.24—67.38 (С(15), С(22), С(16), С(21)), 67.88,
67.97 (С(18), С(19)), 68.72, 68.82 (С(17), С(20)), 111.13
(С(10)), 112.84 (С(13)), 121.27 (С(3), С(5)), 122.24 (С(14)),
123.17 (С(8)), 129.53 (С(9)), 130.98 (С(4´), С(5´)), 131.06
(С(3´), С(6´)), 133.65 (C(1´), C(2´)), 135.50 (С(7)), 146.80
(С(2), С(6)), 147.89 (С(12)), 148.43 (С(4)), 149.06 (С(11)),
169.52 (COOH).
Ligand 2. Ligand 2 (0.3 mg, 0.001 mmol) was dissolved in
CD3CN (0.6 mL) under red light. 1H NMR, δ: 3.84, 3.88 (both s,
3 H each, H(15), H(22)); 6.96 (d, 1 Н, Н(13), J = 8.5 Hz); 7.06,
7.38 (both d, 1 Н each, Н(7), Н(8), J = 16.5 Hz); 7.14 (dd, 1 H,
Н(14), J = 9.4 Hz, J = 1.8 Hz); 7.24 (s, 1 Н, Н(10)); 7.41
(d, 2 Н, Н(3), Н(5), J = 5.5 Hz); 8.52 (d, 2 Н, Н(2), Н(6),
J = 5.5 Hz).
solutions remained almost unchanged upon the further addition
of potassium salt or acid. This indicated the complexation, or the
changes were explained by dilution only, which was accompaꢀ
nied by a uniform decrease in the absorbance over the whole
absorption spectrum. The results of spectrophotometric titration
were processed and the stability constants of the complexes were
calculated using the SPECFIT/32 program.
Calculation of the fluorescence quantum yields. The fluoresꢀ
cence emission spectra of ligand 1 and the complexes with K+
cation and phthalic acid were measured upon photoexcitation
with λ = 330 nm. An aqueous solution of quinine sulfate in 1 N
H2SO4 (ϕ = 0.55 0.03)14 was used as a standard for ligand 1.
fl
All measurements were carried out at low absorbances of the
solution at the excitation wavelength of the ligands.
To determine the fluorescence quantum yield ϕ of the ligand
fl
and its complexes with potassium cations, we recorded noncorꢀ
rected fluorescence spectra of the studied solution and solution
of the standard substance. The fluorescence quantum yields were
calculated by the formula15
:
,
where ϕ and ϕ are the fluorescence quantum yields of the anaꢀ
Ligand 2 in the presence of 0.5 equiv. H2A. Ligand 2 (0.3 mg,
0.001 mmol) and phthalic acid (0.10 mg, 0.0005 mmol) were
dissolved in CD3CN (0.6 mL) under red light. 1H NMR, δ: 3.86,
3.89 (both s, 3 H each, H(15), H(22)); 6.99 (d, 1 Н, Н(13),
J = 8.2 Hz); 7.15, 7.55 (both d, 1 Н each, Н(7), Н(8), J = 16.2 Hz);
7.20 (dd, 1 H, Н(14), J = 8.2 Hz, J = 1.4 Hz); 7.28 (s, 1 Н,
Н(10)); 7.59—7.61 (m, 2 Н, Н(4´), Н(5´)); 7.69 (d, 2 Н, Н(3),
Н(5), J = 5.9 Hz); 8.22—8.23 (m, 2 Н, Н(3´), Н(6´)); 8.60
(d, 2 Н, Н(2), Н(6), J = 5.9 Hz).
i
0
lyzed solution and standard, respectively; Di and D0 are the abꢀ
sorbances of the analyzed solution and standard, respectively;
Si and S0 are the surface areas under the curves of the fluoresꢀ
cence spectrum of the analyzed solution and standard, respecꢀ
tively; ni and n0 are refractive indices of acetonitrile and 1 N
H2SO4 (see Ref. 16), respectively.
Xꢀray diffraction analysis. Single crystals of complex 2•H2A
for Xꢀray diffraction analysis were obtained as follows: phthalic
acid (2.16 mg, 0.013 mmol) and ligand 2 (10 mg, 0.026 mmol)
were dissolved in 6 mL of МеCN under red light. The obtained
crystals were left in the dark at 12—14 °C until transparent crysꢀ
tals precipitated. The crystals were filtered off.
Ligand 2 in the presence of 0.5 equiv. H2A and 0.5 equiv.
KClO4. Ligand 2 (0.3 mg, 0.001 mmol), phthalic acid (0.09 mg,
0.0005 mmol), and KClO4 (0.08 mg, 0.0005 mmol) were disꢀ
1
solved in CD3CN (0.6 mL) under red light. H NMR, δ: 3.86,
A single crystal covered with perfluorinated oil was placed
on a Bruker SMARTꢀCCD diffractometer under a cooled nitroꢀ
gen flow. A set of experimental reflections was obtained in the
ω scan mode of reflections from single crystals on MoꢀKα radiaꢀ
tion (λ = 0.71073 Å). The primary processing of experimental
reflections was performed using the Bruker SAINT program
package.17 The structure was determined by direct methods and
refined by least squares in the fullꢀmatrix anisotropic approxiꢀ
mation on F2. Hydrogen atoms were revealed from the differꢀ
ence Fourier synthesis. Their refinement was performed in the
isotropic approximation. All calculations were carried out using
the SHELXTLꢀPlus program package.18 The main crystalloꢀ
graphic parameters and characteristics of Xꢀray diffraction exꢀ
periment are presented in Table 1.
3.89 (both s, 3 H each, H(15), H(22)); 6.99 (d, 1 Н, Н(13),
J = 8.2 Hz); 7.16, 7.58 (both d, 1 Н each, Н(7), Н(8), J = 16.2 Hz);
7.20 (d, 1 H, Н(14), J = 8.2 Hz); 7.28 (s, 1 Н, Н(10)); 7.59—7.62
(m, 2 Н, Н(4´), Н(5´)); 7.71 (d, 2 Н, Н(3), Н(5), J = 5.9 Hz);
8.21—8.23 (m, 2 Н, Н(3´), Н(6´)); 8.59 (d, 2 Н, Н(2), Н(6),
J = 5.0 Hz).
Calculation of the optimal geometry of complexes of ligand 1
with potassium cations and phthalic acid performed by the moꢀ
lecular mechanics method using the MM+ force field (Hyperꢀ
Chem program package, version 7.5).
Calculation of the stability constants of the complexes of ligand
1 with potassium perchlorate and phthalic acid. The method
of spectrophotometric titration at 20 1 °C was used for measurꢀ
ing stability constants of the complexes. For spectrophotometꢀ
ric titration, we prepared solutions in MeCN of ligand 1 (C1
=
= 4.3•10–5 mol L–1), potassium perchlorate (CK+ = 1•10–3
and 1•10–2 mol L–1), and phthalic acid (CH2A = 1•10–3 and
5•10–3 mol L–1). A solution of ligand 1 was titrated with a soluꢀ
tion of potassium perchlorate or phthalic acid as follows: the
known volume of a solution of ligand 1 in MeCN was poured to
a quartz cell and the absorption spectrum was recorded. Then
a solution of potassium perchlorate or phthalic acid with
a known total concentration was added in portions to the cell.
After each addition, absorption spectra of solutions were recordꢀ
ed. Titration was stopped, when the absorption spectra of the
Results and Discussion
Electronic absorption spectra. The electronic absorpꢀ
tion spectrum of ligand 1 in MeCN is characterized by an
intense longꢀwavelength absorption band (LWAB) with
a maximum at λ = 330 nm. As we have shown earlier,12
ligand 1 is capable of complex forming with alkalineꢀearth
metal cations at the crown ether moiety, which results in
the hypsochromic shift in the absorption spectrum by

Supramolecular assemblies of some crowns
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
283
Table 1. Selected crystallographic characteristics for comꢀ
plex 2•H2A
A (arb. units)
1.2
Parameter
Value
0.9
Molecular formula
Crystal system
Space group
a/Å
b/Å
c/Å
C23H21NO6
Tricl–inic
P1
0.6
0.3
9.2780(3)
10.7899(4)
11.3279(4)
65.9840(10)
82.5030(10)
67.8690(10)
959.19(6)
2
α/deg
β/deg
γ/deg
V/Å–3
280
310
340
370 λ/nm
Z
Fig. 1. Electronic absorption spectra of a solution of ligand 1
(C1 = 4•10–5 mol L–1) at various concentrations of cations K+
in the solution (CK = 0—2.7•10–3 mol L–1). Solvent acetoꢀ
dcalc/g cm–3
F(000)
1.411
428
0.103
+
μ/mm–1
nitrile, temperature 20 1 °C.
Crystal size/mm
Temperature/K
Scan range, θ/deg
Range of h, k, l
0.36×0.24×0.22
120.0(2)
1.97—28.99
–12 ≤ h ≤ 12
–13 ≤ k ≤ 14
–12 ≤ l ≤ 15
5875
shift of the LWAB in the electronic absorption spectra.19—23
Phthalic acid in MeCN is a very weak acid for which the
acidity constants of the first and second dissociation steps24
are 14.3 and 29.8, respectively; therefore, a substantial
excess of phthalic acid is necessary for the complete protoꢀ
nation of compound 1.
Complexation. Complexation of 1 with potassium perꢀ
chlorate and phthalic acid was studied using ESI mass
spectrometry, spectrophotometric titration, and H and
13С NMR spectroscopy.
It is known that large cations and derivatives of benzoꢀ
15ꢀcrownꢀ5 are characterized by the formation of 2 : 1
sandwich complexes.25 The formation of stable 2 : 1 compꢀ
lexes with barium cations was observed for 15ꢀcrownꢀ5ꢀ
containing 4ꢀstyrylpyridine 1 in acetonitrile.12 Complexes
with potassium cations of compositions 1 : 1 and 2 : 1 were
observed for benzoꢀ15ꢀcrownꢀ5 in MeCN.12a Crownꢀconꢀ
taining benzobistiazole with two fragments of benzoꢀ15ꢀ
Number of measured reflections
Number of independent reflections (Rint
Number of reflections with I > 2σ(I)
Number of refined parameters
R factors on reflections with I > 2σ(I)
R1
)
4724 (0.0123)
4015
356
0.0402
0.1159
1
wR2
R factor (on all reflections)
R1
0.0476
0.1217
1.070
wR2
Goodnessꢀofꢀfit on F2
Residual electron density,
–0.246/0.356
e•Å–3, ρmin/ρ
max
14—16 nm. The addition of potassium perchlorate to a soꢀ
lution of compound 1 (2•10–4 mol L—1) in MeCN inducꢀ
es a hypsochromic shift of the LWAB by 9 nm (Fig. 1),
indicating the occurrence of a complexation process inꢀ
volving the crown ether moiety. The electrostatic interacꢀ
tion of the positively charged metal ion with heteroatoms
of crown ether decreases the electronꢀdonating ability of
the crown ether moiety, due to which the hypsochromic
shift of the electronic absorption spectrum was observed.
The addition of phthalic acid to a solution of 1 in
MeCN generates a new absorption band with a maximum
at λ = 394 nm (Fig. 2).
A (arb. units)
1.2
0.9
0.6
0.3
The spectral changes presented above are similar to
those observed previously for the interaction of 1 with
perchloric acid,12 resulting in the protonation of the nitroꢀ
gen atom of the pyridine residue. As known, derivatives in
nitrogenꢀcontaining styryl heterocycles in the presence of
appropriate Brönsted acids can be protonated at the nitroꢀ
gen atom, which is accompanied by the bathochromic
320
370
420
470 λ/nm
Fig. 2. Electronic absorption spectra of a solution of ligand 1
(C1 = 4.3•10–5 mol L–1) at various concentrations of phthalic
acid in the solution (CH A = 0—1.8•10–3 mol L–1). Solvent acetoꢀ
nitrile, temperature 202 1 °C.

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Fedorov et al.
Table 2. Mass spectra (ESI) of complexes 1 with various
anions in MeCN
the method of spectrophotometric titration. The spectroꢀ
photometric titration data were processed by the
SPECFIT/32 program assuming that complexes 1•K+ and
(1)2•K+ were formed upon complexation. The values deꢀ
termined for the stability constants are listed in Table 3.
Calculations using the obtained values of complexation
showed that in a solution of ligand 1 with the total conꢀ
centration C1 = 5•10–5 mol L–1 the maximum concenꢀ
tration of complex (1)2•K+ is observed at the total conꢀ
centration of KClO4 equal to 2•10–4 mol L–1. In this
case, 45% of complex 1 exist as complex (1)2•K+. For
the 1Н NMR study of the complexation of ligand 1
with KClO4, the initial concentration of the ligand was
0.01 mol L–1. The content of compound 1 in the form of
complex (1)2•K+ reached 94% of its total amount.
The reaction of phthalic acid with ligand 1 was also
studied by spectrophotometric titration (see Fig. 2). The
appearance of the LWAB with a maximum at λ = 394 nm
upon the addition of phthalic acid to a solution of 1 can be
due to the transfer of a proton from phthalic acid to the
nitrogen atom of the pyridine moiety of molecule 1. It has
been shown earlier12 that compound 1 is readily protoꢀ
nated in the presence of perchloric acid, resulting in the
appearance of the LWAB with a maximum at λ = 398 nm
in the absorption spectrum. The LWAB maxima of comꢀ
pound 1 in the presence of perchloric and phthalic acid
differ by 4 nm, indicating that the products formed are
different.
Ligand
Anion
m/z
1
1
1
К+
Na+
H+
410.1 [1•K]+, 780.9 [(1)2•K]+
394.3 [1•Na]+
372.3 [1•H]+, 742.9 [(1)2•H]+
crownꢀ5 in one molecule with potassium cations in MeCN
forms a 2 : 2 sandwich complex.26 In the latter case, the
formation of the sandwich complex is favored by stacking
interaction of two neutral molecules of the ligand. It should
be mentioned that the formation of only 1 : 1 complex of
the butadienyl cationic dye containing the fragment of
benzoꢀ15ꢀcrownꢀ5 and potassium perchlorate in MeCN
was observed.27 This is related, most likely, to the fact that
the ligand molecule is positively charged, in this case, and
hence, is not prone to stacking interaction.
To establish what types of complexes are formed beꢀ
tween compound 1 and potassium cations, we studied the
products of their reaction in MeCN using electrospray
ionization mass spectrometry. It was found that even at
a tenfold excess of potassium perchlorate both 1•K+ and
(1)2•K+ complexes are present in a MeCN solution of liꢀ
gand 1, and the peak intensity of complex (1)2•K+ in the mass
spectra is higher than that of complex 1•K+. The data
obtained indicate that ligand 1 is capable of forming with poꢀ
tassium cations rather stable sandwich complexes (1)2•K+.
It should be mentioned that only 1 : 1 complexes were
found in a solution of ligand 1 in the presence of sodium
perchlorate under similar conditions of analysis (Table 2).
Both the protonated form of compound 1 and the reꢀ
action product of 1 with its protonated form (1)2•H+ were
found by ESI mass spectrometry in a solution of ligand 1
in MeCN acidified with perchloric acid (see Table 2).
To determine the values of stability constants of comꢀ
plexes of 1 with potassium perchlorate in MeCN, we used
The reaction of phthalic acid (Н2А) with 1 can be
described by the equation
Н2А + 1
НА– •1•Н+
НА– + 1•Н+.
(1)
The difference in the reaction products of 1 with perꢀ
chloric and phthalic acids may indicate that the second
equilibrium in Eq. (1) is shifted toward the formation of
nondissociated compound НА–•1•Н+. The formation of
similar ion pairs in MeCN has been observed earlier for
the system pyridinium cation—benzoate anion.28
Table 3. Spectral characteristics and stability constants of the complexes of ligand 1 with the potassium cation (K+) and phthalic
acid (H2А)
fl
fl
Compound
λ
abs (Δλabs)/nm
ε•10–4/L mol–1 cm–1
logK
λ (Δλ )/nm
ϕ •10–2
fl
1
332
2.96
3.23
3.05
6.07
2.81
—
427
—
418 (–9)
1.2
—
0.9
1•H+
398 (66)
326 (–6)
331 (–1)
394 (62)
394 (62)
329 (–3);
388 (56)
388 (56)
log K11 = 10.6 0.7
log K11 = 3.7 0.2
log K21 = 8.5 0.3
log K11 = 7.7 0.1
log K11 = 4.0 0.1
log K111 = 7.9 0.1
1•K+
(1)2•K+
1•H+•HA–
1•H2A
1•K+•H2A
545 (118)
545 (118)
418 (–9),
530 (103)
530 (103)
3.4
3.4
1.2
2.81
2.41; 3.19
(1)2•K+•H2A
6.38
log K121 = 14.0 0.17
4.3
abs
fl
abs
fl
Note. Spectral data are given for solutions in MeCN at 293 K. The values of Δλ and Δλ are presented relative to λ and λ
of ligand 1, respectively.

Supramolecular assemblies of some crowns
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
285
A (arb. units)
The data of spectrophotometric titration of compound
1 with phthalic acid were processed by the SPECFIT/32
program; the fixed values of acidity constants for the first
and second dissociation steps of phthalic acid24 for the
following equations were used in the calculations:
3
2
1
1.2
4
0.9
1 + Н+
1•Н+,
(2)
0.6
0.3
5
1 + 2 Н+ + А2–
1•Н2А.
(3)
As a result, we found the values of stability constants
for the protonated form of compound 1 (Eq. (2)) and
complex 1•Н2А formed according to Eq. (3) and of this
complex, whose formation follows the reaction equations
350
400
450
λ/nm
Fig. 3. Theoretical absorption spectra of a solution of ligand 1 (1)
and its complexes with the potassium cation and phthalic acid:
(1)2•K+(2), 1•H2A (3), 1•K+•H2A (4), and (1)2•K+•H2А (5)
calculated by the data of spectrophotometric titration.
1 + Н2А
1•Н2А and НА– + 1•Н+
1•Н2А
(see Table 3). The calculation of the solution composition
during titration using the determined values of stability
constants for the complexes showed that nondissociated
complex 1•Н2А was predominantly formed, while the
concentration of free protonated form 1•Н+ was low.
An analysis of the data of spectrophotometric titration
of a solution of the complexes of ligand 1 with potassium
perchlorate and phthalic acid was carried out taking into
account absorption spectra of (1)2•K+ and 1•K+. It
turned out that at least two mixed complexes with differꢀ
ent stoichiometry are formed during titration. At low conꢀ
centrations of phthalic acid, complex (1)2•K+•Н2A preꢀ
dominates in which two ligand molecules are bonded, on
the one hand, to the potassium cation and, on the other
hand, to one acid molecule. The absorption spectrum of
this complex contains two longꢀwavelength bands with
absorption maxima corresponding to the absorption of the
protonated and nonprotonated forms of ligand 1. It is most
likely that in this complex one molecule of ligand 1 is
protonated by one carboxyl group of phthalic acid, and
the second molecule of 1 forms a hydrogen bond with the
second carboxyl group of phthalic acid. This assumption is
confirmed by the fact that the addition of phthalic acid to
complex (1)2•K+ is more efficient (logK121 – logK21 = 5.5)
lated by the ММ+ molecular mechanics method are preꢀ
sented in Fig. 4.
Using the complexation constants obtained, we calcuꢀ
lated the amount of К+ cations bonded by ligand 1 in the
presence and in the absence of phthalic acid. Figure 5
shows that the concentration of free cations К+ decreases
with an increase in the phthalic acid concentration in the
system containing the constant total amount of ligand 1
(curve 1). Coordination of a phthalic acid molecule by
dimeric complex (1)2•K+ additionally stabilizes the latter.
Spectral luminescence properties. To study the influꢀ
ence of the structural organization of molecules on their
fluorescence characteristics, we measured the fluorescence
emission spectra and calculated the fluorescence quantum
yields of ligand 1 and its complexes with potassium catꢀ
ions and phthalic acid.
It is known that fluorescence and photoisomerization
are two competing processes, where hindrance of rotation
about the central double bond should increase the fluoresꢀ
cence quantum yield.29—32 As shown previously,33 rather
efficient process of EꢀZꢀphotoisomerization (ϕE→Z = 0.45)
occurs in a solution of ligand 1 in MeCN. Therefore,
it is not surprising that the value of fluorescence quantum
yield for this compound is rather low ϕfl = 1.2•10–2
(see Table 3).
An addition of potassium perchlorate to a solution of
ligand 1 causes the hypsochromic shift of the emission
spectrum by 9 nm (Fig. 6). It was shown that complexation
at the crown ether moiety with cation K+ insignificantly
decreases the fluorescence quantum yield of ligand 1, and
this can be due to an enhancement of routes of vibraꢀ
tional relaxation of the excited state in "sandwich" comꢀ
plex (1)2•K+.
The formation of complex 1•H2A with phthalic acid
induces a substantial red shift of λmaxfl of ligand 1 by 118 nm
(see Fig. 6). The fluorescence quantum yield increases
approximately threefold, being ϕfl = 3.4•10–2. As shown
than the addition of phthalic acid to molecule 1 (logK11
=
= 4.0). An increase in the concentration of phthalic acid
in the solution affords one more mixed complex. This
complex can be either 1•K+•Н2A or (1)2•K+•(Н2A)2;
however, we could not make an unambiguous choice beꢀ
cause of the complicated character of the system considꢀ
ered. Therefore, the stability constant for a simpler comꢀ
plex 1•K+•Н2A is given in Table 3 (Scheme 1).
Based on the data of spectrophotometric titration and
obtained values of stability constants for the complexes,
we calculated the absorption spectra of the complex of
ligand 1 with potassium cations and phthalic acid using
the SPECFIT/32 program (Fig. 3).
The optimized spatial structures of the complexes of
ligand 1 with potassium cations and phthalic acid calcuꢀ

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Fedorov et al.
Scheme 1
earlier,33 the protonation of ligand 1 favors decreasing the
photoisomerization quantum yield and, as a consequence,
increasing the probability of radiative deactivation of the
excited state via fluorescence.
For the formation of complex 1•H2A•K+, fluoresꢀ
cence rises more than 3.5 times (see Fig. 6 and Table 3).
In this case, ligand 1 in the complex is protonated, which,
as shown above, increases the probability of deactivation
of the excited state via fluorescence. It is most likely that
coordination of cation K+ to the crown ether moiety favors
an increase in the fluorescence efficiency due to a decrease
in crown ether mobility and, as a consequence, favors
a decrease in the efficiency of thermal relaxation of the
excited state.
Based on the presented results, we may assume that
the interaction of dicarboxylic acids with heterocyclic bases
can proceed via two routes (Scheme 2).
In the first case (route А), the proton is completely
detached from the carboxyl group and adds to the heteroꢀ
cyclic residue. The protonation of pyridine heterocycle is
As can be seen from Fig. 6, the emission spectrum of
complex (1)2•H2A•K+ has two broad bands with λmaxfl at
418 and 530 nm; this may indicate that in the complex
only one molecule of ligand 1 is protonated and the secꢀ
ond molecule is bonded with phthalic acid only by a hyꢀ
drogen bond (see Scheme 1). When protonating the both
molecules of ligand 1, one should expect the appearance
of only one emission band with a maximum about 530 nm.
The formation of this complex does not result in fluoresꢀ
cence rising, and the value of fluorescence quantum yield
of this complex approximately corresponds to the fluoresꢀ
cence quantum yield of free ligand 1.

Supramolecular assemblies of some crowns
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
287
a
b
N
N
K+
N
K+
H
C
O
N
Fig. 4. Optimized structures of the complex of ligand 1 with the potassium cation (1)2•K+•H2А (a) and phthalic acid (1)2•K+•(H2А)2 (b)
according to the data of MM+ quantum chemical calculations.
Scheme 2
combination of dissociation constants the ligands will be
protonated only due to dissociation by the first step, while
only hydrogen bonding will be possible with the second
proton. Evidently, both these interactions occur in the
mixed complexes of ligand 1 with potassium perchlorate
and phthalic acid.
Xꢀray diffraction analysis. The Xꢀray diffraction data
are an additional proof for coordination of 4ꢀstyrylpyriꢀ
dine to phthalic acid. We succeeded to obtain crystals of
complex 2•H2А and to study its structure by Xꢀray difꢀ
Ci•10–5/mol L–1
2.0
accompanied by a strong bathochromic shift of the longꢀ
wavelength absorption band. This situation is characterisꢀ
tic of complexes 1•H2A and 1•H2A•K+ in which all
ligands are protonated. In the second case (route B), assoꢀ
ciation occurs due to hydrogen bonding between the
heterocycle and hydrogen atom of the carboxyl group.
This coordination does not necessarily lead to substantial
changes in the absorption spectra. The second case parꢀ
tially occurs in complex (1)2•H2A•K+, where only one
ligand molecule is protonated and the second molecule is
linked with the carboxyl group of phthalic acid by hydroꢀ
gen bond.
4
1.5
1.0
0.5
0
1
2
3
5
CH A•10–4/mol L–1
2
A possibility of protonation of the pyridine heterocycle
of hydrogen bonding during the reaction of ligand 1 with
acids should be determined by the strength of the acids
and, hence, by easiness of their acidic dissociation. Since
the dissociation of dibasic acids proceeds stepwise and the
dissociation constant of the first step is higher than that of
the second step,16 it is reasonable to assume that at a certain
0
0.4
0.8
Fig. 5. Concentrations of the components (Сi) in a solution of
ligand 1 and potassium perchlorate at their constant total conꢀ
centration, depending on the phthalic acid concentration:
K+ (1), (1)2•K+ (2), 1•K+ (3), (1)2•K+•H2А (4), and
1•K+•H2А (5). (Initial concentrations: С1 = 5•10–5 mol L–1
CK+ = 3.0•10–5 mol L–1, solvent MeCN).
,

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Fedorov et al.
Ifl (arb. units)
320
bonds in the chain N(1)—C(1)—C(2)—C(3) (bond lengths
are 1.342(1), 1.377(2), and 1.403(1) Å, respectively) is
almost the same as in chain N(1)—C(5)—C(4)—C(3)
(bond lengths are 1.348(1), 1.372(2), 1.408(1) Å, respecꢀ
tively). The bonds alternate along one half of the benzene
ring: С(8)—С(9)—С(10)—С(11) (1.409(1), 1.381(1), and
1.412(1) Å). They are almost completely delocalized over
another half: С(8)—С(13)—С(12)—С(11) (1.395(2),
1.391(2), 1.387(2) Å). As usually, deformation of the exꢀ
ternal bond angles at the С(10) and С(11) atoms is obꢀ
served and contradicts the existence of steric repulsion
between the orthoꢀsubstituents (oxygen atoms О(1) and
О(2)). Indeed, the angles О(1)—С(11)—С(10) and О(2)—
С(10)—С(11), which should be increased due to the indiꢀ
cated steric repulsion, are considerably decreased in fact,
being 115.48(9) and 115.62(9)°, respectively, while the
angles О(1)—С(11)—С(12) and О(2)—С(10)—С(9), on
the contrary, are considerably increased, being 125.2(1)
and 124.8(1)°, respectively. This deformation of the styryl
fragment geometry is due to conjugation and involvement
of lone electron pairs of the oxygen atoms on the рꢀorbitꢀ
als in this conjugation. The total electronic effect of two
methoxy groups, one of which is in the paraꢀposition and
another is in the metaꢀposition to the ethylene substituent
of the benzene ring, induces the above discussed nonsymꢀ
metric distribution of bonds in this ring and the deformaꢀ
tion of the bond angles.
In crystal, complex 2•H2A forms layers consisting of
infinite ribbons linked by hydrogen bonds of cations and
anions (see Fig. 7). The cation (type А) and the anion
(type С) are linked by a pair of hydrogen bonds N(1A)—
H(1A)...O(5C) and О(6С)...H(5AA)—C(5A) with the geꢀ
ometry N—H and N—H...O (1.70(2) Å and 174.9(8)°). In
addition, the neighboring anion (type Е) with the same
cation (type A) forms weak hydrogen bonds
О(3Е)...Н(4АА)—С(4Е) and О(3Е)...Н(7АА)—С(7Е)
with the parameters О...H and С—H...O 2.48(3) Å and
155.6(9)° for the first one and 2.35(3) Å and 160.9(9)° for
the second of them. Two adjacent cations (type A and type
C) also form a centrosymmetric pair due to weak interacꢀ
tions of the type О(2А)...Н(15I)—C(15I) with the geoꢀ
metric parameters 2.42(3) Å and 142(1)°. All these interꢀ
actions are repeated in symmetrically bound structural
crystal units. The adjacent layers in crystals are mainly
joined, most likely, by van der Waals interactions, since
any significant projection of conjugated fragments of the
structural units onto each other is absent.
4
3
240
160
80
1
5
2
415
465
515
565
λ/nm
Fig. 6. Fluorescence emission spectra of ligand 1 (1) and its
complexes with the potassium cation and phthalic acid: (1)2•K+ (2),
1•H2A (3), 1•K+•H2А (4), and (1)2•K+•H2А (5). (C1
=
= 9.5•10–5 mol L–1, λ = 330 nm, solvent acetonitrile, temꢀ
exc
perature 20 1 °C).
fraction analysis. In the presence of the acid, the complex
consisting of one molecule 2 and one molecule of phthalic
acid is formed, and one of the protons of phthalic acid is
covalently bonded to the nitrogen atom of the pyridine
fragment and Hꢀbonded to the carbonylic oxygen atom.
The composition and structure of the independent part of
the crystal lattice are shown in Fig. 7.
The crystal of complex 2•H2A is formed by two strucꢀ
tural units: protonated styrylpyridine and anion of the
monobasic residue of phthalic acid. In the anion the H(2)
proton of the carboxyl group predominantly bonded with
the О(4) atom is involved in an intramolecular hydrogen
bond with the O(6) atom of deprotonated carboxylate.
The parameters of this hydrogen bond are the following:
distance О(6)...Н(2) 1.32(3) Å, angle О(4)—Н(2)...О(6)
177(1)°; the О(3)—С(22) and О(4)—С(22) bond lengths
in the carboxyl group are 1.221(1) and 1.304(1) Å, respecꢀ
tively; and the О(5)—С(23) and О(6)—С(23) bond lengths
in the deprotonated carboxyl group are 1.248(1) and
1.304(1) Å, respectively. This completely agrees with
the localization of the H(2) hydrogen atom at the O(4)
oxygen atom.
The cation has characteristic features typical of both
styryl dyes and preceding bases. It is almost planar. The
dihedral angle between the plane of the pyridine cycle and the
plane of the ethylene fragment С(3)—С(6)=С(7)—С(8) is
4.0°, the angle between the latter plane and the benzene
ring plane is 10.4°, and that between the planes of the
pyridine and benzene rings is 14.0°. This geometry correꢀ
sponds to good conditions for πꢀelectron density delocalꢀ
ization over the whole cation. Nevertheless, as usually,
the ethylene bond is substantially localized and is equal to
1.342(1) Å, whereas the both ordinary С(3)—С(6) and
С(7)—С(8) bonds are 1.461(1) Å. The bond length distriꢀ
bution in the pyridine cycle indicates a substantial contriꢀ
bution of the paraꢀquinoid structure. The sequence of
NMR spectroscopy. The data of NMR spectroscopy
(1H, COSY, NOESY, ROESY) were used to establish speꢀ
cific features of the structures of ligand 1 and its complexꢀ
es with potassium perchlorate and phthalic acid. Based on
the value of spinꢀspin coupling constant for the protons at
the double bond, we concluded that in solution ligand 1
exists as an Eꢀisomer. The full assignments of signals of
protons in the 1H NMR spectra of both the ligand and its

Supramolecular assemblies of some crowns
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
289
a
C(5)
C(18)
C(19)
C(20)
C(17)
C(16)
C(23)
O(6)
H(2)
C(21)
O(3)
C(22) O(4)
C(2)
N(1)
C(5)
C(1)
C(3)
C(4)
C(12)
C(6)
C(8)
C(9)
C(14)
b
C(13)
C(7)
N(1B)
O(1)
C(11)
O(2)
C(10)
O(4F)
O(6F)
C(15)
O(3F)
O(5C)
O(5F)
O(3C)
H(1A)
O(6C)
N(1A)
O(4C)
O(2B)
H(2C)
O(1B)
H(5AA)
a
O(1D)
H(4AA)
O(4E)
O(2D)
O(6E)
O(5E)
H(7AA)
O(3E)
O(3B)
O(5B)
O(1A)
O(6B)
O(2A)
O(4B)
c
0
H(15C)
b
H(15I)
O(4D)
O(6D)
N(1D)
O(5D)
O(1C)
O(2C)
O(3D)
O(3A)
H(7AC)
O(5A)
H(2A)
O(6A)
O(4A)
H(4AC)
N(1C)
Fig. 7. Structure of complex 2•H2A (a) according to the Xꢀray diffraction data. Nonꢀhydrogen atoms are shown by thermal vibration
ellipsoids with 50% probability. Crystal packing of 2•H2A (b) (view of perpendicular crystalline axis b). Hydrogen bonds are shown by
dashed lines.
complexes was made on the basis of 2D spectroscopy
(COSY, NOESY (for 1, (1)2•K+, and 1•Н2A), ROESY
(for 1•H2A•K+)). An analysis of the COSY spectrum of
free ligand 1, reflecting spinꢀspin coupling of the protons,
showed crossꢀpeaks of the protons of the aromatic part of
the ligand H(2), H(6) and H(3), H(5); H(7) and H(8),
H(13) and H(14), as well as the protons H(15) and H(16),
H(22) and H(21) of the crown ether fragment. It was
shown on the basis of correlations in the COSY spectra
and the crossꢀpeaks of H(10) and H(22), H(13) and H(15)
in the NOESY spectra of ligand 1 (Fig. 8), reflecting the
spatial interaction of the protons of the crown ether fragꢀ

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Fedorov et al.
δ
6.9
H(8)/H(10)
H(8)/H(14)
7.0
7.1
7.2
7.3
7.4
H(13)/H(15)
H(7)/H(14)
H(7)/H(10)
H(10)/H(22)
7.5
7.4
7.3
7.2
7.1
7.0
4.1
3.9
3.7
δ
Fig. 8. 1H—1H NOESY NMR spectrum (CD3CN) of ligand 1; C1 = 1•10–2 mol L–1
.
ment of the molecule with the aromatic moiety that the
signal from the proton H(22) of crown ether exists in
a weaker field than the signal from the proton H(15).
However, the interaction of the ligand with potassium
perchlorate and phthalic acid with the formation of compꢀ
lexes (1)2•K+, 1•H2A, and (1)2•K+•H2A results in the
upfield shift of the proton H(22) (Fig. 10). The presence
of crossꢀpeaks of the protons H(8) and H(10), H(8) and
H(14), H(7) and H(10), and H(7) and H(14) in the NOESY
spectrum of ligand 1 suggests that a mixture of two conꢀ
formers of the ligand exists in solution. This can be due to
hindered rotation of fragments of the molecule about the
C—C ordinary bond located between the double bond and
benzoꢀ15ꢀcrownꢀ5. In the case of the complexes, analoꢀ
gous crossꢀpeaks were observed in the NOESY (ROESY)
spectra, suggesting that the both conformers are involved
in complexation (Figs 9 and 10).
tions of proton signals made it possible to assign "sandꢀ
wich" structure (1)2•K+ with the arrangement of chromoꢀ
phoric systems 1 in a stack above each other due to interꢀ
molecular π—πꢀinteractions to the complex formed (see
Scheme 1).
The addition of potassium perchlorate to a solution of
ligand 1 changes the 1Н NMR spectrum (Table 4). At the
ratio 1 : K+ = 2 : 1 the most significant downfield shifts of
protons (ΔδH) were observed for the groups of proton of
crown ether H(17)—H(20). At the same time, signals of
the protons H(10) and H(13), of the ethylene and heteroꢀ
cyclic fragments, and the proton H(22) of crown ether
undergo upfield shifts. The characteristic changes in posiꢀ
Fig. 9. Scheme of key correlations for protons of the conformers
of ligand 1 in the 1H—1H NOESY NMR spectra.

Supramolecular assemblies of some crowns
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
291
δ
H(10)/H(22)
H(8)/H(14)
6.9
7.0
7.1
7.2
7.3
7.4
7.5
H(7)/H(10)
H(13)/H(15)
H(8)/H(10)
H(7)/H(14)
7.5
7.4
7.3
7.2
7.1
7.0
6.9
4.1
3.9
3.7
δ
Fig. 10. 1H—1H NOESY NMR spectrum (CD3CN) of complex (1)2•K+•H2A, C1 = 1•10–2 mol L–1
.
An excess of potassium perchlorate in a solution of
ligand 1 changes the complexation process, which is reꢀ
flected in the 1H NMR spectra. At the ratio 1 : K+ = 1 : 5
the upfield shifts from signals of the protons H(2), H(3),
H(10), H(13), and H(14) of the aromatic moiety and the
protons H(7) and H(8) of the ethylene bond in a molecule
of ligand 1 disappear. Signals from the protons H(15) and
H(17)—H(20) of the crown ether fragment remain shifted
1
Table 4. Change in chemical shifts of protons (Δδ ) in the Н NMR spectra of ligands 1 and 2 in the presence of phthalic acid (H2A)
and КClO4
H
a
Ratio
Δδ
H
of reactants
H(2) H(3) H(7) H(8) H(10) H(13) H(14) H(22) H(15) H(16), H(17), H(18), H(3´) H(4´)
H(21)
H(20)
H(19)
1 : K+ = 2 : 1
1 : K+ = 1 : 1
1 : K+ = 1 : 2
1 : K+ = 1 : 5
1 : H2A = 2 : 1
1 : H2A = 1 : 1
–0.03 –0.05 –0.04 –0.05 –0.14 –0.07 –0.02 –0.10 –0.07
–0.04 –0.06 –0.04 –0.06 –0.17 –0.07 –0.01 –0.09 –0.09
–0.03 –0.05 –0.03 –0.04 –0.12 –0.04 0.01 –0.06 –0.04
–0.01 –0.02 –0.01 0.00 –0.03 0.02 0.04 0.00 0.04
0.08 0.20 0.11 0.03 –0.04 0.00 0.05 –0.02 0.05
0.06 0.24 0.11 –0.02 –0.12 –0.05 0.02 –0.09 0.02
–0.11 –0.16 –0.06 –0.02 –0.13 0.02 0.04 –0.11 0.00
–0.03
–0.04
–0.04
–0.02
–0.05
–0.03
–0.04
0.05
0.07
0.07
0.07
0.08
0.07
0.08
0.02
0.03
0.03
0.04
—
—
—
—
—
—
—
—
0.08 0.50 –0.00
0.07 0.35 –0.03
0.01 0.03 –0.05
1 : H2A : K+
=
= 2 : 1 : 1 b
2 : H2A = 2 : 1
0.08 0.25 0.17 0.09 0.04 0.03 0.06 0.01 0.02
0.01 0.02 0.03 0.01 0.00 0.00 0.00 0.00 0.00
—
—
—
—
—
—
0.45 –0.03
0.00 –0.01
2 : H2A : K+
=
= 2 : 1 : 1
a Solvent СD3CN, temperature 293 K, C1 = 1.0•10–2 mol L–1, C2 = 2.0•10–3 mol L–1; ΔδH = δcomplex – δ .
L
b
ΔδH = δ
– δ
.
1:H A:K+
1:H A (2:1)
2
2

292
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
Fedorov et al.
Table 5. Changes in chemical shifts of carbon atoms (Δδ ) in the 13C NMR spectrum of ligand 1 in the presence of phthalic acid (H2A)
C
a
and КClO4
Ratio
Δδ
C
of reactants
C(2) C(3) C(4) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15), C(16), C(17), C(18),
C(22) C(21) C(20) C(19)
1 : K+ = 2 : 1 –0.08 –0.01 –0.20 –0.29 0.38 0.40 –0.49 –1.4 –1.29 –0.45 0.25 –1.48, –1.72 –1.87 –2.03
–1.34
1 : H2A = 2 : 1 –4.54 0.96 4.84 3.83 –1.47 –0.71 –0.10 0.54 –0.25 –0.37 0.85 –0.33, –0.10, –0.23 –0.18
–0.19 0.00
1 : H2A = 1 : 1 –5.44 1.16 5.49 4.64 –1.68 –0.85 –0.12 1.01 –0.29 –0.42 0.97 –0.38, –0.13, –0.29 –0.23
–0.24 –0.03
1 : H2A : K+
= 2 : 1 : 1 b
=
2.10 –0.43 –2.00 –1.94 0.91 0.68 –0.19 –1.73 –0.96 –0.16 0.06 –1.00, –1.54 –1.51 –1.73
–1.06
a Solvent СD3CN, temperature 293 K, C1 = 1.0•10–2 mol L–1; ΔδC = δcomplex – δ .
L
b
ΔδC = δ
– δ
.
1:H A:K+
1:H A (2:1)
2
2
to weak fields, indicating coordination of the potassium
cations to this fragment (see Table 4). The character of
chemical shifts suggested that 1 : 1 complex 1•K+ exists
in the solution.
2 : H2A = 2 : 1 results in changes analogous to those
observed in the 1H NMR spectrum for ligand 1 (see Table 4).
The addition of potassium perchlorate exerts no effect
on the position of signals of the protons of the ligand and
phthalic acid. Since the ligand containing no crown
ether fragment cannot coordinate to metal cations, no
associates containing ligand 2, К+, and phthalic acid
are formed.
The addition of phthalic acid to a solution of 1 in the
ratio 1 : H2A = 2 : 1 most considerably changes the posiꢀ
tions of signals from the protons of the heterocyclic part
1
and the proton Н(7) of the double bond in the Н NMR
spectrum (see Table 4). This corresponds to the scheme of
interaction of the acid with the ligand. The scheme was
proposed on the basis of optical studies (see Scheme 1).
Indeed, the formation of associate "ligand—phthalic acid"
by a hydrogen bond exerts an effect, first of all, on the
position of signals of the heterocyclic protons. For the
protons of phthalic acid, the strong shift of the signal from
the proton Н(3´) also confirms that the acid interacts with
the pyridine moiety of 1.
Almost all signals of protons of ligand exhibit upfield
shifts upon the addition of potassium perchlorate to a soluꢀ
tion of the complex of ligand 1 with phthalic acid in MeCN
(see Table 4). Only the signals of the protons Н(13) and
H(14), H(17)—H(20) of the crown ether fragment exhibit
downfield shifts, which confirms the complexation of catꢀ
ion К+ with the crown ether fragment. The upfield shifts
of signals from the protons of ligand 1 are explained by the
formation a "sandwich" complex, whose structure is preꢀ
sented in Scheme 1. In complex (1)2•K+•H2A, two
chromophoric molecules exert an anisotropic effect on
each other, resulting in the upfield shift of signals of the
protons. Thus, the NMR spectroscopic data agree compꢀ
letely with the results of optical studies of ligand 1.
The 13С NMR spectrum of potassium complex (1)2•K+
shows the upfield shift of signals from the 13C nuclei of all
methylene groups of crown ether. The value ΔδС
=
= 1.48—2.03 (Tables 5 and 6) is typical of complexation
of crown ethers.34 The signals of the 13C nuclei of the
benzene ring С(11) and C(12) exhibit the most significant
upfield shifts (–1.4 and –1.29 ppm), while the signals of
the 13C nuclei of the pyridine residue and double bond are
shifted to a less extent. Coordination of phthalic acid to
the nitrogen atom of the pyridine cycle results in the inꢀ
verse pattern compared to complexation involving crown
ether: the signals of the 13C nuclei of the pyridine fragꢀ
ment and the double bond are shifted, whereas the signals
of the macrocycle are insignificantly shifted. The formaꢀ
Table 6. Changes in chemical shifts of carbon atoms (Δδ ) in the
C
13C NMR spectrum of phthalic acid (H2A) in the supramolecuꢀ
lar complexesa
Ratio
Δδ
C
of reactants
COOH C(2´)
C(3´) C(4´)
We also analyzed the changes that occur in the 1H NMR
spectra of hetarylphenylethene 2 containing two methoxy
groups instead of the crown ether moiety (see Table 4)
upon the addition of potassium salt and phthalic acid
to the solution of this ligand. The addition of phthalic
acid to a solution of hetarylphenylethene 2 in the ratio
1 : H2A = 2 : 1
1 : H2A = 1 : 1
1 : H2A : K+ = 2 : 1 : 1 b
1.66
1.35
0.26
2.22
2.44
–0.12
0.68
0.12
–0.39
1.90
1.97
0.06
a Solvent СD3CN, temperature 293 K, C1 = 1.0•10–2 mol L–1
;
ΔδC = δcomplex – δ
.
H A
b
ΔδC = δ
– 2δ
.
1:H A:K+
1:H A (2:1)
2
2

Supramolecular assemblies of some crowns
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 2, February, 2011
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This work was financially supported by the Russian
Foundation for Basic Research (Project Nos 06ꢀ03ꢀ32899
and 09ꢀ03ꢀ00241а), the International Program of the
European Scientific Association ("Supramolecular Sysꢀ
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in revised form October 27, 2010