Tautomeric chromoionophores derived from 1-aryloxyanthraquinones and 4′-aminobenzo-15-crown-5 ether: Sandwich complex formation enhanced by interchromophoric interactions

Article abstract of DOI:10.1016/j.tet.2016.12.048

A series of tautomeric chromoionophores were prepared photochemically from 1-aryloxyanthraquinones and 4′-aminobenzo-15-crown-5 ether. All the synthesized dyes can bind strontium and barium cations as sandwich-type 2:1 ligand–metal complexes that show higher stability constants (K_2:1) than the corresponding 1:1 complexes (K_1:1), the K_2:1/K_1:1ratio reaching a value of 10 (in MeCN). The inverse relation, i.e. K_2:1?1:1, is observed for the related complexes of unsubstituted benzo-15-crown-5 ether. The sandwich complexes were studied by spectrophotometry,¹H NMR spectroscopy, mass spectrometry, and density functional theory calculations. A correlation was found between the K_2:1/K_1:1ratio and the number of short stacking contacts in the sandwich complex.

Full text of DOI:10.1016/j.tet.2016.12.048

Accepted Manuscript
Tautomeric chromoionophores derived from 1-aryloxyanthraquinones and 4′-
aminobenzo-15-crown-5 ether: Sandwich complex formation enhanced by
interchromophoric interactions
Timofey P. Martyanov, Lubov S. Klimenko, Viacheslav I. Kozlovskiy, Evgeny N.
Ushakov
PII:
S0040-4020(16)31335-7
10.1016/j.tet.2016.12.048
TET 28340
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 10 October 2016
Revised Date: 8 December 2016
Accepted Date: 19 December 2016
Please cite this article as: Martyanov TP, Klimenko LS, Kozlovskiy VI, Ushakov EN, Tautomeric
chromoionophores derived from 1-aryloxyanthraquinones and 4′-aminobenzo-15-crown-5 ether:
Sandwich complex formation enhanced by interchromophoric interactions, Tetrahedron (2017), doi:
10.1016/j.tet.2016.12.048.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
Graphical Abstract
Tautomeric chromoionophores derived from 1-aryloxyanthraquinones and 4’-aminobenzo-
15-crown-5 ether: sandwich complex formation enhanced by interchromophoric interactions
Timofey P. Martyanova, Lubov S. Klimenkob, Viacheslav I. Kozlovskiyc and Evgeny N. Ushakova
aInstitute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russian
Federation
bYugra State University, 16 Chehov St., Khanty-Mansiysk 628012, Russian Federation
cTalrose Institute for Energy Problems of Chemical Physics (Branch), Russian Academy of Sciences,
Chernogolovka 142432, Russian Federation

ACCEPTED MANUSCRIPT
Tautomeric chromoionophores derived from 1-aryloxyanthraquinones
and 4’-aminobenzo-15-crown-5 ether: sandwich complex formation
enhanced by interchromophoric interactions
Timofey P. Martyanova, Lubov S. Klimenkob, Viacheslav I. Kozlovskiyc and
Evgeny N. Ushakova,*
Address:
aInstitute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432,
Russian Federation
bYugra State University, 16 Chehov St., Khanty-Mansiysk 628012, Russian Federation
cTalrose Institute for Energy Problems of Chemical Physics (Branch), Russian Academy of
Sciences, Chernogolovka 142432, Russian Federation
Abstract
A
series of tautomeric chromoionophores were prepared photochemically from 1-
aryloxyanthraquinones and 4’-aminobenzo-15-crown-5 ether. All the synthesized dyes can bind
strontium and barium cations as sandwich-type 2:1 ligand–metal complexes that show higher
stability constants (K2:1) than the corresponding 1:1 complexes (K1:1), the K2:1/K1:1 ratio reaching a
value of 10 (in MeCN). The inverse relation, i.e. K2:1 < K1:1, is observed for the related complexes
of unsubstituted benzo-15-crown-5 ether. The sandwich complexes were studied by
1
spectrophotometry, H NMR spectroscopy, mass spectrometry, and density functional theory
calculations. A correlation was found between the K2:1/K1:1 ratio and the number of short stacking
contacts in the sandwich complex.
Keywords
Crown compounds; Anthraquinones; Sandwich complexes; Stacking interactions; Tautomerism
* Corresponding author. E-mail address: e.n.ushakov@gmail.com (E.N. Ushakov).
1

ACCEPTED MANUSCRIPT
1. Introduction
The optical properties of tautomeric dyes, dependent on the ratio of tautomeric forms, can be
affected by various factors, such as solvent polarity, pH, aggregative state, and photoexcitation.1
Rational integration of an ionophore into a tautomeric dye can lead to a compound with ion-
controllable optical characteristics. Crown ethers are well known as selective ligands for alkali and
alkaline-earth metal cations.2 They are widely used as building blocks in the design and synthesis of
various functionalized compounds, such as photocontrolled molecular receptors3-5 and optical
molecular sensors (chromo- and fluoroionophores).4,6,7 Among the variety of chromogenic crown
compounds reported in the literature, there are very few examples of tautomeric dyes that can
operate as optical sensors for metal ions.8-12
Imine derivatives of 1-hydroxyanthraquinone are known to undergo prototropic
tautomerization to exist as an equilibrated mixture of the imine and enamine isomers both in
solution and in the solid state (Scheme 1).13,14 Recently, we reported the synthesis of a 1-
hydroxyanthraquinone-9-imine derivative containing a benzo-18-crown-6 ether moiety.15 The
tautomeric equilibrium of this dye was found to shift toward the imine form in the presence of
alkaline-earth metal cations.
Scheme 1. Tautomerism of 1-hydroxyanthraquinone-9-imines.
It is well known that 15-crown-5 ethers are able to form sandwich-type 2:1 complexes with
relatively large metal ions, such as K+, Sr2+, and Ba2+.16,17 This feature has been utilized in the
design of various ion-selective molecular devices.18 The sandwich complexes of aromatic crown
ethers can have an enhanced stability owing to weak stacking interactions.19,20 For crown ether dyes
possessing extended π-systems, the effect of stacking interactions on the sandwich complex
formation has been little-studied quantitatively.
Here we report on the synthesis of a series of five 1-hydroxyanthraquinone-9-imine dyes
containing a benzo-15-crown-5 ether moiety. The complexation of these chromoionophores with
1
alkali and alkaline-earth metal cations was comprehensively studied by spectrophotometry, H
NMR spectroscopy, mass spectrometry, and quantum chemical calculations. Particular attention
was paid to the effect of interchromophoric interactions on the thermodynamic stability of the 2:1
complexes of the dyes with Sr2+ and Ba2+.
2

ACCEPTED MANUSCRIPT
2. Results and Discussion
2.1 Synthesis
Crown-containing 1-hydroxyanthraquinone-9-imine dyes 1 (Scheme 2) were synthesized
photochemically according to the general procedure published previously.21 A benzene solution of
photochromic 1-aryloxyanthraquinone 2 with aminobenzo-15-crown-5 ether 3 was exposed to
sunlight for 6–8 hours. The photoinduced migration of the aryl group in 2 resulted in the ana-
quinoid isomer 4 possessing a high reactivity toward nucleophilic agents.13 The subsequent
nucleophilic substitution of the aryloxy group in 4 by the arylamino group of 3 gave the desired
products in 58–75% yields. The synthesis of dyes 1a, 1d, and 1e is reported for the first time. Dyes
1b and 1c, as obtained by solid-state synthesis, have been described previously.22
Scheme 2. Synthesis of dyes 1a–e.
2.2 Spectrophotometric study
The complexation of dyes 1a–e with alkali and alkaline-earth metal cations in MeCN was studied
by spectrophotometric titration (SPT, see the Experimental). Figure 1 shows the SPT data for 1a
and 1c with Ca(ClO4)2 (similar data for dyes 1b, 1d, and 1e are presented in Fig. S1).
Dye 1a exhibits two broad absorption bands between 350 and 600 nm, assignable to the imine
(416 nm) and enamine (464 nm) tautomeric forms (Scheme 1).13 The absorption spectral changes
observed on the addition of Ca(ClO4)2 suggest that the tautomeric equilibrium of 1a shifts toward
the imine isomer. This shift is attributable to the electron-withdrawal effect of the crowned metal
ion on the amine nitrogen atom.15 The same conclusions about the coexistence of two prototropic
tautomers and the nature of cation-induced spectral changes hold also for dyes 1b, 1d, and 1e.
3

ACCEPTED MANUSCRIPT
Fig. 1. Spectrophotometric titration data for the systems (a) 1a–Ca(ClO4)2 and (b) 1c–Ca(ClO4)2 in MeCN
(4.75 cm cell); the total ligand concentration is (a) 3.0×10−5 and (b) 1.25×10−5 M, and the total metal
concentration varies incrementally (a) from 0 to 4.3×10−5 M and (b) from 0 to 3.6×10−5 M.
Dye 1c unlike the others shows a single absorption band peaked at 497 nm, which implies that
in MeCN this dye exists almost completely as a single tautomer, presumably, as the imine one. The
binding of Ca2+ to the crown ether moiety of 1c induces a hypsochromic shift of the absorption
band, indicating a charge-transfer character of the lowest-energy excited state.
The complexation stoichiometry, the complex stability constants, and the absorption spectra
of pure complexes for dyes 1 with metal cations were derived from SPT data using the global
analysis methods described previously.23 In most cases, the SPT data were well fitted to one
equilibrium:
L + Mn+
L· Mn+
(1)
where L is the dye, Mn+ is the metal ion, and K1:1 = [L· Mn+]/([L][Mn+]) is the stability constant of
the 1:1 complex.
More rigorously, the 1:1 complexation of the tautomeric dyes should be described by a model
involving four light absorbing components, the concentrations of which are determined by the
following thermodynamic cycle:
where Im and En are the imine and enamine isomers of the dye, respectively, and K1–K4 are the
equilibrium constants. It is obvious that the concentration ratios [Im]/[En] and [Im· Mn+]/[En · Mn+]
do not depend on the metal cation concentration; therefore, the system can be formally described by
the equilibrium of Equation (1) involving the two light absorbing components L and L· Mn+ with
4

ACCEPTED MANUSCRIPT
the concentrations [L] = (1 + K3)[Im] and [L· Mn+] = (1 + K4)[Im· Mn+]. The observed stability
constant K1:1 is related to K1, K3, and K4 by the following expression:
K1:1 = K1{(K4 + 1)/(K3 + 1)}
(2)
From the experimental data presented in Figure 1a, we know that K3 > K4. Then it follows from
Equation (2) that K1:1 is somewhat lower than the stability constant K1 of the imine tautomer
complex.
For the systems 1–Sr(ClO4)2 and 1–Ba(ClO4)2, the SPT data were well fitted to two equilibria,
viz. the equilibrium of Equation (1) and the other involving a 2:1 dye–metal complex:
L· Mn+ + L
L2· Mn+
(3)
where K2:1 = [L2· Mn+]/([L][L· Mn+]) is the stability constant of the 2:1 complex.
Global analysis of the SPT data obtained for the system 1b–Mg(ClO4)2 revealed the formation
of a 1:2 dye–metal complex. In this case, the data were fitted to the equilibria of Equations (1) and
(4):
L· Mn+ + Mn+
L· (Mn+)2
(4)
where K1:2 = [L· (Mn+)2]/([Mn+][L· Mn+]) is the stability constant of the 1:2 complex.
The stability constants of the complexes of dyes 1 with alkali and alkaline-earth metal cations
in MeCN, as derived from spectrophotometric titrations, are presented in Table 1. The absorption
characteristics of these dyes and their complexes are shown in the same table.
To characterize quantitatively the absorption changes arising from the shift of the tautomeric
equilibrium, we used the dimensionless parameter ∆εrel = 1 – εen(complex)/εen(dye), where εen is the
molar absorptivity (per chromophore) at the absorption maximum λen of the free enamine tautomer.
The λen values for dyes 1a, 1b, 1d, and 1e were estimated by fitting the absorption spectrum to a
sum of lognormal functions (Fig. S2).
Figure 2 shows the plots of ∆εrel vs. the radius of the metal ion (rM) for the 1:1 complexes of
dye 1b with alkali and alkaline-earth metal cations (similar plots for dye 1a are presented in Fig.
S3). The maxima in these plots correspond to the complexes with Na+ and Ca2+. This fact suggests
that these ions better fit into the cavity of benzo-15-crown-5 ether (B15C5). At the same time, the
stability constant K1:1 decreases monotonically with an increase in the rM value both for mono- and
divalent cations (Table 1, Fig. 3). The lower values of ∆εrel for Li+ relative to Na+ and for Mg2+
relative to Ca2+ can be explained by the fact that the Mn+–OAr bonds with Li+ and Mg2+ are weaker
because the ionic radii of Li+ and Mg2+ are smaller than the cavity radius of 15-crown-5 ether.24
However, these ions, due to relatively high charge density, can form stronger bonds with the alkoxy
oxygen atoms of B15C5, which results in the larger values of K1:1.
5

ACCEPTED MANUSCRIPT
Table 1. Stability constants and absorption properties of complexes of dyes 1a–e with metal cations in
MeCN.a
logK
logK
λmax
416, 464
416
416
418
412
410
412
417
413
417
435
430
429
430
424
412
424
424
430
426
429
εmax ×10−3
5.1, 5.2
5.77
5.90
5.78
6.63
6.66
6.50
6.23
6.32
6.24
8.4
∆
εrel
λmax
497
489
491
493
485
482
485
491
485
493
416
419
419
423
419
423
474
415
415
422
416
420
εmax ×10−3
11
∆εrel
∆
λ
∆λ
1a
1a· Li+
1a· Na+
1a· K+
1c
1c· Li+
1c· Na+
1c· K+
4.56
3.93
3.13
6.22
5.71
5.40
5.47
5.06
5.42
0
0.144
0.202
0.117
0.489
0.490
0.429
0.363
0.366
0.373
4.46
3.54
3.07
6.02
5.55
5.20
5.98
4.93
5.95
11.24
11.27
11.19
11.05
11.01
11.13
9.96
–8
–6
0
+2
–4
–5
–4
+1
–3
+1
–4
1a· Mg2+
1a· Ca2+
1a· Sr2+
(1a)2 · Sr2+
1a· Ba2+
(1a)2 · Ba2+
1b
1b· Li+
1b· Na+
1b· K+
1b· Mg2+
1b· (Mg2+)2
1b· Ca2+
1b· Sr2+
(1b)2 · Sr2+
1b· Ba2+
(1b)2 · Ba2+
1c· Mg2+
1c· Ca2+
1c· Sr2+
(1c)2 · Sr2+
1c· Ba2+
(1c)2 · Ba2+
1d
1d· Ca2+
1d· Sr2+
(1d)2 · Sr2+
1d· Ba2+
(1d)2 · Ba2+
1e
–12
–15
–12
–6
11.44
9.99
–12
–4
9.4
4.33
4.12
3.09
6.13
1.04
5.55
5.01
5.96
4.82
5.70
9.21
9.33
8.90
9.68
7.66
9.73
9.64
8.40
9.54
8.46
–5
–6
0.328
0.376
0.279
0.581
5.75
5.50
5.80
4.97
5.57
10.96
10.70
9.82
+3
+3
+7
+3
+7
0.427
0.368
0.290
0.298
0.325
–5
–11
–23
–11
–11
–5
10.67
9.73
0.616
0.557
0.508
0.499
0.526
6.5
1e· Ca2+
1e· Sr2+
(1e)2 · Sr2+
1e· Ba2+
(1e)2 · Ba2+
5.42
5.10
5.55
4.84
5.34
7.93
–59 0.632
–59 0.566
–52 0.528
–58 0.504
–54 0.536
7.69
–9
7.13
–6
7.50
7.10
a K (M−1) = K1:1 for L· Mn+ complexes, K = K2:1 for (L)2· Mn+ complexes, and K = K1:2 for L· (Mn+)2 complexes; the
K values are determined to within about ±20%; λmax is the position of the absorption maximum, nm; εmax is the
molar absorptivity (per chromophore) at
λ
max, M−1cm−1; ∆
λ
=
λ
max(complex) –
λ
max(dye); ∆εrel = 1 –
en of the
ε
en(complex)/ en(dye), where en is the molar absorptivity (per chromophore) at the absorption maximum λ
ε
ε
free enamine tautomer (the λen values for 1a, 1b, 1d, and 1e were estimated by spectral deconvolution to be about
484, 545, 499, and 515 nm, respectively).
Fig. 2. Plots of ∆εrel vs. rM for the 1:1 complexes of dye 1b with alkali and alkaline-earth metal cations in
MeCN; the rM values are taken from ref.25
6

ACCEPTED MANUSCRIPT
In order to analyze the complexing properties of dyes 1, we used B15C5 as the reference
ligand. Table 2 presents the stability constants of the complexes of B15C5 with alkali and alkaline-
earth metal cations in MeCN, as determined by the method described for dyes 1 (the data for Mg2+
and Ca2+ are taken from ref.26).
Table 2. Stability constants and absorption properties of complexes of B15C5 with metal cations in MeCN.a
εmax ×10−3
logK
λmax
∆
λ
B15C5
277
2.6
B15C5· Li+
5.07
273
278
2.47
2.10
−4
B15C5· Na+
B15C5· K+
4.24
3.48
7.2b
6.6b
6.30
5.84
5.81
5.58
273
275
—
2.25
2.45
—
−4
−2
—
—
−8
−6
−6
−6
B15C5· Mg2+
B15C5· Ca2+
B15C5· Sr2+
(B15C5)2 · Sr2+
B15C5· Ba2+
(B15C5)2 · Ba2+
—
—
269
271
271
271
1.81
1.76
1.95
1.81
a K (M−1) = K1:1 for L· Mn+ complexes, and K = K2:1 for
(L)2· Mn+ complexes; the K values are determined to
within about ±20%; λmax is the position of the
absorption maximum, nm; εmax is the molar
absorptivity (per chromophore) at
λ λ =
max, M−1cm−1; ∆
λ
max(complex) –
λ
max(ligand). b Ref.26
The dependencies of K1:1 on rM for B15C5 and dyes 1 show a similar trend (Fig. 3, Tables 1
and 2). The K1:1 values for the complexes of 1 with divalent cations are lower by about an order of
magnitude than those for the corresponding complexes of B15C5. This fact is attributable to the
electron-withdrawal effect of the anthraquinone core on the benzocrown ether moiety of the dye.
On the contrary, the K2:1 values for the complexes of 1b and 1c with Sr2+ and Ba2+ are higher than
those for the corresponding complexes of B15C5.
Fig. 3. Plots of logK vs. rM for the 1:1 and 2:1 complexes of dye 1b and B15C5 with alkaline-earth metal
cations in MeCN; the rM values are taken from ref.25
7

ACCEPTED MANUSCRIPT
Table 3 presents the ratios of the stability constants and the differences between the Gibbs
free energies of formation for the 2:1 and 1:1 complexes of B15C5 and dyes 1 with Sr2+ and Ba2+.
For B15C5, the relation K2:1 < K1:1 holds both for Sr2+ and Ba2+. The inverse relation is observed for
all dyes 1. The dyes containing a benzoylamino group at the 2 and 4 positions of the 1-
hydroxyanthraquinone core (dyes 1b and 1c, respectively) demonstrate the largest values of the
K2:1/K1:1 ratio. In the case of 1c with Ba2+, this ratio reaches a value of 10. It is most likely that the
enhanced stabilities of the sandwich complexes of dyes 1 with Sr2+ and Ba2+, as compared with the
corresponding 1:1 complexes, result from stacking interactions between the chromophoric moieties.
Table 3. Ratios of the stability constants and differences between the Gibbs free energies of formation for
the 2:1 and 1:1 complexes of B15C5 and dyes 1 with Sr2+ and Ba2+ in MeCN.
Ligand
B15C5
1a
H
1b
2-NHCOPh
8.75
1c
4-NHCOPh
5.97
1d
5-NHCOPh
2.00
1e
2-NHCOCF3
2.77
Substituent
K2:1/K1:1
Sr2+
Ba2+
Sr2+
Ba2+
0.35
0.67
2.59
1.01
1.01
2.26
–0.029
–2.02
7.60
10.5
3.93
3.17
∆G,a kJ mol−1
–5.37
–4.43
–1.72
–2.53
δ
–5.02
–5.81
–3.39
–2.86
a δ∆G = –RT(lnK2:1 – lnK1:1), T = 298 K.
Figure 4 shows the absorption spectra of dye 1b and complexes 1b· Sr2+ and (1b)2· Sr2+
(similar data for dyes 1a and 1c–e are presented in Fig. S4). The sandwich complex (1b)2· Sr2+ is
characterized by a higher molar absorptivity at
λ > 640 nm in comparison with the free dye and the
1:1 complex (a similar pattern is observed for 1b with Ba2+, Fig. S5). Presumably, this feature is
due to stacking interactions between the benzoyl amino group of one dye molecule and the
anthraquinone core of the other in the sandwich complexes involving the enamine tautomer of 1b.
The results of molecular structure calculations (see below) support this supposition.
Fig. 4. Absorption spectra of dye 1b and complexes 1b· Sr2+ and (1b)2· Sr2+ in MeCN.
8

ACCEPTED MANUSCRIPT
An interesting feature of dye 1b is the ability to form a weak binuclear complex with Mg2+
(Table 1). Figure 5 represents the absorption spectra of 1b, 1b· Mg2+, and 1b· (Mg2+)2 in MeCN.
The spectrum of 1b· Mg2+ is similar in shape to the spectra of the 1:1 complexes of 1b with Ca2+
(Fig. S1a), Sr2+ (Fig. 4), and Ba2+ (Fig. S5b), which indicates that the Mg2+ ion in 1b· Mg2+ is
bound to the crown ether moiety of the dye. The spectrum of 1b· (Mg2+)2 differs significantly from
that of 1b· Mg2+. It is most likely that the binuclear complex forms owing to the binding of Mg2+ to
the three heteroatoms of the chromophoric moiety of 1b: the carbonyl oxygen of the benzoylamino
group, the hydroxyl oxygen, and the imine nitrogen (see Scheme 3).
Fig. 5. Absorption spectra of dye 1b and complexes 1b· Mg2+ and 1b· (Mg2+)2 in MeCN.
Scheme 3. Formation of the binuclear complex 1b· (Mg2+)2.
9

ACCEPTED MANUSCRIPT
2.3 NMR spectroscopy
1
Figure 6 presents the H NMR spectra of the systems B15C5–Ba(ClO4)2 and 1b–Ba(ClO4)2 in
MeCN-d3 at different metal-to-ligand molar ratios: CM/CL = 0 (curves 1), 0.5 (curves 2), and 15
(curves 3), where CM is the total metal concentration and CL is the total ligand concentration (in
both systems CL = 2 mM). The presence of Ba(ClO4)2 induces significant shifts and broadening of
the proton signals of B15C5 and 1b. The H-1 signal of B15C5 and the H-2' signal of 1b are shifted
upfield at CM/CL = 0.5 and downfield at CM/CL = 15. The increase in the CM/CL ratio to 100 caused
1
narrowing of all signals in the H NMR spectra of the ligands (Fig. S6). These facts suggest the
formation of two different complexes in these systems, viz. L· Ba2+ and L2· Ba2+, the latter
predominating at CM/CL = 0.5.
The spectrum of the aromatic protons of free B15C5 is a single multiplet which splits into two
multiplets at CM/CL = 0.5. When the CM/CL ratio is increased to 15, the H-1 signal (which is shifted
upfield) broadens and moves downfield, so that the positions of the H-1 and H-2 signals are
inverted with respect to each other (cf. the NMR titration spectra in Fig. S7). It is most likely that
the H-1 proton of one ligand molecule in (B15C5)2· Ba2+ is shielded by the benzene ring of the
other, which results in a decrease in the chemical shift (δ) of the H-1 signal.
Fig. 6. 1H NMR spectra of the systems (a) B15C5–Ba(ClO4)2 and (b) 1b–Ba(ClO4)2 in MeCN-d3 at different
metal-to-ligand molar ratios: CM/CL = 0 (curves 1), 0.5 (curves 2), and 15 (curves 3); CL = 2 mM.
The positions of the H-2' and H-6' signals in the 1H NMR spectra of the 1b–Ba(ClO4)2 system
are also inverted on changing the CM/CL ratio from 0.5 to 15. This indicates that the H-2' proton in
(1b)2· Ba2+ is shielded in the same way as the H-1 proton in (B15C5)2· Ba2+.
To confirm the reliability of the K2:1/K1:1 ratios determined by SPT, we carried out NMR
titrations for the systems B15C5–Ba(ClO4)2 and 1b–Ba(ClO4)2 in MeCN-d3. Figure 7 shows the
10

ACCEPTED MANUSCRIPT
plots of
δ on CM for some protons in these systems. From these data, it was not possible to
determine the stability constants K2:1 and K1:1 because of their high values, but it was possible to
evaluate the K2:1/K1:1 ratio. This ratio was estimated by globally fitting the NMR titration curves to
the 2:1 complexation model represented by Equations (1) and (3) (details are given in the
Experimental). In both cases, the experimental dependencies of
δ on CM are well reproduced by this
model, and the best fitted values of K2:1/K1:1 are 0.66 for (B15C5)2· Ba2+ and 7.73 for (1b)2· Ba2+, in
perfect agreement with those determined by SPT (Table 3).
The plots of
δ on CM for the systems 1b–Ba(ClO4)2 and B15C5–Ba(ClO4)2 are similar to each
other. In the conversion of the 2:1 complex (low CM values) into the 1:1 complex (high CM values),
all signals of the aliphatic protons, except the signal of H-β, demonstrate downfield shifts, which is
attributable to longer O–Ba2+ coordination bonds in the sandwich complex. The distinctive behavior
of the H-β signal is presumably due to the fact that the polyether cycle adopts different
conformations in the 2:1 and 1:1 complexes.
Fig. 7. Plots of
δ vs. CM for some protons in the systems (a) B15C5–Ba(ClO4)2 and (b) 1b–Ba(ClO4)2 in
MeCN-d3 (CL = 2 mM); the solid curves are from global fits to the 2:1 complexation model represented by
Equations (1) and (3).
Figures S8–S10 show the NOESY spectra of the 1b–Ba(ClO4)2 system in MeCN-d3–CDCl3
(4:1, v/v) at CL = 2 mM and CM/CL = 0, 1, and 100. The NOE interactions observed for dye 1b and
complexes (1b)2· Ba2+ (CM/CL = 1) and 1b· Ba2+ (CM/CL = 100) are depicted schematically in Figure
8. In all three cases, there are the intramolecular cross-peaks of H-8 with H-2' and H-6' (the atom
numbering is shown in Fig. 6), indicating rapid interconversion between the two dye conformations
associated with the rotation of the benzocrown ether moiety around the Ar–N single bond (s-cis and
s-trans, Fig. 8).
The NOESY spectrum of 1b shows weak cross-peaks of H(hydroxyl) with H-2' and H-6'. In
the spectrum of 1b· Ba2+, these cross-peaks are absent, which can be explained by the shift of the
11

ACCEPTED MANUSCRIPT
dye tautomeric equilibrium toward the imine isomer (the distances from the hydroxyl hydrogen to
H-2' and H-6' are supposed to be larger in the imine isomer than in the enamine one). In the
spectrum of (1b)2· Ba2+, the cross-peak between H(hydroxyl) and H-2' is also absent, but the main
reason for this appears to be a considerable broadening of the H-2' signal (the broadening is due to a
great difference in the H-2' chemical shifts between complexes (1b)2· Ba2+ and 1b· Ba2+). Compared
with the free dye, complex (1b)2· Ba2+ is characterized by a more intense cross-peak between
H(hydroxyl) and H-6' (its intensity is doubled with respect to the cross-peak between H-α and H-
5'). Most likely, it arises from the intermolecular NOE. The results of molecular structure
calculations presented below support this hypothesis.
O
O
O
O
O
O
O
H
O
O
N
O
O
O
H
N
H
N
O
O
H
N
O
O
s-cis-1b
O
s-trans-1b
O
O
O
Ba2+
O
O
H
Ba2+
O
N
O
O
O
H
O
N
H
N
O
O
H
N
O
O
O
O
(s-cis-1b)—Ba2+
O
O
O
O
O
O
O
O
O
(s-trans-1b)—Ba2+
Ba2+
O
O
Ba2+
O
O
O
O
O
O
O
O
N
N
H
H
N
O
N
O
H
H
N
N
O
O
O
O
[anti-(s-cis-1b)2]—Ba2+
[anti-(s-trans-1b)2]—Ba2+
Fig. 8. NOE interactions in different conformers of 1b, 1b· Ba2+, and (1b)2· Ba2+.
2.4 Mass spectrometry
The complexation of (BaClO4)2 with B15C5 and dyes 1b and 1c was investigated by electrosonic
spray ionization mass spectrometry (ESSI-MS, see the Experimental). Figures 9 shows the ESSI-
MS spectra of the systems B15C5–(BaClO4)2 and 1b–(BaClO4)2 in MeCN, obtained at a spray
voltage of 2.7 kV.
12

ACCEPTED MANUSCRIPT
Fig. 9. ESSI mass spectra of the systems (a) B15C5–(BaClO4)2 and (b) 1b–(BaClO4)2 in MeCN (CL = CM =
1×10−4 M), obtained at a spray voltage of 2.7 kV.
In the case of B15C5, the spectrum contains signals from (B15C5)2· Ba2+,
+
+
(B15C5)2· BaClO4 , B15C5· BaClO4 , and complexes with impurity ions (not denoted). The
absence of the signal from the non-associated B15C5· Ba2+ complex, probably, results from a lower
surface activity of this species in comparison with the ion pairs and the non-associated
(B15C5)2· Ba2+ complex. Due to the lower surface activity, the B15C5· Ba2+ complex is located in
the droplet bulk, not on the surface, which suppresses its release into the gas phase through the
droplet fission cascade.27 The decrease in the spray voltage to 150 V led to a significant reduction in
+
+
the signal intensity of (B15C5)2· Ba2+ relative to both B15C5· BaClO4 and (B15C5)2· BaClO4
(Fig. S13) owing to the formation of less charged droplets.
The ESSI-MS spectrum of the 1b–(BaClO4)2 system exhibits the signals from both
(1b)2· Ba2+ and 1b· Ba2+, which suggests that the difference in the surface activity between these
complexes is much less than that between (B15C5)2· Ba2+ and B15C5· Ba2+. The reason for the
smaller difference is that dye 1b contains a bulky hydrophobic moiety. The spectrum shows the
signal from a protonated form of dye 1b (1bH+). Presumably, this signal appears mainly due to the
protonation of (1b)2· Ba2+ followed by the dissociation into 1bH+ and 1b· Ba2+. This presumption is
supported by the fact that the decrease in the spray voltage to 150 V caused a significant
enhancement of the signal intensity of (1b)2· Ba2+ relative to both 1bH+ and 1b· Ba2+ (Fig. S14).
The ESSI-MS spectrum of the system 1c–(BaClO4)2 essentially shows similar features (Fig. S15).
It has been reported that electrospray ionization mass spectrometry can be used to determine
stability constants of crown ether–metal cation complexes.28-30 In the case of dyes 1b and 1c, this
method is not suitable for this purpose due to the observed protonation processes.
2.5 Quantum-chemical calculations
The molecular structures of complexes (1)2· Sr2+ and (B15C5)2· Sr2+ in MeCN were studied using
density functional theory (DFT, see the Experimental). The most stable conformations of the
13

ACCEPTED MANUSCRIPT
complexes, as calculated by DFT, are shown in Figure 10. The dye molecules in (1)2· Sr2+ are
present as the s-trans-conformers with respect to rotation of the benzocrown ether moiety around
the Ar–N single bond. The two 1-hydroxyanthraquinone-imine moieties adopt an anti-conformation
relative to each other, which was found to be much more stable than syn-conformations.
Fig. 10. Most stable conformations of complexes (B15C5)2· Sr2+ and (1a–d)2· Sr2+ in MeCN, as calculated by
DFT; hydrogen atoms are not shown, except the hydroxyl hydrogen.
The calculated sandwich structures are characterized by a different number of short stacking
contacts (SC). The SC number varies in the following order: B15C5 (1 SC) < 1a = 1d (2 SC) < 1c
(3 SC) < 1b (4 SC). According to experimental data (see the K2:1/K1:1 ratios or the δ∆G values in
Table 3), the relative stability of the 2:1 complexes of B15C5 and dyes 1a–d with Sr2+ with respect
14

ACCEPTED MANUSCRIPT
to the corresponding 1:1 complexes increases as follows: B15C5 < 1a < 1d < 1c < 1b. That is, there
is a correlation between the number of stacking contacts in the sandwich complex and its relative
stability.
In the calculated structures [anti-(s-trans-1)2]· Sr2+, the H-2' of one benzocrown unit is in the
shielding region of the benzene ring of the other, which agrees with the observed upfield shift of the
H-2' signal in the NMR spectrum of the related complex (1b)2· Ba2+ (Fig. 6).
The intramolecular distances between H-6' and H-8 and between H(hydroxyl) and H-2' in
structure [anti-(s-trans-1b)2]· Sr2+ are 2.79 and 2.72 Å, respectively. The fact that the NOESY
spectrum of the related complex (1b)2· Ba2+ does not show the expected cross-peak between
H(hydroxyl) and H-2' is due to significant broadening of the H-2' signal.
The intramolecular distance between H(hydroxyl) and H-6' in [anti-(s-trans-1b)2]· Sr2+ is
equal to 4.00 Å, whereas the intermolecular distance is just 3.02 Å. Figure S17 represents the anti-
(s-cis)2 and anti-(s-cis,s-trans) conformations of (1b)2· Sr2+ calculated by the same method. The
relative DFT energies of these conformers with respect to [anti-(s-trans-1b)2]· Sr2+ are about +0.3
and +1.8 kcal/mol, respectively. The intra- and intermolecular distances between H(hydroxyl) and
H-6' in the anti-(s-cis)2 conformer (3.56 and 5.78 Å, respectively) are significantly larger than the
intermolecular distance between these atoms in the anti-(s-trans)2 conformer. In the non-
symmetrical conformer anti-(s-cis,s-trans), the intramolecular distances between H(hydroxyl) and
H-6' (3.32 and 3.62 Å) are also larger than 3.02 Å, whereas the shortest intermolecular distance is
just 2.35 Å. These facts support the conclusion that the cross-peak between H(hydroxyl) and H-6' in
the NOESY spectrum of (1b)2· Ba2+ arises from the intermolecular NOE.
3. Conclusions
Thus, the 15-crown-5-containing 1-hydroxyanthraquinone-imine dyes 1, all except 1c, undergo
prototropic tautomerization in MeCN to exist as an equilibrated mixture of the imine and enamine
isomers. The binding of an alkaline metal cation to the crown ether moiety of the tautomeric dye
causes a shift of the equilibrium toward the imine isomer due to electron-withdrawal effect of the
crowned metal cation on the amine nitrogen atom. This results in significant changes in the
absorption spectrum of the dye. The sandwich-type 2:1 complexes formed by dyes 1 with strontium
and barium cations show higher stability constants than the corresponding 1:1 complexes, with the
K2:1/K1:1 ratio reaching a value of 10. This phenomenon is related to interchromophoric stacking
interactions in the sandwich structures; the greater the number of short stacking contacts in the 2:1
complex, the higher the K2:1/K1:1 ratio.
15

ACCEPTED MANUSCRIPT
4. Experimental
4.1 General methods
13
1H and C NMR spectra were measured on a Bruker AVANCE III 500 spectrometer. The solvent
(MeCN-d3 or CDCl3) was used as the internal reference.31 Absorption spectra were recorded on a
Specord M40 spectrophotometer. Chromatography was conducted on glass columns packed with
silica gel (63–100 µm). Thin layer chromatography (TLC) was carried out on Silufol UV-254
plates. Elemental analysis was performed on a Vario MICRO Cube analyzer. IR spectra were
recorded on a Bruker Vector 22 spectrophotometer in KBr pellets.
4.2 Materials
Acetonitrile (special purity grade, water content < 0.03%, v/v) was used without additional
purification. Benzene and ethanol were dried over anhydrous CaCl2 and CuSO4, respectively,
followed by distillation in vacuo. Mg(ClO4)2, Ca(ClO4)2, Sr(ClO4)2, and Ba(ClO4)2 were dried in
vacuo at 230 °C, and LiClO4, NaClO4, and KClO4 were dried in vacuo at 170 °C.
4.3 Spectrophotometric titration (SPT)
Experiments were conducted in MeCN in 1 and 4.75 cm quartz cells with ground-in stoppers. In
each SPT experiment, the total ligand concentration (CL) was maintained constant, and the total
metal concentration (CM) varied incrementally from 0 up to 2 mM (for the system 1b–Mg(ClO4)2,
the CM value varied up to 0.5 M). The CM-dependent absorption spectra obtained for each of the
ligand–metal perchlorate systems were subjected to global analysis using the methods described
previously.23 The complexation stoichiometry, the complex stability constants, and the absorption
spectra of pure complexes were determined by globally fitting the SPT data to the appropriate
complexation model (see the Results and Discussion section). For those systems, where 2:1 ligand–
metal complexes were detected, the desired characteristics were obtained by globally fitting the SPT
data from the two experiments conducted at different CL values in 1 and 4.75 cm cells. When
needed, a possible systematic error in the CM/CL ratio was taking into account by introducing one
more variable parameter into the fitting procedure (in addition to the complex stability constants).23
The standard deviations in the stability constants as the fitting parameters did not exceed 1%.
4.4 1H NMR titration
Experiments were conducted in MeCN-d3 in 5 mm NMR tubes (Norell, 500 MHz). The systems
studied were B15C5–Ba(ClO4)2 and 1b–Ba(ClO4)2. In the case of 1b, the initial solution contained
both the ligand and Ba(ClO4)2 (5 mL, CL = 2 mM, CM = 1 mM). During the NMR titration, the
value of CL was maintained at the same level, and the value of CM increased incrementally up to 32
16

ACCEPTED MANUSCRIPT
mM. Because of a low solubility of free dye 1b in MeCN-d3, its NMR spectrum was measured
separately at a smaller value of CL. The NMR titration of B15C5 with Ba(ClO4)2 was carried out
similarly, except that the CM value increased from zero. The proton signals that demonstrated the
most significant shifts and that could be assigned unambiguously were used in the subsequent
calculations. The chemical shifts
δ
were estimated by fitting the proton signals to a sum of
on CM obtained for
Lorentzian functions (after the baseline correction). The dependencies of
δ
different protons of the ligand were fitted globally to the 2:1 complexation model represented by
Equations (1) and (3), using the assumption that
δ
= ([L]δL + [L· Mn+]δ1:1 + 2[L2· Mn+]δ2:1)/CL
,
δ1:1, and δ2:1 are the proton chemical shifts of L, L· Mn+, and L2· Mn+, respectively. In
(5)
where δL
these calculations, the stability constant K2:1 was used as a variable parameter, whereas the constant
K1:1 was fixed at the value derived from the SPT measurements (Tables 1 and 2). A variation of the
K
1:1 value by ±30% had insignificant effect on the calculated value of K2:1/K1:1.
4.5 Mass spectrometry
Mass spectra were acquired using a custom-built Ortho-TOF mass spectrometer,32 equipped with a
custom-built electrosonic spray ionization (ESSI) source. Owing to the use of supersonic nebulizing
gas (N2), the ESSI technique provides very efficient desolvation of ionic species and narrow charge-
state distributions.33 The spectrometer provides ~ 10000 FWHM resolution. It contains two
transport radio frequency quadrupoles (RFQ),34 facilitating efficient declusterization and transfer of
ions to the Ortho-TOF mass analyzer. The ions are transferred from atmospheric pressure region via
a metal capillary (0.4 mm ID, 11 cm long) to the interface consisted of two RFQ ion guides. The
electrical potential applied to the sample solution via a stainless steel union (connector) can be
tuned between 0 and 3 kV. The sample solution was injected by a syringe pump with a flow rate of
1 µLmin−1.
4.6 Quantum-chemical calculations
The molecular structures of complexes (1)2· Sr2+ in MeCN were calculated as follows. First, various
conformations of model complexes (1)2· Na+ in the gas phase were analyzed using the
parameterized electronic structure model developed by Laikov35 and implemented in the Priroda 14
program.36 The sodium atom was used in these preliminary calculations because the method has no
parameterization for strontium. For each complex, several most probable conformations were
selected in which sodium atoms were replaced by strontium atoms to perform the subsequent DFT
calculations using the ORCA 3.0 program package.37 Geometry optimizations of complexes
(1)2· Sr2+ were carried out using the BLYP functional38,39 with the def2-TZVP basis set,40 the D3
17

ACCEPTED MANUSCRIPT
dispersion correction,41 and the gCP counterpoise correction.42 The COSMO method43 was used to
simulate effects of MeCN as the experimental solvent.
4.7 Synthesis of precursors
Compound 2a was prepared from 1-chloro-9,10-anthraquinone (5) according to the procedure
described previously.44 4-(tert-Butyl)phenol (16 mmol) and KOH (8 mmol) were mixed with 4
mmol of 5 and a catalytic amount of metallic copper. The mixture was heated at 130 °C with
stirring under reflux for 2 hours, then cooled to 100 °C and added to 50 mL of 10% aqueous KOH.
The resulting yellow precipitate was filtered off and washed, first with 100 mL of 5% aqueous
KOH and then with distilled water to neutral pH. The residue was dried and subjected to column
chromatography on silica gel using toluene as the eluent. The second yellow fraction was collected,
evaporated to dryness and then recrystallized from ethanol to give a flaky yellow solid (1.18 g, 81%
yield). A similar procedure was used to prepare 2-, 4-, and 5-amino derivatives of 2a (6a–c) from
the corresponding amino derivatives of 5. Benzoylation of 6a–c resulted in compounds 2b–d,
respectively.44 Compound 2e was obtained by acylation of 6a with trifluoroacetyl chloride. The 1H
NMR spectra of compounds 2 are presented in Figures S18–S23. 4’-Aminobenzo-15-crown-5 ether
(3) was prepared by Pd/C-catalyzed reduction of 4’-nitrobenzo-15-crown-5 ether by hydrazine
hydrate in diethylene glycol dimethyl ether.45
4.8 Synthesis of dyes 1a–e (general method)
1-Aryloxy-9,10-anthraquinone 2 (0.20 mmol) was dissolved in dry benzene (100 mL), then crown
ether 3 (0.25 mmol) was added, and the solution was exposed to sunlight for 6–8 hours until
compound 2 was completely consumed (monitoring by TLC). The reaction mixture was evaporated
in vacuo at 40 °C. The residue was washed with hexane, filtered off, and dissolved in benzene (15
mL). The solution was subjected to column chromatography on silica gel. First, yellow by-product
(1-hydroxyanthraquinone) was separated by eluation with benzene. Then a deep colored fraction
containing compound 1 was collected by eluation with a 3:1 benzene–ethanol mixture; the solvent
was evaporated in vacuo at 40 °C and the residue was recrystallized from a 1:1 benzene–ethanol
mixture.
4-Hydroxy-10-((2,3,5,6,8,9,11,12-
octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl)imino)anthracen-9(10H)-one
1
(1a). Compound 1a was obtained as an orange solid (0.069 g, 71%); m.p. 125–127 °C. H NMR
(500 MHz, CDCl3, Fig. S24):
δ = 14.88 (s, 1H; OH), 8.30 (dd, J = 7.8, 1.5 Hz, 1H; 5-H), 7.82 (dd, J
= 7.6, 1.3 Hz, 1H; 8-H), 7.51–7.58 (m, 2H; 6,7-H), 7.48 (dd, J = 8.2, 1.2 Hz, 1H; 4-H), 7.33–7.36
(m, 1H; 3-H), 7.31 (dd, J = 8.2, 1.2 Hz, 1H; 2-H), 6.88 (d, J = 8.4 Hz, 1H; 5'-H), 6.57 (d, J = 2.4
18

ACCEPTED MANUSCRIPT
Hz, 1H; 2'-H), 6.53 (dd, J = 8.4, 2.4 Hz, 1H; 6'-H), 4.15–4.20 (m, 2H; α-H), 4.02–4.08 (m, 2H; α'-
H), 3.93–3.97 (m, 2H; β-H), 3.86–3.91 (m, 2H; β'-H), 3.71–3.83 (m, 8H; γ,δ,δ',γ'-H) ppm. 13C NMR
(500 MHz, CDCl3, Fig. S25):
δ = 183.74 (10-C), 161.45 (9-C), 159.53 (1-C), 150.48 (3'-C), 147.18
(4'-C), 141.76 (1'-C), 134.03 (12-C), 132.94 (11-C), 132.37 (7-C), 132.31 (6-C), 132.01 (14-C),
130.01 (13-C), 129.48 (8-C), 128.08 (5-C), 124.11 (3-C), 118.47 (2-C), 118.22 (4-C), 115.03 (5'-C),
112.57 (6'-C), 106.47 (2'-C), 71.17 (δ-C), 71.10 (δ'-C), 70.51 (γ-C), 70.41 (γ'-C), 69.66 (β-C), 69.40
(β'-C), 69.32 (α-C), 68.85 (α'-C) ppm. IR (KBr) ν̃
[cm−1]: 3439 (OH), 3073 (CHar), 2924, 2856
(CH2), 1665 (C=O), 1591 (C=N), 1555, 1512 (C=Car). ESI-MS: m/z calcd for C28H27NO7+H+:
490.186 [M+H+]; found: 490.194. Elemental analysis calcd (%) for C28H27NO7: C 68.70, H 5.56, N
2.86; found: C 68.61, H 5.62, N 2.90.
N-(1-Hydroxy-9-((2,3,5,6,8,9,11,12-
octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl)imino)-10-oxo-9,10-
dihydroanthracen-2-yl)benzamide (1b). Compound 1b was obtained as a brown powder (0.089 g,
1
73%); m.p. 157–159 °C. H NMR (500 MHz, MeCN-d3–CDCl3 (4:1), Fig. S26):
δ = 16.57 (s, 1H;
OH), 9.18 (s, 1H; NH), 8.74 (d, J = 8.4 Hz, 1H; 4-H), 8.28 (dd, J = 7.8, 1.2 Hz, 1H; 5-H), 7.94–7.98
(m, 2H; 2'',6''-H), 7.82 (d, J = 8.4 Hz, 1H; 3-H), 7.60–7.69 (m, 2H; 6,7-H), 7.54–7.58 (m, 2H; 3'',5''-
H), 7.51 (d, J = 8.2, 1.1 Hz, 1H; 8-H), 7.39 (td, J = 7.3, 1.5 Hz, 1H; 4''-H), 7.11 (d, J = 8.4 Hz, 1H;
5'-H), 6.91 (d, J = 2.3 Hz, 1H; 2'-H), 6.82 (dd, J = 8.4, 2.3 Hz, 1H; 6'-H), 4.22–4.29 (m, 2H; α-H),
4.07–4.15 (m, 2H; α'-H), 3.89–3.96 (m, 2H; β-H), 3.81–3.87 (m, 2H; β'-H), 3.68–3.81 (m, 8H;
γ,γ',δ,δ'-H) ppm. 13C NMR (500 MHz, MeCN-d3–CDCl3 (4:1), Fig. S28):
δ = 182.86 (10-C), 166.33
(NHCO), 161.82 (9-C), 154.42 (1-C), 149.36 (3'-C), 146.56 (4'-C), 141.57 (1'-C), 135.47 (2-C),
135.42 (12-C), 135.17 (1''-C), 133.80 (7-C), 133.34 (6-C), 133.08 (4''-C), 130.44 (8-C), 129.98
(3'',5''-C), 129.25 (11-C), 128.75 (5-C), 128.20 (2'',6''-C), 127.31 (14-C), 126.29 (13-C), 122.26 (4-
C), 119.56 (3-C), 116.25 (5'-C), 115.63 (6'-C), 108.57 (2'-C), 69.67 (δ-C), 69.65 (δ'-C), 69.12 (γ-C),
69.04 (γ'-C), 68.75 (β,β'-C), 68.57 (α,α'-C) ppm. IR (KBr) ν̃
[cm−1]: 3431, 3378 (OH, NH), 3073
(CHar), 2912, 2866 (CH2), 1671 (C=O), 1653 (C=N), 1590, 1513 (C=Car). ESI-MS: m/z calcd for
C35H32N2O8+H+: 609.223 [M+H+]; found: 609.260. Elemental analysis calcd (%) for C35H32N2O8: C
69.07, H 5.30, N 4.60; found: C 69.07, H 5.66, N 4.49.
N-(4-Hydroxy-10-((2,3,5,6,8,9,11,12-
octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl)imino)-9-oxo-9,10-
dihydroanthracen-1-yl)benzamide (1c). Compound 1c was obtained as a dark red powder (0.071
g, 58%); m.p. 161–163 °C. 1H NMR (500 MHz, CDCl3, Fig. S29):
δ = 15.58 (s, 1H; OH), 13.28 (s,
1H; NH), 9.16 (d, J = 9.4 Hz, 1H; 3-H), 8.36 (dd, J = 7.9, 1.4 Hz, 1H; 5-H), 8.14–8.18 (m, 2H;
2'',6''-H), 7.55–7.62 (m, 4H; 6,7,3'',5''-H), 7.50 (d, J = 8.1 Hz, 1H; 8-H), 7.44 (d, J = 9.4 Hz, 1H; 2-
19

ACCEPTED MANUSCRIPT
H), 7.33–7.40 (m, 1H; 4''-H), 6.88 (d, J = 8.4 Hz, 1H; 5'-H), 6.61 (d, J = 2.4 Hz, 1H; 2'-H), 6.55 (dd,
J = 8.4, 2.4 Hz, 1H; 6'-H), 4.15–4.20 (m, 2H; 2 × α-H), 4.03–4.09 (m, 2H; 2 × α'-H), 3.93–3.98 (m,
2H; 2 × β-H), 3.87–3.92 (m, 2H; 2 × β'-H), 3.74–3.84 (m, 8H; 2 × γ-H, 2 × γ'-H, 2 × δ-H, 2 × δ'-H)
13
ppm. C NMR (500 MHz, CDCl3, Fig. S30):
δ = 187.27 (10-C), 166.38 (NHCO), 159.36 (9-C),
158.58 (1-C), 150.51 (3'-C), 147.36 (4'-C), 141.25 (1'-C), 135.81 (4-C), 135.13 (12-C), 134.51 (11-
C), 132.51 (14-C), 132.16 (1''-C), 132.10 (13-C), 129.30 (4''-C), 129.21 (7-C), 129.00 (3'',5''-C),
128.30 (6-C), 127.75 (2'',6''-C), 127.69 (8-C), 126.78 (5-C), 116.49 (3-C), 116.36 (2-C), 114.96 (5'-
C), 113.00 (6'-C), 106.83 (2'-C), 71.16 (δ-C), 71.11 (δ'-C), 70.49 (γ-C), 70.40 (γ'-C), 69.63 (β-C),
69.39 (β'-C), 69.28 (α-C), 68.88 (α'-C) ppm. IR (KBr) ν̃
[cm−1]: 3356, 3308 (OH, NH), 3062
(CHar.), 2950, 2921 (CH2), 1671, 1630 (C=O, C=N), 1601, 1582 (C=Car). ESI-MS: m/z calcd for
C35H32N2O8+H+: 609.223 [M+H+]; found: 609.242. Elemental analysis calcd (%) for C35H32N2O8: C
69.07, H 5.30, N 4.60; found: C 68.77, H 5.31, N 4.65.
N-(5-Hydroxy-10-((2,3,5,6,8,9,11,12-
octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl)imino)-9-oxo-9,10-
dihydroanthracen-1-yl)benzamide (1d). Compound 1d was obtained as a dark red powder (0.078
g, 64%); m.p. 163–165 °C. 1H NMR (500 MHz, CDCl3, Fig. S31):
δ = 14.57 (s, 1H; OH), 13.34 (s,
1H; NH), 9.11 (dd, J = 8.4, 1.1 Hz, 1H; 8-H), 8.14–8.19 (m, 2H; 2'',6''-H), 7.82 (dd, J = 7.6, 1.1 Hz,
1H; 6-H), 7.56–7.65 (m, 3H; 3'',4'',5''), 7.54 (t, J = 8.0 Hz, 1H; 7-H), 7.39 (t, J = 8.2 Hz, 1H; 3-H),
7.29–7.34 (m, 2H; 2,4-H), 6.86 (d, J = 8.4 Hz, 1H; 5'-H), 6.56 (d, J = 2.3 Hz, 1H; 2'-H), 6.54 (dd, J
= 8.4, 2.3 Hz, 1H; 6'-H), 4.15–4.20 (m, 2H; 2 × α-H), 4.03–4.09 (m, 2H; 2 × α'-H), 3.93–3.98 (m,
2H; 2 × β-H), 3.87–3.92 (m, 2H; 2 × β'-H), 3.74–3.84 (m, 8H; 2 × γ-H, 2 × γ'-H, 2 × δ-H, 2 × δ'-H)
13
ppm. C NMR (500 MHz, CDCl3, Fig. S32):
δ = 188.15 (10-C), 166.60 (NHCO), 160.74 (9-C),
159.35 (1-C), 150.46 (3'-C), 142.45 (4'-C), 141.61 (1'-C), 134.76 (5-C), 133.94 (12-C), 133.09 (14-
C), 132.95 (11-C), 132.43 (13-C), 131.05 (1''-C), 129.17 (4''-C), 129.09 (3'',5''-C), 127.80 (2'',6''-C),
124.86 (3-C), 124.01 (7-C), 123.82 (8-C), 118.79 (4-C), 118.71 (6-C), 117.76 (2-C), 116.49 (5'-C),
113.15 (6'-C), 106.84 (2'-C); 71.18 (δ-C), 71.12 (δ'-C), 70.53 (γ-C), 70.45 (γ'-C), 69.64 (β-C), 69.40
(β'-C), 69.28 (α-C), 68.92 (α'-C) ppm. ESI-MS: m/z calcd for C35H32N2O8+H+: 609.223 [M+H+];
found: 609.248. Elemental analysis calcd (%) for C35H32N2O8: C 69.07, H 5.30, N 4.60; found: C
68.82, H 5.32, N 4.68.
2,2,2-Trifluoro-N-(1-hydroxy-9-((2,3,5,6,8,9,11,12-
octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl)imino)-10-oxo-9,10-
dihydroanthracen-2-yl)acetamide (1e). Compound 1e was obtained as a dark red powder (0.089
1
g, 74%); m.p. 153–155 °C. H NMR (500 MHz, CDCl3, Fig. S33):
δ = 17.34 (s, 1H; OH), 9.35 (s,
1H; NH), 8.58 (d, J = 8.3 Hz, 1H; 3-H), 8.35 (dd, J = 7.8, 1.1 Hz, 1H; 5-H), 7.82 (d, J = 8.3 Hz, 1H;
20

ACCEPTED MANUSCRIPT
4-H), 7.63 (td, J = 7.8, 1.1 Hz, 1H; 6-H), 7.56 (dd, J = 8.2, 1.0 Hz, 1H; 8-H), 7.38 (td, J = 7.8, 1.5
Hz, 1H; 7-H), 6.92 (d, J = 8.5 Hz, 1H; 5'-H), 6.66–6.71 (m, 2H; 2',6'-H), 4.17–4.22 (m, 2H; α-H),
4.03–4.09 (m, 2H; α'-H), 3.94–3.99 (m, 2H; β-H), 3.87–3.92 (m, 2H; β'-H), 3.74–3.83 (m, 8H;
13
γ,γ',δ,δ'-H) ppm. C NMR (500 MHz, CDCl3, Fig. S35):
δ = 181.94 (10-C), 160.16 (9-C), 156.25
(NHCO), 154.84 (1-C), 150.58 (3'-C), 148.38 (4'-C), 137.65 (1'-C), 134.50 (2-C), 133.11 (7-C),
132.50 (6-C), 131.96 (11-C), 129.38 (8-C), 129.12 (12-C), 128.62 (5-C), 128.36 (14-C), 127.77
(13-C), 122.18 (4-C), 118.49 (3-C), 115.14 (CF3), 114.66 (5'-C), 114.21 (6'-C), 107.53 (2'-C), 71.17
(δ-C), 71.13 (δ'-C), 70.42 (γ-C), 70.37 (γ'-C), 69.52 (β-C), 69.32 (β'-C), 69.15 (α-C), 68.98 (α'-C)
ppm. IR (KBr) ν̃
[cm−1]: 3333 (OH, NH), 3075 (C–Har), 2932, 2860 (C–H), 1719 (C=O in
NHCOCF3), 1655 (C=O, C=N), 1588 (C=Car), 1541, 1510 (C=Car), 1129 (CF3). ESI-MS: m/z calcd
for C30H27F3N2O8+H+: 601.179 [M+H+]; found: 601.170. Elemental analysis calcd (%) for
C30H27F3N2O8: C 60.00, H 4.53, N 4.66; found: C 59.86, H 4.42, N 4.81.
Acknowledgments
The authors thank Dr. A. V. Chernyak for his assistance with NMR experiments.
Supplementary data
Supplementary data related to this article can be found at http://dx.doi.org/...
21

ACCEPTED MANUSCRIPT
References
1.
Antonov L. Tautomerism: Methods and Theories; Wiley-VCH: Weinheim, 2014.
doi:10.1002/9783527658824
2.
Izatt, R. M.; Pawlak, K.; Bradshaw, J. S.; Bruening, R. L. Chem. Rev. 1991, 91, 1721–2085.
doi:10.1021/cr00008a003
3.
4.
Shinkai, S. Pure Appl. Chem. 1987, 59, 425–430. doi:10.1351/pac198759030425
Ushakov, E. N.; Alfimov, M. V.; Gromov, S. P. Macroheterocycles 2010, 3, 189–200.
doi:10.6060/mhc2010.4.189
5.
6.
7.
Natali, M.; Giordani, S. Chem. Soc. Rev. 2012, 41, 4010–4029. doi:10.1039/c2cs35015g
Löhr, H.-G.; Vögtle, F. Acc. Chem. Res. 1985, 18, 65–72. doi:10.1021/ar00111a001
de Silva, A. P.; Gunaratne, H. Q. N.; Gunnlaugsson, T.; Huxley, A. J. M.; McCoy, C. P.;
Rademacher, J. T.; Rice, T. E. Chem. Rev. 1997, 97, 1515–1566. doi:10.1021/cr960386p
Chapoteau, E.; Czech, B. P.; Gebauer, C. R.; Kumar, A.; Leong, K.; Mytych, D. T.; Zazulak,
W.; Desai, D. H.; Luboch, E.; Krzykawski, J.; Bartsch, R. A. J. Org. Chem. 1991, 56, 2575–
2579. doi:10.1021/jo00007a057
8.
9.
Hayvali, Z.; Hayvali, M.; Kiliç, Z.; Hökelek, T.; Weber, E. J. Incl. Phen. Macrocycl. Chem.
2003, 45, 285–294. doi:10.1023/A:1024568309739
10. Dubonosov, A. D.; Minkin, V. I.; Bren, V. A.; Shepelenko, E. N.; Tsukanov, A. V.; Starikov,
A. G.; Borodkin, G. S. Tetrahedron 2008, 64, 3160–3167. doi:10.1016/j.tet.2008.01.096
11. Deneva, V.; Burdzhiev, N.; Stanoeva, E.; Antonov, L. Spectrosc. Lett. 2010, 43, 22–27.
doi:10.1080/00387010903260273
12. Antonov, L. M.; Kurteva, V. B.; Simeonov, S. P.; Deneva, V. V.; Crochet, A.; Fromm, K. M.
Tetrahedron 2010, 66, 4292–4297. doi:10.1016/j.tet.2010.04.049
13. Gritsan, N. P.; Klimenko, L. S.; Leonenko, Z. V.; Mainagashev, I. Ya.; Mamatyuk, V. I.;
Vetchinov, V. P. Tetrahedron 1995, 51, 3061–3076. doi:10.1016/0040-4020(95)00046-B
14. Yatsenko, A. V.; Tafeenko, V. A.; Zhukov, S. G.; Medvedev, S. V.; Popov, S. I. Struct.
Chem. 1997, 8, 197–204. doi:10.1007/BF02263507
15. Martyanov, T. P.; Ushakov, E. N.; Savelyev, V. A.; Klimenko, L. S. Russ. Chem. Bull. 2012,
61, 2282–2294. doi:10.1007/s11172-012-0323-z
16. Pedersen, C. J. J. Am. Chem. Soc. 1970, 92, 386–391. doi:10.1021/ja00705a605
17. An, H.; Bradshaw, J. S.; Izatt, R. M.; Yan, Z. Chem. Rev. 1994, 94, 939–991.
doi:10.1021/cr00028a005
18. Fery-Forgues, S.; Al-Ali, F. J. Photochem. Photobiol. C: Photochem. Rev. 2004, 5, 139–153.
doi:10.1016/j.jphotochemrev.2004.07.001
22

ACCEPTED MANUSCRIPT
19. Sherman, C. L.; Brodbelt, J. S.; Marchand, A. P.; Poola, B. J. Am. Soc. Mass Spectrom. 2005,
16, 1162–1171. doi:10.1016/j.jasms.2005.03.014
20. Frański, R.; Gierczyk, B. J. Am. Soc. Mass Spectrom. 2010, 21, 545–549.
doi:10.1016/j.jasms.2009.12.018
21. Klimenko, L. S.; Kusov, S. Z.; Vlasov, V. M. Mendeleev Commun. 2002, 12, 102–103.
doi:10.1070/MC2002v012n03ABEH001592
22. Klimenko, L. S.; Kusov, S. Z.; Vlasov, V. M.; Tchabueva, E. N.; Boldyrev, V. V. Mendeleev
Commun. 2006, 16, 224–225. doi:10.1070/MC2006v016n04ABEH002294
23. Ushakov, E. N.; Gromov, S. P.; Fedorova, O. A.; Pershina, Yu. V.; Alfimov, M. V.;
Barigilletti, F.; Flamigni, L.; Balzani, V. J. Phys. Chem. A 1999, 103, 11188–11193.
doi:10.1021/jp9929420
24. Arnaud-Neu, F.; Delgado, R.; Chaves, S. Pure Appl. Chem. 2003, 75, 71–102.
doi:10.1351/pac200375010071
25. Shannon, R. D. Acta Cryst. 1976, A32, 751–767. doi:10.1107/S0567739476001551
26. Gromov, S. P.; Vedernikov, A. I.; Ushakov, E. N.; Kuz’mina, L. G.; Feofanov, A. V.;
Avakyan, V. G.; Churakov, A. V.; Alaverdyan, Yu. S.; Malysheva, E. V.; Alfimov, M. V.;
Howard, J. A. K.; Eliasson, B.; Edlund, U. G. Helv. Chim. Acta 2002, 85, 60–81.
doi:10.1002/1522-2675(200201)85:1<60::AID-HLCA60>3.0.CO;2-C
27. Schmidt, A.; Karas, M.; Dülcks, T. J. Am. Soc. Mass Spectr. 2003, 14, 492–500.
doi:10.1016/S1044-0305(03)00128-4
28. Kempen, E. C.; Brodbelt, J. S. Anal. Chem. 2000, 72, 5411–5416. doi:10.1021/ac000540e
29. Nakamura, M.; Fujioka, T.; Sakamoto, H.; Kimura, K. New J. Chem. 2002, 26, 554–559.
doi:10.1039/B111016K
30. Nakamura, M.; Takahashi, K.; Fujioka, T.; Kado, S.; Sakamoto, H.; Kimura, K. J. Am. Soc.
Mass Spectr. 2003, 14, 1110–1115. doi:10.1016/S1044-0305(03)00447-1
31. Gottlieb, H. E.; Kotlyar, V.; Nudelman, A. J. Org. Chem. 1997, 62, 7512–7515.
doi:10.1021/jo971176v
32. Dodonov, A. F.; Loboda, A. V.; Kozlovski, V. I.; Soulimenkov, I. V.; Raznikov, V. V.; Zhen,
Z.; Horwath, T.; Wollnik, H. Eur. J. Mass Spectrom. 2000, 6, 481–490. doi:10.1255/ejms.378
33. Hirabayashi, A.; Sakairi, M.; Takada, Ya.; Koizumi, H. Trends Anal. Chem. 1997, 16, 45–52.
doi:10.1016/S0165-9936(96)00078-7
34. Dodonov, A.; Kozlovski, V.; Loboda, A.; Raznikov, V.; Sulimenkov, I.; Tolmachev, A.;
Kraft, A.; Wollnik, H. Rapid Commun. Mass Spectrom. 1997, 11, 1649–1656.
doi:10.1002/(SICI)1097-0231(19971015)11:15<1649::AID-RCM67>3.0.CO;2-T
35. Laikov, D. N. J. Chem. Phys. 2011, 135, 134120–134130. doi:10.1063/1.3646498
23

ACCEPTED MANUSCRIPT
36. Laikov, D. N. Priroda, Quantum Chemical Program, Version 2014.02.23; Lomonosov
Moscow State University, Moscow, 2014.
37. Neese, F. WIREs Comput. Mol. Sci. 2012, 2, 73–78. doi:10.1002/wcms.81
38. Becke, A. D. Phys. Rev. A 1988, 38, 3098–3100. doi:10.1103/PhysRevA.38.3098
39. Lee, C.; Yang, W.; Parr, R. G. Phys. Rev.
B
1988, 37, 785–789.
doi:10.1103/PhysRevB.37.785
40. Weigend, F.; Ahlrichs, R. Phys. Chem. Chem. Phys. 2005, 7, 3297–3305.
doi:10.1039/B508541A
41. Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. J. Chem. Phys. 2010, 132, 154104–154119.
doi:10.1063/1.3382344
42. Kruse, H.; Grimme, S. J. Chem. Phys. 2012, 136, 154101–153116. doi:10.1063/1.3700154
43. Klamt, A.; Schüürmann, G. J. Chem. Soc., Perkin Trans. 2 1993, 799–805.
doi:10.1039/P29930000799
44. Fokin, E. P.; Russkikh, S. A.; Klimenko, L. S. Izv. Sib. Otd. Akad. Nauk SSSR, Ser. Khim.
Nauk. 1979, 9, 117–124 (in Russian).
45. Berezina, R. N.; Kobrin, V. S.; Kusov, S. Z.; Lubenets, E. G. Zh. Org. Khim. 1998, 34, 1581–
1582; Russ. J. Org. Chem. 1998, 34, 1517–1518.
24