Chemosensor activity of 2-(anthracen-9-yl)-substituted imidazolidines and hexahydropyrimidines

Article abstract of DOI:10.1134/S1070428012010162

A number of 2-(anthracen-9-yl)-substituted imidazolidines and hexahydropyrimidines were synthesized by reaction of N,N'-bis[aryl(hetaryl) methyl]ethylene-1,2-diamines and N,N'-bis[aryl(hetaryl)methyl]-propane-1,3- diamines with anthracene-9-carbaldehyde. The obtained compounds showed chemosensor activity toward Cd2+, Cu2+, and Hg2+ ions. Pleiades Publishing, Ltd., 2012.

Full text of DOI:10.1134/S1070428012010162

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 1, pp. 104–108. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © I.E. Tolpygin, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48, No. 1, pp. 109–113.
Chemosensor Activity of 2-(Anthracen-9-yl)-Substituted
Imidazolidines and Hexahydropyrimidines
I. E. Tolpygin
Institute of Physical and Organic Chemistry, Southern Federal University,
pr. Stachki 194/2, Rostov-on-Don, 344090, Russia
e-mail: tolpygin@ipoc.sfedu.ru
Received June 3, 2011
Abstract—A number of 2-(anthracen-9-yl)-substituted imidazolidines and hexahydropyrimidines were synthe-
sized by reaction of N,N′-bis[aryl(hetaryl)methyl]ethylene-1,2-diamines and N,N′-bis[aryl(hetaryl)methyl]-
propane-1,3-diamines with anthracene-9-carbaldehyde. The obtained compounds showed chemosensor activity
toward Cd2+, Cu2+, and Hg2+ ions.
DOI: 10.1134/S1070428012010162
cent sensors for H+, Zn2+, and Hg2+ cations [10] and
Cyclic aminals containing a saturated five-mem-
bered (imidazolidines) or six-membered ring (hexahy-
dropyrimidines) have found diverse applications due to
broad spectrum of their biological and physicochem-
ical properties. Hydrogenated imidazole and pyrimi-
dine derivatives exhibit anti-inflammatory and anal-
gesic activity [1–3], act as muscarine receptors [4], and
show antiparasitic and antibacterial properties [5, 6].
Coordination compounds based on imidazolidines
possess both ferromagnetic and antiferromagnetic
properties [7, 8]. 1,2,3-Trisubstituted imidazolidines
and hexahydropyrimidines can be used in the synthesis
of ion-active structures [9], as well as effective fluores-
anions [11] due to their strong complexing power.
Among 2-(anthracen-9-yl)imidazolidines, we previ-
ously found highly efficient chemosensors for Cu2+
and Hg2+ cations [12]. With a view to obtain new
fluorogenic derivatives of this class of compounds,
an attempt was made to extend their number via intro-
duction of substituents into positions 1 and 3 of the
heterocyclic fragment in 2-(anthracen-9-yl)-substituted
imidazolidine and hexahydropyrimidine.
1,2,3-Substituted cyclic aminals are generally syn-
thesized by reaction of the corresponding N,N′-disub-
Scheme 1.
Ar
Ar
N
N
CHO
n = 2
(1) PhMe, H+
(2) NaBH4, EtOH
Ar
Ar
IX–XII
H
H
H
H
2ArCHO + H2N(CH2)nNH2
HN
NH
( )n
I–VIII
Ar
N
N
Ar
n = 3
XIII–XVI
I, V, IX, XIII, Ar = 2-MeC6H4; II, VI, X, XIV, Ar = 2-MeOC6H4; III, VII, XI, XV, Ar = 2-HO-4-MeC6H3;
IV, VIII, XII, XVI, Ar = pyridin-2-yl; I–IV, n = 2; V–VIII, n = 3.
104

CHEMOSENSOR ACTIVITY OF 2-(ANTHRACEN-9-YL)-SUBSTITUTED IMIDAZOLIDINES
105
IX
X
XI
XII
12
10
8
6
4
2
0
H+
Zn2+
Cd2+
Ni2+
Co2+
Cu2+
Pb2+
Hg2+
Fig. 1. Relative change of fluorescence intensity of imidazolidines IX–XII (c = 5×10–6 M) in acetonitrile upon addition of metal
cations (c = 2.5×10–5).
stituted ethane-1,2-diamines and propane-1,3-diamines
with aldehydes [13, 14]. This procedure can also be
used for selective detection of a number of natural and
physiologically active compounds having an aldehyde
group [15]. Diarylmethyl and dihetarylmethyl deriva-
tives of ethane-1,2-diamine (compounds I–IV) and
propane-1,3-diamine (V–VIII) were prepared by
reduction of the corresponding diimines [3, 13].
2-(Anthracen-9-yl)-substituted imidazolidines IX–
XII and hexahydropyrimidines XIII–XVI were pre-
pared by classical procedure from equimolar amounts
of anthracene-9-carbaldehyde and the corresponding
diamine I–VIII in toluene in the presence of acid
catalyst.
1
The H NMR spectra of the products characteristi-
cally contained a singlet in the region δ 5.19–5.70 ppm
XIII XIV XV XVI
7
6
5
4
3
2
1
0
H+
Zn2+
Cd2+
Ni2+
Co2+
Cu2+
Pb2+
Hg2+
Fig. 2. Relative change of fluorescence intensity of hexahydropyrimidines XIII–XVI (c = 5×10–6 M) in acetonitrile upon addition of
metal cations (c = 2.5×10–5).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 1 2012

TOLPYGIN
106
from the 2-H proton. Conformational rigidity of the
imidazolidine ring is responsible for nonequivalence of
methylene protons in the heteroring, as well as in the
benzyl fragments. Increase in the size of the heteroring
in going to hexahydropyrimidine derivatives is accom-
panied by considerable complication of the spectral
fluorescence spectra before and after addition of the
corresponding cations (H+, Zn2+, Cd2+, Ni2+, Co2+,
Cu2+, Pb2+, Hg2+; Fig. 1). As reported previously for
structurally related compounds [12], the most appreci-
able variation of fluorescence intensity of imidazoli-
dines IX–XI was induced by addition of Cu2+ and Hg2+
ions; simultaneously, the sensitivity to Zn2+ and Cd2+
cations increased. Bis(pyridylmethyl) derivative XII
turned out to be more selective for Cd2+. Addition of
cadmium acetate to a solution of XII resulted in
11-fold increase of the fluorescence intensity (Fig. 1)
and blue shift of the fluorescence maximum by 26 nm,
indicating effective chelation of cadmium(II) ions.
1
pattern and overlap of signals in the H NMR spectra
as a result of additional conformational distortions of
the heterocyclic fragment. Signals from the 1-H and
8-H protons in the anthracene fragment were displaced
appreciably downfield (by 0.5–2.0 ppm) due to inter-
action with the aryl(hetaryl)methyl substituents in
positions 1 and 3 of the heteroring, and they appeared
as two broadened singlets (imidazolidine derivatives)
or doublets with a coupling constant J of 9.2–9.8 Hz
(hexahydropyrimidines).
All compounds IX–XVI showed weak fluorescence
(λmax 402–450 nm) arising from specific electronic
effects [16]. However, only compounds X and XII
displayed typical anthracene-like fluorescence pattern
(three bands, λmax 402 nm), whereas fluorescence of
the other compounds was characterized by a single
maximum at λmax 420–450 nm.
Increase in the size of the heteroring and hence
increase in conformational mobility leads to enhanced
selectivity of compounds XIII, XV, and XVI for cop-
per(II) ions. However, addition of copper(II) acetate to
hexahydropyrimidines XV and XVI raises the fluores-
cence intensity (I/I0) by a factor of 6–7, whereas com-
plete fluorescence quenching is observed for com-
pound XIII (Fig. 2).
Differences in the sensing activities and their mech-
anisms between the five- and six-membered deriva-
tives were observed most clearly in the reactions of
compounds XII and XVI with Zn2+ cations (Fig. 3).
Imidazolidine derivative XII shows quite weak fluo-
rescence, which is not typical of anthracen-9-yl-substi-
tuted compounds (λmax 450 nm). This is likely to be
related to intramolecular photoinduced charge transfer
(PCT) between the fluorophore and receptor [16, 17].
Complex formation with Zn2+ ions partly restores
anthracene-like fluorescence spectrum (λmax 423 nm)
and simultaneously increases the fluorescence intensity
by a factor of ~3. Obviously, the behavior of hexahy-
dropyrimidine derivative XVI is determined by reverse
photoinduced electron transfer (PET). In the presence
of zinc(II) acetate fluorescence quenching is observed
(I446/I4029 = 0.25), and the fluorescence maximum shifts
by 17 nm toward longer wavelengths.
Chemosensor activity of compounds IX–XVI in so-
lution (c = 5×10–6 M) was studied by comparing their
XVI (λmax 429 nm)
Ifl
Ifl
XII + Zn2+ (λmax 423 nm)
XII (λmax 450 nm)
XVI + Zn2+
(λmax 446 nm)
To conclude, this study on the spectral parameters
and complexing power of new imidazolidine and hexa-
hydropyrimidine derivatives containing an anthracene
fragment revealed high chemosensor activity of some
compounds toward heavy metal cations, such as Cd2+,
Cu2+, and Hg2+.
EXPERIMENTAL
400 450 500 550
400 450 500 550
1
λ, nm
The H NMR spectra were recorded on a Varian
Unity 300 spectrometer (300 MHz) from solutions in
CDCl3 or DMSO-d6 using the residual proton signals
Fig. 3. Fluorescence spectra of aminals XII and XVI before
and after complex formation with Zn2+ ions.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 1 2012

CHEMOSENSOR ACTIVITY OF 2-(ANTHRACEN-9-YL)-SUBSTITUTED IMIDAZOLIDINES
107
212°C (from xylene). IR spectrum, ν, cm–1: 3387,
1595, 1480, 1387. H NMR spectrum, δ, ppm: 2.31 s
of the solvent as reference (CHCl3, δ 7.25 ppm;
1
DMSO-d5, δ 2.50 ppm). The electronic absorption
spectra were measured on a Varian Cary 100 spectro-
photometer, and the luminescence spectra were record-
ed on Hitachi 650-60 and Varian Eclipse spectrofluo-
rimeters from solutions in acetonitrile (c = 5×10–6 M).
The IR spectra were obtained on a Specord 75IR
instrument. The melting points were determined in
glass capillaries using a PTP (M) melting point appa-
ratus. The progress of reactions and the purity of
products were monitored by TLC on Silufol UV-254
plates using CHCl3 as eluent; spots were visualized by
treatment with iodine vapor in a moist chamber.
(6H, CH3), 2.77–2.82 q (2H, CH2CH2), 3.48 d (2H,
CH2, J = 13.5 Hz), 3.50–3.60 q (2H, CH2CH2), 3.96 d
(2H, CH2, J = 13.1 Hz), 5.51 s (1H, CH), 6.71–8.00 m
(12H, Harom), 8.44 s (1H, 10-H), 8.52 d (1H, 1-H, J =
9.2 Hz), 9.14 d (1H, 8-H, J = 9.2 Hz), 9.87 s (2H, OH).
Fluorescence spectrum: λmax 420 nm. Found, %:
C 81.18; H 6.65; N 5.70. C33H32N2O2. Calculated, %:
C 81.12; H 6.60; N 5.73.
2-(Anthracen-9-yl)-1,3-bis(pyridin-2-ylmethyl)-
imidazolidine (XII). Yield 78%, mp 222–223°C (from
butan-1-ol). IR spectrum, ν, cm–1: 1595, 1465, 1385.
1H NMR spectrum, δ, ppm: 2.75–2.83 q and 3.51–
3.59 q (2H each, CH2CH2), 3.62 d (2H, CH2, J =
12.1 Hz), 3.82 d (2H, CH2, J = 12.5 Hz), 5.70 s (1H,
CH), 6.83–8.45 m (15H, Harom), 8.73 br.s (1H, 1-H),
9.76 br.s (1H, 8-H). Fluorescence spectrum:
λmax 450 nm. Found, %: C 81.00; H 6.04; N 12.96.
C29H26N4. Calculated, %: C 80.90; H 6.09; N 13.01.
Initial N,N′-bis(arylmethyl)ethane-1,2-diamines and
N,N′-bis(arylmethyl)propane-1,3-diamines I–VIII
were synthesized according to the procedures de-
scribed in [13–15].
Imidazolidines IX–XII and hexahydropyrimi-
dines XIII–XVI (general procedure). A solution of
3.5 mmol of the corresponding N,N′-disubstituted
ethane-1,2-diamine I–IV or propane-1,3-diamine V–
VIII and 3 mmol of anthracene-9-carbaldehyde in
10 ml of toluene was heated for 2 h in the presence of
acetic acid as catalyst. The mixture was evaporated on
a rotary evaporator, the residue was cooled, and the
precipitate was filtered off, washed with cold metha-
nol, dried in air, and recrystallized from appropriate
solvent.
2-(Anthracen-9-yl)-1,3-bis(2-methylbenzyl)-
hexahydropyrimidine (XIII). Yield 70% (from butan-
1-ol), mp 180–181°C. IR spectrum, ν, cm–1: 1450,
1
1380. H NMR spectrum, δ, ppm: 1.50–2.38 m (10H,
CH2, CH3), 2.63–3.30 m (6H, CH2), 5.19 s (1H, CH),
6.74–8.50 m (15H, Harom), 8.65 d (1H, 1-H, J =
9.2 Hz), 10.15 d (1H, 8-H, J = 9.2 Hz). Fluorescence
spectrum: λmax 402 nm. Found, %: C 86.69; H 7.31;
N 6.00. C34H34N2. Calculated, %: C 86.77; H 7.28;
N 5.95.
2-(Anthracen-9-yl)-1,3-bis(2-methylbenzyl)imid-
azolidine (IX). Yield 87%, mp 184–186°C (from
1
MeCN). IR spectrum, ν, cm–1: 1465, 1380. H NMR
2-(Anthracen-9-yl)-1,3-bis(2-methoxybenzyl)-
hexahydropyrimidine (XIV). Yield 81% (from
xylene), mp 165–166°C. IR spectrum, ν, cm–1: 1450,
spectrum, δ, ppm: 2.43 s (6H, CH3), 2.55–2.64 q (2H,
CH2CH2), 3.35 d (2H, CH2, J = 13.0 Hz), 3.30–3.40 q
(2H, CH2CH2), 3.70 d (2H, CH2, J = 12.0 Hz), 5.58 s
(1H, CH), 7.05–7.78 m (12H, Harom), 8.10 d (2H, 4-H,
5-H, J = 8.6 Hz), 8.50 s (1H, 10-H), 8.86 br.s (1H,
1-H), 9.91 br.s (1H, 8-H). Fluorescence spectrum:
λmax 431 nm. Found, %: C 86.73; H 7.10; N 6.17.
C33H32N2. Calculated, %: C 86.80; H 7.06; N 6.14.
1
1380. H NMR spectrum, δ, ppm: 1.64–2.40 m (4H,
CH2), 2.87–3.55 m (12H, CH2, CH3), 5.31 s (1H, CH),
6.40–10.10 m (17H, Harom). Fluorescence spectrum:
λmax 422 nm. Found, %: C 81.17; H 6.90; N 5.52.
C34H34N2O2. Calculated, %: C 81.24; H 6.82; N 5.57.
2-(Anthracen-9-yl)-1,3-bis(2-hydroxy-4-methyl-
benzyl)hexahydropyrimidine (XV). Yield 74% (from
butan-1-ol), mp 208–209°C. IR spectrum, ν, cm–1:
2-(Anthracen-9-yl)-1,3-bis(2-methoxybenzyl)-
imidazolidine (X). Yield 90%, mp 272–273°C (from
diethylene glycol dimethyl ether). IR spectrum, ν,
1
1
cm–1: 1590, 1485, 1385. H NMR spectrum, δ, ppm:
3150, 1460, 1380. H NMR spectrum, δ, ppm: 1.42–
2.35 m (10H, CH2, CH3), 2.68–3.50 m (6H, CH2),
5.20 s (1H, CH), 6.94–8.00 m (14H, Harom, OH), 8.35 s
(1H, 10-H), 8.80 d (1H, 1-H, J = 9.2 Hz), 10.20 d (1H,
8-H, J = 9.2 Hz). Fluorescence spectrum: λmax 402 nm.
Found, %: C 81.28; H 6.78; N 5.61. C34H34N2O2. Cal-
culated, %: C 81.24; H 6.82; N 5.57.
2.57–2.76 m (4H, CH2CH2), 3.43 s (6H, CH3), 3.50–
3.64 m (4H, CH2), 5.64 s (1H, CH), 6.62–8.14 m (14H,
Harom), 8.58 s (1H, 10-H), 8.80 br.s (1H, 1-H), 9.70 br.s
(1H, 8-H). Fluorescence spectrum: λmax 440 nm.
Found, %: C 81.20; H 6.67; N 5.65. C33H32N2O2. Cal-
culated, %: C 81.12; H 6.60; N 5.73.
2-(Anthracen-9-yl)-1,3-bis(2-hydroxy-4-methyl-
2-(Anthracen-9-yl)-1,3-bis(pyridin-2-ylmethyl)-
benzyl)imidazolidine (XI). Yield 85%, mp 211–
hexahydropyrimidine (XVI). Yield 84%, mp 194–
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 1 2012

TOLPYGIN
108
195°C (from toluene). IR spectrum, ν, cm–1: 1450,
1380. H NMR spectrum, δ, ppm: 1.51–2.56 m (4H,
CH2), 3.04–3.57 m (6H, CH2), 5.40 s (1H, CH), 6.83–
8.44 m (15H, Harom), 8.68 d (1H, 1-H, J = 9.8 Hz),
10.30 d (1H, 8-H, J = 9.8 Hz). Fluorescence spectrum:
λmax 429 nm. Found, %: C 80.97; H 6.40; N 12.63.
C30H28N4. Calculated, %: C 81.05; H 6.35; N 12.60.
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This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 09-03-00052), by the Ministry of Education and
Science of the Russian Federation (special-purpose
program “Development of Scientific Potential at
Higher School,” project no. 2.2.1.1/12630), and by the
Council for Grants at the President of the Russian
Federation (project no. NSh-3233.2010.3).
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