Electrochemical and chemical synthesis of new luminescent schiff base complexes

Article abstract of DOI:10.1134/S1070363210020180

Bis-chelate complexes of zinc, cadmium, lead, and mercury with o-N-tosylbenzylidene imines containing the C₇H₁₅ and C₁₈H₃₇ substituents at the C=N group nitrogen atom were prepared by the methods of electrochemi

Full text of DOI:10.1134/S1070363210020180

ISSN 1070-3632, Russian Journal of General Chemistry, 2010, Vol. 80, No. 2, pp. 292–300. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.D. Garnovskii, A.S. Burlov, A.V. Metelitsa, I.G. Borodkina, K.A. Lysenko, S.O. Bezuglyi, E.D. Garnovskaya, E.V. Sennikova,
G.S. Borodkin, D.A. Garnovskii, 2010, published in Zhurnal Obshchei Khimii, 2010, Vol. 80, No. 2, pp. 267–275.
Dedicated to the 75th anniversary of Academician V.I. Minkin
Electrochemical and Chemical Synthesis
of New Luminescent Schiff Base Complexes
A. D. Garnovskiia, A. S. Burlova, A. V. Metelitsaa, I. G. Borodkinaa,
K. A. Lysenkob, S. O. Bezuglyic, E. D. Garnovskayaa, E. V. Sennikovaa,
G. S. Borodkina, and D. A. Garnovskiic
a Research Institute of Physical and Organic Chemistry of the Southern Federal University,
pr. Stachki, 194/2, Rostov-on-Don, 344090 Russia
e-mail: garn@ipoc.rsu.ru
b Nesmeyanov Institute of Organoelemental Compounds of Russian Academy of Sciences, Moscow, Russia
c Southern Scientific Center, Rostov-on-Don, Russia
Received March 26, 2009
Abstract―Bis-chelate complexes of zinc, cadmium, lead, and mercury with o-N-tosylbenzylidene imines
containing the С7Н15 and С18Н37 substituents at the C=N group nitrogen atom were prepared by the methods of
electrochemical and chemical syntheses. The structure of the azomethines and their complexes was established
1
by the methods of heteronuclear Н, 13С NMR spectroscopy (multidimensional and multinuclear COSY,
HETCOR and HETCOR_LONG techniques). The complexes, as demonstrated by the X-ray analysis for the
zinc chelate, have strongly distorted octahedral structure formed by the four azomethine nitrogen atoms and
two oxygen atoms of the tosyl fragments. The coordination compounds show fluorescence in the blue part of
the spectrum in high quantum yields for the zinc chelates.
DOI: 10.1134/S1070363210020180
The synthesis of metal complexes is the most im-
portant aspect of coordination chemistry [1–6]. Com-
plex compounds are generally prepared by the reaction
of metal salts with ligands of different types:
azomethines [7, 8], β-diketones [9], azo compounds
[10, 11], oximes [12, 13], and their analogs [3, 4]).
Synthetic methods using the template (ligand
precursors on the matrix of the complex-forming
agents), ligand exchange and metal exchange synthetic
transformations are widely applied [3, 4]. Considerable
segment in the synthesis of metal complexes occupy
direct methods: Preparation of coordination com-
pounds from metals in the zero oxidation state under
the conditions of electro- or gas phase reactions [3, 4,
14] as well as in the presence of ammonium salts [3, 4,
15], direct reaction of the complex forming agents with
ligands, and the template electrochemical trans-
formations [3, 4].
for the design of polyfunctional materials, for example,
magnetoactive [16–18], liquid-crystalline [19], metal-
polymeric [20], and luminescent [21, 22].
In the development of this field, we have prepared
the Schiff bases of the type I and using the methods of
electrochemical (ES) and chemical (CS) syntheses
isolated metal chelates II on their basis.
R
Ts
Ts
N
M0
N
N
ES (1)
MAc2
CS (2)
H
N
M
N
N
R
R
Ts
I
II
I, R = C7H15 (a), C18H37 (b); Ts = SO2C6H4CH3-p; II, M =
Zn, Cd, Hg, Pd.
The use of the aforementioned synthetic methods
allows preparation of various coordination compounds
292

ELECTROCHEMICAL AND CHEMICAL SYNTHESIS
293
Azomethines of the type I were obtained from о-N-
tosylaminobenzaldehyde and aliphatic amines with
long-chain alkyl at nitrogen. The latter were used to
increase the solubility of chelates II in nonpolar
solvents.
7.28 ppm, Н21. In the same manner the signals of
Н1–Н7 were assigned.
The signal of the N=CH proton appears at δ =
9.45 ppm, and the tosyl СH3 group resonates at δ =
2.28 ppm.
The data of elemental analysis, the characteristics
of the ligands and metal complexes on their basis are
given in Table 1.
The NH proton chemical shift at δ = 12.82 ppm was
proved by deuteration.
These results are consistent with the presence of the
aminoimine tautomer I which is characteristic of N-
tosylaminobenzylidene-tert-butyl imine also in the
crystal, as shown by the X-ray data [29].
The most typical for the ligands I is the aminoimine
1
tautomeric form. This is proved by the data of the Н
and 13С NMR spectroscopy with due regard of the
literature data [7, 23, 24]. With this, the multidimen-
sional and multinuclear NMR techniques COSY,
HETCOR and HETCOR_LONG were used [25–28].
For unequivocal assignment of the signals of the
protonated carbon atoms in the aromatic fragment in
the 13С NMR spectrum of compound I the two-
dimensional heteronuclear correlation NMR experiment
HETCOR was used.The cross peaks in the HETCOR
NMR spectrum point to the correlation of the
corresponding chemical shifts.
The use of the NMR techniques is demonstrated by
the example of compound I (R = C7H15).
For assignment of the signals in the aromatic
1
fragment in the Н NMR spectrum of compound I the
two-dimensional homonuclear correlation NMR
experiment (COSY) was used. It follows from the
COSY spectrum that the signal of Н11 (δ = 7.46 ppm)
correlates (strong cross peaks appear) with Н12 (δ =
7.04 ppm) and with Н13 (δ = 7.34 ppm). At the same
time, for Н13 (δ = 7.34 ppm) the correlation with Н14 at
δ = 7.49 ppm, is observed. The signal at δ = 7.63 ppm
corresponding to Н20 correlates with the signal at δ =
In such a manner the assignment of the chemical
shifts of the carbon atoms was made: Н1 (δ =
0.82 ppm) correlates with С1 (δ = 13.84 ppm), Н2 (δ =
1.26 ppm) with С2 (δ = 21.99 ppm), Н3 (δ = 1.26 ppm)
with С3 (δ = 31.20 ppm), Н4 (δ = 1.33 ppm) with С4
(δ = 28.42 ppm), Н5 (δ = 1.33 ppm) with С5 (δ =
26.52 ppm), Н6 (δ = 1.62 ppm) with С6 (δ =
Table 1. Elemental analyses of azomethines I and complexes II based thereon
Found, %
Calculated, %
Comp.
no.
Compo-
sition
R
M
mp, °С
Formula
С
Н
N
M
С
H
N
M
C7H15
H
69–70
67.75 7.61
7.48
7.32
7.37
6.26
С21H28N2O2S
67.70 7.59 7.52
Ia
IIaа C7H15
IIab C7H15
IIab C7H15
IIaа C7H15
IIab C7H15
IIaа C7H15
IIab C7H15
Zn
Zn
Hg
Cd
Cd
Pb
Pb
H
ZnL2
ZnL2
264–265 64.88 7.15
263–265 64.86 7.05
8.35
8.31
С42H54N4O4S2Zn 64.98 7.01 7.21
С42H54N4O4S2Zn 64.98 7.01 7.21
С42H54N4O4S2Hg 55.34 5.97 6.15
8.42
8.42
HgL2 198–199 55.43 6.01
CdL2
CdL2
PbL2
PbL2
249–250 61.38 6.56
248–250 61.31 6.52
219–220 55.02 5.84
219–220 55.12 5.81
6.79 13.74
6.83 13.76
6.15 22.64
6.13 22.69
6.18
С42H54N4O4S2Cd 61.27 6.61 6.80 13.65
С42H54N4O4S2Cd 61.27 6.61 6.80 13.65
С42H54N4O4S2Pb
С42H54N4O4S2Pb
С32H50N2O2S
54.94 5.93 6.10 22.57
54.94 5.93 6.10 22.57
72.96 9.57 5.32
C18H37
79–80
73.02 9.64
Ib
IIbа C18H37
IIbb C18H37
IIbа C18H37
IIbb C18H37
Zn
Zn
Cd
Cd
ZnL2
ZnL2
CdL2
CdL2
230–231 68.92 8.73
232–233 68.96 8.69
218–219 64.14 8.53
217–218 64.16 8.43
5.17
5.16
4.92
4.99
5.97
5.99
9.37
9.30
С64H98N4O4S2Zn 68.82 8.84 5.02
С64H98N4O4S2Zn 68.82 8.84 5.02
С64H98N4O4S2Сd 66.04 8.49 4.81
С64H98N4O4S2Сd 66.09 8.41 4.88
5.85
5.85
9.66
9.56
a Complexes obtained by electrochemical synthesis. b Complexes obtained by chemical synthesis.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010

294
GARNOVSKII et al.
Table 2. Chemical shifts 1H, 13C, and coupling constants J(Hg-H10), J(Cd-H10) of compounds Ia and IIa in DMSO-d6
24
24
CH3
CH3
21
21
23
21'
20'
23
21'
20'
20
20
O
O
22
22
13
11
14
16
13
11
14
16
S
S
15
O
15
O
12
12
19N
N
19N
N
18
M/2
H
17
4
2
4
2
6
17
6
10
10
1
1
CH3
CH3
3
5
3
7
5
7
IIа
Iа
Compound Nucleus
1
2
3
4
5
6
7
10
11
7.46
12
13
1H
0.82
13.84
1.26
21.99
1.26
31.20
1.33
28.42
1.33
26.52
1.62
30.34
3.58
58.90
8.45
164.52
7.04
7.34
Ia
13C
139.68 117.35 133.27
7.35 6.85 7.21
137.47 118.24 133.19
7.39 6.90 7.24
139.39 120.40 132.33
7.38 6.85 7.22
138.14 118.32 132.82
7.02 6.75 7.02
139.69 117.42 133.55
1H
0.74
13.77
0.93
21.86
0.93
30.82
1.06
27.99
1.08
26.17
1.35
29.53
4.13
60.55
8.55
170.53
IIa
M = Zn
13C
1H
0.77
13.80
1.06
21.92
1.06
31.00
1.12
28.24
1.36
26.09
1.56
30.08
3.65
61.87
8.55
170.90
IIa
M = Hg
13C
1H
0.74
13.92
0.95
22.04
0.95
30.97
1.07
28.25
1.09
26.32
1.52
30.44
3.69
61.99
8.52
171.71
IIa
M = Cd
13C
1H
0.86
14.02
1.28
22.02
1.28
31.32
1.33
28.53
1.33
26.61
1.69
30.41
3.72
58.85
8.45
164.83
IIa
M = Pb
13C
Table 2. (Contd.)
Compound Nucleus
14
15
16
17(15N) 18[J(M–H10)]
19
20
21
22
23
24
1H
7.49
122.30
12.82
7.63
7.28
2.28
Ia
13C
143.32 120.56 306.90
146.32 119.63
126.48 129.60
7.95 7.16
127.81 129.09
7.75 7.20
127.06 129.20
7.86 7.23
127.98 129.74
7.53 7.17
126.60 129.80
131.48 136.89 20.79
1H
7.47
119.04
138.29 142.05
2.24
20.75
IIa
M = Zn
13C
1H
7.49
121.22
(124.7)
(39.1)
2.28
IIa
M = Hg
13C
147.89 121.62 288.39
147.22 120.36
137.09 141.71 20.79
1H
7.42
119.29
139.81 142.33
2.26
20.92
IIa
M = Cd
13C
1H
7.36
122.55
135.33 136.75
2.26
20.96
IIa
M = Pb
13C
143.59 120.47
30.34 ppm), Н7 (δ = 3.58 ppm) with С7 (δ =
58.90 ppm), Н10 (δ = 8.45 ppm) with С10 (δ =
164.52 ppm), Н11 (δ= 7.46 ppm) with С11 (δ =
139.68 ppm), Н12 (δ = 7.04 ppm) with С12 (δ =
117.35 ppm), Н13 (δ = 7.34 ppm) with С13 (δ =
133.27 ppm), Н14 (δ = 7.49 ppm) with С14 (δ =
122.30 ppm), Н20 (δ = 7.63 ppm) with С20 (δ =
126.48 ppm), Н21 (δ = 7.28 ppm) with С21 (δ =
129.60 ppm).
To assign the signals of quaternary carbon atoms in
the aromatic fragment in the 13С NMR spectrum of
compound the two-dimensional heteronuclear
correlation NMR experiment HETCOR_LONG was
used, which allows to determine long-range couplings
between the protons and carbon atoms (in our case,
mostly 3J). For example, Н13 (δ = 7.34 ppm) correlates
with С15 (δ = 143.32 ppm) and С11 (δ = 139.68 ppm),
whereas Н12 (δ = 7.04 ppm) correlates with С14 (δ =
I
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010

ELECTROCHEMICAL AND CHEMICAL SYNTHESIS
295
Table 3. Chemical shifts 1H, 13C, and coupling constants J(Cd-H10) of compounds Ib and IIb in CDCl3
24
24
CH3
CH3
21
21
23
21'
23
21'
20'
20
20
20'
O
O
N
22
22
13
11
14
16
13
11
14
15
S
S
15
O
O
12
12
1N9
18
19
16
10
M/2
H
17
(4CH2)12
(4CH2)12
6
6
17
N
N
10
5
3
5
3
7
7
2
2
CH3
CH3
1
1
IIb
Ib
Compound
Nucleus
1
2
3
4
5
6
7
10
11
12
13
7.24
1H
0.88
14.08
1.22
22.64
1.25
31.88
1.25
29.31
1.36
27.23
1.72
30.90
3.59
60.77
8.23
7.29
7.02
Ib
13C
163.33 139.42 117.69 137.24
8.22 7.18 6.79 7.20
170.38 141.93 118.99 138.25
8.21 7.22 6.80 7.16
169.37 141.85 118.95 138.25
1H
0.88
14.07
1.02
22.66
1.16
31.19
1.25
29.16
1.26
26.87
1.62
30.98
3.36
63.56
IIb
M = Zn
13C
1H
0.89
14.10
1.02
22.66
1.16
31.89
1.26
29.08
1.26
26.85
1.45
30.19
3.36
62.25
IIb
M = Cd
13C
Table 3. (Contd.)
Compound
Nucleus
14
15
16
18[J(M–H10)]
19
20
21
22
23
24
1H
7.65
122.23
12.21
7.72
127.01
7.19
2.34
21.42
Ib
13C
143.25
120.69
129.39 131.06 132.88
1H
7.54
119.04
(28.5)
8.02
128.27
7.13
2.28
21.35
IIb
M = Zn
13C
148.02
147.12
120.09
119.51
129.20 132.90 137.58
1H
7.49
119.15
8.05
128.35
7.05
2.26
21.34
IIb
M = Cd
13C
129.05 133.38 137.00
122.30 ppm) and С16 (δ = 120.56 ppm), while Н20 (δ =
7.63 ppm) correlates with С23 (δ = 136.89 ppm)
(Tables 2, 3).
type II. This conclusion is confirmed by the data of the
1Н and 13С NMR spectroscopy. The formation of
complexes is proved by disappearance of the NH
group signal.
Electrosynthesis of chelates II was performed
taking into account the data of [1–4, 14, 30] by the
anode dissolution of the complex-forming metals
(except for mercury) in the acetonitrile solution. In the
chemical synthesis [1–4] the method of direct
interaction of azomethines I with metal acetates in
ethanol was used. The composition of complexes ML2
(LH is ligating compound I) and the data of the IR
spectra [disappearance of the NH group stretching
vibrations in the region 3110–3400 cm–1, decrease of
the frequences of the C=N bond at 1630–1640 by 10–
15 cm–1, νas(SO2) at 1338 by 80 cm–1, νs(SO2) at 1155
by 20 cm–1] are indicative [31] of a chelate character of
these first synthesized coordination compounds of the
Chemical shifts of the atoms included in the
metallocycle suffer specific changes upon com-
plexation. The chemical shift of the carbon atom С15 in
compound II (R = C7H15, M = Zn) is shifted downfield
by 3 ppm as compared to the chemical shift of С15 in
the starting ligand I, in compound II (M = Hg) the
same signal is shifted downfield by 4.57 ppm, and in
the cadmium complex II (M = Cd) the downfield shift
of С15 is 3.90 ppm. Unexpectedly, for the lead chelate
II (M = Pb), the downfield shift is as low as 0.37 ppm.
The chemical shift of the Н10 proton is also changed
negligibly, by no more than 0.1 ppm. In this case a
reliable indicator is the 13С signal of the С10 atom
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010

296
GARNOVSKII et al.
whose chemical shift is moved downfield for II (M =
Zn) by 6.01 ppm, for II (M = Hg) by 6.38 ppm, for II
(M = Cd) by 7.19 ppm and for II (M = Pb) by
0.31 ppm.
The structure of the series of the zinc coordination
compounds II was determined by the method of X-ray
analysis by the example of chelate II (R = C7H15, M =
Zn). The complex has the geometry of a strongly
distorted octahedron (ZnN4O2), in which the zinc atom
is bound with the four azomethine nitrogen atoms and
two oxygen atoms of the tosyl fragments (see figure).
For complex II (R = C18H37, M = Zn) the signal of
the С15 atom is shifted downfield by 4.77 ppm, and for
II (M = Cd), by 3.87 ppm. As follows from the given
data, the replacement of the substituent R = C7H15 in
complex II by R = C18H37 for M = Zn results in an
increase of the chemical shift of the С15 atom from
3 ppm to 4.77 ppm. At the same time, in the 13С NMR
spectrum of complex with M = Cd this value remains
practically unchanged.
The Zn–N bond distances are varied within
1.999(2)–2.026(3) Å, the value of 2.00 Å corres-
ponding to the bond with the amine nitrogen atoms N1
and N1', and 2.03 Å, to the bond with the azomethine
atoms N2 and N2' (Table 4). The arrangement of the O2
and O2' atoms with respect to the zinc atom [Zn1–O2
2.691(2) Å, Zn1–O2' 2.661(2), N1–Zn1–O2 146.6(1)°,
N1–Zn1–O2 148.9(1)°] and the elongation of the S1=O2
and S(1’)=O2' bonds by 0.003(4) and 0.005(4) Å as
compared to the corresponding S1=O2 and S1'=O2'
bonds also suggests that the O2 and O2' atoms of the
tosyl groups form weak coordination bonds with zinc,
which suggests that the surrounding of the zinc atom is
a distorted octahedron. Another reason for such an
arrangement of the oxygen atoms could be the
formation of strong intramolecular C–H…O interact-
tions С6–H6A…O2' [C…O 3.260(3) Å, C–H…O 161.5(2)°]
and С6'–H6'A…O2 [C…O 3.279(3) Å, C–H…O 160.8(2)°].
The six-membered metallocycles have the sofa con-
The downfield shift of the С10 atom in II (R =
C18H37, M = Zn) as compared to that in the free ligand
is 7.05 ppm, and for II (M = Cd) it is 6.04 ppm. That
means that the effect of substituent R in the complex
on the chemical shift of the C10 atom is opposite to that
of the С15 atom.
The chemical shift of the Н10 atom in compound II
(M = Zn) is practically unchanged (no more than
0.1 ppm) as compared to the free ligand I, whereas the
chemical shift of С10 is moved downfield by 8.99 ppm,
and С15 is shifted by 8.79 ppm as compared to the
corresponding chemical shifts in the starting ligand I.
C7
C7'
C4
C4'
C5
C5'
C3'
C3
C6'
C6
C2
C2'
C1
C1'
O2'
O2
S1
S1'
O1'
O1
N1'
C9
N1
C9'
C8
C8'
C10
C11
C20'
Zn1
C10'
C11'
C20
N2
C13
C13'
C14
C14'
C12
C15
C12'
C15'
C18
C18'
C16'
C16
C19
C21
C21'
C17'
C17
C19'
General view of the molecule of complex (II, R = C7H15, M = Zn). The atoms are represented as thermal ellipsoids (p = 50%)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010

ELECTROCHEMICAL AND CHEMICAL SYNTHESIS
297
Table 4. Selected bond distances and bond angles in complex (II, R = C7H15, M = Zn).
Bond
d, Å
Bond
d, Å
Bond
d, Å
Bond
d, Å
Zn1–N1
Zn1–N1'
Zn1–N2
Zn1–N2'
Zn1–O2'
Angle
1.999(2)
2.003(2)
2.024(3)
2.026(3)
2.661(2)
ω, deg
S1–O1
S1–O2
S1–N1
S1–C1
1.447(2)
1.450(2)
1.610(3)
1.776(3)
1.403(4)
ω, deg
Zn1–O2
S1'–O1'
S1'–O2'
S1'–N1'
S1'–C1'
2.691(2)
N1–C8
N2–C14
N2–C15
N2'–C14'
N2'–C15'
Angle
1.399(4)
1.281(4)
1.471(4)
1.281(4)
1.480(4)
ω, deg
1.448(2)
1.453(2)
1.600(3)
N1'–C8'
1.769(3)
Angle
Angle
ω, deg
N1Zn1N1'
N1Zn1N2
N1'Zn1N2
N1Zn1N2'
N1'Zn1N2'
N2Zn1N2'
N1Zn1O2'
N1'Zn1O2'
N2Zn1O2'
N2'Zn1O2'
N1Zn1O2
N1'Zn1O2
145.41(11)
92.02(10)
106.71(10)
106.69(10)
92.03(10)
114.26(10)
93.04(9)
59.72(8)
88.14(9)
148.90(9)
59.45(8)
91.83(9)
O2S1N1
O1S1C1
O2S1C1
N1S1C1
S1O2Zn1
S1'O2'Zn1
C8'N1'S1'
C8'N1'Zn1
S1'N1'Zn1
C8N1S1
C8N1Zn1
S1N1Zn1
103.35(13)
106.78(14)
108.27(14)
107.33(14)
86.31(10)
86.83(10)
122.1(2)
127.7(2)
109.96(13)
121.6(2)
127.8(2)
110.55(13)
N2Zn1O2
N2'Zn1O2
O2'Zn1O2
O1'S1'O2'
O1'S1'N1'
O2'S1'N1'
O1'S1'C1'
O2'S1'C1'
N1'S1'C1'
O1S1O2
O1S1N1
C14N2C15
146.60(9)
91.99(9)
C14N2Zn1
C15N2Zn1
C14'N2'C15'
C14'N2'Zn1
C15'N2'Zn1
C2'C1'S1'
C6'C1'S1'
C2C1S1
123.9(2)
119.07(19)
117.4(3)
124.6(2)
117.98(19)
120.2(2)
119.2(2)
120.3(2)
119.1(2)
77.38(7)
116.40(13)
114.31(13)
103.00(13)
106.61(14)
107.98(14)
108.20(14)
116.42(13)
114.28(13)
117.0(3)
C6C1S1
formation with deviation of the Zn1 atom by 0.28 and
0.18 Å. The geometry of both ligands in the complex is
very similar. The conformation of the heptyl fragments
almost completely corresponds to their trans-trans
arrangement with the torsional angles С–С–С–С close
to 180°, except for the С15–С16 bond for which the
torsional angle С14–С15–С16–С17 is ~70° in both
ligands. Intermolecular interactions in the crystal II
(R = C7H15, M = Zn) are confined to weak H…H and
C–H…O interactions.
Azomethine complexes occupy an important place
among luminescent materials [22, 32]. Therefore, we
have studied the luminescence of the hitherto
undescribed azomethine ligating compounds I and bis-
chelates prepared on their basis II (R = C7H15, C18H37).
The results of the spectral studies are summarized in
Table 5. Note the complete spectral identity of the zinc
complexes II (R = C7H15), prepared under the condi-
tions of electrochemical (1) and chemical (2)
syntheses.
high quantum yields of fluorescence (φflu = 0.23–0.37)
for the zinc complexes. These circumstances make the
described
coordination
compounds
of
N-
tosylaminobenzylidene alkylimines promising for
preparation of electroluminescent organometal diodes
(OLED) [21, 22, 33].
EXPERIMENTAL
Absorption spectra were taken on a Varian Cary
100 spectrophotometer. Fluorescent studies were
performed on a Varian Eclipse spectrofluorimeter. IR
spectra were taken on a Varian 3100 FI-IR
spectrometer by the method of frustrated total internal
1
reflection in powder. Н and 13С NMR spectra were
recorded on a Varian UNITY-300 spectrometer in the
regime of internal stabilization of the polar-resonance
line of 2Н in CDCl3 and DMSO-d6.
X-Ray analysis was performed on a Bruker
SMART APEX2 CCD diffractometer for complex II
(R = C7H15, M = Zn). Colorless crystals of composi-
tion C42H54N4O4S2Zn were grown from the mixture
chloroform : methanol (1 : 2). At 120 K the crystals are tri-
clinic, space group P-1, a = 8.6273(12), b = 8.8175(12),
A valuable property of the majority of the
synthesized chelates is their fluorescence in the blue
flu
region of the spectrum (λ
= 428–430 nm) as well as
max
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010

298
GARNOVSKII et al.
Table 5. Characteristics of absorption and fluorescence spectra of ligands I and complexes II
abs
abs
ex
flu
Comp. no.
R/M
λ
, nm
ε(λ ), M–1 cm–1
λ
, nm
λ
, nm
φflu
max
max
max
max
C7H15/H
258 sh
310
415
10890
3130
230
314; 411
520
< 0.001
I
IIab
IIbb
C7H15/Zn
C7H15/Zn
233
270
350
233
270
350
274 sh
358
262 sh
350
258
310 sh
415
232
274
72110
20800
11490
70030
20360
10540
–
347
428
428
0.23
0.23
347
IIаb
IIаa,b
I
C7H15/Hg
C7H15/Cd
C18H37/H
350–390
348
440–490
433
< 0.001
0.13
–
10750
3040
290
–
313; 410
350
520
428
< 0.001
0.37
IIbа,b
IIba,b
C18H37/Zn
C18H37/Cd
353
232
–
348
433
0.12
270 sh
353
a Complexes obtained by electrochemical synthesis. b Complexes obtained by chemical synthesis.
c = 27.749(3) Å, α = 93.178(3)°, β = 91.013(4)°, γ =
[14, 30, 31] by the reaction of azomethines I dissolved
in acetonitrile with the complex-forming metal anodes
(Zn, Cd, Pb).
99.245(3)°, V = 2079.5(5) Å3, Z = 2 (Z' = 1), dcalc
=
1.291 g cm–3, μ(MoKα) = 0.736 cm–1, F(000) = 856.
The intensities of 22529 reflections were measured at
100 K [λ(MoKα) = 0.71073 Å, ω-scanning, 2θ < 58°]
and 10939 independent reflections (Rint = 0.0382) were
used for further refinement. The treatment and
averaging of the experimental data was performed by
the use of the program package Bruker SAINT [34]
and SADABS [35]. All calculations were made using
the SHELXTL package of programs [36].
Electrochemical cell can be represented as follows:
Pt(–)/CH3CN//H2L/M(+). The acetonitrile solution
(25 ml) contained 1 mmol of ligand I and 0.01 g of
Et4NClO4 as a conducting additive. The electrosyn-
thesis was carried out at constant current of 40 mA and
voltage of 15 V during 2 h. The precipitate formed was
filtered off, washed thrice with 10 ml of hot ethanol,
and dried at 150°С in a vacuum-drying chamber.
Synthesis of the ligating compounds I. The Schiff
bases of the type I were prepared by the general
procedure. To the solution of 2.75 g of о-N-tosyl-
aminobenzaldehyde [37] in 50 ml of ethanol the
solution of 1.15 g of heptylamine or 2.69 g of octa-
decylamine in 5 ml of ethanol was added. The mixture
was refluxed for 2 h, the precipitated azomethine was
filtered off, washed thrice with 5 ml of methanol,
crystallized from the mixture benzene–hexane (2 : 1),
and dried in a vacuum-drying chamber.
Chemical synthesis of complexes. Chemical syn-
thesis was performed by direct reaction of the
azomethine derivatives I with the metal acetates in
ethanol [3, 4]. The mixture was refluxed for 1 h, the
precipitates of the complexes were filtered off, washed
thrice with 10 ml of hot ethanol, and dried at 150°С in
a vacuum-drying chamber.
The data of elemental analysis (Table 1), IR, and
NMR spectra point to the identity of the complex
compounds prepared under the conditions of electro-
synthesis and chemical synthesis.
Electrochemical synthesis of complexes. Electro-
synthesis was carried out using the standard procedure
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ELECTROCHEMICAL AND CHEMICAL SYNTHESIS
299
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ACKNOWLEDGMENTS
This work was performed with the financial support
from the Ministry of Education and Science
“Development of scientific potential of the High
School” (grant no. RNP 2.1.1/2371), Grant of the
President of RF (grant no. NSh 363.2008.3), Russian
Foundation for Basic Research (grants nos. 08-03-
00154, 07-03-00256), CRDF (grant no. Y4-С04-02).
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