Synthesis and characterization of 1,2-benzylidenedioxy-7-(2-hydroxybenzylideneamino)-4-azaheptane and its complexes with transition metals

Article abstract of DOI:10.1023/A:1020844216503

1,2-Benzylidenedioxy-7-(2-hydroxybenzylideneamino)-4-azaheptane was synthesized by reaction of 1,2-benzylidenedioxy-3-chloropropane with 1,3-diaminopropane and subsequent condensation of 1,2-benzylidenedioxy-7-amino-4-azaheptane with salicylaldehyde. Comp

Full text of DOI:10.1023/A:1020844216503

Russian Journal of General Chemistry, Vol. 72, No. 8, 2002, pp. 1266 1270. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 8, 2002,
pp. 1349 1353.
Original English Text Copyright
2002 by Boybay, Sekerci.
,
Synthesis and Characterization of 1,2-Benzylidenedioxy-
7-(2-hydroxybenzylideneamino)-4-azaheptane and Its Complexes
with Transition Metals1
M. Boybay and M. Sekerci
,
Chemistry Department, Faculty of Arts and Science, Firat University, 23119 Elazig, Turkey
Received December 22, 2000
Abstract 1,2-Benzylidenedioxy-7-(2-hydroxybenzylideneamino)-4-azaheptane was synthesized by reaction
of 1,2-benzylidenedioxy-3-chloropropane with 1,3-diaminopropane and subsequent condensation of 1,2-ben-
zylidenedioxy-7-amino-4-azaheptane with salicylaldehyde. Complexes of 1,2-benzylidenedioxy-7-(2-hydroxy-
benzylideneamino)-4-azaheptane with cobalt(II), nickel(II), and copper(II) salts were obtained. The structure
of the ligand and its complexes was established on the basis of their elemental compositions, IR, UV, and
1H NMR spectra, magnetic susceptibilities, and thermogravimetric data.
Schiff bases possessing at least two donor centers
are important as ligands capable of forming fairly
stable chelate complexes with transition metals. Some
Schiff bases and their complexes exhibit a consider-
able biological activity (e.g., antifungal) [1]. Metal
complexes of Schiff bases occupy a central place in
the development of inorganic chemistry of chelate
systems [2 4]. A number of Schiff bases and their
Here, we describe the synthesis and spectral and
magnetic properties of cobalt(II), nickel(II), and
copper(II) complexes of 1,2-benzylidenedioxy-7-(2-
hydroxybezylideneamino)-4-azaheptane (I) which was
prepared in three steps as shown in the scheme below.
The first step is the synthesis of 1,2-benzylidenedi-
oxy-3-chloropropane (II) by reaction of benzaldehyde
with epichlorohydrin in the presence of boron tri-
comlexes with Cu(II), Ni(II), and Zn(II) were reported fluoride ether complex as catalyst. In the second step,
in [5]. Complexes of Schiff bases are used in many
areas such as medicine and industry [6, 7]. The goal
of the present study was to synthesize a new Schiff
base ligand and its complexes and to investigate their
structures. We also planned to test the compounds
obtained for antifungal and antibacterial activity.
compound II was brought into reaction with 1,3-di-
aminopropane to obtain 7-amino-1,2-benzylidenedi-
oxy-4-azaheptane (III). Finally, condensation of
amine III with salicylaldehyde gave Schiff base I.
Its structure was proved by a combination of data of
1
elemental analysis and IR, UV, and H NMR spec-
CH2 CH CH2 Cl
O
CH2 CH CH2 NH CH2 CH2 CH2 NH2
O
O
O
O
CH
CH
CH
NH2 CH2 CH2 CH2 NH2
.
BF3 OEt2
CH2 CH CH2 Cl +
O
II
CH2 CH CH2 NH CH2 CH2 CH2 N=C
III
H
O
CH
O
O
HO
HO
CH
I
1
The original article was submitted in English.
1070-3632/02/7208-1266$27.00 2002 MAIK Nauka/Interperiodica

SYNTHESIS AND CHARACTERIZATION OF 1,2-BENZYLIDENEDIOXY-7-...
1267
Table 1. Yields, melting points, elemental analyses, and magnetic susceptibilities ( ) of ligand I and complexes IV VI
Found, %
H
Calculated, %
H
Comp. Yield,
mp, C (color)
, BM
Formula
no.
%
C
N
C
N
I
IV
V
68
75
62
79
89 (red)
122 (green)
143 (dirty yellow)
103 (brown)
70.10
51.35
30.11
58.19
7.11
5.95
5.18
7.45
8.20 C20H24N2O3
7.18 C20H27N2O5ClCu
5.35 C20H45N2O14Cl3Ni2 31.54
7.04 C40H56N4O11Co 58.04
70.59
50.63
7.06
5.70
5.91
6.77
8.24
5.90
3.68
6.77
1.46
2.54
4.17
VI
Table 2. IR and UV spectra of ligand I and complexes IV VI
Comp.
no.
UV spectrum (CHCl3),
max, nm
1
IR spectrum (KBr), , cm
I
3446 (OHphenol); 3365 (N H); 3062 (C Harom); 2950, 2853 (C Haliph); 2000 1600 240.0, 250.0, 260.0, 333.3
[ (C Harom)]; 1666 [ (N H)]; 1633 (C N); 1581 (C C); 1175 (C O)
IV 3562 (H2Ocoord); 3235 (N H); 3052 (C Harom); 2953, 2951 (C Haliph); 1651 308.0, 380.0, 666.6
[ (N H)]; 1600 (C N); 1548 (C C); 1114 (C O); 859 [ (H2Ocoord)]; 576, 450
(M N, M O)
V
3565, 3520 (H2Ocoord); 3438 (H2Ocryst); 3240 (N H); 3042 (C Harom); 2953, 306.0, 380.0, 470.0, 630.0,
2876 (C Haliph); 1651 [ (N H)]; 1600 (C N); 1548 (C C); 1114 (C O); 855 795.0
[ (H2Ocoord)]; 578, 455 (M N, M O)
VI 3438 (H2Ocryst); 3230 (N H); 3050 (C Harom); 2953, 2876 (C Haliph); 1651 270.0, 360.0, 400.0, 730.0,
[ (N H)]; 1610 (C N); 1548 (C C); 1114 (C O); 578, 455 (M N, M O) 810.0
troscopy (see Experimental). The most characteristic
six water molecules. Complex V includes five mole-
cules of crystallization water. Cobalt complex VI is
characterized by a metal-to-ligand ratio of 1:2; it
contains five molecules of crystallization water [9].
Complexes IV VI show in the IR spectra a broad
bands in the IR spectrum of I are the following: 3446
1
(OH), 1633 (C N), and 1175 cm (C O) [8]. The
1H NMR spectrum of I contains singlets at 9.86
(OH) and 8.23 ppm (N CH) [8].
1
band in the region of 3450 cm , which belongs to
The reactions of ligand I with Cu(II), Ni(II), and
Co(II) salts in anhydrous ethanol gave complexes
corresponding to the formulas [CuL(H2O)2] Cl (IV),
[NiCl3(H2O)6] 5H2O (V), and [CoL2] 5H2O (VI),
respectively.
stretching vibrations of water molecules [9]. The
(C N) band in the spectra of the complexes is
1
displaced by 30 cm toward lower frequencies rela-
tive to the corresponding band of the free ligand.
1
Analogous shift of the (C O) band is 61 cm .
I + CuCl2 2H2O
[CuL(H2O)2] Cl + HCl,
These data show that the phenolic hydroxy group and
the CH N bond are involved in complex formation.
Ligand I in the complexes is deprotonated; therefore,
no (OH) band is observed in the IR spectra of
IV VI. Some new absorption bands appearing in
the low-frequency region were attributed to stretching
vibrations of the M O and M N bonds [9].
EtOH
IV
I + 2NiCl2 6H2O
[Ni2LCl3(H2O)6] 5H2O + HCl,
V
EtOH
2I + CoCl2 6H2O
[CoL2] 5H2O + 2HCl + H2O.
EtOH
VI
The analytical and spectral data and other param-
eters of complexes IV VI are given in Tables 1 3.
The metal-to-ligand ratio in copper complex IV is
1:1; in addition, there are two molecules of coor-
dination water and one chloride ion. In nickel com-
plex V, the metal-to-ligand ratio is 2:1. Its inner coor-
dination sphere also contains three chloride ions and
The cobalt(II), nickel(II), and copper(II) complexes
are paramagnetic; the magnetic susceptibilities of
complexes IV VI are 1.46, 2.54, and 4.17 BM,
respectively. These data led us to presume that the
copper(II) and cobalt(II) complexes are tetrahedral
[2, 10], while the nickel(II) complex is characterized
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 8 2002

1268
BOYBAY, SEKERCI
,
Table 3. Data of thermogravimetric analysis of complexes IV VI
Temperature range,
C
Weight loss,a
2nd stage
%
Residue (MO), %
Comp.
no.
1st stage
2nd stage
3rd stage
1st stage
3rd stage
found
calculated
IV
V
VI
115 165
58 230
45 220
165 490
230 350
220 580
490 720
350 645
580 715
6.85 (7.49) 36.75 (37.54) 39.25 (38.20) 17.15
11.21 (11.84) 26.02 (25.22) 43.77 (43.78) 19.00
16.77
19.16
9.05
9.15 (10.88) 43.02 (43.05) 38.98 (37.02)
8.85
a
The calculated values are given in parentheses.
by a high-spin distorted octahedral geometry [11]. The
proposed structures of IV VI are shown below.
Insofar as all the complexes are paramagnetic, their
1H NMR spectra could not be obtained.
CH
O
O
H
Cl
CH2 CH CH2 NH CH2 CH2 CH2 N=C
O
Cu
H2O
IV
CH
O
O
H
5H2O
CH2 CH CH2 NH CH2 CH2 CH2 N=C
O
Cl
Cl
OH2
OH2
H2O
Cl
Ni
Ni
OH2
OH2
OH2
V
CH
O
O
H
CH2 CH CH2 NH CH2 CH2 CH2 N=C
O Co
5H2O
O
C=N CH2 CH2 CH2 NH CH2 CH CH2
O
O
CH
VI
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 8 2002

SYNTHESIS AND CHARACTERIZATION OF 1,2-BENZYLIDENEDIOXY-7-...
1269
The electronic spectra of complexes IV VI contain
the corresponding metal oxides CuO, NiO, and CoO
[10, 11, 13].
strong absorption bands at 270.0 306.0 and 360.0
*
*
380.0 nm due to n
and
transitions in the
ligand and also weak d d bands at 666.6 nm; 470.0,
630.0, 795.0 nm; and 400.0, 730.0, 810.0 nm for the
Co(II), Ni(II), and Cu(II) complexes, respectively. The
EXPERIMENTAL
The elemental compositions of ligand I and com-
plexes IV VI were determined at the TUBITAK
Laboratory (Scientific and Technical Research Council
of Turkey). The IR spectra were recorded in KBr on
3
molar conductivity value for a 10 M solution of the
copper(II) complex in anhydrous ethanol is
1
47 1 cm2 mol ; this indicates that complex IV is a
1
a Mattson IR-1000FT spectrometer. The H NMR
1:1 electrolyte [12]. The nickel(II) and cobalt(II) com-
plexes are nonelectrolytes, as follows from their
spectra were obtained on Bruker DPX-400
(400 MHz) or Jeol FX-90Q instruments. The magnetic
susceptibilities were determined on a Sherwood
Scientific magnetic susceptibility balance (Model
MK-1) at room temperature (20 C) using
Hg[Co(SCN)2] as calibrant; diamagnetic corrections
were calculated from Pascal’s constants [14]. The
refractive indices were measured on a Bellingam
Stanley 60/70 Abbe instrument using a calibration oil
with n20 = 1.47577. Thermogravimetric curves were
recorded on a Shimadzu TG-50 thermobalance at
a heating rate of 10 deg/min over the temperature
range from 23.0 to 949.9 C under nitrogen. The elec-
tronic spectra were recorded on a Secoman S-1000
spectrophotometer. The molar conductivities were
measured on a CMD-750WPA conductometer from
0.001 M solutions in anhydrous ethanol.
molar conductivities in anhydrous ethanol: 3 and
1
8
1 cm2 mol , respectively [12].
The thermal stability of the complexes was studied
by thermogravimetric analysis (Table 3). Nickel com-
plex V is stable up to 58 C, where dehydration
begins, and the decomposition is complete at 650 C
with formation of NiO (19%). The process includes
three stages corresponding to the temperature ranges
58 230 C (loss of five molecules of crystallization
water), 230 350 C (loss of six water molecules and
two chloride ligands from the inner coordination
sphere) and 350 645 C (decomposition of the organic
fragment). All three stages are irreversible.
Copper(II) complex IV begins to decompose at
115 C, and the temperature of complete decomposi-
tion is 720 C (CuO, 17.15%). The process also con-
sists of three stages in the temperature ranges 115
165 C (loss of chlorine), 165 490 C (elimination
of the 2,3-benzylidenedioxypropylamino group), and
490 720 C (loss of two molecules of coordination
water and decomposition of the remaining organic
moiety. All decomposition stages are irreversible.
Reagent grade chemicals were used. Benzaldehyde,
1,3-diaminopropane, salicylaldehyde, and epichloro-
hydrin of pure grade were purchased from Merck and
were used without additional purification. 1,2-Ben-
zylidenedioxy-3-chloropropane (II) and 7-amino-1,2-
benzylidenedioxy-4-azaheptane (III) were synthesized
as described in [15].
The decomposition of cobalt(II) complex VI starts
at 45 C with loss of crystallization water. The process
is complete at 715 C to give CoO (8.85%). As with
complexes IV and V, three decomposition stages are
observed, which are accompanied by weight losses
corresponding to five molecules of crystallization
water (45 220 C), 2,3-benzylidenedioxypropylamino
group (220 580 C), and the remaining organic frag-
ment (580 715 C). All stages are irreversible.
1,2-Benzylidenedioxy-7-(2-hydroxybenzylidene-
amino)-4-azaheptane (I). A solution of 2 3 ml of
glacial acetic acid 50 ml of anhydrous ethanol was
added dropwise to 1.416 g of 7-amino-1,2-benzyli-
denedioxy-4-azaheptane (III). The mixture was heated
to the boiling point, and 0.53 g of salicylaldehyde
was added dropwise under continuous stirring. The
mixture was refluxed under stirring for 24 h, and
the precipitate was filtered off, washed with cold
ethanol, diethyl ether, and acetone, and dried at room
temperature. Yield 1.16 g (68%). The product is
soluble in common organic solvents, such as chloro-
Thus, the copper(II) complex is the most stable.
The nickel(II) and cobalt(II) complexes, which contain
crystallization water, begin to decompose at consider-
ably lower temperatures (58 and 45 C, respectively).
The weight loss corresponds to five water molecules
per complex molecule: 11.21% for complex V
(230 C) and 9.15% for VI (220 C). The presence
of crystallization water in these compounds is also
confirmed by the appearance of a broad band in the
IR spectra at 3200 3600 cm 1 [ (OH)] [13]. The com-
plete decomposition of all complexes IV VI gives
1
form, DMSO, DMF, and ethanol. H NMR spectrum
(CDCl3), , ppm: 1.20 1.80 m (3H, CH2, NH), 2.59
2.72 m (4H, NCH2), 2.83 3.60 m (2H, N CH), 3.60
3.80 m (2H, CH2O), 3.83 4.16 m (1H, CHO), 4.16
4.56 s (1H, OCHO), 6.63 7.63 m (9H, C6H5, C6H4),
8.23 s (1H, N CH), 9.86 s (1H, OH).
Complexes of 1,2-benzylidenedioxy-7-(2-hy-
droxybenzylideneamino)-4-azaheptane (I) with
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 8 2002

1270
BOYBAY, SEKERCI
,
Cu(II), Ni(II), and Co(II). A 50-ml round-bottomed
flask was charged with a solution of 0.34 g [0.68 g in
the synthesis of the cobalt(II) complex] of ligand I in
10 ml of anhydrous ethanol. The solution was heated
to the boiling point, and a solution of 0.4574 g of
NiCl2 6H2O or 0.1705 g CuCl2 2H2O in 10 ml of
anhydrous ethanol or of 0.2379 g of CoCl2 H2O in
5 ml of anhydrous ethanol was added dropwise over
a period of 30 min under continuous stirring. The
mixture was refluxed for 24 h and then stirred
for 2 h at room temperature. The precipitate was
filtered off, washed with cold ethanol, diethyl ether,
and acetone, and dried at room temperature. The
yields of complexes IV VI were, respectively, 0.36
(75%), 0.47 (62%), and 0.65 g (79%). Complexes
IV VI are soluble in chloroform, DMSO, DMF,
methylene chloride, ethanol, and water. Their melting
points, elemental analyses, magnetic susceptibilities,
and IR and UV spectra are given in Tables 1 and 2.
National Chemistry Congress, Diyarbakir (Turkey),
2000, p. 414; Sekerci M., Alkan, C., Cukurovali, A.,
,
,
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ACKNOWLEDGMENTS
11. Sekerci, M., Synth. React. Inorg. Met. Org. Chem.,
,
2000, vol. 30, p. 117; Sekerci, M., Russ. J. Inorg.
,
The authors thank the FUNAF (Firat Universitesi
Chem., 1999, vol. 44, p. 1147; Sekerci, M., Russ. J.
,
Arastima Fonu) for financial support.
’
Inorg. Chem., 2000, vol. 45, p. 1348.
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 8 2002