Synthesis and characterization of tetrahalogen substituted salamo-type bisoximes possessing more flexible O-alkyl chain

Article abstract of DOI:10.14233/ajchem.2014.16034

Four tetrahalogen substituted Salamo-type bisoximes H₂L ¹-H₂L⁴ have been synthesized from 3-bromo-5-chloro-2-hydroxybenzaldehyde and 1,7-bis(aminooxy)heptane, 1,8-bis(aminooxy)octane, 1,9-bis(aminooxy)nonane or 1,10-bis(aminooxy)decane in ethanol medium, respectively and characterized by elemental analyses as well as IR, UV-visible and ¹H NMR spectroscopy. Salamo-type bisoxime compound is much more useful to assemble supramolecular systems than a Salen moiety.

Full text of DOI:10.14233/ajchem.2014.16034

Asian Journal of Chemistry; Vol. 26, No. 4 (2014), 1136-1138
http://dx.doi.org/10.14233/ajchem.2014.16034
Synthesis and Characterization of Tetrahalogen Substituted Salamo-type
Bisoximes Possessing More Flexible O-Alkyl Chain
*
YU-HUA YANG, GANG LI , XIU-YAN DONG, YU-JIE ZHANG and MENG-MENG ZHAO
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, P.R. China
*Corresponding author: E-mail: li_gang78@126.com
Received: 11 July 2013;
Accepted: 12 September 2013;
Published online: 15 February 2014;
AJC-14716
Four tetrahalogen substituted Salamo-type bisoximes H2L1-H2L4 have been synthesized from 3-bromo-5-chloro-2-hydroxybenzaldehyde
and 1,7-bis(aminooxy)heptane, 1,8-bis(aminooxy)octane, 1,9-bis(aminooxy)nonane or 1,10-bis(aminooxy)decane in ethanol medium,
respectively and characterized by elemental analyses as well as IR, UV-visible and 1H NMR spectroscopy. Salamo-type bisoxime compound
is much more useful to assemble supramolecular systems than a Salen moiety.
Keywords: Salamo-type bisoxime, Synthesis, Characterization.
without further purification. The other reagents and solvents
were analytical grade reagents from Tianjin Chemical Reagent
Factory. C, H and N analyses were carried out with a GmbH
VariuoELV3.00 automatic elemental analyzer. IR spectra were
recorded on aVERTEX70 FT-IR spectrophotometer using KBr
pellets. UV/visible absorption spectra were recorded on a
INTRODUCTION
H2Salen [N,N-bis(salicylidene)ethylenediamine] deriva-
tives have played a pivotal role in the development of modern
coordination chemistry1-4. In particular, H2Salen-type com-
pounds capable of coordinating to metal ions, are important
for the investigation of supramolecular interactions5. These
substances have also been used for various applications, such
as various organic reaction processes as catalysts, models of
reaction centers of metalloenzymes and nonlinear optical
materials6. Numerous researchers have used Schiff-base
condensation as the reaction step to synthesize H2Salen-type
compounds, often in high yield7. With the goal of developing
H2Salen-type compounds that could coordinate to multiple
metals and be easily prepared, we identified H2Salamo-type
compounds as an attractive target. If an O-alkyl oxime moiety
(-CH=N-(CH2)n-N=CH-) is used instead of a Schiff base
(-CH=N-O-(CH2)n-O-N=CH-), the larger electronegativity of
oxygen atoms is expected to affect strongly the electronic
properties of N2O2 coordination sphere, which can lead to
different and novel properties and structures of the resulted
complexes8-10 . In this paper, we report the synthesis and spec-
troscopic properties of a series of multihalogen substituted
Salamo-type compounds, which bearing two salicylidene
moieties and two O-alkyloxime linkages.
1
Shimadzu UV-2550 spectrometer. H NMR spectra were
recorded on a Mercury-400BB spectrometer. Melting points
were measured by the use of a microscopic melting point
apparatus made in Beijing Taike Instrument Limited Company
and the thermometer was uncorrected.
Preparation of 4,4'-dichloro-6,6'-dibromo-2,2'-[(1,7-
heptanediyldioxy)bis(nitrilomethylidyne)]diphenol (H2L1):
Synthetic route to Salamo-type bisoxime H2L1 is shown in
Scheme-I. 1,7-bis(Aminooxy)heptane was synthesized
according to an analogous method reported earlier10,11
.
O
C
O
C
O
C
N OH
C
O
NH2NH2·H2O
Br
Br
N
O
O
N
C
O
C
O
O
N
O
N
CHO
OH
Br
Cl
O
NH2
Cl
HO
Cl
H2N
O
OH
Ethanol
Br
Br
Scheme-I: Synthesis of Salamo-type bisoximes H2L1
EXPERIMENTAL
3-Bromo-5-chloro-2-hydroxybenzaldehyde, 1,7-dibromo-
heptane, 1,8-dibromoctane, 1,9-dibromnonane and 1,10-dibro-
modecane (≥ 99 %) were purchased fromAlfaAesar and used
To an ethanolic solution (8 mL) of 3-bromo-5-chloro-
2-hydroxybenzaldehyde (94 mg, 0.40 mmol) was added an

Vol. 26, No. 4 (2014)
Synthesis of Tetrahalogen Substituted Salamo-Type Bisoximes Possessing More Flexible O-Alkyl Chain 1137
ethanolic solution (3 mL) of 1,7-bis(aminooxy)heptane (32.0
mg, 0.20 mmol). After the solution had been stirred at 55 °C
for 4 h, When cooled to room temperature, the white precipitate
was filtered and washed successively with ethanol/hexane and
hexane, respectively. The product was dried under reduced
pressure to obtain white crystalline solid H2L1.
ethanol solution (3 mL) of 1,9-bis(aminooxy)nonane (38.1
mg, 0.20 mmol).After the solution had been stirred at 55 °C for
4 h, the mixture was filtered, washed successively with ethanol/
hexane and hexane, respectively. The product was dried under
reduced pressure to obtain white crystalline solid H2L3.
Preparation of 4,4'-dichloro-6,6'-dibromo-2,2'- [(1,10-
decanediyldioxy)bis(nitrilomethylidyne)]diphenol (H2L4):
Synthetic route to Salamo-type bisoxime H2L1 is shown in
Scheme-IV. 1,10-bis(Aminooxy)decane was synthesized
Preparation of 4,4'-dichloro-6,6'-dibromo-2,2'-[(1,8-
octanediyldioxy)bis(nitrilomethylidyne)]diphenol (H2L2):
Synthetic route to Salamo-type bisoxime H2L1 is shown in
Scheme-II. 1,8-bis(Aminooxy)octane was synthesized according
according to an analogous method reported earlier10,11
.
to an analogous method reported earlier10,11
.
O
C
C
O
C
N OH
O
O
C
O
C
N
O
Br
C
O
C
NH2NH2·H2O
N
OH
O
N
C
O
C
O
Br
O
N
Br
NH2NH2·H2
O
C
O
O
N
C
O
Br
C
O
O
O
N
CHO
OH
Br
Ethanol
N
Cl
O
O
N
H2N
O
CHO
OH
Br
Ethanol
N
O
NH2
Cl
OH
HO
Cl
Cl
H2N
O
O
NH2
Cl
OH
Br
HO
Cl
Br
Scheme-IV: Synthesis of Salamo-type bisoximes H2L4
Br
Br
Scheme-II: Synthesis of Salamo-type bisoximes H2L2
To an ethanolic solution (8 mL) of 3-bromo-5-chloro-2-
hydroxybenzaldehyde (126.0 mg, 0.54 mmol) was added
an ethanolic solution (3 mL) of 1,10-bis(aminooxy)decane
(54 mg, 0.26 mmol). After the solution had been stirred at
55 °C for 4 h, the mixture was filtered, washed successively
with ethanol/hexane and hexane, respectively. The product was
dried under reduced pressure to obtain white crystalline solid
H2L4.
To an ethanolic solution (8 mL) of 3-bromo-5-chloro-2-
hydroxybenzaldehyde (103.0 mg, 0.44 mmol) was added an
ethanolic solution (3 mL) of 1,8-bis(aminooxy)octane (37.0
mg, 0.21 mmol). After the solution had been stirred at 55 °C
for 4 h, The formed precipitate was separated by filtration and
washed successively with ethanol/hexane and hexane, respec-
tively. The product was dried under reduced pressure to obtain
pale-yellow solid H2L2.
RESULTS AND DISCUSSION
Preparation of 4,4'-dichloro-6,6'-dibromo-2,2'-[(1,9-
nonanediyldioxy)bis(nitrilomethylidyne)]diphenol (H2L3):
Synthetic route to Salamo-type bisoxime H2L3 is shown in
Scheme-III. 1,9-bis(Aminooxy)nonane was synthesized
A series of multihalogen substituted Salamo-type
bisoximes H2L1-H2L4 have been synthesized with good yields
and the composition are confirmed by elemental analyses, IR,
UV-visible spectra and 1H NMR data.
according to an analogous method reported earlier10,11
.
The colour, yields, melting points and elemental analytical
results of the synthesized Salamo-type bisoxime compounds
H2L1-H2L4 are presented in Table-1. Their compositions agree
with the formulae. All the compounds are white microcrysta-
lline solid, stable in air and soluble in hot DMF and DMSO,
insoluble in methanol, ethanol, acetone, acetonitrile, chloro-
form, dichloromethane, tetrahydrofuran, n-hexane, ether and
water.
O
C
O
C
O
C
N OH
C
O
NH2NH2·H2
O
Br
Br
N
O
O
N
C
O
C
O
O
N
O
N
CHO
OH
Br
Cl
O
NH2
Cl
H2N
O
OH
HO
Cl
Ethanol
IR spectra of multihalogen substituted Salamo-type
bisoxime compounds H2L1-H2L4 are given in Table-2. In the
IR spectra of the title compounds H2L1-H2L4, the bands due to
characteristic C=N stretching absorption bands appear at 1604-
1602 cm-1, respectively11,12. The Ar-O stretching frequencies
Br
Br
Scheme-III: Synthesis of Salamo-type bisoximes H2L3
To an ethanolic solution (8 mL) of 3-bromo-5-chloro-2-
hydroxybenzaldehyde (95.0 mg, 0.40 mmol) was added an
TABLE-1
COLOUR, YIELDS, MELTING POINTS AND ANALYTICAL DATA OF
TETRAHALOGEN SUBSTITUTED SALAMO-TYPE BISOXIMES H2L1-H2L4
Elemental analysis (%): Found (Calcd.)
Comp.
Colour
m.p. (°C)
Yield (%)
m.f. (m.w.)
C
H
N
H2L1
H2L2
H2L3
H2L4
White
White
White
White
205-206
211-212
213-215
221-222
65.2
70.1
68.7
78.1
C21H22N2O4Br2Cl2 (597.1)
C22H24N2O4Br2Cl2 (611.2)
C23H26N2O4Br2Cl2 (625.2)
C24H28N2O4Br2Cl2 (639.2)
42.14 (42.24)
43.13 (43.24)
44.17 (44.19)
44.84 (45.10)
3.73 (3.71)
4.10 (3.96)
4.08 (4.19)
4.26 (4.42)
4.69 (4.69)
4.57 (4.58)
4.63 (4.48)
4.47 (4.38)

1138 Yang et al.
Asian J. Chem.
TABLE-2
KEY IR BANDS (cm–1) FOR THE TETRAHALOGEN SUBSTITUTED SALAMO-TYPE BISOXIMES H2L1-H2L4
Compound
ν(O-H)
3744
3747
3743
3664
ν(Ar-O)
1215
ν(C=N)
1604
ν(C-C)benzene ring
1554, 1450, 1446
1555, 1481, 1440
1553, 1512, 1461
1475, 1460, 1442
ν(CHarom
3070
)
ν(CH2)
H2L1
H2L2
H2L3
H2L4
2931, 2858
2941, 2858
2933, 2850
2925, 2846
1209
1602
3074
1215
1604
3074
1242
1604
3078
TABLE-3
1H NMR DATA FOR THE TETRAHALOGEN SUBSTITUTED SALAMO-TYPE BISOXIMES H2L1-H2L4
π–π*(nm)
274, 327
274, 326
276, 328
277, 328
1H NMR (400 MHz, DMSO-d6, δ/ppm)
Compound
H2L1
H2L2
H2L3
H2L4
2.45-2.53 (m, 10H), 4.44 (s, 4H), 7.54 (d, J = 2.0 Hz, 2H), 7.70 (d, J = 2.2 Hz, 2H), 8.44 (s, 2H), 9.92 (s, 2H).
2.43-2.52 (m, 12H), 4.43 (s, 4H), 7.53 (d, J = 2.0 Hz, 2H), 7.71 (d, J = 2.2 Hz, 2H), 8.45 (s, 2H), 9.83.02 (s, 2H).
2.43-2.50 (m, 14H), 4.42 (s, 4H), 7.52 (d, J = 2.0 Hz, 2H), 7.69 (d, J = 2.2 Hz, 2H), 8.40 (s, 2H), 9.75 (s, 2H).
2.42-2.52 (m, 16H), 4.42 (s, 4H), 7.50 (d, J = 2.0 Hz, 2H), 7.70 (d, J = 2.2 Hz, 2H), 8.42 (s, 2H), 9.76 (s, 2H).
appear within 1242-1209 cm-1 as reported for similar bisoxime
compounds13. These provide evidence for the formation of the
title compounds. The O-H stretching frequency of the bisoxime
compound is expected in the 3300-3800 cm-1 region11, here a
strong band at 3747-3664 cm-1 was observed in the title comp-
ounds H2L1-H2L4 and assigned to phenolic alcohol stretching
absorption bands. In addition, in the 1555-1440 cm-1 region,
the observed bands were attributed to aromatic C=C vibrations.
UV-visible spectra and 1H NMR data: The UV-visible
spectra of the title compounds H2L1-H2L4 in 5 × 10-5 DMF
solution are presented in Table-3. UV-visible spectra of the
title compounds H2L1-H2L4 exhibit two intense peaks at around
274 and 327 nm. The former absorption peak at about 277 nm
can be assigned to the π-π* transition of the benzene rings,
while the latter can be attributed to the intra-ligand π-π*
transition of the C=N bonds11,14. It is of note that there was no
absorption around 400 nm, which is seen in the correspon-
ding Salen derivatives. The absorption is ascribed to the quinoid
form of H2Salen15.
metal ions such as copper, manganese, iron, cobalt, nickel and
zinc is now in progress.
REFERENCES
1. J. Kim, B. Chen, T.M. Reineke, H. Li, M. Eddaoudi, D.B. Moler, M.
O'Keeffe and O.M. Yaghi, J. Am. Chem. Soc., 123, 8239 (2001).
2. D. Braga, L. Maini, M. Polito, E. Tagliavini and F. Grepioni, Coord.
Chem. Rev., 246, 53 (2003).
3. H.Y. Han, Y.L. Song, H.W. Hou, Y.T. Fan and Y. Zhu, J. Chem. Soc.,
Dalton Trans., 1972 (2006).
4. M.E. Braun, C.D. Steffek, J. Kim, P.G. Rasmussen and O.M. Yaghi,
Chem. Commun. (Camb.), 24, 2532 (2001).
5. S.M. Saylor, R.M. Supkowski and R.L. LaDuca, Inorg. Chim. Acta,
361, 317 (2008).
6. J. Kim, B. Chen, T.M. Reineke, H. Li, M. Eddaoudi, D.B. Moler, M.
O'Keeffe and O.M. Yaghi, J. Am. Chem. Soc., 123, 8239 (2001).
7. J.P. Costes, F. Dahan and A. Dupuis, Inorg. Chem., 39, 165 (2000).
8. S. Akine, T. Taniguchi and T. Nabeshima, Chem. Lett., 30, 682 (2001).
9. S. Akine, T. Tadokoro and T. Nabeshima, Inorg. Chem., 51, 11478
(2012).
10. S. Akine, S. Hotate and T. Nabeshima, J. Am. Chem. Soc., 133, 13868
(2011).
11. (a) W.K. Dong, Y.X. Sun, C.Y. Zhao, X.Y. Dong and L. Xu, Polyhe-
dron, 29, 2087 (2010); (b) W.K. Dong, Y.X. Sun, Y.P. Zhang, L. Li,
X.N. He and X.L. Tang, Inorg. Chim. Acta, 362, 117 (2009); (c) W.K.
Dong, X.N. He, H.B.Yan, Z.W. Lv, X. Chen, C.Y. Zhao and X.L. Tang,
Polyhedron, 28, 1419 (2009); (d) W.K. Dong, Y.X. Sun, Y.P. Zhang, L.
Li, X.N. He and X.L. Tang, Inorg. Chim. Acta, 362, 117 (2009); (e)
W.K. Dong, C.Y. Zhao,Y.X. Sun, X.L. Tang and X.N. He, Inorg. Chem.
Commun., 12, 234 (2009); (f) W.K. Dong,Y.X. Sun, X.N. He, J.F. Tong
and J.C. Wu, Spectrochim. Acta A, 76, 476 (2010); (g) W.K. Dong, S.J.
Xing, Y.X. Sun, L. Zhao, L.Q. Chai and X.H. Gao, J. Coord. Chem.,
65, 1212 (2012); (h) W.K. Dong, Y.X. Sun, S.J. Xing, Y. Wang and
X.H. Gao, Z. Naturforsch, 67b, 197 (2012); (i) W.K. Dong, Y.X. Sun,
G.H. Liu, L. Li, X.Y. Dong and X.H. Gao, Z. Anorg. Allg. Chem., 638,
1370 (2012).
1
The H NMR spectra of the title compounds H2L1-H2L4
1
in DMSO-d6 are shown in Table-3. The H NMR spectra
showed a singlet at about 8.40-8.44 ppm indicating the the
existence of oxime bonds15.
Conclusion
In this paper, a series of variational tetrahalogen substituted
Salamo-type compounds H2L1-H2L4 that have two oxime bonds
instead of imine bonds have been designed and synthesized
by the reaction of 2 equivalents of 3-bromo-5-chloro-2-
hydroxybenzaldehyde with 1,7-bis(aminooxy)heptane,
1,8-bis(aminooxy)octane, 1,9-bis(aminooxy)nonane or 1,10-
bis(aminooxy)decane under mild conditions, respectively. It
is shown that an O-alkyl oxime moiety is much more useful to
assemble supramolecular systems than a Schiff base moiety.
Further investigation on the synthesis and structures of
tetrahalogen substituted Salamo-type complexes with transition
12. S. Akine, T. Taniguchi, W. Dong, S. Masubuchi and T. Nabeshima, J.
Org. Chem., 70, 1704 (2005).
13. J.A. Faniran, K.S. Patel and J.C. Bailar Jr., J. Inorg. Nucl. Chem., 36,
1547 (1974).
14. T. Ghosh, B. Mondal, T. Ghosh, M. Sutradhar, G. Mukherjee and M.
Drew, Inorg. Chim. Acta, 360, 1753 (2007).
15. H.E. Smith, Chem. Rev., 83, 359 (1983).