Synthesis and characterization of four new chloro-group substituted salamo-type bisoxime compounds

Article abstract of DOI:10.14233/ajchem.2014.16295

A series of chloro-substituted Salamo-type bisoxime compounds 4,4',6,6'-tetrachloro-2.2'-[(1,7-heptanediyldioxy)bis(nitrilomethylidyne)] diphenol (H₂L¹), 4,4',6,6'-tetrachloro-2.2'-[(1,8- octanediyldioxy)bis(nitrilomethylidyne)]diphenol (H₂L²), 4,4',6,6'-tetrachloro-2.2'-[(1,9- nonanediyldioxy)bis(nitrilomethylidyne)] diphenol (H₂L³) and 4,4',6,6'-tetrachloro-2.2'-[(1,10- decanediyldioxy)bis(nitrilomethylidyne)]diphenol (H₂L⁴) have been synthesized and characterized by elemental analyses, IR spectra, UV-visible and ¹H NMR spectroscopy. The chloro-group substitutied salamo-type bisoxime compounds H₂L¹-H₂L ⁴ may be a promising units for the construction of supramolecular complexes.

Full text of DOI:10.14233/ajchem.2014.16295

Asian Journal of Chemistry; Vol. 26, No. 9 (2014), 2733-2735
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2014.16295
Synthesis and Characterization of Four New Chloro-Group
Substituted Salamo-Type Bisoxime Compounds
1
2
3
3,*
RUO-YAN LI , LI JING , JIAO-LONG MENG and GANG LI
1Lanzhou Huanqiu Contracting & Engineering Company, Lanzhou 730060, P.R. China
2Petrochemical Research Center, PetroChina, Lanzhou 730060, P.R. China
3School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, P.R. China
*Corresponding author: E-mail: li_gang78@126.com
Received: 6 September 2013;
Accepted: 18 November 2013;
Published online: 28 April 2014;
AJC-15109
A series of chloro-substituted Salamo-type bisoxime compounds 4,4',6,6'-tetrachloro-2.2'-[(1,7-heptanediyldioxy)bis(nitrilomethylidyne)]
diphenol (H2L1), 4,4',6,6'-tetrachloro-2.2'-[(1,8-octanediyldioxy)bis(nitrilomethylidyne)]diphenol (H2L2), 4,4',6,6'-tetrachloro-2.2'-[(1,9-
nonanediyldioxy)bis(nitrilomethylidyne)]diphenol (H2L3) and 4,4',6,6'-tetrachloro-2.2'-[(1,10-decanediyldioxy)bis(nitrilomethylidyne)]diphenol
(H2L4) have been synthesized and characterized by elemental analyses, IR spectra, UV-visible and 1H NMR spectroscopy. The chloro-group
substitutied salamo-type bisoxime compounds H2L1-H2L4 may be a promising units for the construction of supramolecular complexes.
Keywords: Salamo-type bisoxime compound, Synthesis.
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.
General procedure: Synthetic route to chloro-group substi-
tutied Salamo-type bisoxime compounds H2L1-H2L4 are shown
in Fig. 1. 1,7-bis(Aminooxy)heptane, 1,8-bis(aminooxy)octane,
1,9-bis(aminooxy)nonane and 1,10-bis(aminooxy) decane
were synthesized according to an analogous method reported
earlier10.
INTRODUCTION
The favourable ligand properties of tetradentate Schiff
base Salen (N,N'-bis(salicylidene)-1,2-ethylenediamine) and
their derivatives have ensured continued interest in their comp-
lexes for many years1-5. Comparing the ligand properties of
Salen and its oxime-based analogue Salamo, the Salamo deri-
vatives are at least 104 times more stable than Salen derivatives
and the large 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 complexes6-9. Herein, we have recently
studied some novel Salen-type bisoxime chelating compounds
on the basis of O-alkyloxime moiety (-CH=NO-(CH2)n-O-
N=CH-) instead of the imine (-CH=N-(CH2)n-N=CH-) group10.
Here we report the synthesis and characterization of a series
of chloro-group substituted Salamo-type bisoxime compounds.
4,4',6,6'-Tetrachloro-2.2'-[(1,7-heptanediyldioxy)bis-
(nitrilomethylidyne)]diphenol (H2L1): To an ethanolic solu-
tion (5 mL) of 1,7-bis(aminooxy)heptane (146.7 mg, 1 mmol)
was added an ethanolic solution (8 mL) of 3,5-dichloro-2-
hydroxybenzaldehyde (382.2 mg, 2 mmol), a pale-yellow
precipitation was obtained immediately.After the solution had
been stirred at 55 °C for 4 h, The formed precipitate was sepa-
rated by filtration and washed successively with ethanol and
ethanol/hexane (1:4), respectively. The product was dried under
reduced pressure to obtain 338.4 mg pale-yellow title
compound H2L1. Yield, 80.20 %. m.p. 100.0-101.0 °C.
4,4',6,6'-Tetrachloro-2.2'-[(1,8-octanediyldioxy)bis-
(nitrilomethylidyne)]diphenol (H2L2): To an ethanolic solution
(5 mL) of 1,8-bis(aminooxy)octane (161.71 mg, 1 mmol) was
added an ethanolic solution (8 mL) of 3,5-dichloro-2-hydroxy-
benzaldehyde (380.7 mg, 1.99 mmol), a orange mixture was
obtained immediately. After the solution had been stirred at
55 °C for 4 h. The formed precipitate was separated by filtration
EXPERIMENTAL
3,5-Dichlorosalicylaldehyde was purchased from Alfa
Aesar and used 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 VariuoEL V3 automatic elemental analyzer.
IR spectra were recorded on aVERTEX70 FT-IR spectrophoto-
meter using KBr pellets. UV-visible absorption spectra were
1
recorded on a Shimadzu UV-2550 spectrometer. H NMR
spectra were recorded on a Mercury-400BB spectrometer.

2734 Li et al.
Asian J. Chem.
O
O
O
n
Br
n
NH2NH2·H2O
95% Ethanol, Ar
Br
N OH
N O
O N
rt, 75 h, DMF, Et3N
O
O
O
n
CHO
O
N
O
Cl
OH
N
n
Cl
OH
Cl
OH
Cl
NH2
O
O NH2
55 °C, stirring, Ethanol
( n = 6,7,8,9)
Cl
Cl
Fig. 1. Synthetic route to chloro-group substituted salamo-type bisoxime compounds (H2L1-H2L4)
and washed successively with ethanol and ethanol/hexane
(1:4), respectively. The product was dried under reduced pressure
to obtain 371.8 mg yellow title compound H2L2.Yield, 71.50 %.
m.p. 110.0-111.0 °C.
high yields and the compositions are confirmed by elemental
analyses, IR, UV-visible spectra and 1H NMR data.
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, chloroform,
dichloromethane, tetrahydrofuran, n-hexane, ether and water.
IR spectra: IR spectra of the ligands H2L1, H2L2, H2L3
and H2L4 exhibit various bands from 4000 to 400 cm-1. The IR
spectral details of the ligand H2L1, H2L2, H2L3 and H2L4 are
given in Table-2.
4,4',6,6'-Tetrachloro-2.2'-[(1,9-nonanediyldioxy)bis
(nitrilomethylidyne)]diphenol (H2L3): To an ethanolic solu-
tion (5 mL) of 1,9-bis(aminooxy)nonane (51.9 mg, 0.27 mmol)
was added an ethanolic solution (8 mL) of 3,5-dichloro-2-
hydroxybenzaldehyde (104.2 mg, 0.55 mmol). After the pale-
purple solution had been stirred at 55 °C for 4 h, precipitation
was obtained and stirred for 6 h. The formed precipitate was
separated by filtration and washed successively with ethanol
and ethanol/hexane (1:4), respectively. The product was dried
under reduced pressure to obtain 105 mg white title compound
H2L3. Yield, 72.80 %. m.p. 66.5-68.0 °C.
TABLE-2
IR SPECTRAL DATA (cm-1) FOR H2L1, H2L2, H2L3 AND H2L4
4,4',6,6'-Tetrachloro-2.2'-[(1,10-decanediyldioxy)bis
(nitrilomethylidyne)]diphenol (H2L4): To an ethanolic solution
(5 mL) of 1,10-bis(aminooxy)decane (203.8 mg, 0.99 mmol)
was added an ethanolic solution (8 mL) of 3,5-dichloro-2-
hydroxybenzaldehyde (382.6 mg, 2 mmol). The color of the
mixing solution immediately turned pale-yellow and a white
precipitation was obtained. After the solution had been stirred
at 55 °C for 6 h, The formed precipitate was separated by
filtration and washed successively with ethanol and ethanol/
hexane (1:4), respectively. The product was dried under reduced
pressure to obtain 435.2 mg pale-yellow title compound H2L4.
Yield, 80.20 %. m.p. 91.0-91.5 °C.
ν (C=C) benzene
ring skeleton
Comp.
ν(C=N)
ν (Ar-O)
ν (O-H)
H2L1
H2L2
H2L3
H2L4
1607
1605
1607
1609
1215
1209
1215
1209
3431
3431
3433
3432
1586, 1464, 1452
1582, 1447, 1452
1587, 1466, 1448
1585, 1463, 1445
TheAr-O stretching bands occur at 1215, 1209, 1215 and
1209 cm-1 for the ligands H2L1-H2L4, respectively11. And the
characteristic C=N stretching bands of H2L1-H2L4 appear at
1609-1605 cm-1, indicating that 3,5-dichloro-2-hydroxybenzal-
dehyde has been condensated with 1,7-bis(aminooxy)heptane,
1,8-bis(aminooxy)octane, 1,9-bis(aminooxy)nonane and 1,10-
bis(aminooxy)decane, respectively and formed new Salamo-
type compounds12. In the 1587-1445 cm-1 region, the observed
bands were attributed to aromatic C=C vibrations. In addition,
RESULTS AND DISCUSSION
A series of chloro-group Salamo-type bisoxime com-
pounds H2L1, H2L2, H2L3 and H2L4 have been synthesized with
TABLE-1
COLOUR, YIELDS, MELTING POINTS AND ANALYTICAL DATA FOR H2L1, H2L2, H2L3 AND H2L4
Elemental analysis (%): Found (Calcd.)
Comp.
Colour
m.p. (°C)
Yield (%)
m.f. (m.w.)
C
H
N
H2L1
H2L2
H2L3
H2L4
Pale-yellow
Yellow
White
100-101
110-111
66.5-68.0
91.0-91.5
80.20
71.50
72.80
80.20
C21H22N2O4Cl4 (508.22)
C22H24N2O4Cl4 (522.25)
C23H26N2O4Cl4 (536.27)
C24H28N2O4Cl4 (550.30)
49.67 (49.63)
50.52 (50.60)
51.49 (51.51)
52.45 (52.38)
4.42 (4.36)
4.74 (4.63)
4.95 (4.89)
5.28 (5.31)
5.39 (5.51)
5.31 (5.36)
5.17 (5.22)
5.00 (5.09)
White

Vol. 26, No. 9 (2014)
Synthesis of Four New Chloro-Group Substituted Salamo-Type Bisoxime Compounds 2735
TABLE-4
1H NMR DATA FOR H2L1, H2L2, H2L3 AND H2L4
1H NMR (400 MHz, DMSO-d6, δppm )
Comp.
H2L1
H2L2
H2L3
H2L4
2.42-.50 (m, 10H), 4.45 (s, 4H), 7.55 (d, J = 2.0 Hz, 2H), 7.71 (d, J = 2.2 Hz, 2H), 8.45 (s, 2H), 9.95 (s, 2H)
2.43-.51 (m, 12H), 4.45 (s, 4H), 7.52 (d, J = 2.0 Hz, 2H), 7.72 (d, J = 2.2 Hz, 2H), 8.46 (s, 2H), 9.85 (s, 2H)
2.43-.53 (m, 14H), 4.43 (s, 4H), 7.52 (d, J = 2.0 Hz, 2H), 7.68 (d, J = 2.2 Hz, 2H), 8.41 (s, 2H), 9.76 (s, 2H)
2.40-.54 (m, 16H), 4.43 (s, 4H), 7.50 (d, J = 2.0 Hz, 2H), 7.72 (d, J = 2.2 Hz, 2H), 8.43 (s, 2H), 9.77 (s, 2H)
the O-H stretching bands of the ligands at 3600-3200 cm-1
region disappear in the ligands and the strong absorption
bands of the ligands appear at about 3431 cm-1, which are the
evidence for the existence of hydroxyl group in ligands13. IR
spectral results of the ligands further confirmed the correctness
of the target ligands.
or 1,10-bis(aminooxy)decane under mild conditions, respec-
tively. The Salamo-type compounds may be a promising units
for the construction of supramolecular complexes.
REFERENCES
1. P.A. Vigato and S. Tamburini, Coord. Chem. Rev., 252, 1871 (2008).
2. Y. Sui, D.P. Li, C.H. Li, X.H. Zhou, T. Wu and X.Z. You, Inorg. Chem.,
49, 1286 (2010).
UV-Vis spectra: The UV-visible spectra of the title comp-
ounds H2L1-H2L4 in 5 × 10-5 chloroform solution are shown in
Table-3.
3. C. Meermann, K.W. Törnroos and R. Anwander, Inorg. Chem., 48,
2561 (2009).
4. T.K. Saha, V. Ramkumar and D. Chakraborty, Inorg. Chem., 50, 2720
(2011).
TABLE-3
UV-VISIBLE SPECTRA DATA FOR H2L1, H2L2, H2L3 AND H2L4
5. R.M. Haak, A. Decortes, E.C. Escudero-Adán, M.M. Belmonte, E. Mar-
tin, J. Benet-Buchholz and A.W. Kleij, Inorg. Chem., 50, 7934 (2011).
6. S. Akine, T. Taniguchi and T. Nabeshima, Angew. Chem. Int. Ed., 41,
4670 (2002).
First band
Second band
C (×10-5 mol L-1)
Comp.
λmax1 (nm)
275
λmax2 (nm)
313
7. S.Akine, W.K. Dong and T. Nabeshima, Inorg. Chem., 45, 4677 (2006).
8. S. Akine, T. Tadokoro and T. Nabeshima, Inorg. Chem., 51, 11478
(2012).
H2L1
H2L2
H2L3
H2L4
5.02
5.01
5.03
5.08
276
315
278
318
9. S. Akine, S. Hotate and T. Nabeshima, J. Am. Chem. Soc., 133, 13868
(2011).
280
321
10. (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, L.
Wang, Y.X. Sun, J.F. Tong and J.C. Wu, Chinese J. Inorg. Chem., 27,
372 (2011); (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); (j) W.K. Dong, S.J. Xing, Y.X. Sun, L. Zhao, L.Q. Chai and
X.H. Gao, J. Coord. Chem., 65, 1212 (2012); (k) W.K. Dong and Y.J.
Ding, Cryst. Res. Technol., 43, 321 (2008).
The absorption spectra of H2L1-H2L4 have small diffe-
rence. Each ligand exhibits two intense peaks at 275 and 313
nm. The former absorption peaks can be assigned to the π-π*
transition of the benzene rings, while the latters one can be
attributed to the intra-ligand π-π* transition of the C=N bonds13.
It is of note that there was no absorption at 400 nm, which is
seen in the corresponding salen derivatives. The absorption is
ascribed to the quinoid form of H2 salen14,15
.
1H NMR data:The 1H NMR spectra of the title compounds
H2L1-H2L4 in DMSO-d6 are shown in Table-4.
The 1H NMR spectra showed a singlet at about 8.41-8.46
ppm indicating the the existence of oxime bonds14.
11. S. Akine, T. Taniguchi, W. Dong, S. Masubuchi and T. Nabeshima, J.
Org. Chem., 70, 1704 (2005).
Conclusion
A new series of Salamo-type compounds H2L1-H2L4 posse-
ssing two oxime bonds instead of imine bonds have been
designed and synthesized by the reaction of 2 equivalents of
3,5-dichloro-2-hydroxybenzaldehyde with 1,7-bis(aminooxy)-
heptane, 1,8-bis(aminooxy)octane, 1,9-bis(aminooxy)nonane
12. J.A. Faniran, K.S. Patel and J.C. Bailar Jr., J. Inorg. Nucl. Chem., 36,
1547 (1974).
13. T. Ghosh, B. Mondal, T. Ghosh, M. Sutradhar, G. Mukherjee and M.
Drew, Inorg. Chim. Acta, 360, 1753 (2007).
14. H.E. Smith, Chem. Rev., 83, 359 (1983).
15. S. Akine, T. Taniguchi and T. Nabeshima, Chem. Lett., 30, 682 (2001).