Synthesis and structural characterization of bromo-substituted salamo-type bisoximes based on bis(aminooxy)alkane and 3,5-dibromosalicylaldehyde

Article abstract of DOI:10.14233/ajchem.2015.17470

A series of bromo-substituted Salamo-type bisoximes H₂L¹-H₂L³ have been synthesized through condensation reactions of 3,5-dibromosalicylaldehyde with 1,2-bis(aminooxy)ethane, 1,3-bis(aminooxy)propane and 1,4-bis

Full text of DOI:10.14233/ajchem.2015.17470

Asian Journal of Chemistry; Vol. 27, No. 2 (2015), 663-666
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2015.17470
Synthesis and Structural Characterization of Bromo-Substituted Salamo-Type
Bisoximes Based on Bis(aminooxy)alkane and 3,5-Dibromosalicylaldehyde
*
G.-X. AN, Y. ZHANG, L. WANG, Y.-X. SUN, X.-Y. DONG and W.-K. DONG
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, P.R. China
*Corresponding author: E-mail: dongwk@126.com
Received: 25 February 2014;
Accepted: 26 May 2014;
Published online: 10 January 2015;
AJC-16642
A series of bromo-substituted Salamo-type bisoximes H2L1-H2L3 have been synthesized through condensation reactions of 3,5-
dibromosalicylaldehyde with 1,2-bis(aminooxy)ethane, 1,3-bis(aminooxy)propane and 1,4-bis(aminooxy)butane in ethanol medium,
respectively and characterized by elemental analyses, IR and 1H NMR spectra. In the crystal structure of Salamo-type bisoximes H2L1, an
infinite 1D supramolecular double chain-like structure is formed by intramolecular hydrogen bonds, π···π stacking interactions and
intermolecular Br···Br halogen bondings.
Keywords: Synthesis, Salamo-type bisoxime, Characterization, Crystal structure.
diphenol (H2L2), 4,4',6,6'-tetrabromo-2.2'-[(butylene-1,4-
INTRODUCTION
diyldioxy)bis(nitrilo-methylidyne)]diphenol (H2L3) and the
crystal structure of Salamo-type bisoxime H2L1 has also been
Oxime-type compounds have been widely studied for their
prospective application in many fields, such as pharmacolo-
studied.
gical, biological activity reagents, metallurgy, dyes and lumi-
nescent materials1-4. So, preparing more and more novel oxime-
EXPERIMENTAL
type compounds with different properties and applications
3,5-Dibromosalicylaldehyde (≥ 98 %), 1,2-dibromoethane,
1,3-dibromopropane and 1,4-dibromobutane were purchased
from Alfa Aesar and used without further purification. The
other reagents and solvents were analytical grade reagents from
Tianjin Chemical Reagent Factory. The physical-chemical
measurements are the same as literature early11.
General procedure: Synthetic route to Salamo-type
bisoximes H2L1-H2L3 are shown in Fig. 1. 1,2-Bis(aminooxy)-
ethane, 1,3-bis(aminooxy)propane and 1,4-bis(aminooxy)butane
were synthesized according to an analogous method reported
earlier11.
Preparation of 4,4',6,6'-tetrabromo-2.2'-[(ethyl-
enedioxy)-bis(nitrilomethylidyne)]diphenol (H2L1): To an
ethanolic solution (5 mL) of 3,5-dibromosalicylaldehyde
(559.9 mg, 2 mmol) was added a ethanol solution (5 mL) of
1,2-bis(aminooxy)ethane (92.1 mg, 1 mmol).After the solution
had been stirred at 55 °C for 3 h, then cooled to room tempe-
rature, 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 white powder H2L1.Yield, 78.6 %. m.p. 462-
462.5 K.
are of great importance to the development of coordination
chemistry. Especially, bisoxime compounds are being widely
concerned because of the new molecular structure, using an
O-alkyloxime unit [-CH=N-O-(CH2)n-O-N=CH-] instead of
the [-CH=N-(CH2)n-N=CH-] group and have been used to
preparing the neutral complexes with divalent transition metal
ions5. The complexes not only display fluorescence properties,
but can also trace the certain ions as the extracting reagents6.
The oxygen atoms, in the molecular structure, possess strong
electronegativity can lead to different and novel properties and
structures of the resulting complexes by affecting strongly the
electronic properties of the N2O2 coordination sphere7-9.
Therefore, the researches of novel bisoxime-type complexes
with different properties are great significance for the widely
applications in scientific research and industrial development
in the future10. In this article, we report the synthesis and
characterization of three Salamo-type bisoximes from 3,5-
dibromosalicylaldehyde and 1,2-bis(aminooxy)ethane, 1,3-
bis(aminooxy)propane and 1,4-bis(aminooxy)butane
molecules, 4,4',6,6'-tetrabromo-2.2'-[(ethylenedioxy)bis-
(nitrilomethylidyne)]diphenol (H2L1), 4,4',6,6'-tetrabromo-
2.2'-[(propylene-1,3-diyldioxy)bis(nitrilomethylidyne)]-

664 An et al.
Asian J. Chem.
O
O
O
n
Br
C
C
C
C
C
n
Br
n
2
NH2 O
O NH2
N OH
O
N O
O N
95% EtOH, Ar
rt, 75h, Et3N
C
O
O
n
O
N
O
N
CHO
OH
Br
EtOH
n
Br
OH HO
Br
2 Br
NH2 O O NH2
+
55°C; stirring
Br
Br
Fig. 1. Synthetic route to Salamo-type bisoxime compounds H2L1-H2L3 (n = 1-3)
Preparation of 4,4',6,6'-tetrabromo-2.2'-[(propylene-
1,3-diyldioxy)bis(nitrilomethylidyne)]diphenol (H2L2): To
an ethanolic solution (5 mL) of 3,5-dibromosalicylaldehyde
(559.9 mg, 2 mmol) was added ethanolic solution (5 mL) of
1,3-bis(aminooxy)propane (106.1 mg, 1 mmol). After the
solution had been stirred at 55 °C for 3 h, then cooled to room
temperature, 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 white powder H2L2, Yield, 81.4 %. m.p.
515-516 K.
RESULTS AND DISCUSSION
A series of new Salamo-type bisoximes H2L1-H2L3 have
been synthesized and the composition are confirmed by
elemental analyses, IR, UV-visible and 1H NMR spectra.
Physical and chemistry property of Salamo-type
bisoximes H2L1-H2L3: The colour, yields and elemental analy-
tical results of the synthesized Salamo-type bisoximes H2L1-
H2L3 are presented in Table-2.
Salamo-type bisoxime H2L1 is a white solid, stable in air
and slightly soluble in chloroform, insoluble in methanol and
Preparation of 4,4',6,6'-tetrabromo-2.2'-[(butylene-
1,4-diyldioxy)bis(nitrilomethylidyne)]diphenol (H2L3): To
a ethanol solution (10 mL) of 3,5-dibromosalicylaldehyde
(559.9 mg, 2 mmol) was added a ethanol solution (5 mL) of
1,4-bis(aminooxy)butane (11.2 mg, 1 mmol).After the solution
had been stirred at 55 °C for 3 h, then cooled to room tempe-
rature, 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 white powder H2L3, Yield, 78.7 %. m.p. 487-488 K.
X-Ray structure determination of Salamo-type
bisoximes H2L1: The crystal data and structure refinement for
the title compound H2L1 are given in Table-1.
TABLE-1
CRYSTAL DATA AND STRUCTURE REFINEMENT
FOR THE TITLE COMPOUND H2L1
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
C16H12Br4N2O4
615.89
298(2)
0.71073
Triclinic
P-1
a = 9.252(1), b = 9.345(1),
c = 11.888(1), α = 110.007(2),
β = 92.363(1), γ = 94.727(1)
959.9(2)
2
2.134
2.415
596
-11 ≤ h ≤ 11, -11 ≤ k ≤ 11,
-14 ≤ l ≤ 14
6135/3384 [R(int) = 0.0729]
1724
3384/0/236
1.024
Space group
Cell dimensions, (Å, deg)
Volume (Å3)
Z
Density (calculated) (mg/m3)
Absorption coefficient (mm-1)
F(000)
The single crystal of the title compound H2L1 with the
approximate dimensions of 0.37 × 0.24 × 0.17 mm was placed
on a Bruker Smart 1000 CCD area detector. The reflections
were collected using a graphite monochromated MoKα
radition (λ = 0.71073 Å) at 298(2) K. The structure was solved
by using the program SHELXL-97 and Fourier difference
techniques and refined by the full-matrix least-squares
method on F2. The non-hydrogen atoms were refined anisotro-
pically. All hydrogen atoms were added theoretically. CCDC:
987936.
Index ranges
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness of fit indicator
R [I > 2σ(I)]
R1 = 0.0361, wR2 = 0.1012
Largest diff. peak and hole (e Å-3) 1.198 and -1.036
TABLE-2
COLOUR, YIELDS, MELTING POINTS AND ANALYTICAL DATA OF SALAMO-TYPE BISOXIMES H2L1-2L3
Elemental analysis (%): Found (Calcd.)
Comp.
Colour
m.p. (K)
Yield (%)
m.f. (m.w.)
C
H
N
H2L1
H2L2
H2L3
White
White
White
462-462.5
515-516
487-488
78.6
81.4
78.7
C16H12N2O4Br4 (615.9)
C17H14N2O4Br4 (629.9)
C18H16N2O4Br4 (643.9)
31.18 (31.20)
32.44 (32.41)
33.53 (33.57)
1.93 (1.96)
2.23 (2.24)
2.48 (2.50)
4.57 (4.55)
4.43 (4.45)
4.39 (4.35)

Vol. 27, No. 2 (2015)
Synthesis and Structural Characterization of Bromo-Substituted Salamo-Type Bisoximes 665
ethanol. Salamo-type bisoxime H2L2 is a white solid, stable in
air and soluble in THF, DMF and DMSO, slightly soluble
in chloroform, insoluble in methanol, ethanol, acetone and
acetonitrile. Salamo-type bisoxime H2L3 is a white solid, stable
in air and soluble in DMF, DMSO and THF, insoluble in
methanol, ethanol, acetone and acetonitrile. The elemental
analysis data and the composition of the ligands show that the
elemental analysis data of Salamo-type bisoximes H2L1-H2L3
close to the theoretical value, prove their compositions agree
with the given formulae.
Salamo-type bisoximes H2L1-H2L3 occurs at 1269, 1273 and
1271 cm-1, respectively, indicating that 3,5-dibromosali-
cylaldehyde has been condensated with 1,2-bis(aminooxy)ethane
1,3-bis(aminooxy)propane and 1,4-bis(aminooxy)butane,
respectively and formed new Salamo-type bisoximes11. IR
spectral results of Salamo-type bisoximes H2L1-H2L3 further
confirmed the correctness of the target compounds.
1H NMR spectra of Salamo-type bisoximes H2L1-H2L3:
The 1H NMR spectra of Salamo-type bisoximes H2L1-H2L3 in
DMSO-d6 are shown in Table-4. The 1H NMR spectra shows
a singlet at about 8.44-8.47 ppm indicating the existence of
oxime bonds12.
IR spectra of Salamo-type bisoximes H2L1-H2L3: The
most important IR spectra data for Salamo-type bisoximes
H2L1-H2L3 are given in Table-3.
Crystal structure of Salamo-type bisoxime H2L1:
ORTEP representation of Salamo-type bisoxime H2L1 is shown
in Fig. 2. Selected bond lengths and angles are listed in Table-5.
In the crystal structure, two intramolecular O3-H3···N1
and O4-H4···N2 hydrogen bonds involving the hydroxyl
groups and oxime N atoms generate S(6) ring motifs in each
molecule (Table-6). Moreover, a pair of intermolecular Br···Br
halogen bondings link two neighbouring molecules into a 1D
chain, in which the Br-Br distance is 3.643(2) Å. In addition,
In the IR spectra of Salamo-type bisoximes H2L1-H2L3,
an O-H stretching band appears at 3438-3431 cm-1, which is
the evidence for the existence of associating hydroxyl group
in Salamo-type bisoximes H2L1-H2L3 11. In the 1559-1425 cm-1
region, the observed bands were attributed to aromatic C=C
vibrations. In addition, a characteristic C=N stretching band
of Salamo-type bisoximes H2L1-H2L3 appears at 1608-1605
cm-1, respectively11. And a strong Ar-O stretching band in
TABLE-3
KEY IR SPECTRAL BANDS (cm-1) FOR SALAMO-TYPE BISOXIMES H2L1-H2L3
Compound
ν (O-H)
ν (CH2)
ν (C=N)
ν (C-C)
ν (Ar-O)
H2L1
H2L2
H2L3
3431
3438
3437
2955, 2893
2955, 2889
2945, 2885
1605
1603
1604
1552, 1479, 1458
1555, 1458, 1425
1559, 1474, 1445
1269
1273
1271
TABLE-4
1H NMR DATA FOR SALAMO-TYPE BISOXIMES H2L1-H2L3
1H NMR (400 MHz, DMSO-d6, δ/ppm)
4.49 (s, 4H, CH2-O), 7.68 (d, J = 2.4 Hz, 2H, Ar-H), 7.82 (d, J = 2.4 Hz, 2H, Ar-H), 8.47 (s, 2H, N=CH), 10.43 (s, 2H, OH)
2.45-2.51 (m, 2H, CH2), 4.48 (s, 4H, CH2-O), 7.66 (d, J = 2.4 Hz, 2H, Ar-H), 7.80 (d, J = 2.4 Hz, 2H, Ar-H), 8.45 (s, 2H,
N=CH), 10.40 (s, 2H, OH)
Compound
H2L1
H2L2
2.46-2.56 (m, 4H, CH2), 4.50 (s, 4H, CH2-O), 7.67 (d, J = 2.4 Hz, 2H, Ar-H), 7.81 (d, J = 2.4 Hz, 2H, Ar-H), 8.44 (s, 2H,
N=CH), 10.41 (s, 2H, OH)
H2L3
TABLE-5
SELECTED BOND LENGTHS (Å) AND ANGLES (º) FOR SALAMO-TYPE BISOXIME H2L1
Bond
Br1-C6
Br4-C15
N2-C10
O2-C2
C1-C2
C4-C9
C7-C8
Lengths
1.89(2)
1.90(2)
1.28(2)
1.43(3)
1.54(2)
1.42(2)
1.36(2)
1.41(2)
1.37(2)
Angles
Bond
Br2-C8
N1-C3
N2-O2
O3-C5
C3-C4
C5-C6
C8-C9
Lengths
1.89(2)
1.27(2)
1.41(2)
1.35(2)
1.45(2)
1.38(2)
1.39(2)
1.45(2)
1.40(2)
Angles
Bond
Br3-C13
N1-O1
O1-C1
O4-C12
C4-C5
C6-C7
C10-C11
C12-C13
C15-C16
Bond
Lengths
1.90(2)
1.38(2)
1.43(3)
1.34(3)
1.41(2)
1.39(2)
1.43(2)
1.36(2)
1.35(2)
Angles
C11-C16
C13-C14
Bond
C11-C12
C14-C15
Bond
C3-N1-O1
N2-O2-C2
N1-C3-C4
C9-C4-C3
C6-C5-C4
C7-C6-Br1
C7-C8-Br2
N2-C10-C11
C10-C11-C12
C13-C12-C11
C14-C13-Br3
C16-C15-Br4
112.4(3)
109.9(3)
122.0(3)
119.2(3)
118.3(3)
119.2(3)
118.6(3)
121.2(3)
124.0(3)
118.2(3)
119.1(3)
119.0(3)
C10-N2-O2
O1-C1-C2
C5-C4-C9
O3-C5-C6
C5-C6-C7
C8-C7-C6
C9-C8-Br2
C16-C11-C10
O4-C12-C13
C12-C13-C14
C13-C14-C15
C14-C15-Br4
109.7(3)
110.1(3)
119.7(3)
119.0(3)
122.1(3)
119.0(3)
119.1(3)
119.2(3)
122.5(3)
124.1(3)
117.7(3)
119.9(3)
N1-O1-C1
O2-C2-C1
C5-C4-C3
O3-C5-C4
C5-C6-Br1
C7-C8-C9
C8-C9-C4
C16-C11-C12
O4-C12-C11
C12-C13-Br3
C16-C15-C14
C15-C16-C11
109.2(3)
112.4(3)
121.1(3)
122.7(3)
118.5(3)
122.3(3)
118.4(3)
116.7(3)
119.2(3)
116.8(3)
121.1(3)
121.9(3)

666 An et al.
Asian J. Chem.
ACKNOWLEDGEMENTS
This work was supported by the Fundamental Research
Funds for the Gansu Province Universities (212086) and the
Science and Technology support funds of Lanzhou Jiaotong
University (ZC2012003), which are gratefully acknowledged.
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3.911(7) Å.
TABLE-6
DATA FOR HYDROGEN-BONDING INTERACTIONS (Å, º)
D-H···A
O(3) -H(3) ···N(1)
O(4) -H(4) ···N(2)
d(D-H)
0.82
0.82
d(H···A)
1.91
1.93
d(D···A)
2.63(3)
2.66(3)
∠D-H···A
146
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148