Synthesis, characterization and crystal structure of N,N′-Bis(2,3- dimethoxybenzylidene)-1,2-diaminoethane

Article abstract of DOI:10.1007/s10870-011-9988-7

Synthesis and characterization of single crystals of a new organic Schiff-base derivative, N,N′-bis(2, 3-dimethoxybenzylidene)-1,2- diaminoethane is reported. Good quality single crystals with size 10 mm × 1 mm × 1 mm were grown by slow evaporation techni

Full text of DOI:10.1007/s10870-011-9988-7

J Chem Crystallogr (2011) 41:1955–1960
DOI 10.1007/s10870-011-9988-7
ORIGINAL PAPER
Synthesis, Characterization and Crystal Structure
of N,N0-Bis(2,3-Dimethoxybenzylidene)-1,2-Diaminoethane
•
Aliakbar Dehno Khalaji Karla Fejfarova
•
•
Michal Dusek Hamid Reza Bijanzadeh
Received: 13 June 2009 / Accepted: 10 January 2011 / Published online: 26 January 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Synthesis and characterization of single crys-
tals of a new organic Schiff-base derivative, N,N0-bis(2,
3-dimethoxybenzylidene)-1,2-diaminoethane is reported.
Good quality single crystals with size 10 mm 9 1 mm 9
1 mm were grown by slow evaporation technique from a
methanol solution at room temperature. The grown crystals
have been characterized by elemental analyses and func-
applications in various areas, such as nonlinear optic [1],
photochromism [2], antimicrobial activity [3] and anion
sensor [4]. Schiff-bases compounds, an important class of
organic materials, which shown good crystallizability, have
been extensively studied as a corrosion inhibitors for steel
and iron [5, 6]. These compounds are typically formed by
the condensation of suitable amines and aldehydes [7–10].
They have been extensively studied as ligands in the
development of coordination compounds of transition
metals [11–15]. On the industrial scale, they have wide
range of applications such as dyes and pigments [16].
As an additional contribution to the synthesis, charac-
terization and crystal structures of Schiff-base compounds
and theirs transition metal complexes and in the course of
our ongoing studies of these kinds of materials [17–30] in
this work, we report the synthesis of bidentate Schiff-
base ligand N,N0-bis-(2,3-dimethoxybenzylidene)-1,2-di-
aminoethane (Scheme 1) and growth of its crystals from
methanol solution. The grown crystals were characterized
by crystal structure determination by single crystal X-ray
1
tional groups were identified using FT-IR and H-NMR
spectroscopy. Crystal structure of the title compound
has been determined by single crystal X-ray diffraction.
The title compound has a monoclinic symmetry, space
˚
group P21/c, lattice parameters are a = 4.4159(3) A, b =
˚
˚
14.2333(9) A, c = 15.0601(10) A, b = 97.755(5)°, Z = 2,
3
V = 937.91(11) A .
˚
Keywords Characterization ꢀ Single crystals ꢀ
Schiff-base ꢀ X-ray diffraction
Introduction
1
diffraction, FT-IR, H-NMR and elemental analyses.
Schiff base compounds, having imine groups (–CH=N–),
are widely studied during recent years due to their different
Experimental Procedure
Physical Techniques and Materials
A. D. Khalaji (&)
Department of Chemistry, Golestan University, Gorgan,
Iran
e-mail: alidkhalaji@yahoo.com; ad.khalaji@gu.ac.ir
All reagents (2,3-methoxybenzaldehyde and ethylenedia-
mine) and solvent (methanol) for synthesis, growth and
analysis were commercially available and used as received
without further purification. Elemental analyses were car-
ried out using a Heraeus CHN-O-Rapid analyzer. 1H-NMR
spectra were measured with a BRUKER DRX-500
AVANCE spectrometer at 500 MHz and all chemical shifts
are reported in d units downfield from TMS. The infrared
K. Fejfarova ꢀ M. Dusek
Institute of Physics of the ASCR, v.v.i., Na Slovance 2,
182 21 Prague 8, Czech Republic
H. R. Bijanzadeh
Department of Chemistry, Tarbiat Modarres University,
14115-175 Tehran, Iran
123

1956
J Chem Crystallogr (2011) 41:1955–1960
OMe
nucleated. They were allowed to grow to a maximum pos-
sible dimension and then filtered. Yield: 3.03 g, 85%. Col-
orless crystals. Anal. Calc. for C20H24N2O4: C, 67.42; H,
6.74; N, 7.86%. Found: C, 67.35; H, 6.69; N, 7.79%. IR (KBr
pellet, cm-1): 2830–3010 (m, C–H aromatic and aliphatic),
H2N
MeO
+
O
NH2
1
1639 (s, C=N). H-NMR (CDCl3, d(ppm)): 3.76 (s, 6H3),
3.84 (s, 6H4), 3.99 (s, 4H1), 6.91 (dd, 2H7), 7.02 (t, 2H6),
7.51 (dd, 2H5), 8.64 (s, 2H2).
CH3OH
The solubility of the title compound was determined by
adding the solvent to a known amount of compound until
completely dissolved. It was found that the synthesized
compound is moderately soluble in methanol (0.15 g/ml),
ethanol (\0.15 g/ml) and acetonitrile (0.17 g/ml), insoluble
in water and completely soluble in chloroform (&70 g/ml)
and dichloromethane (&70 g/ml). However, this compound
is moderately soluble in ethanol and acetonitrile, we can’t
get suitable crystals from these solvents. The resulting
grown colorless transparent crystals of maximum dimension
10 mm 9 1 mm 9 1 mm are shown in Fig. 1.
OMe H 2 H 1
N
H 3
H 1
H 4
N
MeO
OMe
OMe
H 7
H 5
H 6
Scheme 1 Structure of ligands N,N0-bis-(2,3-dimethoxybenzylidene)-
1,2-diaminoethane
spectrum was recorded on a JASCO 680 plus FT-IR
spectrophotometer as a KBr pellet.
Characterization
Preparation and Crystal Growth
Synthesis and Characterization
A solution of 2,3-dimethoxybenzaldehyde (3.30 g, 0.02
mol) in 25 ml methanol was heated for 15 min at 50 °C and
then stirred for about 15 min. To this stirring solution, a
solution of ethylenediamine (0.6 g, 0.01 mol) in 15 ml
methanol was added dropwise with constant stirring. The
mixture was heated at about 50 °C for 1.5 h and then
allowed to cool for overnight at 273 K. The resulting crude
solid was collected by filtration and dried at room temper-
ature. Crystals were grown by the slow evaporation tech-
nique at room temperature in 25 ml methanol as a solvent for
5 days. At the period of super saturation, tiny crystals were
Reaction between 2,3-dimethoxybenzaldehyde and ethy-
lenediamine at suitable temperature yielded the bidentate
Schiff-base ligand N,N0-bis-(2,3-dimethoxybenzylidene)-
1,2-diaminoethane (see Scheme 1). The title compound is
air-stable in the solid state for about 3–5 months. It is very
slightly soluble in common organic solvents such as ace-
tonitrile and methanol but completely soluble in chloro-
form and dichloromethane. The stability of dissolved
compound is much shorter than in the solid state and
depends on the nature of the solvent. In methanol and
Fig. 1 Single crystals of N,N0-
bis-(2,3-dimethoxybenzylidene)
-1,2-diaminoethane
123

J Chem Crystallogr (2011) 41:1955–1960
1957
acetonitrile solution it is stable about 10 days at room
temperature and about 30 days at 273 K. In chloroform and
dichloromethane it remains unchanged for about 1 day at
room temperature and about 3 days at 273 K.
around 1,400–1,600 cm-1 correspond to vibrations of the
aromatic rings of the title compound, while the strong and
sharp stretching vibration at 1,639 cm-1 was assigned to
m(C=N).
In order to confirm the chemical composition of the
synthesized compound, CHN analysis was carried out on the
recrystallized sample. The result of the analysis is presented
in the experimental section. Theoretical values of CHN have
suggested the molecular formula C20H24N2O4. The experi-
mental and calculated values of C, H, and N agree with each
other, confirming the formation of C20H24N2O4.
Single Crystal X-ray Analysis
A single crystal of the title compound with the dimensions
0.42 mm 9 0.07 mm 9 0.07 mm was chosen for X-ray
diffraction study. Crystallographic measurements were
done at room temperature with four circle CCD diffrac-
tometer Geminy of Oxford diffraction, Ltd., mirrors-colli-
The 1H-NMR spectra of N,N0-bis-(2,3-dimethoxybenzy-
lidene)-1,2-diaminoethane (Fig. 2) display two singlet sig-
nals at 3.75 and 3.83 ppm which are assigned to protons of
the methoxy groups, H3 and H4, respectively, and one singlet
signal at 3.99 ppm assigned to protons of H1. One triplet
signal at 7.02 ppm is assigned to aromatic H6 protons, while
two doublets of doublet signals at 6.91 and 7.51 ppm are
assigned to aromatic H7 and H5 protons, respectively. One
singlet signal at 8.64 ppm is assigned to C=N group (H2).
The FT-IR analysis of N,N0-bis-(2,3-dimethoxybenzy-
lidene)-1,2-diaminoethane was carried out to investigate the
presence of functional groups and their vibrational modes.
The spectrum was recorded between 400 and 4,000 cm-1
using a JASCO 680 plus FT-IR spectrophotometer. The
relatively weak absorption bands around 2,830–3,010 cm-1
was assigned to the C–H vibration modes involving the
aromatic and aliphatic hydrogen atoms and variable intensity
˚
mated Cu Ka radiation (k = 0.54184 A). The crystal
structures were solved by direct methods with program
SIR2002 [31] and refined with program package Jana2006
[32] by full-matrix least-squares technique on F2. The
molecular structure plots were prepared by ORTEP III
[33]. Hydrogen atoms were mostly discernible in differ-
ence Fourier maps and could be refined to reasonable
geometry. According to common practice they were nev-
ertheless kept in ideal positions during the refinement. The
isotropic atomic displacement parameters of hydrogen
atoms were evaluated as 1.2Ueq of the parent atom. Crys-
tallographic data and details of the data collection and
structure refinements are listed in Table 1. Selected bond
distances and angles are listed in Table 2.
The ORTEP diagram (Fig. 3) shows the title compound
N,N0-bis-(2,3-dimethoxybenzylidene)-1,2-diaminoethane with
Fig. 2 1H-NMR spectra
of N,N0-bis-(2,3-dimethoxyben-
zylidene)-1,2-diaminoethane
123

1958
J Chem Crystallogr (2011) 41:1955–1960
similar Schiff-base compounds [17–19, 29]. The symmetry
equivalent C=N double bonds C7–N1 and C7i–N1i
Table 1 Crystallographic and structure refinement of the title
compound
˚
(Fig. 3a). The C7=N1 bond length of 1.251 (2) A conforms
Empirical formula
Formula weight
C20H24N2O4
356.4
to the value for a double bond while the bond length of
˚
C8–N1, 1.456 (2) A, conforms to the value for a single
˚
Wavelength (A)
1.5418
Monoclinic, P21/c
295
bond. Similar situation can be found in (E,E)-N,N0-bis-
(3,4,5-dimethoxybenzylidene)ethylenediamine [18], where
the bond lengths of C2=N1and C1–N1 are 1.257 (3) and
Crystal system, Space group
T (K)
˚
a (A)
4.4159(3)
14.2333(9)
15.0601(10)
97.755(5)
937.91(11)
2
˚
1.643 (2) A, respectively. The bond angles C1–C7–N1 and
˚
b (A)
C7–N1–C8 are 123.24(14) and 117.84(14), respectively,
and they are consistent with the sp2 hybrid character for C7
and N1 atoms [17–19, 29]. The torsion angles of the title
compound, C2–C1–C7–N1, C1–C7–N1–C8 and C7–N1–
C8–C8i are -167.188(149)°, -177.791(139)° and -126.326
(158)°, respectively, indicating a virtually planar E-config-
uration with respect to the imine C=N bond. There are
intermolecular O_H–C hydrogen bonds in the crystal
packing of the title compound N,N0-bis-(2,3-dimethoxyben-
zylidene)-1,2-diaminoethane that shown in Fig. 4. The
investigated samples exhibited single crystal diffraction
down to 170 K. Below this temperature they were damaged
and only very weak powder-like diffraction could be
observed. This occurred regularly for slow as well as fast
cooling with all of the ten tested samples. The structure at
170 K was calculated and compared with the one measured
at room temperature. Both structures were identical except
small rotation of methyl groups. Probably a destructive
phase transition occurs below 170 K which cannot be
investigated by means of single-crystal X-ray diffraction due
to cracking of the samples.
˚
c (A)
b (deg)
3
V (A )
˚
Z
l (mm-1
)
0.72
Density Mg m-3
1.261
Tmin
0.708
Tmax
0.949
F000
380
Measured reflections
Independent reflections
Reflection with I [ 3r(I)
Rint
3987
1441
1157
0.014
S
1.98
R[F2 [ 2r(F2)]
wR(F2)
0.037
0.111
Parameters
118
-3
˚
Dqmax (e A
)
0.12
-3
)
˚
Dqmin (e A
-0.12
Crystal size (mm3)
0.42 9 0.07 9 0.07
Index ranges
-4 B h B 2; -16 B k B 16;
-14 B l B 17
Conclusions
The new bidentate Schiff-base derivative, N,N0-bis-(2,3-di-
methoxybenzylidene)-1,2-diaminoethane, was synthesized
and characterized by elemental analyses, FT-IR and
1H-NMR spectroscopy. Single crystals were successfully
grown from solution by slow evaporation technique at room
temperature using a 25 ml methanol as a solvent. FT-IR and
1H-NMR are used to confirm the functional groups, partic-
ularly –HC=N imine group. The single crystal X-ray dif-
fraction has revealed a monoclinic structure with space
˚
Table 2 Selected bond lengths (A) and angles (°) of the title
compound
O1–C2
1.3791(17)
1.429(2)
O2–C10
1.421(2)
1.251(2)
O1–C9
N1–C7
O2–C3
1.357(2)
N1–C8
1.456(2)
N1–C8–C8i
C7–N1–C8
C3–O2–C10
O1–C2–C1
O1–C2–C3
111.34(13)
117.84(14)
117.69(13)
119.31(13)
119.72(14)
N1–C7–C1
C2–O1–C9
O2–C3–C2
O2–C3–C4
123.24(14)
115.19(12)
115.99(13)
125.12(15)
˚
group P21/c, lattice parameters a = 4.4159(3) A, b =
˚
˚
14.2333(9) A, c = 15.0601(10) A, b = 97.755(5)° and one
symmetry independent molecule C20H24N2O4 in almost
planar E-configuration with respect to the imine C=N bond.
Symmetry codes: (i) -x ? 1, -y, -z ? 1
Acknowledgments We acknowledge the Golestan University (GU)
for partial support of this work, the institutional research plan no.
AVOZ10100521 of the Institute of Physics and the project Praemium
Academiae of the Academy of Sciences of the Czech Republic.
the displacement ellipsoids of all non-hydrogen atoms at
40% probability level. Selected bond distances and angles
(Table 2) are in good agreement with those reported in
123

J Chem Crystallogr (2011) 41:1955–1960
1959
Fig. 3 ORTEP view of N,N0-
bis-(2,3-dimethoxybenzy-
lidene)-1,2-diaminoethane,
showing 40% probability
displacement ellipsoids and the
atomic numbering (a),
non-planar and centre
of symmetry (b)
Fig. 4 Packing diagram of
N,N0-bis-(2,3-dimethoxybenzy-
lidene)-1,2-diaminoethane
along a axis. Dashed lines
represent hydrogen bonds
7. Stilinovic V, Cincic D, Kaitner B (2008) Acta Chim Slov
55:874–879
Appendix A. Supplementary Data
8. Jeseentharani V, Selvakumar J, Dayalan A, Varghese B, Nagaraja
KS (2010) J Mol Struct 966:122–128
9. Albayrak C, Kosar B, Demir S, Odabasoglu M, Buyukgungor O
(2010) J Mol Struct 963:211–218
10. Petek H, Albayrak C, Odabasoglu M, Senel I, Buyukgungor O
(2010) Struct Chem 21:681–690
11. Marjani K, Asgarian J, Mousavi M, Amani V (2009) Z Anorg
Allg Chem 635:1633–1637
Crystallographic data (excluding structure factors) for the
structure reported in this paper has been deposited with the
Cambridge Crystallographic Center, CCDC Nos. 731883.
Copies of the data can be obtained free of charge on
application to The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK, fax: ?44 1223 336 033, e-mail:
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk.
12. Dehghanpour S, Mahmoudi
6:121–130
A (2007) Main Group Chem
13. Montazerozohori M, Johari S, Musavi SA (2009) Spectrochim
Acta Part A 73:231–237
14. Dolaz M, McKee V, Golcu A, Tumer M (2009) Spectrochim
Acta Part A 71:1648–1654
References
15. Laye RH (2007) Inorg Chim Acta 360:439–447
16. Baul TSB, Das P, Chandra AK, Mitra S, Pyke SM (2009) Dyes
Pigment 82:379–384
17. Khalaji AD, Ng SW (2008) Acta Cryst E64:o1771
18. Khalaji AD, Brad K, Zhang Y (2007) Acta Cryst E63:o7389
19. Khalaji AD, Weil M (2007) Anal Sci 23:x187–x188
20. Khalaji AD, Jian FF, Xiao H, Mojdekanlou S (2008) Anal Sci
24:x91–x92
1. Karakas A, Unver H, Elmali A (2008) J Mol Struct 877:152–157
2. Hadjoudis E, Rontoyianni A, Ambroziak K, Dziembowska T,
Mavridis IM (2004) J Photochem Photobiol A162:521–530
3. Aslantas M, Kendi E, Demir N, Sabik AE, Tumer M, Kertmen M
(2009) Spectrochim Acta A74:617–624
4. Hijji YM, Barare B, Kennedy AP, Butcher R (2009) Sens
Actuators B136:297–302
5. Bayol E, Gurten T, Gurten AA, Erbil M (2008) Mat Chem Phys
112:624–630
6. Emregul KC, Atakol O (2004) Mat Chem Phys 83:373–379
21. Khalaji AD, Zhang Y, Mojdekanlou S (2008) Anal Sci 24:x131–
x132
123

1960
J Chem Crystallogr (2011) 41:1955–1960
22. Khalaji AD, Hadadzadeh H, Gotoh k, Ishida H (2009) Acta Cryst
E65:m70
28. Morshedi M, Amirnasr M, Triki S, Khalaji AD (2009) Inorg
Chim Acta 362:1637–1640
23. Khalaji AD, Welter R, Amirnasr M, Barry AH (2008) Anal Sci
24:x137–x138
29. Khalaji AD, Fejfarova K, Dusek M (2010) Acta Chim Slov
57:257–261
24. Khalaji AD, Aoki K, Amirnasr M (2007) J Coord Chem
60:201–206
30. Khalaji AD, Weil M, Grivani G, Jalali Akerdi S (2010) Monatsh
Chem 141:539–543
25. Amirnasr M, Khalaji AD, Falvello LR, Soler T (2006) Polyhe-
dron 25:967–971
26. Khalaji AD, Amirnasr M, Triki S (2009) Inorg Chim Acta
362:587–590
27. Morshedi M, Amirnasr M, Slawin AMZ, Woollins JD, Khalaji
AD (2009) Polyhedron 28:167–171
31. Burla MC, Camalli M, Carrozzini B, Cascarano G, Giacovazzo
C, Polidori G, Spagna R, SIR2002: the program (2003) J Appl
Cryst 36:1103
32. Petricek V, Dusek M, Palatinus L (2008) Jana2006. Structure
determination software programs. Institute of Physics, Praha
33. Farrugia LJ (1997) J Appl Cryst 30:565
123