Crystal structure of 1,7-bis(4-chlorophenyl)-4-(1,3-dithiolan-2-ylidene)-1, 6-heptadiene-3,5-dione

Article abstract of DOI:10.1007/s10870-008-9362-6

The synthesis and crystal structure of 1,7-bis(4-chlorophenyl)-4-(1,3- dithiolan-2-ylidene)-1,6-heptadiene-3,5-dione is described. This compound is a curcuminoid analogue, configurationally symmetric about the C4-C5 atoms and also retains the two fold axis in the crystal phase. This compound crystallizes in the space group C2/c with unit cell parameters a = 19.203(1) A, b = 13.147(1) A, c = 8.801(1) A, β = 112.99(1)°, with half a molecule in the asymmetric unit. The ketenedithioacetal functionality present between the carbonyl groups prevents the possibility of keto-enol tautomerization in this compound. The push-pull nature of the ketenedithioacetal functionality organizes the cinnamoyl groups parallel to each other.

Full text of DOI:10.1007/s10870-008-9362-6

J Chem Crystallogr (2008) 38:641–644
DOI 10.1007/s10870-008-9362-6
ORIGINAL PAPER
Crystal Structure of 1,7-Bis(4-chlorophenyl)-4-(1,3-dithiolan-2-
ylidene)-1,6-heptadiene-3,5-dione
S. G. Bubbly Æ S. B. Gudennavar Æ Babu Verghese Æ
Dhanya Viswam Æ C. Sudarsanakumar
Received: 8 July 2007 / Accepted: 27 March 2008 / Published online: 8 April 2008
Ó Springer Science+Business Media, LLC 2008
Abstract The synthesis and crystal structure of 1,7-bis
(4-chlorophenyl)-4-(1,3-dithiolan-2-ylidene)-1,6-heptadiene-
3,5-dione is described. This compound is a curcuminoid
analogue, configurationally symmetric about the C4–C5
atoms and also retains the two fold axis in the crystal phase.
This compound crystallizes in the space group C2/c with
Introduction
The title compound 1,7-bis(4-chlorophenyl)-4-(1,3-dithio-
lan-2-ylidene)-1,6-heptadiene-3,5-dione is a derivative of
curcumin, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-hept-
adiene-3,5-dione, a natural food dye used in traditional
cooking in Asia. Curcuminoids (1,7-diaryl-1,6-heptadiene-
3,5-diones) constitute the most important active chemical
components in the herbaceous medicinal plant Curcuma
longa Linn(turmeric). Natural and synthetic curcuminoid
analogues are reported to possess antitumour, antioxidant,
antimutagenic and anti-inflammatory activities [1–6]. The
synthetic curcuminoid analogue 1,7-bis(2-chlorophenyl)-
1,6-heptadiene-3,5-dione which also shows antitumour
activity is closely related to the title compound except for
the substitution at the C(4) position [7]. The structure
investigation of the title compound gains considerable
attention in this context.
˚
unit cell parameters a = 19.203(1) A, b = 13.147(1) A,
˚
˚
c = 8.801(1) A, b = 112.99(1)°, with half a molecule in the
asymmetric unit. The ketenedithioacetal functionality pres-
ent between the carbonyl groups prevents the possibility of
keto-enol tautomerization in this compound. The push-pull
nature of the ketenedithioacetal functionality organizes the
cinnamoyl groups parallel to each other.
Keywords Crystal structure Á 1,7-Bis(4-chlorophenyl)-4-
(1,3-dithiolan-2-ylidene)-1,6-heptadiene-3,5-dione Á
Curcumin analogue Á X-ray diffraction
Curcumin and its analogues usually exist in the com-
pletely enolized form as shown by their crystal structures
[8, 9]. In the crystal structure of Curcumin, the substituted
˚
cinnamoyl groups are far apart (5.015 A) [8]. The com-
S. G. Bubbly (&) Á S. B. Gudennavar
pound 1,6-hexadiene-3,5-dione having an unsubstituted
methylene group between the carbonyl groups and 1,7-
diphenyl-4-butyl-1,6-heptadiene-3,5-dione having a butyl
group between the carbonyl groups do have linear struc-
tures [10]. The extended conjugation resulting from the
enolization contributes to the stability of their linear
structure. In bis(cinnamoyl) ketenedithioacetal, the ket-
enedithioacetal functionality present between the carbonyl
groups prevent the possibility of keto-enol tautomerization
observed in enolizable 1,3-carbonyl compounds [11–13].
The crystal structure of the title compound shows that the
two cinnamoyl groups are parallel to each other and the
double bonds are very close to each other. The push-pull
Post Graduate Department of Physics, Christ College
(Autonomous), Hosur Road, Bangalore 560 029,
Karnataka, India
e-mail: bubblysg@rediffmail.com; bubbly.sg@christcollege.edu
B. Verghese
Sophisticated Analytical Instrument Facility, Indian Institute
of Technology, Chennai 600 036, India
D. Viswam
School of Chemical Sciences, Mahatma Gandhi University,
Kottayam 686 560, Kerala, India
C. Sudarsanakumar
School of Pure and Applied Physics, Mahatma Gandhi
University, Kottayam 686 560, Kerala, India
123

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J Chem Crystallogr (2008) 38:641–644
nature of the ketenedithioacetal functionality organizes the
cinnamoyl groups parallel to each other.
Table 1 Crystal data, intensity collection conditions and refinement
parameters for 1,7-bis(4-chlorophenyl)-4-(1,3-dithiolan-2-ylidene)-
1,6-heptadiene-3,5-dione
CCDC No.
273894
Empirical formula
Formula weight
Temperature (K)
C22 H16 Cl2 O2 S2
447.36
Experimental
293 (2)
Synthesis
˚
Wavelength (A)
1.54180
Sodium metal (0.45 g, 20 mmol) was dissolved in ethanol
(20 mL) to which cyclic diacetyl ketenedithioacetal
(1.01 g, 5 mmol) was added followed by para-chloro
benzaldehyde (10 mmol). The reaction mixture was stirred
at 0–5 °C for 4 h. The solid obtained was filtered, washed
in ethanol and recrystallized from a mixture of hexane and
ethyl acetate to give the title compound.
Crystal system, space group
Monoclinic, C2/c
a = 19.203 (1), b = 13.147 (1),
c = 8.801 (1), b = 112.99 (1)
2045.4 (3)
˚
Unit cell dimensions (A, °)
3
˚
Volume (A )
Z, Calculated density (Mg/m3)
4, 1.453
Absorption coefficient (mm-1
Absorption correction
Max. and min. transmission
Crystal size (mm)
)
4.892
Psi-scan [17]
0.65 and 0.26
0.2 9 0.2 9 0.1
920
Crystallography
F(000)
Needle shaped yellow crystals of the title compound were
obtained from a solution of methanol–chloroform by slow
evaporation. The dimension of the crystal used for data
collection was 0.2 mm 9 0.2 mm 9 0.1 mm. The crystals
of this compound belong to the monoclinic space group
h range for data collection (°)
Index ranges
4.19–69.94
-23 B h B 21, 0 B k B 16,
0 B l B 10
Reflections collected/unique
Completeness to 2h = 70
Refinement method
1871/1871 (R(int) = 0.0)
98.4%
Full-matrix least-squares on F2
˚
C2/c with unit cell parameters a = 19.203(1) A, b =
˚
˚
Goodness-of-fit on F2
1.037
13.147(1) A, c = 8.801(1) A, b = 112.99(1)°. The inten-
sity data were collected upto 2h max of 139.8° by an
Enraf-Nonius CAD-4 diffractometer using crystal mono-
Data/parameters
1871/153
Final R indices (I [ 2r(I))
R indices (all data)
R1 = 0.0483, wR2 = 0.1321
R1 = 0.0547, wR2 = 0.1430
0.00039 (17)
˚
chromated CuKa radiation (k = 1.5418 A). The x-2h scan
mode was used. The usual precaution of checking the con-
sistency of the intensities of three strong reflections
periodically (every one hour) for monitoring the stability of
the crystal during X-ray exposure was observed. The inten-
sities were corrected for Lorentz, polarization and absorption.
The structure was solved by direct methods using
SHELXS-97 [14] and all the non-hydrogen atoms were
located from the E-map. The structure was refined using
SHELXL-97 [14]. The ideal hydrogen atom coordinates
were calculated by the program and were made to ride on
the coordinates and temperature factors of the respective
carbon atoms. The refinement was continued until the
maximum shift/e.s.d was zero. The final difference map
was featureless with maximum and minimum electron
Extinction coefficient
Largest diff. peak and
-3
0.305 and -0.315
˚
hole (e A
)
The parallel alignment of the cinnamoyl groups in the
title compound apparently results from the push-pull nature
of the ketene dithioacetal moiety [15]. The carbon atoms a
to the carbonyl groups (C(2) and C(2a)) are separated by
˚
2.968(2) A. Due to the electron releasing nature of the
ketene dithioacetal functionality, the oxygen atoms of
the carbonyl groups develop partial negative charges while
the sulphur atoms develop partial positive charges. This
would bring the ketene dithioacetal group and the carbonyl
groups into the same plane, forming a relatively more
stable conformation. The sulphur atoms S(1) & S(1a) are
close to the oxygen atoms O(1) & O(1a) respectively. The
-3
˚
densities at 0.305 and -0.315 e A respectively. The
crystal data, intensity collection conditions and refinement
parameters are presented in Table 1.
˚
non-bonded distances between S(1)ÁÁÁO(1) = 2.569(2) A.
Thus the ketene dithioacetal functionality organizes the
cinnamoyl groups parallel and close to each other. Bond
lengths and angles in this compound are comparable with
those reported for other curcumin analogues [9, 10, 15, 16]
(Table 2).
Results and Discussion
The title compound shows perfect symmetry in its crys-
talline form. In the crystal phase, it retained the two fold
axis passing through the middle atoms C(4)–C(5) (Fig. 1).
The asymmetric unit is half a molecule of the compound.
The phenyl plane (C(7)–C(8)–C(9)–C(10)–C(11)–C(12))
and the dithiolan plane (S(1)–C(5)–S(1)a–C(6)a–C(6))
123

J Chem Crystallogr (2008) 38:641–644
643
Table 3 Torsion angles (deg.) for 1,7-bis(4-chlorophenyl)-4-(1,3-
dithiolan-2-ylidene)-1,6-heptadiene-3,5-dione
C(7)–C(1)–C(2)–C(3)
C(1)–C(2)–C(3)–O(1)
C(1)–C(2)–C(3)–C(4)
O(1)–C(3)–C(4)–C(5)
C(2)–C(3)–C(4)–C(5)
O(1)–C(3)–C(4)–C(3)#1
C(2)–C(3)–C(4)–C(3)#1
C(3)–C(4)–C(5)–S(1)#1
C(3)#1–C(4)–C(5)–S(1)#1
C(3)–C(4)–C(5)–S(1)
C(3)#1–C(4)–C(5)–S(1)
C(6)–S(1)–C(5)–C(4)
C(6)–S(1)–C(5)–S(1)#1
C(5)–S(1)–C(6)–C(6)#1
C(2)–C(1)–C(7)–C(8)
C(2)–C(1)–C(7)–C(12)
C(12)–C(7)–C(8)–C(9)
C(1)–C(7)–C(8)–C(9)
C(7)–C(8)–C(9)–C(10)
C(8)–C(9)–C(10)–C(11)
C(8)–C(9)–C(10)–Cl(1)
C(9)–C(10)–C(11)–C(12)
Cl(1)–C(10)–C(11)–C(12)
C(10)–C(11)–C(12)–C(7)
C(8)–C(7)–C(12)–C(11)
C(1)–C(7)–C(12)–C(11)
179.4(2)
14.2(3)
-169.7(2)
18.4(2)
-157.8(2)
-161.6(2)
22.2(2)
174.4(1)
-5.6(1)
-5.6(1)
174.4(1)
168.9(1)
-11.1(1)
35.3(4)
5.0(4)
-174.6(2)
0.0(4)
Fig. 1 ORTEP drawing of 1,7-bis(4-chlorophenyl)-4-(1,3-dithiolan-
2-ylidene)-1,6-heptadiene-3,5-dione [18]
-179.7(2)
0.9(4)
˚
Table 2 Bond lengths (A) and angles (deg.) for 1,7-bis(4-chloro-
phenyl)-4-(1,3-dithiolan-2-ylidene)-1,6-heptadiene-3,5-dione
-1.4(4)
178.4(2)
0.9(4)
˚
Bond length (A)
Angle (deg.)
S(1)–C(5)
1.739(2)
1.813(3)
1.737(3)
1.231(3)
1.332(3)
1.452(3)
1.476(3)
1.473(3)
1.379(5)
1.473(3)
1.739(2)
1.487(6)
1.397(3)
1.400(3)
1.373(4)
1.382(4)
1.381(4)
1.370(4)
C(5)–S(1)–C(6)
C(2)–C(1)–C(7)
C(1)–C(2)–C(3)
O(1)–C(3)–C(4)
O(1)–C(3)–C(2)
C(4)–C(3)–C(2)
C(5)–C(4)–C(3)
C(5)–C(4)–C(3)#1
C(3)–C(4)–C(3)#1
C(4)–C(5)–S(1)#1
C(4)–C(5)–S(1)
S(1)#1–C(5)–S(1)
C(6)#1–C(6)–S(1)
C(8)–C(7)–C(12)
C(8)–C(7)–C(1)
C(12)–C(7)–C(1)
C(9)–C(8)–C(7)
C(8)–C(9)–C(10)
C(11)–C(10)–C(9)
C(11)–C(10)–Cl(1)
C(9)–C(10)–Cl(1)
C(12)–C(11)–C(10)
C(11)–C(12)–C(7)
95.8(2)
127.5(2)
120.0(2)
119.4(2)
119.5(2)
121.0(2)
118.5(1)
118.5(1)
123.1(3)
122.8(1)
122.8(1)
114.5(2)
107.6(2)
117.7(2)
123.2(2)
119.0(2)
121.2(2)
119.3(2)
121.2(2)
119.3(2)
119.5(2)
119.0(2)
121.6(2)
-178.9(2)
0.1(4)
S(1)–C(6)
Cl(1)–C(10)
O(1)–C(3)
C(1)–C(2)
C(1)–C(7)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(4)–C(3)#1
C(5)–S(1)#1
C(6)–C(6)#1
C(7)–C(8)
C(7)–C(12)
C(8)–C(9)
C(9)–C(10)
C(10)–C(11)
C(11)–C(12)
-0.5(4)
179.2(2)
The five member ring S1–C(5)–S(1)a–C(6)a–C(6) is in a
distorted half chair conformation which is twisted on C(6)–
C(6)a bond [19, 20]. A similar conformation is also
observed for other compounds with a dithiolane ring sub-
stitution [15, 21].
The molecules related by the c-glide are arranged to form
a layer of molecules almost parallel to the bc-plane (Fig. 2)
[22]. The molecules related by the C-centering form another
˚
layer separated by *9 A from this layer. There is a probable
hydrogen bonding between the carbon atom in the chloro-
phenyl ring and carbonyl oxygen at x, -y, z - 1/2 position
within a layer. The hydrogen bonding parameters are:
D–HÁÁÁA
Symm
HÁÁÁA
DÁÁÁA
D–HÁÁÁA
˚
˚
C(8)–H(8)ÁÁÁO(1) x, -y, z - 1/2 2.4085 A 3.3272 A 169.44°
Symmetry transformations used to generate equivalent
atoms: #1 -x + 1, y, -z + 1/2
Conclusion
make an angle of 32.07(2)°. The chlorine atom lies in
the plane of the phenyl ring as seen from the torsion angle
C(8)–C(9)–C(10)–Cl [178.4(2)°] (Table 3).
The title compound crystallized in the space group C2/c
with the two-fold axis passing through C(4)–C(5) atoms so
123

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J Chem Crystallogr (2008) 38:641–644
Fig. 2 Packing of molecules
down a-axis
3. Kunchandy E, Rao MNA (1990) Int J Pharm 58:237
4. John VD, Krishnankutty K (2005) Transition Metal Chem
30:229–233
5. Anto RJ, George J, Dineshbabu KV, Rajasekharan KN, Kuttan R
(1996) Mutat Res 370:127
6. Nagabushan M, Bhide SV (1992) J Am Cell Nutr 11:192
7. John VD, Krishnankutty K (2006) Appl Organomet Chem
20:477–482
that there is only half a molecule in the asymmetric unit.
The ketene dithioacetal functionality present in the com-
pound organizes the cinnamoyl groups close and parallel to
each other. The five member ring S1–C(5)–S(1)a–C(6)a–
C(6) is in a distorted half chair conformation.
8. Tonnesen HH, Karlsen J, Mostad A (1982) Acta Chem Scand
B36:475–479
Supplementary Material
9. Gorbitz CH, Mostad A (1993) Acta Chem Scand 47:509–513
10. Mostad A, Pedersen U, Rasmussen PB, Lawesson SO (1984)
Acta Chem Scand B38:479–484
11. Hollander FJ, Templeton DH, Zalken A (1973) Acta Crystallogr
B29:1552
12. Williams DE, Dumke WL, Rundle RE (1962) Acta Crystallogr
15:627
13. Williams DE (1966) Acta Crystallogr 21:340
14. Sheldrick GM (1997) SHELX-97, University of Gottingen,
Germany
All crystallographic data for this paper are deposited with
the Cambridge Crystallographic Data Centre (CCDC-
273894). The data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html [or from Cam-
bridge Crystallographic Data Centre (CCDC), 12 Union
Road, Cambridge CB2 1EZ, UK; fax: +44 (0) 1223-
336033; e-mail:deposit@ccdc.cam.ac.uk].
15. Bubbly KJ, Verghese B, Sudarsanakumar C, Deepa S, Dhanya V,
Prakash C, Asokan CV (2002) J Chem Soc Chem Commun 736–
737
16. Karlsen J, Mostad A, Tonnesen HH (1988) Acta Chem Scand
B42:23–27
Acknowledgements The authors are indebted to (the late) Dr. C. V.
Asokan, School of Chemical Sciences, Mahatma Gandhi University,
Kottayam, Kerala, for all the help received, especially in the synthesis
of this compound.
17. North ACT, Phillips DC, Mathews FS (1968) Acta Crystallogr
A24:351–359
References
18. Zsolnai L (1997) ZORTEP 1997, University of Heidelberg
19. Brahde LB (1954) Acta Chem Scand 8:1145
20. Schmidt WH, Tulinsky (1967) Tetrahedron Lett 5311
21. Deepak C, Mohan TP, Rao KS, Guru Row TN (2005) Acta
Crystallogr E61:o3–o5
1. Ramsewek RS, Dewitt DL, Nair MG (2000) Phytomedicine
7:303
2. Ruby Anto J, Dineshbabu KV, Rajasekharan KN, Kuttan R
(1995) Cancer Lett 94:74
22. Spek AL (1990) Acta Crystallogr A46:C-34
123