Syntheses and crystal structures of two soybean isoflavone derivatives

Article abstract of DOI:10.1007/s10870-005-3477-x

Two soybean isoflavone derivatives, 7-methoxy-4′-hydroxyisoflavone (1) and 4′, 7-diethoxyl-5-hydroxyisoflavone (2) were synthesized and their crystal structures were determined by single-crystal X-ray diffraction. Two derivatives crystallize in the monocl

Full text of DOI:10.1007/s10870-005-3477-x

ꢀC
Journal of Chemical Crystallography, Vol. 35, No. 9, September 2005 ( 2005)
DOI: 10.1007/s10870-005-3477-x
Syntheses and crystal structures of two soybean
isoflavone derivatives
Zun-Ting Zhang(1)∗ and Qiu-Ya Wang(1)
Received December 14, 2004; accepted February 3, 2005
Two soybean isoflavone derivatives, 7-methoxy-4ꢁ-hydroxyisoflavone (1) and 4ꢁ,
7-diethoxyl-5-hydroxyisoflavone (2) were synthesized and their crystal structures were
determined by single-crystal X-ray diffraction. Two derivatives crystallize in the mono-
˚
clinic crystal system, space group P21/c. The cell dimensions of 1 are a = 8.696(4) A, b =
◦
3
3
˚
˚
˚
11.947(5) A, c = 12.078(5) A, β = 93.594(7) , Dc = 1.423 Mg/m , V = 1252.3(10) A ,
˚
˚
˚
Z = 4, and those of 2 are a = 37.672(12) A, b = 11.228(4) A, c = 7.582(3) A,
◦
3
3
˚
β = 94.150(6) , Dc = 1.355 Mg/m , V = 3198.6(18) A and Z = 8. They have the same
isoflavone skeleton which is composed of a benzopyranone moiety and a phenyl moi-
ety. Hydrogen bonding and π · · · π stacking interactions assemble 1 into supramolecule
with a three-dimensional network. And in the crystal structure of 2, hydrogen bond-
---
ing and C H · · · π stacking interactions lead to the formation of a two-dimensional
network.
KEY WORDS: Soybean isoflavone; 7-methoxy-4ꢁ-hydroxyisoflavone; 4ꢁ,7-diethoxyl-5-hydroxy-isoflavone;
crystal structure; hydrogen bonding; π · · · π stacking.
Introduction
have the close relations with their biological ac-
tivities, for instance, Meng et al.16 found nei-
Daidzein (4ꢁ,7-dihydroxy-isoflavone) and
ther genistein nor daidzein, in their aglycone
form, have antioxidant properties of Low Den-
sity Lipoprotein (LDL), while the fatty acid es-
ters of both genistein and daidzein have antiox-
idant properties of LDL; Eun-AH Bae et al.17
have investigated the inhibitory effect of eight
isoflavones on the growth of Helicobacter py-
lori (HP), their activities have large differ-
ence due to the different substituents in the
isoflavone skeletons. In order to study the pos-
sible biological effects, we have synthesized
the derivatives of genistein, 4ꢁ,7-dimethoxyl-
5-hydroxyisoflavone, and studied its crystal
structure.18 In this paper, two soybean isoflavone
derivatives, 7-methoxy-4ꢁ-hydroxyisoflavone (1)
and 4ꢁ,7-diethoxyl-5-hydroxyisoflavone (2) were
genistein (4ꢁ,7-dihydroxy-isoflavone), as two eff-
ective principals of soybean isoflavone, dis-
play a wide range of biological activities. They
have been pharmacologically shown with the ef-
fects of antidysrhythmic,1 antioxidant,2,3 poten-
tial phytoestrogen,4,5 getting rid of hyperkinesias6
and inhibiting cancer cells growth.7,11 Stud-
ies have also found daidzein and genistein eff-
ective in inhibiting cardiovascular disease12 and
tyrosine kinases,13 and accelerating the formation
of bone cells.14,15 The structures of flavonoids
(1) School of Chemistry and Materials Science, Shaanxi Normal
University, Xi’an 710062, People’s Republic of China.
∗To whom correspondence should be addressed: e-mail: zhangzt@
snnu.edu.cn.
679
ꢀ
C
1074-1542/05/0900-0679/0 2005 Springer Science+Business Media, Inc.

680
Zhang and Wang
Scheme 1. Route of synthesis of 1.
synthesized and their crystal structure were exam-
ined by single-crystal X-ray diffraction.
precipitate was filtered off and washed with wa-
ter until the pH of the filtrate was 7 to obtain
the derivative 1. Finally, it was recrystallized
from ethanol to give hexagonal colorless blocks.
1H NMR(DMSO-d6, ppm): 10.02 (s, 1H,
Experimental
---
---
ꢁ
HO C4 ), 8.28 (s, 1H, H C2), 8.01 (d, 1H,
Reagent grade chemicals were used directly
without further purification. The infrared spec-
tra were recorded as KBr pellets on a Nico-
---
J = 9.0 Hz, H C5), 7.34 (d, 2H, J = 8.4 Hz,
---
---
ꢁ
ꢁ
H C2 , C6 ), 7.12 (s, 1H, H C8), 7.07 (d, 1H,
---
J = 9.0 Hz, H C6), 6.72 (d, 2H, J = 8.4 Hz,
1
let 170SX FT-IR spectrometer. The H NMR
---
ꢁ
ꢁ
H C3 ,C5 ), 3.90 (s, 3H, OCH3).
Spectra were recorded on a Bruker-1000 CCD
spectrometer with TMS as internal reference
and DMSO-d6 as solvent. The crystal structures
were determined with a Bruker Smart-1000 CCD
diffractometer.
Synthesis of derivative 2
Genistein (1.0 g) was dissolved into acetone
(30 mL), and KOH (1 mL, 0.3%) added. Then,
diethyl sulfate (1 mL) was added dropwise to
the solution with strong stirring. After the mix-
ture was stirred at room temperature for 4 h, it
was poured into 50 mL water and white precip-
itation appeared. The precipitate was filtered off
and dissolved in 50 mL NaOH (2 mol/L). Af-
ter that, the solution was filtered off and washed
with water until the pH of the filtrate was 7
to obtain the derivative 2. Finally, it was re-
crystallized from ethyl acetates to give prismatic
Synthesis of derivative 1
Daidzein (1.0 g) was dissolved into acetone
(30 mL), and KOH (1 mL, 0.3%) added. Then
dimethyl sulfate (1 mL) was added dropwise to
the solution with strong stirring. After the mix-
ture was stirred at room temperature for 4 h, it
was poured into water (50 mL) and white pre-
cipitation appeared. The precipitate was filtered
off and dissolved in NaOH (50 mL, 3 mol/L).
After that, the solution was filtered and the filtrate
was adjusted to pH = 10 with H2SO4 (3 mol/L),
and some white precipitate came into being. The
1
crystal. H NMR(DMSO-d6, ppm): 12.92(s, 1H,
---
---
HO C5), 8.43(s, 1H, H C2), 7.49 (d, 2H, J =
---
ꢁ
ꢁ
8.4 Hz, H C2 , C6 ), 6.98(d, 2H, J = 8.4 Hz,
--- ---
ꢁ
ꢁ
H C3 , C5 ), 6.64(s, 1H, H C8), 6.39 (s, 1H,
Scheme 2. Route of synthesis of 2.

Syntheses and crystal structures of two soybean isoflavone derivatives
681
---
---
---
H C6), 4.12(m, 4H, OCH2 ), 1.34 (m, 6H,
The selected bond lengths and angles of 1 and 2
are listed in Tables 2 and 3, respectively.
--- ---
OC CH3).
X-ray crystal structure determinations
Results and discussion
In the determination of the structures of the
crystals 1 and 2, X-ray determination data were
collected on a Bruker Smart-1000 CCD diffrac-
tometer with graphite-monochromated Mo Kα
The molecular structures of two derivatives
are illustrated in Figs. 1 and 2, respectively. Com-
pound 1 is composed of a benzopyranone moiety,
a phenyl moiety, a hydroxyl and a methoxyl group.
The atoms of benzopyranone moety, including
˚
radiation (λ = 0.71073 A) using ω − 2θ scan
---
---
technique. The structures were solved by direct
methods and refined on F2 by full matrix least-
squares with the Bruker’s SHELXL-97 program.
All non-hydrogen atoms were refined anisotrop-
ically. All hydrogen atoms were treated using a
riding model. The crystals used for the diffraction
study showed no decomposition during data col-
lection. The crystals data, experimental details,
and refinement results are summarized in Table 1.
ring A(C4 C9) and ring C(C1 C4,C9,O1), dis-
play a coplanar configuration with a mean de-
˚
viation to the least square plane of 0.0031 A.
To avoid steric conflicts, the two rigid ring sys-
---
tems, phenyl ring B (C10 C15) and benzopy-
ranone moiety are rotated by 43.2◦ with respect
to each other. The methoxyl group at C7 is
nearly planar with its corresponding rings, ring A
--- --- ---
and ring C, the torsion angle C16 O3 C7 C8
Table 1. Crystal Data and Structure Refinement for 1 and 2
Compound 1
Crystal data
CCDC deposit no.
Empirical formula
Formula weight
Crystal size (mm)
Temperature (K)
Crystal system
Compound 2
258208
16H12O4
268.26
258209
C19H18O5
326.33
C
0.43 × 0.29 × 0.25
0.58 × 0.48 × 0.11
298(2)
273(2)
Monoclinic
P2(1)/c
Monoclinic
P2(1)/c
Space group
Unit cell dimensions
˚
a (A)
8.696(4)
11.947(5)
12.078(5)
93.594(7)
1252.3(10), 4
1.423
0.103
2.35 to 25.03
37.672(12)
11.228(4)
7.582 (3)
94.150(6)
3198.6(18), 8
1.355
0.098
1.63 to 25.03
˚
b (A)
˚
c (A)
β (◦)
3
˚
Volume, Z (A )
Density(calculated, Mg/m3)
Absorption coefficient (mm−1
)
ꢀ range for data collection (◦)
Limiting indices
−10 ≤ h ≤ 10
−14 ≤ k ≤ 13
−13 ≤ l ≤ 14
6282/2205 [Rint = 0.0321]
0.9748 and 0.9572
Full-matrix least-squares on F2
2205/0/229
−44 ≤ h ≤ 40
−13 ≤ k ≤ 12
−9 ≤ l ≤ 8
Reflections collected/unique
Max. and min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
15936/5501 [Rint = 0.0733]
0.9893 and 0.9453
Full-matrix least-squares on F2
5501/0/433
1.021
1.007
Final R indices [I > 2σ(I)]
R indices (all data)
R1 = 0.0384, wR2 = 0.0877
R1 = 0.0681, wR2 = 0.1054
0.140 and −0.168
R1 = 0.0688, wR2 = 0.1587
R1 = 0.1472, wR2 = 0.2057
0.266 and −0.183
Largest diff. peak and hole (eA−3
)

682
Zhang and Wang
◦
˚
Table 2. Selected Bond Lengths (A) and Angles ( ) for 1
˚
Bond lengths (A)
----
----
C(4) C(9)
O(1) C(1)
1.358(2)
1.238(2)
1.356(2)
1.429(3)
1.362(2)
0.93(3)
1.336(3)
1.484(3)
1.451(3)
1.381(2)
1.409(3)
1.400(3)
1.393(3)
1.392(3)
1.396(3)
1.375(3)
1.383(3)
1.383(3)
----
----
O(2) C(3)
----
C(4) C(5)
----
C(6) C(7)
O(3) C(7)
----
----
O(3) C(16)
C(8) C(9)
----
O(4) C(13)
----
C(10) C(11)
----
----
O(4) H(9)
----
C(10) C(15)
----
C(11) C(12)
C(1) C(2)
----
----
C(2) C(10)
C(13) C(14)
----
----
C(14) C(15)
C(3) C(4)
Bond angles (◦)
----
----
----
----
----
----
----
----
C(1) O(1) C(9)
118.09(15)
118.11(18)
109.5(19)
126.31(19)
121.01(16)
122.50(17)
115.64(16)
116.56(18)
123.23(17)
119.18(19)
C(6) C(5) C(4)
121.2(2)
C(7) O(3) C(16)
---- ----
O(3) C(7) C(8)
---- ----
124.76(18)
120.16(19)
121.01(16)
123.57(18)
121.19(17)
121.63(19)
120.3(2)
C(13) O(4) H(9)
---- ----
C(8) C(7) C(6)
---- ----
C(2) C(1) O(1)
---- ----
O(1) C(9) C(4)
---- ----
C(1) C(2) C(3)
---- ----
C(4) C(9) C(8)
---- ----
O(2) C(3) C(4)
---- ----
C(11) C(10) C(15)
---- ----
C(4) C(3) C(2)
---- ----
C(12) C(11) C(10)
---- ----
C(9) C(4) C(5)
---- ----
C(11) C(12) C(13)
---- ----
O(4) C(13) C(14)
---- ----
C(13) C(14) C(15)
---- ----
C(14) C(15) C(10)
120.08(19)
121.49(19)
C(14) C(13) C(12)
◦
˚
Table 3. Selected Bond Lengths (A) and Angles ( ) for 2
˚
Bond lengths (A)
----
----
C(10) C(15)
O(1) C(1)
----
1.360(4)
1.249(4)
1.341(4)
1.368(5)
1.372(4)
1.356(4)
1.243(4)
1.346(4)
1.356(5)
1.381(4)
1.348(5)
1.384(5)
1.381(5)
1.383(5)
1.375(5)
1.506(6)
1.498(5)
1.339(5)
1.387(5)
1.402(5)
1.373(5)
1.382(5)
1.377(5)
1.377(5)
1.504(6)
1.476(6)
----
O(2) C(3)
C(11) C(12)
----
----
C(16) C(17)
O(3) C(5)
----
----
O(4) C(7)
----
C(18) C(19)
----
C(20) C(21)
O(5) C(13)
----
----
O(6) C(20)
C(23) C(28)
----
----
C(25) C(26)
O(7) C(22)
----
----
O(8) C(24)
C(27) C(28)
----
----
C(29) C(34)
O(9) C(26)
----
----
O(10) C(32)
C(30) C(31)
----
----
C(33) C(34)
C(1) C(2)
----
----
C(4) C(9)
C(35) C(36)
----
----
C(37) C(38)
C(7) C(8)
Bond angles (◦)
----
----
----
----
----
----
----
----
C(1) O(1) C(9)
118.8(3)
O(4) C(16) C(17)
108.3(4)
109.2(3)
126.2(4)
117.7(4)
121.3(3)
116.0(3)
116.2(4)
122.1(3)
119.4(4)
121.4(4)
123.9(4)
120.9(4)
116.0(3)
124.6(4)
119.4(4)
116.6(3)
122.8(3)
120.4(3)
125.1(3)
115.4(3)
119.4(3)
107.8(3)
109.0(3)
C(7) O(4) C(16)
---- ----
118.2(3)
118.1(3)
118.9(3)
118.7(3)
118.5(3)
125.8(3)
120.9(3)
116.0(3)
117.1(4)
121.9(3)
119.8(4)
120.6(4)
119.9(4)
123.6(4)
121.3(4)
120.6(3)
123.2(4)
116.3(4)
120.5(4)
124.8(3)
118.9(4)
123.5(3)
O(5) C(18) C(19)
---- ----
C(13) O(5) C(18)
---- ----
C(21) C(20) O(6)
---- ----
C(20) O(6) C(28)
---- ----
C(20) C(21) C(22)
---- ----
C(26) O(9) C(35)
---- ----
O(7) C(22) C(23)
---- ----
C(32) O(10) C(37)
---- ----
C(23) C(22) C(21)
---- ----
C(2) C(1) O(1)
---- ----
C(28) C(23) C(24)
---- ----
O(2) C(3) C(4)
---- ----
C(24) C(23) C(22)
---- ----
C(4) C(3) C(2)
---- ----
O(8) C(24) C(25)
---- ----
C(9) C(4) C(5)
---- ----
C(25) C(24) C(23)
---- ----
C(5) C(4) C(3)
---- ----
O(9) C(26) C(27)
---- ----
O(3) C(5) C(6)
---- ----
C(27) C(26) C(25)
---- ----
C(6) C(5) C(4)
---- ----
C(27) C(28) O(6)
---- ----
C(5) C(6) C(7)
---- ----
C(27) C(28) C(23)
---- ----
O(4) C(7) C(8)
---- ----
O(6) C(28) C(23)
---- ----
C(8) C(7) C(6)
---- ----
C(34) C(29) C(30)
---- ----
O(1) C(9) C(4)
---- ----
C(30) C(29) C(21)
---- ----
C(4) C(9) C(8)
---- ----
C(30) C(31) C(32)
---- ----
C(15) C(10) C(11)
---- ----
C(33) C(32) O(10)
---- ----
C(12) C(11) C(10)
---- ----
O(10) C(32) C(31)
---- ----
O(5) C(13) C(14)
---- ----
C(34) C(33) C(32)
---- ----
C(14) C(13) C(12)
---- ----
O(9) C(35) C(36)
---- ----
O(10) C(37) C(38)
C(14) C(15) C(10)

Syntheses and crystal structures of two soybean isoflavone derivatives
683
Fig. 1. The molecular structure of 1 showing 30% probability displacement
ellipsoids.
being 2.1◦. In the crystal structure of 2,
the basic asymmetric unit contains two
molecules, and the isoflavone skeletons of them
out of the benzopyranone moiety, as indicated by
--- --- ---
the torsion angle C(18) O(4) C(13) C(14) =
◦
◦
---
---
---
−3.1 , C(37) O(11) C(32) C(33) = 0.4 .
As is shown in Fig. 3, in the crystal structure
of 1, there are two kinds of hydrogen bonds that
link the molecules into a sheet (Details of hydro-
gen bond lengths and angles are given in Table 4).
The carbonyl oxygen atom accepts proton from
the adjacent molecule to form the hydrogen bond
---
---
---
are A(C4 C9)C(O1,C1 C4,C9)–B(C10 C15)
--- ---
and A(C23 C28) C(O8, C20 C23, C28)–
---
B(C29 C34), respectively. The atoms in the ben-
zopyranone moiety of two molecules are nearly
coplanar, and the dihedral angle between ring A
and C are 1.1◦ and 2.4◦, respectively. To avoid
steric conflicts, the two rigid ring systems, phenyl
ring and benzopyranone moiety are rotated by
35.90◦ and 31.10◦ with respect to each other,
respectively. The ethoxyl group at C-7, C-26
are slightly twisted out of phenyl ring with the
---
O2 · · · H9# O4#, which link the molecules into
an infinite zig-zag chain. The zig-zag chain is fur-
¯
ther extended into a sheet along (1, 0, 1) direction
∗
∗---
by hydrogen bond C6 H3 · · · O1. In addition,
π · · · π stacking interactions exist in crystal struc-
◦
---
---
---
---
---
torsion angle C(16) O(3) C(7) C(8) = 0.1
ture of 1 (Fig. 4). The ring B (C1 C4,C9,O1)
◦
---
---
and C(35) O(10) C(26) C(25) = 7.5 , and the
of one molecule is nearly parallel to the ring
---
etholxy group at C-13, C32 are slightly oriented
C (C10 C15) of a neighboring molecule, the
Fig. 2. A general view of the asymmetric unit of 2. Ellipsoids are drawn at the 30% probability. Thin dashed
lines represent the hydrogen bonds.

684
Zhang and Wang
Fig. 3. The sheet of molecules formed via two kinds of hydrogen bonds
in 1. Symmetry code: ∗(2−x, y + 0.5, 2.5 − z); # (1 − x, 1 − y, 1.5 − z).
angle between them being 8.3◦. They stack with
each other and its centriod-centriod distance is
O2 accepts proton from the other molecule
---
to form intermolecular hydrogen bond C37
˚
3.706 A, which is in the normal range of 3.3–
H37A · · · O2, which links two molecules of the
19
˚
3.8 A. π · · · π stacking interactions and hydro-
asymmetry unit together (Fig. 2).
gen bonding assemble 1 into supramolecule with
a three-dimensional network (Fig. 5).
The asymmetry units are further linked into a
¯
chain along the (3, 0, 2) direction by the hydrogen
---
Two intramolecular hydrogen bonds,
bond C18 H18B · · · O7. (Details of hydrogen
---
---
O3 H3 · · · O2 and O8 H8 · · · O7 exist in the
bond lengths and angles are also given in Table 4).
Additionally, the C H · · · π stacking exists in the
---
crystal structure of 2. The carbonyl oxygen atom
◦
˚
Table 4. Typical Hydrogen Bond Lengths (A) and Bond Angles ( ) for 1 and 2
◦
˚
˚
˚
----
----
----
D
D
H · · · A
D
H (A) H · · · A (A) D · · · A (A)
H · · · A( )
----
1
2
O4# H9# · · · O2
0.928
0.966
0.821
0.819
0.970
0.970
1.772
2.552
1.830
1.836
2.564
2.587
2.770
3.435
2.563
2.557
3.325
3.449
177.63
161.53
147.94
146.23
139.39
148.21
∗
∗ ----
C6 H3 · · · O1
----
O3 H3 · · · O2
----
O8 H8 · · · O7
----
C37 H37A · · · O2
----
C18 H18B · · · O7
Note. Symmetry code: ∗(2 −x, y + 0.5, 2.5 − z); #(1 − x, 1 − y, 1.5 − z).

Syntheses and crystal structures of two soybean isoflavone derivatives
685
Fig. 4. The π · · · π stacking interactions in 1. Symmetry code: #(x, 1.5 − y, z + 0.5);
∗(x, 1.5 − y, z − 0.5).
stacking.20−22 The C H · · · π stacking interac-
tions link the chains into a two-dimensional
network.
crystal stru∗cture of 2 (Fig. 6). The distance of the
---
˚
H15 to Cg , the centroid of ring B, is 2.710 A,
---
which lies in the normal range of the C H · · · π
Fig. 5. The packing diagram of 1.

686
Zhang and Wang
---
Fig. 6. The intermolecular C H · · · π stacking in 2. Symmetry code: # (x, 1.5 − y,
z + 0.5); ∗(x, 1.5 − y, z − 0.5).
Supplementary material “CCDC-258208 and 258209 contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge at www.ccdc.cam.ac.uk/conts/
retrieving.html [or from the Cambridge Crystallographic Data Centre
(CCDC), 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)12
23-336033; e-mail: deposit@ccdc.cam.ac.uk].”
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