Structural characterization of monomers for non-linear optical polymers. X-ray analysis and molecular mechanics calculations of 2-(4-methacryloxy-3- methoxyphenyl)-1,1-dicyanoethylene, 2-(3-methacryloxy-4-methoxyphenyl)-1,1- dicyanoethylene, and 2-(2-meth

Article abstract of DOI:10.1016/S0022-2860(99)00417-2

The results of molecular mechanics calculations, hyperpolarizabilities calculations, synthesis, and X-ray analysis of three monomers for non-linear optical polymers are presented. All monomers are derivatives of dicyanovinylbenzene with methoxy and methac

Full text of DOI:10.1016/S0022-2860(99)00417-2

Journal of Molecular Structure 523 (2000) 309–318
www.elsevier.nl/locate/molstruc
Structural characterization of monomers for non-linear optical
polymers. X-ray analysis and molecular mechanics calculations of
2
-(4-methacryloxy-3-methoxyphenyl)-1,1-dicyanoethylene,
-(3-methacryloxy-4-methoxyphenyl)-1,1-dicyanoethylene, and
-(2-methacryloxy-3-methoxyphenyl)-1,1-dicyanoethylene
2
2
a
a
a,
a,b
a
*
V.N. Nesterov , X. Deng , T.V. Timofeeva , M.Yu. Antipin , R.D. Clark ,
c
c
D.O. Frazier , B. Penn
a
Department of Physical Sciences, New Mexico Highlands University, Las Vegas, NM 87701, USA
b
Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov St., B-334, Moscow, Russian Federation
c
Space Science Laboratory, NASA George C. Marshall Space Flight Center, Huntsville, AL 35812, USA
Received 10 August 1999; accepted 26 October 1999
Abstract
The results of molecular mechanics calculations, hyperpolarizabilities calculations, synthesis, and X-ray analysis of three
monomers for non-linear optical polymers are presented. All monomers are derivatives of dicyanovinylbenzene with methoxy
and methacryloxy substituents in different positions (full isomers): 2-(4-methacryloxy-3-methoxyphenyl)-1,1-dicyanoethylene
6
a, 2-(3-methacryloxy-4-methoxyphenyl)-1,1-dicyanoethylene 6b, and 2-(2-methacryloxy-3-methoxyphenyl)-1,1-dicyano-
ethylene 6c. On the basis of structural results for molecules 6a–c and calculations of molecular hyperpolarizability, monomer
a was found to be the most prospective candidate for NLO polymer preparation. ᭧ 2000 Elsevier Science B.V. All rights
6
reserved.
Keywords: Non-linear optical polymers; Molecular mechanics calculations; X-ray analysis; Dicyanovinylbenzene derivatives
1
. Introduction
[1–4]. Only a few of these compounds have acentric
crystal structure with polar molecular orientation that
is necessary for second harmonic generation (SHG) in
solid state. The latter circumstance makes a prepara-
tion of polymer NLO materials containing organic
chromophores in the side chains especially attractive,
since the requirement of acentricity might be fulfilled
in polymers by poling of the materials. The other
important properties of the polymers are their
stability, better mechanical processing, and easier
film formation [5].
The present investigation is part of a program
which includes molecular modeling, synthesis,
preparation of non-linear optical (NLO) materials,
and characterization of their structure and properties.
Recently we prepared and characterized a series of
substituted phenyl-1,1-dicyanoethylene derivatives
*
Corresponding author. Tel.: ϩ1-505-454-3362; fax: ϩ1-505-
4
54-1303.
E-mail address: tanya@mount.nmhu.edu (T.V. Timofeeva).
In the present work structural investigation of three
0
022-2860/00/$ - see front matter ᭧ 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-2860(99)00417-2

3
10
V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
monomers which can form polymers or copolymers of
poly(methylmethacrylate) (PMMA) type is presented.
7.31 (1H, d.d, C H), 7.64 (1H, s, C H), 7.71 [1H, s,
6 2
1
3
1
H–CyC(CN) ]. C[ H] NMR (CDCl ): d, 56.2, 78.0,
2
3
1
1
10.4, 113.6, 114.4, 115.2, 123.9, 128.9, 147.0, 152.1,
59.4.
2
-(3-Hydroxy-4-methoxyphenyl)-1,1-dicyanoethyl-
2
. Experimental part and calculation details
ene 3b: The yield of compound 3b was ca. 90%, (m.p.
249–250ЊC). H NMR (pyridine-d ) d, 3.81 (3H, s,
5
1
2.1. Materials
OCH ), 5.02 (1H, w.s, OH), 6.97 (1H, d, C H), 7.47
3
5
Compounds 3a, 3b, 5 and 6a–c have been prepared
(1H, d, C
6
H), 7.96 (1H, s, C
2
H), 8.08 [1H, s, H–
1
3
1
using the standard procedures described in papers [6–
3]. The scheme for the synthesis of these compounds
is shown below:
CyC(CN) ]. C[ H] NMR (pyridine d ): d, 56.0,
2 5
77.7, 112.1, 114.5, 115.6, 116.7, 123.9, 125.4,
148.8, 154.6, 160.5.
1
CHO
CH=C(CN)
2
B
+
CH (CN)
2
2
2
R
100%
EtOH
2
R
1
CH =C(CH )COCl
2 3
R
1
R
Et N,DMF
3
1
a,b
2
3a,b
CH=C(CN)
2
1 2
a, 3a R = OCH ; R = OH
3
1
1
R
3
R
1
2
1
b, 3b R = OH; R = OCH
3
2
R
6
a-c
2
/B
1
00% EtOH
1 2 3
a R = H; R = OCH ; R = OCO(CH )C=CH
3 3 2
6
CHO
OH
CHO
1 2 3
b R = H; R = OCO(CH )C=CH ; R = OCH
3 2 3
6
CH =C(CH )COCl
2
3
1
2
3
6
c R = OCO(CH )C=CH ; R = OCH ; R = H
3
2
3
Et N,DMF
3
OCOC=CH
2
CH
3
OCH
3
OCH
3
4
5
Intermediate compounds and final products have
2-Methacryloxy-3-methoxybenzaldehyde 5: The
yield of compound 5 was ca. 52%, (m.p. 70–71ЊC).
1
13
been characterized by H NMR and C NMR spectra
that were collected using a Bruker Model AC 300 MHZ
Broad Band High Field FT-NMR Spectrometer.
1
H NMR (CDCl ): d, 2.11 (3H, s, CH ), 3.87 (3H, s,
3
3
OCH ), 5.84 and 6.43 (2H, s, s, CH yC, Z and E
3
2
2
-(4-Hydroxy-3-methoxyphenyl)-1,1-dicyanoethyl-
isomers), 7.23 (1H, t.d, C H), 7.36 (1H, d.d, C H),
5 4
1
3
1
ene 3a: The yield of compound 3a was ca. 85%, (m.p.
34–135ЊC). H NMR (CDCl ) d; 3.98 (3H, s,
7.50 (1H, d, C H), 10.16 (1H, s, CHO). C[ H]
6
1
1
NMR (CDCl ): d, 18.4, 56.3, 117.8, 120.5, 126.7,
3
3
OCH ), 6.44 (1H, w.s, OH), 7.03 (1H, d.d, C H),
128.1, 129.4, 134.9, 142.2, 151.8, 165.0, 188.6.
3
5

V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
311
Table 1
Crystal structure determination summary for compounds 6a–c
6
a
6b
6c
Empirical formula
Formula weight
Temperature (K)
Crystal size (mm)
Crystal system
Space group
C
268.3
298(2)
15
H
12
N
2
O
3
C
268.3
298(2)
15
H
12
N
2
O
3
15 12 2 3
C H N O
268.3
298(2)
0:2 × 0:3 × 0:2
0:3 × 0:3 × 0:2
0:3 × 0:2 × 0:4
Triclinic
Triclinic
Monoclinic
¯
¯
P1
P1
1
P2 /n
Z
2
2
4
Unit cell dimensions
˚
a (A)
8.226(2)
9.320(3)
10.397(3)
88.32(2)
76.16(2)
65.04(2)
699.3(3)
1.274
6.741(2)
10.257(3)
10.942(4)
74.31(2)
74.18(2)
82.08(2)
699.2(3)
1.274
4.896(2)
19.710(9)
14.652(6)
90
93.19(3)
90
1412(1)
1.262
0.090
˚
b (A)
˚
c (A)
a (Њ)
b (Њ)
g (Њ)
3
˚
Volume (A )
3
Density (calc., g/cm )
Absorbtion coeff. (mm
F(000)
Ϫ1
)
0.091
280
0.091
280
560
u range (Њ)
Scan range v (Њ)
Reflections collected
2.0–25.0
1.80
2664
2.0–25.0
1.90
2566
2.0–25.0
1.80
2806
Independent reflections
2475
2333
2495
Data/restraints/parameters
Goodness of fit
2435/0/229
1.112
2299/0/229
1.033
2382/0/229
1.077
Final R=wR ‰I Ͼ 2sꢀI†Š
0.056/0.147
0.087/0.187
0.30
0.040/0.095
0.065/0.118
0.22
0.072/0.132
0.169/0.181
0.15
R=wR indices (all data)
3
˚
˚
Largest difference peak (e/A )
Largest difference hole (e/A )
3
Ϫ0.21
Ϫ0.12
Ϫ0.17
2-(4-Methacryloxy-3-methoxyphenyl)-1,1-dicyano-
2-(2-Methacryloxy-3-methoxyphenyl)-1,1-dicyano-
ethylene 6a: The yield of compound 6a was ca. 73%
ethylene 6c: The yield of compound 6c was ca. 79%
1
1
(
m.p. 109–110ЊC). H NMR (CDCl ): d, 2.06 (3H, s,
(m.p. 144–145ЊC). H NMR (CDCl ): d, 2.09 (3H, s,
3
3
CH ), 3.88 (3H, s, OCH ), 5.82 and 6.39 (2H, s, s,
CH ), 3.86 (3H, s, OCH ), 5.88 and 6.43 (2H, s, s,
3
3
3
3
CH yC, Z and E isomers), 7.22 (1H, d, C H), 7.38
CH yC, Z and E isomers), 7.21 (1H, d, C H), 7.36
2 4
2
5
(
1H, d, C H), 7.70 (1H, d, C H), 7.74 [1H, d, H–
(1H, t.d, C H), 7.85 (1H, d, C H), 7.88 [1H, d, H–
5 6
2
6
13
1
13
1
CyC(CN)2], C[ H] NMR (CDCl ): d, 18.3, 56.1,
CyC(CN)2]. C[ H] NMR (CDCl ): d, 18.3, 56.3,
3
3
8
1
2.2, 112.5, 112.7, 113.6, 124.0, 125.6, 128.3,
29.4, 134.9, 145.2, 152.1, 159.0, 164.6.
84.9, 112.1, 113.6, 117.9, 119.5, 125.2, 127.2,
129.0, 134.5, 140.3, 151.7, 153.3, 164.5.
2-(3-Methacryloxy-4-methoxyphenyl)-1,1-dicyano-
ethylene 6b: The yield of compound 6b was ca. 73%
2
.2. X-ray analysis
1
(
m.p. 131–132ЊC). H NMR (CDCl ): d, 2.07 (3H, s,
3
CH ), 3.93 (3H, s, OCH ), 5.81 and 6.38 (2H, s, s,
Single crystals of 6a–c suitable for X-ray analysis
3
3
CH yC, Z and E isomers), 7.10 (1H, d, C H), 7.63
were obtained by slow evaporation from ethanol.
Single crystalline samples of 6a–c are colorless
needles. The experimental data were obtained at
room temperature using MoKa-radiation and a
2
5
(
1H, d, C H), 7.72 (1H, d, C H), 7.83 [1H, d, H–
2
6
13
1
CyC(CN)2], C[ H] NMR (CDCl ): d, 18.3, 56.4,
3
7
1
9.7, 112.6, 112.9, 114.1, 123.9, 125.1, 128.2,
31.5, 134.9, 140.5, 156.7, 158.1, 164.8.
ꢀ
graphite monochromator ꢀl ˆ 0:7107 A† with

3
12
V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
Table 2
Atomic coordinates ( × 10 ) and their equivalent isotropic displace-
Table 3
4
4
Atomic coordinates ( × 10 ) and their equivalent isotropic displace-
2
3
2
3
˚
˚
ment coefficients (A × 10 ) in structure 6a
ment coefficients (A × 10 ) in structure 6b
a
Atom
x
y
z
U(eq)
Atom
x
y
z
U(eq)
53(1)
O(1)
O(2)
O(3)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
H(2)
H(5)
H(6)
H(7)
H(131)
H(132)
H(141)
H(142)
H(143)
H(151)
H(152)
H(153)
2800(2)
1699(3)
5372(3)
2803(4)
8717(2)
8281(2)
5881(2)
Ϫ232(3)
4759(3)
4575(3)
4494(3)
5843(3)
7315(3)
7419(3)
6064(3)
3070(3)
2715(3)
1080(3)
3861(3)
9062(3)
10520(3)
11244(4)
11060(6)
4390(5)
3524(29)
8483(32)
6187(32)
2114(30)
3162(2)
1506(2)
1937(2)
6747(2)
8245(3)
4837(2)
3647(2)
3067(2)
3681(2)
4858(2)
5437(2)
5338(2)
6435(2)
6630(2)
7440(3)
2011(2)
1489(2)
2056(5)
336(5)
75(1)
89(1)
83(1)
92(1)
107(1)
58(1)
60(1)
62(1)
63(1)
67(1)
64(1)
60(1)
60(1)
69(1)
72(1)
66(1)
67(1)
O(1)
O(2)
O(3)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
H(2)
H(5)
H(6)
H(7)
H(131)
H(132)
H(141)
H(142)
H(143)
H(151)
H(152)
H(153)
1973(2)
4292(2)
1688(2)
10505(3)
5644(4)
5884(3)
4592(3)
3271(3)
3110(3)
4404(3)
5774(3)
7355(3)
7677(3)
9256(3)
6527(4)
2654(3)
1181(3)
Ϫ714(4)
1966(6)
1407(4)
4648(25)
4316(27)
6678(29)
8201(31)
2467(1)
1924(1)
4926(1)
3013(2)
720(3)
4103(2)
3125(2)
3440(2)
4732(2)
5698(2)
5376(2)
3891(2)
2869(2)
2935(2)
1683(2)
1761(2)
799(2)
2702(1)
986(1)
74(1)
63(1)
81(1)
134(1)
50(1)
49(1)
47(1)
50(1)
54(1)
53(1)
54(1)
57(1)
62(1)
80(1)
50(1)
59(1)
102(1)
97(1)
67(1)
54(5)
60(5)
66(5)
75(6)
162(15)
119(9)
112(9)
146(12)
199(17)
79(7)
85(7)
82(7)
1129(1)
6364(2)
6218(3)
3440(2)
3462(2)
2666(2)
1832(2)
1786(2)
2568(2)
4235(2)
5235(2)
5866(2)
5775(2)
1755(2)
1800(2)
2566(4)
953(3)
Ϫ533(4)
2895(3)
4177(3)
4154(3)
2810(3)
1539(4)
1569(3)
3045(3)
2068(3)
2459(3)
611(4)
2252(3)
2412(3)
3179(6)
1655(9)
6608(6)
5051(32)
628(36)
714(41)
4003(35)
3287(48)
3713(63)
1847(51)
2455(68)
343(112)
7258(58)
5903(54)
7449(54)
107(1)
121(1)
104(1)
57(6)
75(7)
82(8)
806(3)
Ϫ127(3)
6255(2)
1199(4)
302(3)
3250(22)
5274(25)
6215(30)
4802(24)
1607(35)
2887(46)
2(36)
Ϫ344(50)
555(68)
442(45)
921(37)
1780(39)
2217(19)
6534(20)
6066(19)
4663(22)
1358(38)
174(31)
Ϫ650(29)
425(34)
Ϫ392(44)
6880(23)
6200(22)
6520(23)
4012(17)
1230(18)
2535(17)
4010(20)
3039(38)
2488(26)
991(25)
68(6)
12053(44)
10839(52)
11957(50)
10123(62)
11118(81)
4661(46)
3833(46)
3567(46)
113(11)
152(15)
121(11)
160(18)
230(30)
134(13)
125(13)
125(12)
Ϫ1228(58)
Ϫ1509(44)
862(41)
2568(54)
3687(67)
886(34)
271(36)
2677(39)
Ϫ40(37)
755(42)
826(21)
Ϫ62(22)
Ϫ363(23)
a
Equivalent isotropic U defined as one third of the trace of the
orthogonalized Uij tensor.
parameters are given in Tables 2–4. Bond lengths
and bond angles are presented in Tables 5–7.
Siemens P3/PC 4-circle automatic diffractometer
using the u=2u-scan technique. The structures were
solved by direct methods and refined by a full-matrix
least-squares procedure in the anisotropic approxima-
tion for non-hydrogen atoms. All hydrogen atoms
were unambiguously located on a difference Fourier
map and refined in isotropic approximation. All calcu-
lations were carried out with a personal computer
using the Shelxtl Plus program package [14].
Important details of the data collection and structure
refinement are summarized in Table 1. Atomic coor-
dinates and their isotropic equivalent displacement
2
.3. Molecular mechanics and hyperpolarizability
calculations
Molecular mechanics (MM) calculations of the
isomers 6a–c were performed using the MM3
program. For every isomer several most probable
conformations corresponding to energy minima were
found using a stochastic search procedure [15]. For
the calculations of molecular polarizabilities a modi-
fication of the static field method [16] developed in
Refs. [17,18] was used: 252 static-field calculations

V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
313
Table 4
Atomic coordinates ( × 10 ) and their equivalent isotropic displace-
Table 5
˚
4
Bond lengths (A) and bond angles (Њ) in molecule 6a
2
3
˚
ment coefficients (A × 10 ) in structure 6c
O(1)–C(11)
O(1)–C(4)
O(2)–C(11)
O(3)–C(3)
O(3)–C(15)
N(1)–C(9)
N(2)–C(10)
C(1)–C(6)
C(1)–C(2)
C(1)–C(7)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(7)–C(8)
C(8)–C(10)
C(8)–C(9)
C(11)–C(12)
C(12)–C(13)
C(12)–C(14)
1.361(3)
1.396(3)
1.195(3)
1.360(3)
1.432(4)
1.142(3)
1.134(3)
1.398(3)
1.401(3)
1.447(3)
1.373(3)
1.394(3)
1.382(3)
1.377(3)
1.349(3)
1.434(4)
1.437(3)
1.493(3)
1.327(4)
1.462(5)
C(11)–O(1)–C(4)
C(3)–O(3)–C(15)
C(6)–C(1)–C(2)
C(6)–C(1)–C(7)
C(2)–C(1)–C(7)
C(3)–C(2)–C(1)
O(3)–C(3)–C(2)
O(3)–C(3)–C(4)
C(2)–C(3)–C(4)
C(5)–C(4)–C(3)
C(5)–C(4)–O(1)
C(3)–C(4)–O(1)
C(6)–C(5)–C(4)
C(5)–C(6)–C(1)
C(8)–C(7)–C(1)
C(7)–C(8)–C(10)
C(7)–C(8)–C(9)
C(10)–C(8)–C(9)
N(1)–C(9)–C(8)
N(2)–C(10)–C(8)
O(2)–C(11)–O(1)
O(2)–C(11)–C(12)
O(1)–C(11)–C(12)
C(13)–C(12)–C(14)
C(13)–C(12)–C(11)
C(14)–C(12)–C(11)
115.9(2)
116.7(2)
118.9(2)
125.0(2)
116.1(2)
121.4(2)
125.4(2)
115.9(2)
118.7(2)
120.8(2)
118.6(2)
120.5(2)
120.3(2)
119.9(2)
131.7(2)
124.8(2)
119.2(2)
116.0(2)
177.9(3)
179.3(3)
122.9(2)
125.3(2)
111.8(2)
124.1(3)
121.3(3)
114.7(3)
Atom
x
y
z
U(eq)
53(1)
80(1)
69(1)
90(1)
119(1)
48(1)
48(1)
52(1)
59(1)
66(1)
61(1)
49(1)
54(1)
66(1)
76(1)
52(1)
62(1)
O(1)
O(2)
O(3)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
H(4)
H(5)
H(6)
H(7)
H(131)
H(132)
H(141)
H(142)
H(143)
H(151)
H(152)
H(153)
1020(4)
4220(5)
5160(4)
Ϫ6456(7)
Ϫ607(10)
979(5)
2132(5)
4271(6)
5263(7)
4121(7)
5552(1)
5512(1)
5470(1)
7063(2)
8500(2)
6774(1)
6156(1)
6110(2)
6696(2)
7313(2)
7361(2)
6766(2)
7272(2)
7154(2)
7956(2)
5244(1)
4585(2)
4298(2)
4280(2)
5391(3)
2358(1)
1334(2)
3578(1)
111(2)
1185(2)
2441(2)
2714(2)
3378(2)
3785(2)
3523(2)
2871(2)
1756(2)
1242(2)
611(2)
1229(2)
1668(2)
1419(2)
627(3)
2002(4)
4265(3)
2030(7)
Ϫ1295(6)
Ϫ2353(6)
Ϫ4631(7)
Ϫ1336(8)
2344(7)
1097(7)
1932(11)
Ϫ759(12)
7328(8)
6834(57)
4712(57)
1235(58)
103(2)
110(2)
76(1)
57(8)
58(9)
6681(14)
7683(15)
7756(16)
6337(15)
4551(19)
3875(20)
3849(23)
4541(22)
4122(43)
4900(23)
5613(16)
5624(17)
4230(19)
3789(20)
2721(19)
1661(19)
224(27)
61(9)
59(8)
Ϫ2105(57)
3064(77)
1179(73)
Ϫ1549(85)
Ϫ1989(90)
767(155)
7650(78)
6806(64)
8983(71)
102(13)
103(13)
120(14)
113(16)
273(39)
110(15)
80(11)
85(11)
459(26)
less than 1.0 kcal/mol were found, for monomers 6b
and 6c, respectively, 22 and 17 possible conformers
were found in the same energy interval. The energy
differences (in kcal/mol) between the most
energetically preferable conformers and conformers
corresponding to the X-ray structures are equal to
1820(28)
2254(29)
2640(56)
4252(27)
4846(25)
4041(23)
0
.72 (6a), 0.56 (6b), and 0.04 (6c), respectively. For
some of these conformers the geometry differences
are rather small (6c), while the other conformers (6a
and 6b) differ significantly due to the substituents
orientations. The most energetically preferable
conformers of molecules 6a–c found as a result of
stochastic search are shown in Fig. 1.
were obtained (mopac program, AM1), which were
analyzed by the Hyper program [19]. Molecular
geometries obtained by molecular mechanics and
X-ray analysis were used to calculate molecular polar-
izabilities.
Molecular crystal structures of isomers 6a–c are
presented in Fig. 2. Comparison of Figs. 1 and 2
shows the difference between conformations of
isolated molecules and molecules in crystals. One
can see that calculated and X-ray conformations of
molecule 6c resemble each other while for molecules
6a and 6b they differ significantly.
3
. Results and discussion
A stochastic search of the preferable conformers of
the molecules 6a–c has shown that for all molecules
studied several conformations with different orienta-
tions of substituents are possible. For instance, for
monomer 6a 11 conformers with energy difference
Because of small energy difference for isolated and
solid state conformers (see above), we can suggest

3
14
V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
Table 6
Bond lengths (A) and bond angles (Њ) in molecule 6b
Table 7
˚
˚
Bond lengths (A) and bond angles (Њ) in molecule 6c
O(1)–C(11)
O(1)–C(3)
O(2)–C(11)
O(3)–C(4)
O(3)–C(15)
N(1)–C(9)
N(2)–C(10)
C(1)–C(6)
C(1)–C(2)
C(1)–C(7)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(7)–C(8)
C(8)–C(10)
C(8)–C(9)
C(11)–C(12)
C(12)–C(13)
C(12)–C(14)
1.365(2)
1.401(2)
1.193(2)
1.349(2)
1.438(2)
1.143(2)
1.145(3)
1.400(2)
1.407(2)
1.448(3)
1.360(2)
1.401(2)
1.390(2)
1.374(3)
1.338(3)
1.432(3)
1.435(3)
1.476(2)
1.323(3)
1.453(3)
C(11)–O(1)–C(3)
C(4)–O(3)–C(15)
C(6)–C(1)–C(2)
C(6)–C(1)–C(7)
C(2)–C(1)–C(7)
C(3)–C(2)–C(1)
C(2)–C(3)–C(4)
C(2)–C(3)–O(1)
C(4)–C(3)–O(1)
O(3)–C(4)–C(5)
O(3)–C(4)–C(3)
C(5)–C(4)–C(3)
C(6)–C(5)–C(4)
C(5)–C(6)–C(1)
C(8)–C(7)–C(1)
C(7)–C(8)–C(10)
C(7)–C(8)–C(9)
C(10)–C(8)–C(9)
N(1)–C(9)–C(8)
N(2)–C(10)–C(8)
O(2)–C(11)–O(1)
O(2)–C(11)–C(12)
O(1)–C(11)–C(12)
C(13)–C(12)–C(14)
C(13)–C(12)–C(11)
C(14)–C(12)–C(11)
115.67(13)
117.88(14)
117.9(2)
117.0(2)
125.1(2)
119.9(2)
121.9(2)
119.70(14)
118.3(2)
125.4(2)
115.99(14)
118.6(2)
119.7(2)
121.9(2)
131.4(2)
125.2(2)
119.5(2)
115.2(2)
178.7(2)
178.5(2)
121.8(2)
124.9(2)
113.3(2)
123.7(2)
121.1(2)
115.3(2)
O(1)–C(11)
O(1)–C(2)
O(2)–C(11)
O(3)–C(3)
O(3)–C(15)
N(1)–C(9)
N(2)–C(10)
C(1)–C(2)
C(1)–C(6)
C(1)–C(7)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(7)–C(8)
C(8)–C(9)
C(8)–C(10)
C(11)–C(12)
C(12)–C(13)
C(12)–C(14)
1.373(4)
1.397(3)
1.188(3)
1.361(3)
1.429(4)
1.137(4)
1.135(4)
1.392(4)
1.402(4)
1.457(4)
1.393(4)
1.377(4)
1.383(5)
1.364(5)
1.338(4)
1.428(5)
1.437(5)
1.472(4)
1.374(5)
1.415(6)
C(11)–O(1)–C(2)
C(3)–O(3)–C(15)
C(2)–C(1)–C(6)
C(2)–C(1)–C(7)
C(6)–C(1)–C(7)
C(1)–C(2)–C(3)
C(1)–C(2)–O(1)
C(3)–C(2)–O(1)
O(3)–C(3)–C(4)
O(3)–C(3)–C(2)
C(4)–C(3)–C(2)
C(3)–C(4)–C(5)
C(6)–C(5)–C(4)
C(5)–C(6)–C(1)
C(8)–C(7)–C(1)
C(7)–C(8)–C(9)
C(7)–C(8)–C(10)
C(9)–C(8)–C(10)
N(1)–C(9)–C(8)
N(2)–C(10)–C(8)
O(2)–C(11)–O(1)
O(2)–C(11)–C(12)
O(1)–C(11)–C(12)
C(13)–C(12)–C(14)
C(13)–C(12)–C(11)
C(14)–C(12)–C(11)
117.5(2)
117.9(3)
117.4(3)
118.1(3)
124.5(3)
122.4(3)
119.7(2)
117.9(3)
125.7(3)
115.5(2)
118.8(3)
119.3(3)
122.2(3)
119.9(3)
129.6(3)
120.5(3)
125.7(3)
113.8(3)
179.5(3)
177.0(4)
120.9(3)
127.6(3)
111.5(3)
124.4(4)
115.7(4)
119.8(3)
that intermolecular interactions in the crystals are
mostly responsible for the solid state molecular
conformations at least for compounds 6a and 6b.
According to the X-ray analysis, molecules 6a–c
have similar geometry, however they are also
characterized by different features due to different
positions of substituents in the benzene ring which
will be described below. For instance, the dihedral
angles between the dicyanovinyl group and the
benzene ring are equal to 5.1 (6a), 9.0 (6b) and
contacts between substituents in ortho-positions in
molecule 6c responsible for non-planar orientation
of the dicyanovinyl group, such as O(1)···C(7)
˚
2.770(4), and O(1)···H(7) 2.37(3) A, and a short
contact between carbon atom of the nitrile group
and hydrogen atom of the benzene ring C(10)···H(6)
˚
2.49(3) A. The methoxy substituents in molecules
6a–c are in a position ortho to the bulky methacrylo-
carboxy substituent. Nevertheless, out-of-plane
displacements of the methoxy groups are insignificant:
8.5Њ in 6a, 3.5Њ in 6b, and 1.0Њ in 6c. Significant out-of-
plane displacement of the methoxy group was found
only for molecules where the OMe group is located
between two other substituents, for instance in 3,4,5-
trimethoxydicyanovinylbenzene, where the OMe
group in position 4 is almost perpendicular to the
benzene ring [2]. In all three molecules studied, orien-
tation of the methacryloxy groups to the benzene ring
plane are almost perpendicular. Dihedral angles
between their planes are equal to 75.6Њ in 6a, 89.6Њ
in 6b, and 91.0Њ in 6c. According to the molecular
19.6Њ (6c). For molecules 6a and 6b these values
belong to the standard interval (0–15Њ) of such angles
in the other molecules with the dicyanovinyl group
studied before (see Ref. [4]), where there is no
influence of the bulky substituents in the ortho-
positions [4,20]. In molecules with such substituents,
for instance, in ortho-pyrrolidino-dicyanovinylben-
zene, the dihedral angle between the dicyanovinyl
group and the benzene ring is larger (21.9Њ) [20],
and the latter value is close to that found in molecule
6c. We should note several short intramolecular

V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
315
Table 8
Ϫ51
3
2
Calculated dipole moments m (D), second-order b (10 C m /V ),
and third-order g (10 C m /V ) molecular polarizabilities for
monomers 6a–c
Ϫ61
4
3
Molecule
m
b
g
6a
X-ray
MM
4.89
4.57
30.16
27.00
7.99
7.34
6b
X-ray
MM
6.12
4.90
39.37
31.44
8.13
7.52
6c
X-ray
MM
5.95
5.04
14.74
12.24
4.77
4.06
the centrosymmetric dimers are formed via contacts
between nitrogen atoms of the cyano group and
hydrogen atoms of the ethylene group (N(1)···H(7)
˚ ˚
.61 A in 6a, and N(1)···H(7) 2.54 A in 6b). Similar
2
dimers were also found in dicyanovinylbenzene [1],
˚
where the same contacts were equal to 2.56 A. We
suggest that such contacts are due to the electrostatic
interactions between positively charged hydrogen
atoms H(7) and negatively charged atoms N(1) of
the cyano group. Ab initio calculations of charge
distribution in several dicyanovinylbenzene deriv-
atives have been presented earlier [4]. Namely
formation of centrosymmetric dimers by molecules
6
a, 6b, and dicyanovinylbenzene [1] is apparently
the main reason for the centrosymmetric crystal struc-
ture found for these compounds. In Ref. [1] we
observed that in same other dicyanovinylbenzene
derivatives, substituents in the position ortho to the
dicyanovinylgroup can prevent the dimer formation,
and in some cases this leads to a formation of acentric
crystals. For instance, ortho-methoxy-dicyanovinyl-
benzene [1] and ortho-fluoro-dicyanovinylbenzene
form non-centrosymmetric crystal structures [4].
This observation of course is not general. For
instance, molecular dimers of the type mentioned
above were not found in ortho-chloro-dicyanovinyl-
benzene [4] and ortho-nitro-dicyanovinylbenzene [4],
but destruction of the dimers formation is not suffi-
cient enough for acentric structure formation in these
cases. The same situation was found for crystal 6c.
There are no molecular dimers in this crystal, but
crystal 6c as well as 6a and 6b are centrosymmetric.
Fig. 1. Calculated conformations of isolated molecules 6a–c.
mechanics calculations, the methacryloxy groups are
also significantly rotated out of the benzene ring
planes but dihedral angles for calculated molecules
are somewhat smaller than in crystals: 56 (6a), 49
6b), and 68Њ (6c).
No intermolecular contacts that are significantly
shorter than sum of van der Waals radii were found
in the crystals 6a–c. Nevertheless it is possible to
mention some intermolecular contacts which in our
opinion may be responsible for a particular molecular
pattern (Fig. 3). For instance, in crystals of 6a and 6b
(

3
16
V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
Fig. 2. Molecular structure of compounds 6a–c in crystals.
So, none of the crystals under investigation can
demonstrate NLO properties in the solid state.
Results of the molecular dipole moments and
hyperpolarizability calculations based on mole-
cular structure from MM calculations (the most
energetically preferable conformers) and X-ray
data are listed in Table 8. Due to different conform-
ations for isolated molecules and the molecules in
crystals the results are somewhat different but
definitely show the same trend: b values increase
in the series 6c Ͻ 6a Ͻ 6b. It is obvious that the
most important for calculated properties in question

V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
317
6
b
6
a
6
c
Fig. 3. Projections of molecular packings in crystals 6a–c.
is relative substituents positions in phenyl ring but
not their relative orientation. Calculated positions
of the side chromophore substituents with respect
to polymer backbone direction and relative orien-
tations of the dipole moments are shown in Fig. 4.
It is possible to see that it will be easier to orient
dipole moments in one direction (for instance by
poling) for 6b and 6c. As monomer 6b has a large
b value (see above) we believe that this monomer
will be the most prospective candidate for NLO
polymer preparation.
Supporting information available: Tables of the
X-ray structure determination summary, tables of
the non-hydrogen atom coordinates and their equiva-
lent displacement parameters, bond lengths, bond
angles, anisotropy displacement parameters for
non-hydrogen atoms, hydrogen atoms coordinates,
and their isotropic displacement parameters.

3
18
V.N. Nesterov et al. / Journal of Molecular Structure 523 (2000) 309–318
6a
6b
6c
Fig. 4. Orientation of chromophores 6a–c and chromophore dipole moments relative to polymer chain direction (dashed line).
Ordering information is given on any masthead
page.
[6] F. Freeman, Chem. Rev. 69 (1969) 591.
[
[
[
7] A.J. Fatiadi, Synthesis N3 (1978) 165.
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Acknowledgements
[
[
[
1
The project was supported by NASA Alliance for
Nonlinear Optics, Grant NAG3-6532.
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