Preparations, crystal structures and DFT calculations of novel diacetylenes incorporating ynamine moieties

Article abstract of DOI:10.1016/j.molstruc.2012.07.003

Two diacetylene molecules incorporating an ynamine moiety, 5-(diphenylamino)-2,4-pentadiyne-1-ol (1) and 6-(diphenylamino)-2-methylhexa-3, 5-diyn-2-ol (2), were prepared and characterized by single crystal X-ray diffraction, ¹H and ¹³

Full text of DOI:10.1016/j.molstruc.2012.07.003

Journal of Molecular Structure 1029 (2012) 135–141
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Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Preparations, crystal structures and DFT calculations of novel diacetylenes
incorporating ynamine moieties
⇑
Yui Tokutome, Natsuki Kubo, Tsunehisa Okuno
Department of Material Science and Chemistry, Wakayama University, Wakayama 640-8510, Japan
h i g h l i g h t s
"
"
"
Two diacetylene molecules were characterized by NMR and Xꢀray diffraction.
The crystal structures were controlled by the intermolecular hydrogenꢀbondings.
The molecular structures were compared with those obtained by DFT alculations.
a r t i c l e i n f o
a b s t r a c t
Article history:
Two diacetylene molecules incorporating an ynamine moiety, 5-(diphenylamino)-2,4-pentadiyne-1-ol
(1) and 6-(diphenylamino)-2-methylhexa-3,5-diyn-2-ol (2), were prepared and characterized by single
crystal X-ray diffraction, 1H and 13C NMR. The crystal structures of 1 and 2 were solved successfully
and were interpreted to be controlled mainly by the intermolecular hydrogen-bondings. The difference
in the crystal structures between 1 and 2 was well explained by consideration of the steric repulsion with
the methyl groups connected to the carbon atom adjacent to the hydroxyl group in 2. The steric effects of
the methyl groups on intra and intercolumnar interaction were found to be important for designing
molecular and crystal structures of diacetylene molecules. Although the geometries obtained by DFT cal-
culations showed a good agreement on 2 except for the butadiynyl part, a significant difference was rec-
ognized at the environment around the nitrogen of 1. The difference could be explained by the effect of
the crystal packing.
Received 24 April 2012
Received in revised form 3 July 2012
Accepted 3 July 2012
Available online 10 July 2012
Keywords:
Diacetylenes
Ynamines
X-ray crystal structure
DFT calculation
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
ynamine moiety have been prepared and have given varieties of
PDAs which carry amino groups as a pendant group, such as
Polydiacetylenes (PDAs), which are obtained by solid-state
polymerization of diacetylene derivatives [1,2], have been paid
much attention from the viewpoint of physical properties originat-
carbazol-9-yl [7,8], phenothiazin-10-yl [9] and diphenylamino
groups [10–12].
While the reactivity in solid-state polymerization of diacetylene
derivatives is known to depend heavily on the relative orientation
of diacetylene monomers. The conditions of relative packing
parameters [13] are given by stacking intervals (d = 4.4–5.9 Å)
ing in their one-dimensional
p-conjugated systems. In order to
improve their physical properties, expansion of
p-conjugation
has been thought to be effective. According to this strategy, intro-
duction of aromatic groups [3–6] and/or hetero atoms [7–12] has
been examined extensively.
Ynamines, where an acetylene group connects directly to a
nitrogen atom, have been known unstable because of polymeriza-
tion and hydrolysis. The instability of ynamines originates in high
and inclination angles (
u = 36–51°) between the stacking axis
and the diacetylene moiety as shown in Scheme 1. Therefore the
correlation between chemical modifications and crystal packing
becomes significantly important in order to establish the method-
ology for designing an appropriate one-dimensional stacking of
diacetylenes.
electron density owing to conjugation of
p-electrons with a lone
pair of a nitrogen atom. On the contrary, electron richness is
thought to be suitable for enhancement of physical properties of
PDAs. Several reactive diacetylene derivatives incorporating an
In order to control the relative orientation of diacetylene mono-
mers to the appropriate one-dimensional stack, amido, urethane
and/or hydroxyl groups have been introduced in the side chain of
the monomers [2]. When hydroxyl groups are introduced in the
side chain, the molecules have a tendency to form one-dimensional
columnar stacks with intercolumnar hydrogen-bondings.
⇑
Corresponding author.
E-mail address: okuno@center.wakayama-u.ac.jp (T. Okuno).
0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2012.07.003

136
Y. Tokutome et al. / Journal of Molecular Structure 1029 (2012) 135–141
i
ii
2
2
2
2
2
2
3
2
RV
iii
1
1
1
1
2
h
or heat
d
3
Scheme 2. Preparation of 1 and 2: (i) PCl5, toluene, 90 °C (ii) n-BuLi, THF, ꢀ65 °C
(iii) 2-propyn-1-ol or 2-methyl-3-butyne-2-ol, O2, CuCl, TMEDA, acetone, ꢀ20 °C.
1
Table 1
Crystal data and refinement details for 1 and 2.
1
Compounds
1
2
Scheme 1. General representation of solid-state polymerization of diacetylene
monomers accompanied by the packing parameters.
Empirical formula
Formula weight
Crystal system
Crystal size
Crystal color
Space group
a (Å)
C
17H13O1N1
C19H17O1N1
275.35
Orthorhombic
0.10 ꢁ 0.10 ꢁ 0.04
Colorless
P212121
5.836(2)
12.054(4)
21.913(8)
90.000
1541.5(10)
4
247.30
Monoclinic
0.14 ꢁ 0.08 ꢁ 0.04
Colorless
P21/n
11.849(5)
5.219(2)
22.004(10)
104.957(7)
1314.6(10)
4
DFT calculation is one of the most useful methods for molecular
modeling. The calculation, however, has not been applied to
diacetylene molecules yet because the modeling does not give
the similar structure to the crystal structure in the case when the
compounds have many flexible bonds or a hydrogen-bonding
donor (or acceptor) group.
We wish to report the preparations and the crystal structures of
5-(diphenylamino)-2,4-pentadiyne-1-ol (1) and 6-(diphenyl-
amino)-2-methylhexa-3,5-diyn-2-ol (2), where the diphenylamino
and hydroxymethyl groups are connected to the both ends of the
diacetylenes. The effects of methyl groups for the molecular struc-
ture and the crystal packing structure are discussed. And the crystal
structures are also compared with those obtained by DFT method.
b (Å)
c (Å)
b (°)
V (Å3)
Z
Dx (Mg/m3)
1.249
0.08
1.8–27.5
1.186
0.07
3.3–27.5
l
(mmꢀ1
)
Theta range for data
collection (°)
Limiting indices
ꢀ14 6 h 6 15,
ꢀ7 6 h 6 7,
ꢀ6 6 k 6 6, ꢀ28 6 l 6 25 ꢀ15 6 k 6 15,
ꢀ28 6 l 6 19
Reflections collected/ 10224/3028
unique
Reflections with
128158/2048
(Rint = 0.0435)
1780
(Rint = 0.0384)
2259
I > 2r(I)
Refined parameters/
2. Experimental
224/0
257/1
restrains
Goodness of fit on F2
1.099
1.073
2.1. General procedure
R1(I > 2
r(I)), wR2 (all
0.0567, 0.145
0.0596, 0.162
data)
All chemicals were purchased from Kanto Chemical Co. Ltd. or
Tokyo Kasei Kogyo Co. Ltd. and were used without further purifica-
tion. Gel permeation chromatography (GPC) was performed on a
JAI LC-918 equipped with JAIGEL-1H and -2H columns. 1H and
13C NMR spectra were recorded on a JEOL JNM-ECA-400 spectrom-
eter in a deuterated solvent (chloroform-d) with tetramethylsilane
as an internal standard. All 13C NMR spectra were obtained with
complete proton decoupling. IR spectra were recorded on a JASCO
FT/IR-420 spectrometer by using a KBr pellet. Elemental analysis
was performed on a J-SCEINCE LAB MICRO CORDER JM10.
Data completeness
Data/restrains/
parameters
Max. and min.
transmission
0.998
3028/0/224
0.990
2048/1/257
0.993 and 0.997
0.995 and 0.997
Largest diff. peak and 0.21 and ꢀ0.23
0.28 and ꢀ0.25
hole (e Åꢀ3
)
2.2. Preparation of N-phenyl-N-(1,2,2-trichlorovinyl)aniline
X-ray crystallographic data were obtained by a RIGAKU Saturn
724+ CCD device using multi-layered mirror monochromatic Mo
A solution of N,N-diphenylacetamide (3.00 g, 14.2 mmol) and
phosphorus pentachloride (12.0 g, 57.5 mmol) in dry toluene
(50 ml) was heated at 90 °C for 5 h under a nitrogen stream. The
solution was poured into an ice water (100 ml), and the water layer
was extracted with toluene (50 ml). The combined organic layer
was washed with 5% sodium carbonate solution (50 ml). The
organic layer was dried over anhydrous sodium sulfate, and con-
centrated after filtration. The residue was purified by column chro-
matography on a silica gel with hexane as an eluant to give 1.02 g
(yield 24%) of N-phenyl-N-(1,2,2-trichlorovinyl)aniline as an yel-
low oil.
Ka
radiation at ꢀ180 °C. In compound 2, Friedel pairs were merged
because the molecule itself was achiral and because there were not
any anomalous scattering effects. The structures were solved by a
direct method (SIR 92) [14], and were refined by full-matrix least-
squares method (Shelx 97) [15]. The positions of non-H atoms
were obtained from difference Fourier maps and were refined
anisotropically. The C-bound H atoms were obtained by calculation
and were refined as riding on their parent C atoms. Uiso(H) values
of the H atoms were set at 1.2Ueq (parent atom for Csp2) and
1.5Ueq (parent atom for Csp3). The O-bound H atoms were obtained
from a difference Fourier map and were not refined in 1. In 2, the
isotropic thermal factor of the O-bound H atom was set at Ui-
so(H) = 1.2 Ueq (parent atom) and the position of the atom was re-
fined with the restraint on O–H range between 0.994 and 1.034 Å.
1H NMR (400 MHz, CDCl3): 7.08 (d, 4H, 3J = 8 Hz, C6H5–H2, H6);
7.12 (t, 2H, 3J = 8 Hz, C6H5–H4); 7.32 (t, 4H, 3J = 8 Hz, C6H5–H3, H5).
Anal. Calc. for C14H10Cl3N1: C, 56.31; H, 3.38; N, 4.69. Found: C,
55.91; H, 3.36; N, 4.65.

Y. Tokutome et al. / Journal of Molecular Structure 1029 (2012) 135–141
137
Table 2
Selected experimental and calculated geometric parameters (Å, °) for crystal 1 and 2.
Exp. (1)
Cal.
Da
Exp. (2)
Cal. (2) Da
(1)
Bond distances (Å)
O1ꢀC17
1.419(3)
1.451(3)
1.420(3)
1.340(3)
1.385(3)
1.379(3)
1.388(4)
1.385(4)
1.373(3)
1.390(4)
1.388(3)
1.400(3)
1.392(3)
1.389(4)
1.388(3)
1.384(3)
1.205(3)
1.370(3)
1.204(3)
1.457(3)
–
1.428
0.009
1.446(4)
1.440 ꢀ0.006
1.437 ꢀ0.001
N1ꢀC1
1.436 ꢀ0.015
1.435 0.015
1.335 ꢀ0.005
1.438(4)
1.424(4)
1.340(4)
1.389(5)
1.397(4)
1.381(5)
1.394(5)
1.373(6)
1.391(5)
1.392(5)
1.394(5)
1.393(5)
1.393(5)
1.388(5)
1.390(5)
1.205(4)
1.368(4)
1.207(4)
1.472(5)
1.532(5)
1.518(5)
N1ꢀC7
1.434
0.010
N1ꢀC13
C1ꢀC2
1.335 ꢀ0.005
1.397
1.398
1.392
1.393
1.394
1.391
1.398
0.012
0.019
0.004
0.008
0.021
0.001
0.010
1.396
1.398
1.392
0.007
0.001
0.011
C1ꢀC6
C2ꢀC3
C3ꢀC4
1.393 ꢀ0.001
C4ꢀC5
1.394
1.391
1.399
1.397
0.021
0.000
0.007
0.003
C5ꢀC6
C7ꢀC8
C7ꢀC12
C8ꢀC9
1.397 ꢀ0.003
1.391 ꢀ0.001
1.391 ꢀ0.002
C9ꢀC10
C10ꢀC11
C11ꢀC12
C13ꢀC14
C14ꢀC15
C15ꢀC16
C16ꢀC17
C17ꢀC18
C17ꢀC19
1.394
1.393
1.392
1.215
0.005
0.005
0.008
0.010
1.394
1.393
1.391
1.215
0.001
0.005
0.001
0.010
1.357 ꢀ0.013
1.358 ꢀ0.010
Fig. 1. The asymmetric unit of 1 with atom-numbering scheme. Displacement
ellipsoids are drawn at the 50% probability level and H atoms are shown as small
spheres.
1.212 0.008
1.214 0.007
1.452 ꢀ0.005
1.469 ꢀ0.003
–
–
–
–
1.540
1.533
0.008
0.015
–
Bond angles (°)
C1ꢀN1ꢀC7
121.53(14) 121.82
116.96(16) 118.99
0.31 121.6(3)
2.03 118.1(3)
121.91
118.72
0.3
0.6
C1ꢀN1ꢀC13
C7ꢀN1ꢀC13
121.47(17) 119.19 ꢀ2.28 120.1(3)
119.37 ꢀ0.7
N1ꢀC13ꢀC14 178.1(2)
179.70 1.6 178.7(4)
179.74
179.75
179.60
178.79
110.49
1.0
4.2
2.0
0.7
1.8
C13ꢀC14ꢀC15 177.89(18) 179.82
C14ꢀC15ꢀC16 179.68(18) 179.89
C15ꢀC16ꢀC17 176.58(18) 179.18
O1ꢀC17ꢀC16 110.33(15) 110.35
1.93 175.6(4)
0.31 177.6(4)
2.60 178.1(3)
0.02 108.7(3)
a
Differences between the calculated values and the observed ones.
2.3. Preparation of N-ethynyl-N-phenylaniline
Butyllithium in hexane (5.4 ml, 8.6 mmol) was added dropwise
to a solution of N-phenyl-N-(1,2,2-trichlorovinyl)aniline (1.00 g,
3.35 mmol) in dry tetrahydrofuran (60 ml) at ꢀ65 °C under an
argon atmosphere. After the solution was stirred for 1 h, methanol
(0.4 ml) was added to the solution. It was allowed to warm to
ꢀ10 °C and was poured into water (20 ml). The water layer was
extracted with ether (50 ml), and the combined organic layer
was washed with saturated brine (30 ml), and dried over anhy-
drous sodium sulfate. After filtration, the solution was concen-
trated to give N-ethynyl-N-phenylaniline as brown oil. Since this
compound was unstable, it was used to the following preparation
without purification.
Fig. 2. A view of the hydrogen-bonding interactions in 1. [Symmetry codes: (i)
ꢀx + 3/2, y + 1/2, ꢀz + 3/2; (ii) x, y + 1, z.]
Table 3
Hydrogen-bonding geometry (Å, °) for crystal 1 and 2.
DꢀHꢂꢂꢂA
d(DꢀH)
0.898
d(HꢂꢂꢂA)
1.917
d(DꢂꢂꢂA)
2.764(3)
3.179(5)
\DHA
157(3)
142(4)
Crystal 1
O1iꢀH1iꢂꢂꢂO1
Crystal 2
1H NMR (400 MHz, CDCl3): 2.89 (s, 1H, CH); 7.11 (tt, 2H, 3J = 7.2
and 4J = 1.5 Hz, C6H5ꢀH4); 7.29 (dd, 4H, 3J = 7.4 and 4J = 1.4 Hz,
C6H5–H2, H6); 7.34 (t, 4H, 3J = 7.2 Hz, C6H5–H3, H5).
O1ꢀH1ꢂꢂꢂO1iii
1.00(3)
2.33(4)
Symmetry codes: (i) ꢀx + 3/2, y + 1/2, ꢀz + 3/2; (iii) x + 1/2, ꢀy + 1/2, ꢀz.
Table 4
2.4. Preparation of 5-(diphenylamino)-2,4-pentadiyne-1-ol(1) [16]
Stacking parameters of the diacetylene moieties (Å, °) for crystal 1 and 2.
Crystal 1
Crystal 2
After a suspension of cupper (I) chloride (0.38 g, 3.91 mmol) in
acetone (6.9 ml) was degassed by argon bubbling for 30 min,
Stacking intervals
d(C13ꢂꢂꢂC16ii)
5.219(2)
3.474(3)
41.70(4)
Stacking intervals
5.836(2)
5.332(5)
63.18(7)
N,N,N0,N0–tetramethylethylenediamine
(TMEDA)
(0.19 ml,
d(C13ꢂꢂꢂC16iv
)
\C13ꢀC16ꢀC16ii
\C13ꢀC16ꢀC16iv
1.29 mmol) was added to the suspension, and it was stirred for
30 min. The supernatant solution containing CuCl–TMEDA catalyst
Symmetry codes: (ii) x, y + 1, z; (iv) x + 1, y, z.
was transferred into
a mixture of N-ethynyl-N-phenylaniline
(0.65 g, 3.35 mmol) and 2-propyn-1-ol (1.1 ml, 18.3 mmol) in ace-
tone at ꢀ20 °C. The solution was stirred for 14 h under an oxygen
atmosphere. The solvent was evaporated, and the residue was
extracted with chloroform. The solution was washed with 5%
ammonium hydroxide, and the water layer was extracted twice
with chloroform. The combined organic layer was washed with
water, and dried over anhydrous sodium sulfate. After the solvent

138
Y. Tokutome et al. / Journal of Molecular Structure 1029 (2012) 135–141
Fig. 3. Crystal packing structure of 1. Hydrogen atoms are omitted for clarity.
was evaporated, the residue was purified by GPC to give 0.14 g
(yield 70%) of 1 as a brown solid.
1H NMR (400 MHz, CDCl3): 1.71 (t, 1H, 3J = 6.4 Hz, OH); 4.40 (d,
2H, 3J = 6.4 Hz, CH2); 7.16 (tt, 2H, 3J = 7.3 and 4J = 1.4 Hz, C6H5–H4);
7.26 (dd, 4H, 3J = 7.3 and 4J = 1.4 Hz, C6H5–H2, H6); 7.35 (t, 4H,
3J = 7.3 Hz, C6H5–H3, H5). 13C NMR (100 MHz, CDCl3): 51.95;
54.27; 71.35; 77.66; 80.29; 121.20; 124.96; 129.42; 142.17. IR
(KBr): 3411, 2232, 2160 cmꢀ1. Anal. Calc. for C17H13NO: C, 82.57;
H, 5.30; N, 5.66. Found: C, 82.46; H, 5.49; N, 5.65.
2.5. Preparation of 6-(diphenylamino)-2-methylhexa-3,5-diyn-2-ol(2)
After a suspension of cupper (I) chloride (0.29 g, 2.96 mmol) in
acetone (8.3 ml) was degassed by argon bubbling for 30 min, TME-
DA (0.15 ml, 1.01 mmol) was added to the suspension, and it was
stirred for 45 min. The supernatant solution containing CuCl–TME-
DA catalyst was transferred into a mixture of N-ethynyl-N-pheny-
laniline (0.52 g, 2.69 mmol) and 2-methyl-3-butyn-2-ol (1.0 ml) in
acetone at ꢀ20 °C. The solution was stirred for 18 h under an oxy-
gen atmosphere. The solvent was evaporated, and the residue was
extracted with dichloromethane. The solution was washed with 5%
ammonium hydroxide, and the water layer was extracted twice
with dichloromethane. The combined organic layer was washed
with water, and dried over anhydrous sodium sulfate. After the
solvent was evaporated, the residue was purified by column
Fig. 4. The asymmetric unit of 2 with atom-numbering scheme. Displacement
ellipsoids are drawn at the 50% probability level and H atoms are shown as small
spheres.
Fig. 5. A view of the hydrogen-bonding interactions in 2. [Symmetry codes: (iii) x + 1/2, ꢀy + 1/2, ꢀz; (iv) x + 1, y, z.]

Y. Tokutome et al. / Journal of Molecular Structure 1029 (2012) 135–141
139
Fig. 6. Crystal packing structure of 2. Hydrogen atoms are omitted for clarity.
chromatography on a silica gel with dichloromethane as an eluant
to give 0.31 g (yield 42%) of 2 as a white solid.
are summarized in Table 1. Selected bond distances and angles of
1 and 2 are listed in Table 2.
1H NMR (400 MHz, CDCl3): 1.56 (s, 6H, 2 ꢁ CH3); 2.00 (s, 1H,
OH); 7.15 (dt, 2H, 3J = 7.3 and 4J = 1.4 Hz, C6H5–H4); 7.26 (dd, 4H,
3J = 7.3 and 4J = 1.4 Hz, C6H5–H2, H6); 7.35 (t, 4H, 3J = 7.3 Hz,
C6H5–H3, H5). 13C NMR (100 MHz, CDCl3): 31.29; 53.91; 65.89;
67.64; 77.53; 86.12; 121.17; 124.86; 129.39; 142.21. IR (KBr):
3454, 2250, 2166 cmꢀ1. Anal. Calc. for C19H17NO: C, 82.88; H,
6.22; N, 5.09. Found: C, 82.70; H, 6.41; N, 5.17.
Fig. 1 shows the crystal structure of 1. The structure around the
nitrogen (the N1/C1/C7/C13 plane; r.m.s. deviation = 0.007 Å) is pla-
nar. The dihedral angles of the plane with two phenyl groups (the
C1–C6 plane and the C7–C12 plane) are 82.5(9)° and 7.05(9)°,
respectively. It clearly shows that the C7–C12 phenyl group conju-
gates with acetylenic groups and the C1–C6 ring does not contribute
to the
C7 are 1.451(3) Å and 1.420(3) Å. The difference in the bond dis-
tances is thought to originate in -conjugation. Such geometry is
p-conjugated system. The bond distances of N1–C1 and N1–
2.6. Computational methods
p
unusual for that of a diphenylamino group.
DFT calculations of 1 and 2 were performed using the Spartan
04 software [17] (Wavefunction, Inc.) with B3LYP 6-311G (d, p)
level. The geometrical optimization was carried out without sym-
metry constraints, where the initial structures for calculations
were set at those obtained by crystallographycal analyses.
The bond length of N1ꢀC13 is 1.340(3) Å, which is consistent
with the reported lengths [7–12,18–21]. The distances of C13–
C14, C14–C15 and C15–C16 are 1.205(3) Å, 1.370(3) Å and
1.204(3) Å, showing a clear bond alternation. The diacetylene group
curves slightly, where the angles of N1–C13–C14, C13–C14–C15,
C14–C15–C16 and C15–C16–C17 are 178.1(2)°, 177.89(18)°,
179.68(18)° and 176.58(18)°.
3. Results and discussion
Fig. 2 shows the intermolecular interaction observed in 1. The
molecules stack along the b axis making regular one-dimensional
columns. The intermolecular polymeric O–Hꢂ ꢂ ꢂO hydrogen-
bondings were recognized between the columnar stacks. The
geometries of the hydrogen-bonding patterns are summarized at
Table 3. The distance between O1 and O1i atoms [symmetry codes:
(i) ꢀx + 3/2, y + 1/2, ꢀz + 3/2] is 2.764(3) Å and the angles of
O1iꢀH1iꢂ ꢂ ꢂO1 is 157(3)°. The stacking parameters of the diacety-
lene moieties are also listed in Table 4. Stacking intervals of the
molecules 1 are 5.219(2) Å, and the inclination angle between
the diacetylene moiety and the b axis (C13ꢀC16ꢀC16ii [symmetry
codes: (ii) x, y + 1, z]) is 41.70(4)°. Intermolecular distance between
C13 and the neighboring C16ii atom is 3.474(3) Å. These packing
parameters satisfy the Baughman’s condition for solid-state poly-
merization of diacetylenes. Fig. 3 shows the crystal packing struc-
ture of 1. The one-dimensional columnar stacks fill in the crystal
space capably. The inter-columnar interactions are not recognized
except for the hydrogen-bonding.
3.1. Preparation of 1 and 2
Preparation of 1 and 2 is shown in Scheme 2. Treatment of
N,N-diphenylacetamide with phosphorus pentachloride in dry tol-
uene gave N-phenyl-N-(1,2,2-trichlorovinyl)aniline in 24% yield.
Reaction of N-phenyl-N-(1,2,2-trichlorovinyl)aniline with n-BuLi
afforded N-ethynyl-N-phenylaniline. Since this compound was
unstable, it was used to the following preparation without purifica-
tion. Hay coupling reaction between N-ethynyl-N-phenylaniline
and the corresponding acetylenes gave 1 and 2 in 70% and 42%
yield, respectively.
3.2. Crystal structure of 1 and 2
The single crystals of 1 and 2 suitable for X-ray crystallography
were obtained by slow evaporation of chloroform and hexane,
respectively. Crystal data and details of refinement for 1 and 2

140
Y. Tokutome et al. / Journal of Molecular Structure 1029 (2012) 135–141
142(4)°. The stacking parameters of diacetylene moieties are also
(a)
listed in Table 4. Stacking intervals of the molecules are
5.836(2) Å, and the inclination angle between the molecular axis
and the a axis (C13ꢀC16ꢀC16iv [symmetry code: (iv) x + 1, y, z.])
is 63.18(7)°. Intermolecular distance between C13 and neighboring
C16iv atom is 5.332(5) Å. These packing parameters do not satisfy
the Baughman’s condition. Fig. 6 shows the crystal packing struc-
ture of 2. The one-dimensional columnar stacks fill in the crystal
space capably. The intercolumnar interactions are not recognized
except for the hydrogen-bondings.
C3
C4
C2
C5
C1
C17
C16
C15
C14
C13
C6
The following is the difference in the molecular structures and
crystal packings between 1 and 2. The differences in the structures
are recognized at around the N1 and the O1 atoms. Although the
environment around the N1 atom is planar in both compounds,
the dihedral angles of the N1/C1/C7/C13 planes with the two phe-
nyl rings are significantly different. The perpendicular orientation
of two phenyl rings in 1 is thought to be suitable for crystal packing
judged by the rather high density.
N1
O1
C7
C8
C9
C12
C11
C10
The significant difference is also observed at the bond distance
of O1ꢀC17, where the distances of 1 and 2 are 1.419(3) Å and
1.446(4) Å, respectively. The geometry of the intermolecular
hydrogen-bonding and the stacking parameters showed a signifi-
cant difference. These differences are well explained by consider-
ing the bulkyness of methyl groups. A large stacking intervals
and weak hydrogen-bonding of 2 suggest that the methyl groups
prevent the tight stacking and the close contact between the
hydrogen bonded oxygen atoms.
(b)
C4
C3
C2
C18
C5
C6
C1
N1
3.3. Geometry optimization
C17
C13
C14
C16
C15
The optimized molecular structures of 1, 2 with their number-
ing schemes are shown in Fig. 7 in accordance with the atom num-
bering given in Figs. 1 and 4. The optimized structural parameters
of 1 and 2 calculated using B3LYP functional with 6-311 G (d,p)
basis set are listed and compared with the experimental ones in
Table 2. In the case of 2, the DFT calculation reproduced the crystal
structure well except for C4ꢀC5 bond and the diacetylene moiety.
In the case of 1, however, a significant difference was recognized at
the dihedral angles around the N1/C1/C7/C13 plane in addition to
the exceptions observed at 2. Although we do not have any clear
answers concerning shrinkage of C4ꢀC5 bond, the difference in
the remaining parts is thought to originate in the crystal packing.
Diacetylene moieties are known to bend easily by the effect of
the crystal packing. This may be the reason that the calculation
underestimated the C14ꢀC15 bond lengths. The difference in the
environment around the nitrogen atom is considered to be affected
by the unusual structure of the diphenylamino group which is
aforementioned in the crystal structure.
C7
O1
C12
C8
C9
C19
C11
C10
Fig. 7. Optimized molecular structures of 1 (a) and 2 (b) with atom-numbering
scheme.
Fig. 4 shows the crystal structure of 2. The structure around the
nitrogen (the N1/C1/C7/C13 plane; r.m.s. deviation = 0.018 Å) is
planar. The dihedral angles of the plane with two phenyl groups
(the C1ꢀC6 plane and the C7ꢀC12 plane) are 52.3(1)° and
23.5(1)°, respectively. In crystal 2, both phenyl rings are found to
contribute to the
p conjugated system. The bond distances of
4. Conclusions
N1ꢀC1 (1.438(4) Å) and N1ꢀC7 (1.424(4) Å) show a tendency to
depend on the dihedral angles. The bond length of N1ꢀC13 is
1.340(4) Å, which is consistent with the reported lengths. The dis-
tances of C13ꢀC14, C14ꢀC15 and C15ꢀC16 are 1.205(4) Å,
1.368(4) Å and 1.207(4) Å, showing a clear bond alternation. The
diacetylenic group curves slightly, where the angles of
N1ꢀC13ꢀC14, C13ꢀC14ꢀC15, C14ꢀC15ꢀC16 and C15ꢀC16ꢀC17
are 178.7(4)°, 175.6(4)°, 177.6(4)° and 178.1(3)°.
Fig. 5 shows the intermolecular interaction observed at 2. The
molecules stack along the a axis making regular one-dimensional
columns. The intermolecular polymeric OꢀHꢂꢂꢂO hydrogen-bonds
were recognized between the columnar stacks. The geometries of
the hydrogen-bonding patterns are summarized at Table 3. The
distance between O1 and O1iii atoms [symmetry code: (iii) x + 1/
2, ꢀy + 1/2, ꢀz.] is 3.179(5) Å and the angles of O1ꢀH1ꢂꢂꢂO1iii is
We have succeeded in preparations and crystallographical anal-
yses of the novel diacetylene compounds, 1 and 2, where the mol-
ecules incorporate an ynamine moiety. The crystal structures of
both compounds were interpreted to be controlled mainly by the
intermolecular hydrogen-bondings. The difference in crystal struc-
tures between 1 and 2 was well explained by consideration of the
steric repulsion with methyl groups connected to the carbon atom
adjacent to the hydroxyl group. The unusual structure of the
diphenylamino group in 1 was also interpreted as the effect of
crystal packing. The steric effects of the methyl groups on intra
and intercolumnar interaction should be important for designing
molecular and crystal structures of diacetylene molecules. The
DFT calculations could reproduce the crystal structures except for
the parts which were easily affected by the crystal packing.

Y. Tokutome et al. / Journal of Molecular Structure 1029 (2012) 135–141
141
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Acknowledgement
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This work was supported by Research for Promoting Technolog-
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Appendix A. Supplementary material
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The supplementary crystallographic data for 1 and 2 have been
deposited with the Cambridge Crystallography Data Centre, 12 Un-
ion road, Cambridge CB22 1EZ, UK (Fax: +44 1223 336 033); E-mail:
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk) and are
available free of charge on request quoting the deposition number
CCDC 871688 and CCDC 871689 for 1 and 2, respectively. Supple-
mentary data associated with this article can be found, in the online
version, at http://dx.doi.org/10.1016/j.molstruc.2012.07.003.
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