Discotic metallomesogens: Mesophase crossover of columnar rectangular to hexagonal arrangements in bis(hydrazinato) nickel(II) complexes

Article abstract of DOI:10.1039/a800657a

Three series of N-(3,4-dialkoxybenzylidene)-N′-(3′,4′,5′- trialkoxybenzoyl)hydrazine and their nickel(II) complexes, bis[N-(3,4-dialkoxybenzylidene)-N′-(3′,4′,5′- trialkoxybenzoyl)hydrazinato]nickel(II), were prepared and characterized. The mesomorphic properties of these disc-like compounds were also studied in terms of liquid crystallinity. The orange nickel(II) complexes with ten soft alkoxy side chains exhibited columnar disordered mesophases, which were characterized based on DSC analysis and optical polarized microscopy. Nickel complexes with shorter side chains (n = 5-8) displayed a monotropic columnar rectangular disordered (Col_rd) phase; however, complexes with longer side chains showed monotropic (n = 10) and enantiotropic (n = 12, 14) columnar hexagonal disordered (Col_hd) phases. Similar nickel complexes (n = 14) with eight side chains exhibited a columnar hexagonal phase, whereas complexes (n= 14) with six side chains formed crystalline phases. The structures of these columnar disordered phases were confirmed by X-ray powder diffraction. XRD data indicated that mesophase crossover from columnar rectangular (Col_r) to hexagonal arrangements (Col_h) was observed with increasing side chain lengths.

Full text of DOI:10.1039/a800657a

J O U R N A L O F
Discotic metallomesogens: mesophase crossover of columnar
rectangular to hexagonal arrangements in bis(hydrazinato)nickel(II
complexes
)
Chung K. Lai,* Chun-Hsien Tsai and Yung-Shyen Pang
C H E M I S T R Y
Department of Chemistry, National Central University, Chung-L i, Taiwan, ROC
Three series of N-(3,4-dialkoxybenzylidene)-N∞-(3∞,4∞,5∞-trialkoxybenzoyl)hydrazine and their nickel() complexes, bis[N-(3,4-
dialkoxybenzylidene)-N∞-(3∞,4∞,5∞-trialkoxybenzoyl)hydrazinato]nickel(), were prepared and characterized. The mesomorphic
properties of these disc-like compounds were also studied in terms of liquid crystallinity. The orange nickel() complexes with ten
soft alkoxy side chains exhibited columnar disordered mesophases, which were characterized based on DSC analysis and optical
polarized microscopy. Nickel complexes with shorter side chains (n=5–8) displayed a monotropic columnar rectangular
disordered (Col ) phase; however, complexes with longer side chains showed monotropic (n=10) and enantiotropic (n=12, 14)
rd
columnar hexagonal disordered (Col ) phases. Similar nickel complexes (n=14) with eight side chains exhibited a columnar
hd
hexagonal phase, whereas complexes (n=14) with six side chains formed crystalline phases. The structures of these columnar
disordered phases were confirmed by X-ray powder diffraction. XRD data indicated that mesophase crossover from columnar
rectangular (Col ) to hexagonal arrangements (Col ) was observed with increasing side chain lengths.
r
h
Recently, many disc-like coordination complexes with a
central geometry of either square planar (Cu, Ni, Pd) or
square pyramidal (VO) structure as the rigid core have been
prepared, and these metal complexes have been found to
exhibit novel mesomorphic properties.1 In general this type
of metallomesogenic structure was generated by incorporation
of single or multiple metal centers2 into traditional organic
molecules. This synthetic strategy has been widely used to
design metallomesogenic materials with a variety of geometri-
cal structures and molecular shapes.1e The rich electronic and
magnetic properties originating from metal centers makes
such materials potential candidates1e,3 for molecular based
applications.
Columnar hexagonal and rectangular arrangements are
among the two common phases observed among discotic2e,4,5
molecules. Moreover, certain molecules, which are not them-
selves disc-shaped,6 may also exhibit similar columnar phases.
A typical monomesomorphic transition7 of the crystal-to-
columnar-to-isotropic (KAColAI) has often been observed
for this type of columnar mesogen; however, discotic molecules
with polymesomorphic properties are relatively rare.4 Among
them mesophase crossover from columnar rectangular to
hexagonal arrangements identified by high-resolution X-ray
diffraction (XRD) with increasing side chain lengths has been
observed in several columnar systems.4,8 This type of phase
transition9 has generally been attributed to the fact that shorter
side chain complexes favored the greater core interaction
OR
RO
X
OR
Y
N
O
O
N
N
Ni
Y
N
RO
X
OR
OR
R = (CH2)nH
1 X = Y = OR
2 X = H, Y = OR
3 X = Y = H
Results and Discussion
Synthesis
The synthetic procedures for this type of monodentate hydra-
zone Schiff base10 are quite straightforward, and summarized
in Scheme 1. Reaction of methyl 3,4,5-trialkoxybenzoate esters
with hydrazine hydrate in refluxing absolute ethanol gave
3,4,5-trialkoxybenzoylhydrazine as a white solid. The Schiff
bases of N-(3,4-dialkoxybenzylidene)-N∞-(3∞,4∞,5∞-trialkoxyben-
zoyl)hydrazine were obtained by the condensation reactions
of these hydrazine derivatives with 3,4-dialkoxybenzaldehyde
in refluxing ethanol. The Schiff bases were isolated by
recrystallization from ethanol as light yellow solids.
needed for the formation of Col phases. A similar preference
of Col over the Col phase for larger metal centers, such as
rd
r
h
M=Pd over the Cu analogue8a also occurs in bis(b-diketonate)
metal complexes.
In this paper, we report the preparation, characterization
and mesomorphic properties of a series of nickel() com-
plexes 1–3 of N-(3,4-dialkoxybenzylidene)-N∞-(3∞,4∞,5∞-trialkox-
ybenzoyl)hydrazine. These disc-like molecules exhibited col-
umnar mesophases as expected. The mesophase crossover of
rectangular to hexagonal phase with increasing side chain
length was also observed in these nickel() complexes. In
addition, the effect of side chain density on the formation
and/or stability of columnar mesophases was also studied
in detail.
Aroylhydrazone derivatives11 exist in two different keto–enol
tautomeric forms (Scheme 2). The conjugating ability12 of the
substituents on the ketone moiety was found to influence the
ratio of these two isomers. The increasing conjugating ability
of aryl substituents preferred the enolic tautomer form.
Two different structural types10 of nickel() complexes could
be prepared and isolated depending on the nickel() salts used.
Reaction of Schiff bases with nickel() acetate produced the
square planar bis(aroylhydrazinato)nickel() complexes; how-
ever, the reaction with nickel() chloride gave the octahedral
J. Mater. Chem., 1998, 8(6), 1355–1360
1355

Scheme 1 Reagents and conditions: (a) RBr (3.0 equiv.), K CO (7.0 equiv.), Kl (catalyst), refluxing in MeCOMe, 72 h, 73–94%. (b) NH NH
(1.5 equiv.), refluxing in absolute EtOH, 12 h, 85–90%. (c) RBr (2.0 equiv.), K CO (3.0 equiv.), Kl, refluxing in MeCOMe, 24 h, 79–88%.
(d) Acetic acid (3 drops), refluxing in EtOH, 12 h, 70–75%. (e) Ni(OAc) (1.1 equiv.), refluxing in absolute C H OH, 24 h 73–80%.
2
3
2
2
2
3
2
2 5
OR
that the formation2d,e,6a and stability of the columnar phases
by disc-like molecules were strongly dependent on the numbers
of flexible side chains, i.e. side chain density. Increasing the
number of side chains often improved the liquid crystalline
behavior in this type of metallomesogenic system.
RO
OR
RO
OR
NH
N
O
Keto
Complexes with ten side chains
These nickel complexes all exhibited the liquid crystalline
behavior of columnar discotics and were characterized based
on DSC analysis and polarized optical microscopy. The phase-
transition temperatures and enthalpies of nickel complexes 1–3
are given in Table 1. Complexes with shorter carbon chain
length, n=5–8, exhibited monotropic columnar phase
behavior. On heating the crystals melt directly to isotropic
liquids above 203.0–218.0 °C, whereas the transition of meso-
phases at ca. 187.0–219.0 °C took place on cooling from the
isotropic phase. The temperature range of the mesophases was
quite wide depending on the carbon chain length during the
cooling process. The columnar rectangular phases4,8a were
easily identified by observation of the mosaic textures dis-
playing prominent wedge-shaped defect patterns (Fig. 1) under
the polarized microscope. All these complexes were also studied
at various temperatures by XRD to examine their mesophase
structures. Rectangular4,8 columnar phases often displayed two
intense peaks in the low angle region, which were indexed as
(200) and (110) reflections. The XRD data for the nickel
complexes 1 and 2 are summarized in Table 2. For example,
complexes n=5 gave a diffraction of two strong reflections at
OR
RO
OR
RO
OR
N
N
HO
Enol
Scheme 2
dichlorobis(aroylhydrazone)nickel() complexes. Dehalopro-
tonation with alcoholic potassium hydroxide converted the
octahedral nickel() to planar nickel() complexes. The prep-
aration of octahedral complexes was not attempted in this
work. The square planar nickel() complexes studied in this
work were prepared by reaction of N-(3,4-dialkoxybenzylid-
ene)-N∞-(3∞,4∞,5∞-trialkoxybenzoyl)hydrazine with Ni(OAc) in
refluxing ethanol. The nickel complexes were then isolated as
2
˚
˚
d 25.94 and 21.70 A, a weaker peak at d 8.57 A and also a
orange crystals by recrystallization from absolute ethanol in a
high yield of 76–86%. All the nickel() complexes are diamag-
netic, and all display sharp peaks in their 1H NMR spectra.
Elemental analyses also confirmed the identity of the
complexes.
˚
broad diffuse peak at d 4.75 A at 130 °C. This diffraction
pattern (Fig. 2) corresponded to rectangular lattice constants:
˚
a=51.88, b=23.89 A. Three different columnar Col phases4
rd
have now been identified: P(2 /a), P(2/a) and C(2/m)
1
depending on the point symmetry of the molecules. In rectangu-
lar phases the average molecular plane is not perpendicular to
the column axis, and the tilt angle can be determined only by
known molecular symmetry.
Mesomorphic properties
Mesomorphic studies in columnar systems of metal bis(b-
diketonates) with various numbers of side chains indicated
Interestingly, the nickel complexes with longer side chains,
1356
J. Mater. Chem., 1998, 8(6), 1355–1360

Table 1 Phase behaviora of nickel() complexes 1–3
79.9 (6.59)
216.6 (5.46)
211.4 (6.05)
K2
K2
K2
K2
1
n = 5
K1
K1
I
I
Colrd
Colrd
Colrd
Colrd
35.7 (22.8)
224.5 (7.39)
218.6 (7.35)
74.8 (37.7)
27.2 (2.77)
63.5 (28.7)
6
42.4 (36.7)
217.8 (4.87)
208.8 (4.83)
K1
K1
7
8
I
I
42.2 (2.77)
17.2 (29.8)
21.1 (32.9)
217.8 (4.99)
214.5 (4.83)
203.5 (4.91)
200.9 (4.75)
73.6 (28.2)
68.8 (12.0)
K1
K1
10
K2
K2
I
I
Colhd
Colhd
78.2 (34.9)
25.2 (46.6)
189.9 (4.58)
187.2 (4.45)
12
14
173.9 (2.31)
170.2 (2.18)
78.4 (11.3)
44.8 (41.6)
72.4 (29.8)
75.7 (24.2)
K1
K1
K2
K2
I
I
I
Colhd
Colhd
K2
158.0 (0.13)
154.8 (0.80)
131.9 (0.76)
39.6 (24.7)
14
14
2
3
116.3 (52.1)
92.6 (55.0)
76.1 (5.71)
56.9 (3.91)
K1
an represents the number of carbon atoms in the alkoxy chain. K , K =crystal phases; Col =columnar hexagonal
1
2
hd
disordered phase; Col =columnar retangular disordered phase; I=isotropic. The transition temperatures (°C)
rd
and enthalpies (in parentheses, kJ mol−1) were determined by DSC at a scan rate of 10.0 °C min−1.
n=10, 12 and 14, showed a typical columnar hexagonal phase.
Two transitions10 of crystal-to-columnar-to-isotropic (KA
ColAI), and additional crystal-to-crystal (K AK ) transitions
1
2
were also observed for these complexes. From DSC analysis a
typical larger enthalpy for the crystal-to-liquid crystal trans-
ition at lower temperatures (ca. 78.0 °C) and a lower enthalpy
for the liquid crystal-to-isotropic transition at higher tempera-
tures (174.0–190.0 °C) were observed. This lower value of the
transition enthalpy indicated that the mesophases were rela-
tively highly disordered. The temperature range of columnar
mesophases for nickel complexes is quite wide (between
125–162 °C) in the cooling process and slightly sensitive to the
carbon number of the side chains. The melting and clearing
points both decrease as the side chain length increases. Upon
heating, orange complexes melt to give birefringent fluid phases
with columnar superstructures. When cooled from their iso-
tropic phases, they displayed an optical texture (Fig. 3) which
was a mixture of pseudo focal-conics and mosaic regions with
linear birefringent defects, suggesting hexagonal columnar4,6,8
structures. The existence of a large area of homeotropic
domains may lead to the conclusion of preferred uniaxial
character4a in this phase.
A summary of the diffraction peaks and lattice constants for
these nickel complexes is also given in Table 1. For example,
nickel complex 1 (n=14) displays a diffraction pattern of a
two-dimensional hexagonal lattice (Fig. 4) with an intense
˚
peak and two weaker peaks of 36.65, 21.77 and 18.86 A at
155 °C. These are characteristic of the columnar hexagonal
columnar (Col ) phase with a d-spacing ratio of 1, (1/3)1/2
hd
and (1/4)1/2, corresponding to Miller indices (100), (110) and
(200), respectively. This reflection pattern corresponds to an
intercolumnar distance (a parameter of the hexagonal lattice)
˚
of 43.20 A. In the hexagonal lattice the column axes are located
at the nodes of the two-dimensional structure and are oriented
along the c axis. However, a broad diffuse band, which is likely
˚
due to molten alkyl chains, occurred at 4.73–4.82 A in the
Fig. 1 Optical texture (100×) observed for complex 1 (n=8): Col
phase at (a) 207 °C (thick sample) and (b) 195 °C (thin sample)
rd
J. Mater. Chem., 1998, 8(6), 1355–1360
1357

Table 2 Variable-temperature X-ray diffraction data for nickel()
complexes 1 and 2
˚
d-spacing/A
obs. (calcd.)
lattice
spacing/A
Miller
indices
˚
complex
mesophase
1
n=5
Col at 100 °C
a=52.28
b=24.10
26.14 (26.14)
21.89 (21.89)
8.57 (8.86)
(200)
(110)
(420)
rd
4.80 (br)
Col at 130 °C
a=51.88
b=23.89
25.94 (25.94)
21.70 (21.70)
8.57 (8.79)
(200)
(110)
(420)
rd
4.75 (br)
6
7
Col at 200 °C
a=54.44
b=24.92
27.22 (27.22)
22.66 (22.66)
12.58 (12.46)
4.91 (br)
29.04 (29.04)
25.67 (25.67)
16.30 (16.03)
14.65 (14.31)
4.75 (br)
(200)
(110)
(020)
rd
Col at 150 °C
a=58.08
b=28.62
(200)
(110)
(310)
(020)
rd
8
Col at 200 °C
a=56.84
b=28.23
28.42 (28.42)
25.28 (25.28)
5.18 (br)
(200)
(110)
rd
10
Col at 100 °C
a=37.49
a=37.03
a=40.64
a=43.20
a=43.92
32.40 (32.40)
18.60 (18.70)
16.38 (16.20)
4.73 (br)
32.07 (32.07)
18.39 (18.51)
16.08 (16.03)
4.73 (br)
35.63 (35.63)
21.17 (20.57)
17.58 (17.81)
4.79 (br)
36.65 (36.65)
21.77 (21.60)
18.86 (18.32)
4.82 (br)
(100)
(110)
(200)
hd
Col at 190 °C
(100)
(110)
(200)
hd
12
14
14
Col at 120 °C
(100)
(110)
(200)
hd
Fig. 2 X-Ray diffraction data for complex 1 (n=5): (a) Col phase at
rd
130 °C and (b) K phase at room temperature
Col at 155 °C
(100)
(110)
(200)
hd
2
Col at 120 °C
38.04 (38.04)
21.85 (21.96)
19.62 (19.62)
4.78 (br)
(100)
(110)
(200)
hd
wide-angle region. The absence of distinct peaks at a high
angle rules out the existence of periodicity along the columns,
and is also consistent with the DSC analysis showing low
enthalpies for the columnar-to-isotropic transition. This posi-
tively indicates a highly disordered mesophase; i.e. there is no
long-range order along the columns. The temperature depen-
dence of the lattice parameters in these complexes was also
studied. We find that the low-angle reflections of complexes
generally shift to a larger d-spacing with decreasing tempera-
˚
˚
tures (i.e. d=37.03 A at 190 °C and d=37.49 A at 100 °C for
complex 1; n=10). The hexagonal lattices are also correlated
well with increasing side chain length.
The mesophase change of columnar rectangular to hexag-
onal arrangements with increasing side chain length was
observed in this system; with increasing carbon number the
hexagonal phase arrangement predominates over the rectangu-
lar phase. The mesophase crossover from Col to Col has
rd
hd
been observed in similar metallomesogenic systems, and was
generally attributed to the greater core interaction necessary
for the formation of the Col phases. The tilted Col phase
rd
rd
reduced the interactions between the bulky side chains and
allowed closer contacts between the cores. Similar mesophase
crossover was also observed in systems4,8a,b,d with the larger
Pd replacing Cu in the Cu analogue.8a This pseudohexagonal
lattice constant, i.e. a rectangular lattice with an axial ratio of
b/a from the ideal hexagonal of 31/2 (Scheme 3), for this series
of nickel complexes was in the range of 2.01–2.18 (from
Fig. 3 Optical texture (100×) observed for complex 1 (n=12): (a) Col
phase at 180 °C and (b) K phase at room temperature
hd
1358
J. Mater. Chem., 1998, 8(6), 1355–1360

Conclusion
The mesomorphic studies of the title nickel complexes indicated
that the formation of columnar phases was found to be strongly
dependent on the number of side chains around the core
group. The complexes with a total of ten and eight side chains
exhibited columnar phases, however, complexes with six and
four side chains exhibited crystalline phases. Therefore, the
number of side chains for this type of disc-like nickel complexes
studied must be at least eight to form a stable mesogen.
Experimental section
All chemicals and solvents were reagent grade from Aldrich
Chemical Co., and used without further purification. 1H and
13C NMR spectra were measured on a Bruker DRS-200.
J Values are in Hz. Infrared spectra were recorded on a Bio-
Rad FTS-155 using polystyrene as a standard. DSC thermo-
graphs were recorded on a Perkin-Elmer DSC-7 and calibrated
with a pure indium sample. All phase behavior was determined
at a scan rate of 10.0 °C min−1 unless otherwise noted.
Optical polarized microscopy was carried out on a Nikkon
MICROPHOT-FXA with a Mettler FP90/FP82HT hot stage
system. X-Ray powder diffraction (XRD) studies were conduc-
ted on an INEL MPD-diffractometer with a 2 kW Cu-Ka X-
ray source equipped with an INEL CPS-120 position sensitive
detector and a variable temperature capillary furnace with an
accuracy of 0.10 °C in the vicinity of the capillary tube. The
detector was calibrated using mica and silicon standards. The
powder samples were charged in Lindemann capillary tubes
(80 mm long and 0.01 mm thick) from Charles Supper Co.
with a diameter of 0.1 or 0.2 mm, and the end was flame
sealed. The samples were heated above the isotropic tempera-
tures and left for ca. 10 min. The samples were then cooled at
a rate of 5.0 °C min−1 to the desired temperature and the
diffraction data collected. The methyl 3,4,5-trialkoxybenzoate
esters, methyl 4-alkoxybenzoate esters, ethyl 3,4-dialkoxy-
benzoate esters, and 3,4-dialkoxybenzaldehyde were prepared
by literature2a–d,6a procedures.
Fig. 4 X-Ray diffraction data for complex 1 (n=14): (a) Col phase
hd
at 155 °C and (b) K phase at room temperature
a
a
b
Methyl 4-tetradecyloxybenzoate
White solid, yield 90%. d (CDCl ): 0.82 (t, J 6.73, MCH ,
b = 31/2
a
H
3
3
3H), 1.24–1.84 [m, M(CH ) , 24H], 3.85 (s, MOCH , 3H),
2 12
3
4.27 (t, J 7.31, MOCH , 2H), 6.84 (d, J 8.82, MC H , 2H),
Scheme 3
2
6 4
7.92 (d, J 8.82, MC H , 2H). d (CDCl ): 14.76, 23.26, 26.58,
6
4
C
3
29.79, 29.98, 30.05, 30.30, 30.33, 30.36, 32.53, 52.54, 68.83,
114.62 (C2,6), 122.91 (C1), 132.13 (C3,5), 163.45 (C4), 167.53
(CNO).
n=5–10). This value indicated that the structural departure
from the ideal hexagonal lattice was about 20% in this system.
Complexes 2 and 3 with eight and six side chains
Ethyl 3,4-bis(tetradecyloxy)benzoate
Nickel complexes 2 and 3 (n=14) were also prepared to study
the effect of side chain density on the formation of mesophases.
DSC analysis and XRD diffraction showed that complex 2
with eight side chains exhibited a similar columnar hexagonal
White solid, yield 89%. d (CDCl ): 0.87 (t, MCH , 9H),
H
3
3
1.24–1.83 (m, MCH , 44H), 3.97 (t, J 8.19, OCH , 2H), 4.34
2
2
(tt, MOCH , 2H), 6.80 (d, J 8.44, MC H , 1H), 7.51 (s, MC H ,
2
6
3
6 3
1H), 7.57 (d, J 6.42, MC H , 1H). d (CDCl ): 13.91, 14.21,
disordered phase (Col ). The isotropic point for the complex
6
3
C
3
hd
22.51, 25.84, 28.93, 29.21, 31.74, 60.48, 68.84, 69.13, 111.7 (C6),
114.2 (C2), 122.6 (C5), 123.2 (C1), 148.3 (C4), 152.9 (C3),
166.3 (CNO).
was ca. 20 °C lower, and the temperature of the mesophase
was narrower than for the similar complex 1 (n=14). This
result indicated that higher side chain density tended to easily
stabilize the mesogenic core, as is often observed in this type
of columnar system. However, complex 3 (n=14) with six side
chains showed only a transition of the crystal to isotropic
phase at 116.3 °C. Similar nickel complexes (n=12) of disc-like
molecules have also been prepared, in which nickel complexes10
with two or four dodecyloxy chains were found to be non-
mesogenic. The broadening10 of the molecular width and the
non-coplanarity of the benzylidene ring were attributed to this
non-mesomorphic behavior.
Methyl 3,4,5-tris(dodecyloxy)benzoate
White solid, yield 90%. d (CDCl ): 0.86 (t, MCH , 9H),
H
3
3
1.26–1.84 (m, CH , 60H), 3.88 (s, MOCH , 3H), 4.03 (tt,
2
3
MOCH , 6H), 7.25 (s, C H , 2H). d (CDCl ): 14.18, 22.75,
2
6
2
C
3
26.14, 29.36, 29.45, 29.62, 29.71, 29.75, 29.39, 30.39, 32.00, 52.13,
69.22, 75.53, 105.02 (C2,6), 124.69 (C1), 142.01 (C3,5), 152.83
(C4), 166.89 (CNO).
J. Mater. Chem., 1998, 8(6), 1355–1360
1359

3,4-Bis(dodecyloxy)benzaldehyde
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3
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(d) A. G. Serrette, C. K. Lai, T. M. Swager, Chem. Mater., 1994, 6,
2252; (e) J. Barbera´, A. Elduque, R. Gime´nez, L. A. Oro and
J. L. Serrano, Angew. Chem., Int. Ed. Engl., 1996, 35, 2832;
( f ) S. Eguchia, T. Nozaki, H. Miyasaka, N. Matsumoto,
H. Okawa, S. Kohata and N. Hoshino-Miyajima, J. Chem. Soc.,
Dalton T rans., 1996, 1761; (g) L. Bonnet, F. D. Cukiernik,
P. Maldivi, A.-M. Giroud-Godquin, J.-C. Marchon, M. Ibn-Elhaj,
D. Guillon and A. Skoulios, Chem. Mater., 1994, 6, 31;
(h) R. H. Cayton, M. H. Chisholm and F. D. Darrington, Angew.
Chem., Int. Ed. Engl., 1990, 29, 1481; (i) M. Ghedini, D. Pucci,
G. D. Munno, D. Viterbo, F. Neveal and S. Armentano, Chem.
Mater., 1991, 3, 65; ( j) W. Pyzuk, A. Krowczynski, L. Chen,
E. Gorecka and I. Bickczantaev, L iq. Cryst., 1995, 19, 675;
(k) M. Ghedini, M. Longeri and R. Bartolino, Mol. Cryst. L iq.
Cryst., 1982, 84, 207; (l) M. Ghedini, S. Licoccia, S. Armentano and
R. Bartolino, Mol. Cryst. L iq. Cryst., 1984, 108, 269.
4-Tetradecyloxybenzoylhydrazine
White solid, yield 90%. d (CDCl ): 0.84 (t, J 6.30, MCH ,
H
3
3
3H), 1.23–1.83 (m, MCH , 24H), 3.28 (br, MOCNHNH , 2H),
2
2
2
3.92 (t, J 6.47, MOCH , 2H), 6.79 (d, J 8.76, MC H , 2H),
6 4
7.73 (d, MC H , 2H), 8.53 (br, MCONH, 1H). d (CDCl ):
6
4
C
3
13.94, 16.26, 22.51, 25.37, 25.81, 28.94, 29.18, 29.46, 30.74, 31.74,
68.05, 114.14 (C2,6), 125.24 (C1), 129.04 (C3,5), 161.89 (C4),
168.74 (CNO).
3,4-Bis(tetradecyloxy)benzoylhydrazine
White solid, 78%. d (CDCl ): 0.85 (t, J 6.69, MCH , 6H),
H
3
3
1.23–1.84 (m, MCH , 48H), 3.72 (br, MOCNHNH , 2H), 4.05
2
2
(tt, MOCH , 4H), 6.83 (d, J 8.47, MC H , 1H), 7.51 (s, MC H ,
1H), 7.58 (br, MCONH, 1H), 7.62 (d, J 8.39, MC H , 1H).
d (CDCl ): 13.93, 14.22, 22.53, 25.84, 28.92, 29.04, 29.22, 31.77,
68.81, 69.10, 111.71 (C3), 114.13 (C4), 122.58 (C1), 123.28 (C5),
148.31 (C2), 152.95 (C6), 168.12 (CNO).
2
6
3
6 3
6
3
3
(a) N. Boden, R. J. Bushby and J. Clements, J. Chem. Phys., 1993,
98, 5920; (b) D. Adam, P. Schuhmacher, J. Simmerer, L. Haussling,
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C
3
4
5
(a) S. Chandrasekhar, Adv. L iq. Cryst., 1982, 5, 47; (b) C. Destrade,
P. Foucher, H. Gasparoux, H. T. Nguyen, A. M. Levelut and
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M. M. Zurbano, Adv. Mater. 1991, 3, 602; (c) L. Bonnet,
F. D. Cukiernik, P. Maldivi, A.-M. Giroud-Godquin, J.-
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Mater., 1994, 6, 31; (d) W. Pyzuk, A. Krowczynski, L. Chen,
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7, 2067; (b) A. Takada, N. Ide, T. Fukuda, T. Miyamoto,
K. Yamagata and J. Watanabe, L iq. Cryst., 1995, 19, 441;
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40-C3, 17; (d) C. Destrade, M. C. Monodon-Bernaud and
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Cryst. L iq. Cryst., 1981, 66, 115.
3,4,5-Tris(dodecyloxy)benzoylhydrazine
White solid, yield 80%. d (CDCl ): 0.82 (t, J 7.46, MCH ,
H
3
3
3H), 1.23–1.81 (m, MCH , 60H), 3.33 (br, MCONHNH , 2H),
2
2
3.96 (tt, J 6.16, MOCH , 6H), 6.90 (s, MC H , 2H), 7.34 (br,
MCONH, 1H). d (CDCl ): 14.09, 22.67, 26.05, 29.29, 29.34,
29.37, 29.55, 30.28, 31.90, 69.27, 73.50, 105.41, 127.38 (C2,6),
141.33 (C1), 153.16 (C3,5), 168.62 (CNO).
2
6 2
6
C
3
N-(3,4-Dialkoxybenzylidene)-N∞-(3∞,4∞,5∞-trialkoxybenzoyl)
hydrazine
7
8
n/cm−1 (thin film): 3421, 2923, 2847, 1640, 1626, 1599, 1576,
1514, 1470, 1437, 1387, 1337, 1264, 1233, 1177, 1144, 1069, 1069.
General procedures for preparation of nickel complexes.
Bis[N-(3,4-diheptyloxybenzylidene)-N∞-(3∞,4∞,5∞-
triheptyloxybenzoyl)hydrazinato]nickel(II
)
A suspension of N-(3,4-diheptyloxybenzylidene)-N∞-(3∞,4∞,5∞-
triheptyloxybenzoyl)hydrazine (0.31 g, 0.342 mmol) and nickel
acetate (0.090 g, 0.362 mmol) in 100 ml of absolute ethanol
was heated under reflux overnight. The orange solid was
filtered off, and then washed with hot ethanol (3×20 ml). The
product was isolated as orange crystals after twice recrystalliz-
ation from THF–ethanol. Yield 73%. n/cm−1 (thin film): 2929,
2855, 1597, 1522, 1502, 1466, 1473, 1397, 1362, 1273, 1221,
9
(a) C. R. Safinya, K. S. Liang, W. A. Varady, N. A. Clark and
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Cryst. L iq. Cryst., 1985, 123, 205.
10 (a) M. N. Abser, M. Bellwood, C. Buckley, M. C. Holmes and
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11 (a) L. Sacconi, J. Am. Chem. Soc., 1952, 74, 4503; (b) H. Ohta, Bull.
Chem. Soc. Jpn., 1958, 31, 1056; 1960, 33, 202.
1180, 1137, 1069, 1038. (Calc. for C
H 9.91, N 3.40. Found C 71.17, H 10.06, N 3.44%).
H
N O Ni: C 71.46,
138 242
4 12
12 (a) L. Sacconi, J. Am. Chem. Soc., 1954, 76, 3400; (b) R. A. Morton,
A. Hassan and T. C. Calloway, J. Chem. Soc., 1934, 883.
We thank the National Science Council of Taiwan, ROC for
generous funding (NSC-87-2113-M008-007) of this work.
Paper 8/00657A; Received 23rd January, 1998
1360
J. Mater. Chem., 1998, 8(6), 1355–1360