The π-π interactions enhanced in salicylaldimines and salicylaldazines

Article abstract of DOI:10.1016/j.tet.2015.07.049

Four new series of salicylaldazines 1 and salicylaldimines 2-4 were prepared, characterized and their mesomorphic properties were studied. The structures of all compounds were identified and confirmed by spectroscopic techniques such as ¹H, ¹³C NMR, MS and elemental analysis. Three single crystallographic structures of compounds 1a (n=3, 6) and 2 (n=3) were determined by X-ray analysis in order to correlate the molecular structures with the formation of mesophases. Crystallographic data indicated that the better mesomorphic properties might be controlled by CH-π, π-π or/and H-bonds in such system. Except for crystalline compounds 4, all other compounds 1-3 showed mesomorphic behavior of nematic, smectic A or/and smectic C phases, which were characterized by differential scanning calorimetry, optical polarizing microscope and X-ray diffraction experiments. All compounds 1-4 showed yellow-green photoluminescence in THF occurred at 519-521 nm.

Full text of DOI:10.1016/j.tet.2015.07.049

Accepted Manuscript
The π−π interactions enhanced in salicylaldimines and salicylaldazines
Hsiu−Ming Kuo, Yu−Te Hsu, Yi−Wen Wang, Gene−Hsiang Lee, Chung K. Lai
PII:
S0040-4020(15)01108-4
10.1016/j.tet.2015.07.049
TET 26994
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 15 June 2015
Revised Date: 14 July 2015
Accepted Date: 16 July 2015
Please cite this article as: Kuo H−M, Hsu Y−T, Wang Y−W, Lee G−H, Lai CK, The π−π interactions
enhanced in salicylaldimines and salicylaldazines, Tetrahedron (2015), doi: 10.1016/j.tet.2015.07.049.
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ACCEPTED MANUSCRIPT
The π−π interactions enhanced in salicylaldimines and salicylaldazines
Hsiu−Ming Kuo, Yu−Te Hsu, Yi−Wen Wang, Gene−Hsiang Lee, Chung K. Lai*
X
RO
HO
N
N
X
OH
HO
OR
RO
HO
N
N
OH
OR
OH
Key words: salicylaldazines, salicylaldimines, mesogens, smectic, nematic
1

ACCEPTED MANUSCRIPT
The π−π interactions enhanced in salicylaldimines and salicylaldazines
Hsiu−Ming Kuo, Yu−Te Hsu, Yi−Wen Wang, Gene−Hsiang Lee,† Chung K. Lai*
Department of Chemistry, National Central University, Chung−Li, Taiwan, ROC
†Instrumentation Center, National Taiwan University, Taipei 10660, Taiwan, ROC
Abstract. Four new series of salicylaldazines 1 and salicylaldimines 2−4 were prepared,
characterized and their mesomorphic properties were studied. The structures of all compounds
were identified and confirmed by spectroscopic techniques such as 1H, 13C−NMR, MS and
elemental analysis. Three single crystallographic structures of compounds 1a (n = 3, 6) and 2
(n = 3) were determined by X−ray analysis in order to correlate the molecular structures with
the formation of mesophases. Crystallographic data indicated that the better mesomorphic
properties might be controlled by CH−π, π−π or/and H−bonds in such system. Except for
crystalline compounds 4, all other compounds 1−3 showed mesomorphic behavior of nematic,
smectic A or/and smectic C phases, which were characterized by differential scanning
calorimetry, optical polarizing microscope and X−ray diffraction experiments. All compounds
1−4 showed yellow−green photoluminescence in THF occurred at 519−521 nm.
* Corresponding author. Tel.: +886 03 4259207; fax: +886 03 4277972.
E-mail address: cklai@cc.ncu.edu.tw (C.K.Lai)
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1.0 Introduction
The demeric liquid crystals have been extensively investigated since the first example1
reported on 1927. In general, the structures of dimeric LCs constituted two mesogenic
moieties linked via a flexible spacer or a rigid core. Mesogenic structures linked by a flexible
spacer such as alkyls (−CH2−), esters (−COOCH2OOC−) and ethers (−OCH2O−) are often
called twin liquid crystals or liquid crystal dimers. These dimers were particularly of
appealing because of their unique thermal behavior and structural features as model
compounds similar to polymeric liquid crystals. These compounds are also known as
bimesogens. The molecular conformations and mesomorphic behavior were quite differential
from classical (or monomeric) mesogens. On the other hand, their mesomorphic properties
were significantly influenced by the spacer length and also the linking group. This type of
molecules is often made by linking either two identical or non−identifical moieties through a
flexible central spacer. Numerous examples2 of DLCs were reported. Three types of layered
smectic phases; monolayer, interdigitated or intercalated conformations were proposed
depending on their spacing and/or molecular length. Shape−effect3 caused by odd or even
carbon atoms incorporated in the spacer was often observed. Among them, salicylaldehydes
are probably one of the core structures utilized the most to generate the mesogenic materials,
including symmetric and asymmetric structures during the past decades. A variety of novel
metallomesogens4 derived from salicylaldehydes or their Schiff bases of salicyladimines were
reported. Numerous salicyladimine−based dimeric LCs5 were prepared, and most of
mesogenic dimeric LCs have a flexible central spacer. However, known examples6 of similar
mesogenic structures with a more rigid spacer were relatively rare.
In contrast, salicylaldazines (R1R2C=N−N=CR1R2), similar to salicylaldimines
(R1R2C=N−R−N=C R1R2) can be prepared by the condensation reactions7 of salicylaldes with
hydrazine. It has been used as precursors8-9 to synthesize hydrazones (R1R2C−NNH2)10, diazo
(R1R2C=N2) and heterocyclic compounds11. In alicyclic chemistry, azines are compounds
resulting from the reactions of two identical or different carbonyl compounds with hydrazine.
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Azines that are N−N linked diimines are 2,3−diaza analogs of 1,3−butadiene. An azine moiety
formed by two imine bonds can be considered as polar acceptor oriented in opposite
directions.12 Azines are two conjugated double-bond structure, similar to 1,3−dienes,
1,2−diimines, 1,2−diones. However, extensive X−ray analyses about the N−N and Ar−C
bonds showed no evidence13 of conjugation, and in fact the azine unit is a “conjugation
stopper”. Asymmetric azines appended with donor and acceptor moieties incorporated on the
terminal backbone showed novel organic non linear optical (NLO) materials.14 A few similar
examples15 of mesogenic azines (such as Ia−b) have been reported and studied.
R2
R1
RO
N
N
N
N
R4
OR
R3
Ia: R1 = OMe, R2 = H, Me,
R3 = H, Me, R4 = CN, NO2
Ib
In order to understand the core effect on the formation of mesophases in azines and more
rigid diimines, in this work, we describe the synthesis, characterization, and the mesomorphic
properties of four series of compounds 1−4 derived from salicylaldehydes. An extended π–
conjugated structure by incorporation of phenylene or biphenylene was also studied in
compounds 2−4. All compounds 1−3 were mesogenic, giving nematic, smectic A or smectic C
phases, whereas, compounds 4 were crystals. Three single crystals were investigated to
understand the possible correlation of mesomoropisms and structures. The structural analysis
appeared that a better core planarity was formed by intramolecular H−bonds in this type of
compounds. On the other hand, a good layered arrangements enhanced by π−π intermolecular
interactions also facilitated the formation of meosophases. Most of known mesogenic dimeric
LCs have a flexible central spacer. However, examples of similar mesogenic structures with a
more rigid spacer were relatively rare.
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2.0 Results and Discussion
2.1 Synthesis and characterization
The synthetic procedures for all the compounds are summarized in scheme 1. 4−Alkoxy−
salicylaldehyde was alkylated by controlling the basicity and equivalent of alkyl bromides.
The compounds 1−4 were carried out by double imination of alkylated salicylaldehydes and
diamines with EtOH/THF as solvents. The compounds 1−4 were isolated as yellow to orange
powder, depending on the spacers and yields were in the range 33−78%. Most derivatives
were characterized by 1H and 13C NMR spectroscopy, elemental analysis and mass
spectrometry. However, for some derivatives with a poor solubility in organic solvents to
perform NMR spectroscopy, mass spectrometry and elemental analysis data were obtained.
On 1H NMR spectra, a characteristic broad peak often appeared at δ 6.53−8.56 and
11.11−11.71 ppm assigned for imine–CHN and phenolic−OH was observed for compounds 1a.
In contrast, this phenolic−OH was slightly shifted to δ 13.81 ppm. These characteristic peaks
were also slightly shifted to upfield, as summarized in Table 1.
Table 1. The characteristic chemical peaksa on 1H−NMR spectroscopes for compounds 1−4.
Compds
1a
1b
2
3
4
−C=NH
8.53−8.56
11.11−11.71
−
13.81
8.53−8.54
8.87−8.90
9.92−9.99
8.94−8.97
9.78−9.85
14.40−14.44
−OH (phenolic)
−OH (phenolic)
−
−
−
13.64−13.70 14.51
a: 1b measured in DMSO−d6 and 1a, 2−4 measured in CDCl3, unit (δ ) in ppm.
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X
X
a
RO
HO
O
O
OH
OH
b
X
N
RO
HO
RO
HO
N R' N
N
X
OH
OR
OH
OR
R = O(CH2)nH
R = O(CH2)nH
1a; X = H,
1b; X = CH3
2; R' =
3; R' =
HO
OH
OH
4; R' =
HO
Scheme 1. Reactions and reagents: (a) RBr (1.1 eq.), KHCO3 (1.5 eq.), KI, refluxed in
acetone, 24 h, 41%; (b) I2 (cat.), hydrazine monohydrate, p-phenylenediamine, 4,4'-
diaminobiphenyl-3,3'-diol, or 3,3'-diaminobiphenyl-4,4'-diol, stirred at rt.
2.2 Single crystals and molecular structures of compounds 1a (n = 3, 6) and 2 (n = 3)
In order to understand the possible correlation between the molecular arrangements and
their mesomorphic behavior, three single crystals of compound 1a (n = 3, 6) and 2 (n = 3)
suitable for crystallographic analysis were obtained by slow diffusion from THF/EtOH at
room temperature and their structures resolved. Figure 1 shows their molecular structures.
Table 2 lists their crystallographic and structural refinement data for the crystals. They
crystallize in a monoclinic space P2(1)/c for compound 1a (n = 3) and a triclinic space group
P-1 for compounds 1a (n = 6) and 2 (n = 3). All three crystals were considered as slightly
linear−shaped with a molecular length of 22.38 Å (C10−10’), 28.78 Å (C20-C26) and 24.12 Å
(C26-C26’), required for the formation of nematic or smectic phases.
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Fig. 1 Three ORTEP plots and molecular lengths for crystals 1a (n = 3), 1a (n = 6) and 2 (n =
3). The thermal ellipsoids of the non−hydrogen atoms are drawn at the 50% probability level.
Table 2 Crystal data and structure refinements for 1a (n = 3, 6) and 2 (n = 3).
Compd.
1a (n = 3)
1a (n = 6)
2 (n = 3)
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
a(Å)
C10H12NO2
178.21
C26H36N2O4
440.57
C26H28N2O4
432.50
296(2)
150(2)
150(2)
Monoclinic
P2(1)/c
Triclinic
P-1
Triclinic
P-1
8.8100(5)
10.8004(6)
9.9027(5)
90
7.7266(2)
11.0341(3)
15.2879(5)
102.594(2)
101.332(2)
100.517(2)
1212.14(6), 2
1.207
6.3422(7)
7.0827(8)
24.585(3)
83.588(2)
82.952(2)
88.981(2)
1089.2(2), 2
1.319
b(Å)
c(Å)
α(o)
β(o)
98.807(3)
90
γ(o)
Volume (Å3), Z
Density (calculated, Mg/m3)
Crystal size (mm3)
θ range for data collection(o)
Reflections collected
Final R1, wR2
931.15(9), 4
1.271
0.4x0.1875x0.05
2.34‒28.46
8517
0.60x0.18x0.12 0.38x0.36x0.05
1.41‒27.50
20213
0.84‒25.00
10296
0.0415, 0.1023
0.0534, 0.1312
0.0860, 0.2146
As expected, intramolecular H−bonds were all observed in the crystal lattices for all three
crystals shown in Figure 2. Each crystal has two intramolecular H−bonds; they are relatively
strong and their bond lengths ranged from d = 1.848−1.936 Å, summarized in Table 3.
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However, there was no intermolecular H−bond observed in all three crystals. A dihedral angle
of ca ~ 0° and ~ 5.74 ° between the two phenyl rings was observed for in crystals 1a (n = 3
and n = 6), respectively. In contrast, a larger dihedral angle of ~ 47.8 ° in crystal 2 (n = 3) was
observed. A better planar structure and an extended molecular shape are often responsible for
a good packing in solid and/or liquid crystal state. In addition, intermolecular interactions of
σ−π or π−π interactions were also observed in these crystals, and their distances ranged from
2.65−4.15 Å, listed in Table 4. These intermolecular forces apparently facilitated the formation
of mesophases in this type of compounds. All molecules arranged in a style of layered
structure. The molecular arrangements of three crystals in crystal lattices are shown in Figure
3.
Fig. 2 Intramolecular H−bonds and intermolecular interactions (π−π and/or CH−π) observed
in compounds 1a (n = 3, top plot), 1a (n = 6, middle plot) and 2 (n = 3, bottom plot). Bond
distances are in red figures (Å).
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Table 3. Intramolecular H−bonds observed in 1a (n = 3, 6) and 2 (n = 3).
Compds.
no. H−bonds
(O−H…N)
bond distance/Å
angles/°
1 (n = 3)
1 (n = 6)
2
2
N1−H2A = 1.94
N1−H1 = 1.88
N2−H2 = 1.91
N2−H3A = 1.85
∠N1−H2A−O2 = 144.36
∠N1−H1−O1 = 146.18
∠N1−H2−O2 = 146.76
∠N2−H3A−O3 = 147.56
2 (n = 3)
2
Table 4. Intermolecular interactions observed in 1a (n = 3, 6) and 2 (n = 3).
Compds.
no. of σ−π or
distancea/Å
angles/°
π−π interactions
1 (n = 3)
1 (n = 6)
2 (n = 3)
4
ring−H2A = 2.87
ring−ring = 4.15
ring−H1A= 2.89
ring−H20= 2.92
ring−H23= 2.65
∠ring−H2A−C9 =145.78
∠ring−H1A−C1 =128.29
∠ring−H1A−C1 =128.29
∠ring−H20−C20 =128.29
∠ring−H23−C23 =133.80
2 (Ar…Ar)
2 (Ar−H…Ar)
2 (Ar−H…Ar)
2 (Ar−H…Ar)
a: measured from the center of ring to the atom.
Fig. 3 Layer structures of compound 1a (n = 3, left), 1a (n = 6, middle) and 2 (n = 3, right)
along a axis.
2.3 Mesomorphic properties of compound 1-4
The thermal behavior of compounds 1−4 was investigated by polarized optical microscopy
(POM) and differential scanning calorimetry (DSC). The transition temperatures and
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enthalpies of the compounds are listed in Table 5. Except for compounds 4, all other
compounds 1−3 are mesogenic. All compounds 1a exhibited kinetically stable enantiotropic
behavior, giving smectic C phase at lower temperatures or/and nematic at higher temperatures.
Both melting and clearing temperatures decreased with carbon lengths of alkoxy chains. The
melting temperatures were ranged between Tmelting = 173.7 (n = 3) − 107.8 °C (n = 10), while
clearing temperatures were ranged between Tcl = 183.7 °C (n = 3) − 147.6 °C (n = 16). On the
other hands, the temperature ranges of mesophases remained at ∆TM = 23.2 (n = 3) – 68.8 °C
(n = 8) during the cooling process. Under optical microscope, compounds 1a exhibited
fan−shaped or focal−conics textures at lower temperatures and Schlieren textures at higher
temperatures (Fig. 4). These optical textures were characteristic of a SmC phase or N phases,
expected for the rod−like molecules. Under optical microscope, the texture of SmC phase
showed no homeotropic domains.
In order to understand the effect of core planarity on the formation of the mesophases,
two compounds 1b (n = 3, 6) incorporated with a methyl group bonded to the imine moiety
(−C=NH) were prepared and their mesomorphic behavior compared with compounds 1a. The
geometry of methyl group is relatively bulkier tetrahedron. The bulkier methyl moiety, when
close to the core center, will reduce the molecular interactions between the neighboring layers.
Thus, a lower clearing temperature was often observed. Compounds 1b (n = 3, 12) exhibited
SmC/SmA or N phase, however, compounds 1a (n = 3, 12) formed SmC or N phase.
Interestingly, the data indicated that the clearing temperatures of both derivative 1b (n = 3, 6)
were slightly higher than those of compounds 1a (n = 3, 12) by ca. ∆T = 31.3 (n = 3) and 13.1
°C (n = 12), respectively. On the other hand, the temperature of mesophases for derivative 1b
(n = 3) was much wider than that of derivative 1a (n = 3), ∆Tmeso = 103.6 > 23.1 °C. In
contrast, other derivative 1b (n = 12) had a narrower temperature range than that of 1a (n =
12), ∆Tmeso = 45.0 < 50.2 °C. Apparently, the derivative 1b (n = 3) has a better aspect ratio (d/l)
of molecules, required to be improved mesogens. A tetrahedral methyl moiety, not near by the
core might exert little effect on the formation of mesophases.
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When a phenylene group in compounds 2 was incorporated as a core group, the
mesomorphic behavior was apparently altered. The phenylene group was structurally
considered as a more rigid and more planar moiety, and potential π−π interactions might be
better induced. Indeed, the mesomorphic properties were greatly improved. Both melting and
clearing temperatures of compounds 2 was raised; the clearing temperatures were higher than
those of compounds 1a by ∆T = 103.5 (n = 3) > 99.6 (n = 8) > 87.3 °C (n = 14). In contrast,
the melting temperatures of compounds 2 were higher by ∆Tmelting = 9.10 (n = 8) > 4.30 (n = 3)
> 1.00 (n = 14) °C, thus giving a much wider temperature range of mesophases by ∆Tmeso
=
136.1 (n = 3) −184.9 °C (n = 8). The stronger σ−π or π−π interactions between the neighboring
phenylene groups within the layers might be attributed to the improved mesophases. This is
quite consistent with the single crystalline crystallographic data, discussed later. Optical
textures observed under POM also confirmed the mesophases.
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Table 5. Phase transitionsa and enthalpies of compounds 1-4.
173.7 (50.6)
183.7 (0.72)
1a; n = 3
Cr
SmC
SmC
Cr3
N
N
N
I
I
I
159.2 (53.1)
160.1 (2.15)
182.4 (0.87)
175.0 (1.82)
130.9 (38.5)
6
8
Cr
112.2 (36.6)
111.6 (43.2)
157.0 (1.88)
169.1 (9.09)
174.3 (1.64)
169.2b
Cr1
Cr1
Cr2
Cr2
93.1 (6.27)
51.8 (1.74)
98.0 (36.4)
73.4 (3.28)
165.9 (7.35)
107.8 (38.8)
166.8 (2.03)
165.4 (10.2)
10
12
SmC
SmC
SmC
SmC
I
I
I
I
45.3 (5.88)
99.4 (39.8)
111.9 (50.6)
161.0 (9.01)
158.9 (12.6)
58.4 (10.3)
Cr1
Cr2
157.6 (11.9)
149.4 (11.8)
61.4 (9.08)
75.1 (5.20)
107.4 (51.8)
112.6 (55.6)
Cr3
14
16
Cr1
Cr2
Cr
82.1 (4.24)
148.0 (10.4)
147.6 (14.8)
66.7 (2.05)
107.4 (55.4)
116.3 (72.9)
Cr2
Cr
95.8 (3.37)
145.9 (14.6)
215.0b
112.2 (72.4)
111.9 (50.6)
1b; n = 3
12
N
I
I
107.4 (51.8)
163.2 (0.59)
211.0 (0.80)
172.0 (11.6)
138.4 (43.2)
125.2 (43.8)
SmC
Cr1
SmA
162.8 (0.35)
178.0 (28.2)
170.2 (11.1)
287.2 (1.19)
2; n = 3
Cr
SmC
Cr2
SmA
SmA
SmC
N
I
133.7 (23.5)
254.8 (2.51)
269.8 (0.53)
268.8 (5.95)
120.7 (31.3)
8
Cr
I
250.9b
113.6 (52.9)
260.9 (5.69)
236.7 (12.7)
76.0 (27.1)
103.9 (39.7)
Cr1
14
I
91.5 (41.7)
98.5 (51.5)
343.6
234.0 (12.4)
349.8
Id
Id
Id
3; n = 3
Cr
Cr
Cr
348.1
332.5
310.9
8
14
SmA
SmA
Cr
323.9
300.4 (74.9)
297.4 (98.4)
284.2 (96.9)
Id
Id
4; n = 3
8
Cr
Id
Cr
14
a: n is the carbon number of alkoxy groups. Cr1, Cr2, Cr3 = crystal, SmC = smectic C, SmA = smectic A,
nematic = N, I = isotropic phase and Id = isotropic phase with a decomposition at a scan rate of 10 0Cmin-1.
b: observed by POM.
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Fig. 4 Optical textures observed. SmC phase at 160 oC (top left) by 1a (n = 8), SmC phase at
154oC (top right) by 1a (n = 10), N phase at 306 oC (bottom left) by 2 (n = 3) and SmA phase
at 262 oC (bottom right) by 2 (n = 8).
Fig. 5 Bar graphs showing the phase behavior of compounds 1−4. All temperatures were taken
from cooling process.
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To further test the structural effect on the formation of the mesophases, compounds 3 and
4 were also prepared and studied. A biphenylene with two hydroxyl groups substituted at 3,
3’− and 4, 4’−position was incorporated to generate the compounds 3 and 4, respectively.
H−bonds might be also induced between the neighboring layers if all molecules were correctly
supplementary. All compounds 3 were truly mesogenic, whereas, all compounds 4 were not
mesogenic. The results were in fact not surprising. Compounds 3 were more linear−like and
more rod in shapes, while compounds 4 were more lath−like or more ellipsoid (See Fig. 6).
Both compounds 3−4 were not all thermally stable, and partial decompositions on heating
above their clearing temperatures were observed. The results showed that all compounds 3 (n
= 3, 8, 14) formed N or SmA phase, however, all compounds 4 exhibited crystalline phases.
All clearing temperatures of compounds 3 were ranged in 323.9−349.8 °C, all much higher
than those of compound 1a and 2 due to their more rigid structures and/or larger molecules.
The temperature ranges of mesophases were relatively short, ∆T = 6.2 (n = 3) < 13.0 (n = 14)
< 15.6 °C (n = 8) on the heating process. Compounds 4 were all crystalline solids, and a
transition temperature of crystal−to−isotropic states at T = 300.4 (n = 3) > 297.4 (n = 8) >
284.2 °C (n = 14) were only observed.
OH
HO
HO
N
RO
HO
OR
N
N
RO
OH
OR
N
OH
OH
HO
3
4
Fig. 6 Schematic representation of molecular shaped by compounds 3 and 4.
The thermal stability of compounds 1a, and 2−4 (n = 8) was also performed by
thermogravimetric analyses (TGA) under nitrogen atmosphere, shown in Fig. 7. All four
compounds showed relatively good thermal stability at temperature below ca. 295.0 °C, with a
relative thermal stability of 1a > 2 > 3~ 4. The decomposition temperatures for a 5% weight
loss were listed in Table 6. Surprisingly, the decomposition temperature of 1a and 2 was
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slightly higher than that of 3−4 by ca. ∆T = 30 °C, which is not consistent with the DSC data
of these two compounds. Compound 1a and 2 has a flexible alkyl spacer, in contrast,
compounds 3−4 have a more rigid phenyl or biphenyl spacer. The clearing temperature of
compounds was decreasing at Tcl = 348.1 (3, n = 8) > 297.4 (4, n = 8) > 268.8 (2, n = 8) >
169.2 (1a, n = 8) °C.
1a (n = 8)
2 (n = 8)
3 (n = 8)
100
80
4 (n = 8)
60
40
20
0
200
400
600
Temperature(oC)
Fig. 7 The TGA thermographs of compounds 1a and 2−4 (all n = 8) under nitrogen gas at a
heating rate of 10.0 °Cmin-1
Table 6. The decomposition temperaturesa of compounds 1−4 by TGA analysis.
Compds
Tdec (℃)
1a (n = 8)
2 (n = 8)
3 (n = 8)
4 (n = 8)
326.3
325.1
295.0
295.0
a: Temperatures taken with a 5% weight loss.
2.4 Powder X−ray diffraction of compounds 1−2
Variable−temperature powder X−ray diffraction experiments were conducted to confirm
the structure of the mesophases of compounds 1a (n = 12) and 2 (n = 8). The X−ray diffraction
plots of both compounds are present in Figure 8. It displayed a typical diffraction pattern with
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one strong peak at low angle region followed by a weak peak and a broad peak at wider angle.
These are characteristic of layered arrangements of SmC phases with d−spacing ratio of 1 and
1/2, corresponding to Miller indices; 100 and 200, respectively. For example, a diffraction
pattern at 140 oC with d
−spacing at 34.23 Å, 17.09 Å and a broad diffused peak (~ 4.62 Å) at
wide
−angle region was observed for compound 1a (n = 12) and this diffraction pattern
corresponded to a SmC phase. The d
−spacing of 34.23 Å was slightly smaller than 43.06 Å,
which was obtained from calculated molecular length by MM2 model. This might indicate
that the molecules were tilted and/or the side chains were interdigitated. The broad peak
observed at about 4.62 Å was assigned to the molten side chains. Similarly, the two powder
X
−
ray diffractions of compounds
smectic C phase at 140 C, it showed one strong peak at 32.85 Å and a much weaker peak at
16.35 Å. These two diffraction peaks corresponded to Miller indices 100 and 200. However, in
smectic A phase at higher temperature of 257 C, it showed only one strong peak at 37.30 Å.
2 (n = 8) at 140 °C and 257 °C was shown in Figure 8. In
°
°
The diffraction intensity at SmA phase was much weaker than that at SmC phase. Two halo
peaks were also observed at 4.54 and 4.81 Å.
16

ACCEPTED MANUSCRIPT
d001 = 34.23 Å
20000
10000
0
d002 = 17.09 Å
4
6
8
dhalo = 4.62 Å
20
0
0
0
10
30
30
30
2 Theta(o)
40000
30000
20000
10000
0
d001 = 32.85 Å
d002 = 16.35 Å
4
5
6
dhalo = 4.54 Å
10
20
2 Theta(o)
d001 = 37.30 Å
10000
dhalo = 4.81 Å
20
0
10
2 Theta(o)
Fig. 8 The powder X
−ray diffraction plots of SmC by compound 1a (n = 12, top plot) at 140
°
C SmC by (n = 8, middle plot) at 140
2
°
C and SmA by (n = 8, bottom plot) at 257 C.
2
°
17

ACCEPTED MANUSCRIPT
2.5 Optical properties
The UV–vis absorption and PL spectra of the compounds 1−4 (all n = 8) measured in
THF solution at room temperature are presented in Figure 9. The max peaks of UV–vis
absorption and the em of PL spectra were listed in Table 7. The two strong absorption λmax
peaks of compounds 1−4 occurred at ca. 283 305 and 352 390 nm, which were attributed to
−π* and π−π* transitions arising from salicylaldehyde moiety. The absorption peaks
increased with an extended core conjugation introduced from compound to compound
Compound has a largest absorption of 390 nm due to its biphenyl core. In contrast, the
absorptions of compound decreased to 352 due to its meta position. The PL spectra of all
compounds 1−4 were quite similar, showing one intense and broad peak occurred at λem
519 521 nm. Interestingly, an extended conjugated length in compounds 2−3 showed no
apparent red shift emission compared to compounds 1a. This was probably due to the poor
coplanarity of the molecules in the crystal packing, reducing the effect of aggregation induced
red shift. In fact, this result was quite consistent with single crystallographic data obtained in
crystal (n = 3); a twisting angle of 47.8 between the central phenyl ring and
λ
λ
−
−
n
1
3.
3
4
−
=
−
−
−
2
~
°
salicylaldimine was observed. A relatively weak emission was obtained for compounds 1−4
which be attributed to a possible proton transfer16 between the imine moiety and neighboring
phenolic−OH.
18

ACCEPTED MANUSCRIPT
1 (n = 8)
1.0
0.8
0.6
0.4
0.2
0.0
2 (n = 8)
3 (n = 8)
4 (n = 8)
300
400
500
600
700
Wavelength(nm)
1 (n = 8)
1.0
0.8
0.6
0.4
0.2
0.0
2 (n = 8)
3 (n = 8)
4 (n = 8)
400
500
600
700
Wavelength(nm)
Fig. 9 Absorption (top) and PL (bottom) spectra of compounds 1−4 measured in THF at room
temperature.
Table 7. The UV−vis absorptions and PL−
emissionsa of compounds 1−4.
Compd.
absorption/nn
emission λmax /nm
1a (n = 8)
305, 370
284, 380
283, 390
288, 352
520.9
519.8
520.8
518.9
2
3
4
(n = 8)
(n = 8)
(n = 8)
a: all measured in THF solution (1.0×10-5 M) at rt.
3. Conclusions
Four new series of salicylaldazines
1 and salicylaldimines 2−4 were prepared,
characterized and their mesomorphic properties studied. All compounds 1−3 showed
mesomorphic behavior of nematic, smectic A or/and smectic C phases and exhibited relatively
good thermal stability on TGA. Crystallographic data indicated that the mesomorphic
19

ACCEPTED MANUSCRIPT
properties were greatly improved by CH−π
compounds 1−4 showed yellow green photoluminescence in THF occurred at 519
An extended core π−conjugated structure in compounds 2−4 showed no red shift
coplanar core planes. Their possible metallomesogens
,
π−π or/and H
−bonds in such system. All
−
−521 nm.
−
photoluminescence due to their non
will be explored in the future.
−
4.0 Experimental Section
4.1 General materials and methods
All chemicals and solvents were reagent grade from Aldrich Chemical Co., and solvents
were dried by standard techniques. 1H and 13C NMR spectra were measured on a Bruker
DRS
pure indium sample. All phase transitions are determined by a scan rate of 10.0
Optical polarized microscopy was carried out on Zeiss Axioplan 2 equipped with a hot stage
system of Mettler FP90/FP82HT. The UV vis absorption and fluorescence spectra were
obtained using a Jasco V 530 and Hitachi F 4500 spectrometer. Elemental analyses were
performed on a Heraeus CHN Rapid elemental analyzer. The powder diffraction data were
collected from the Wiggler A beam line of the National Synchrotron Radiation Research
−300. DSC thermographs were carried out on a Mettler DSC
−822 and calibrated with a
°
C/min.
−
−
−
−O−
−
Center (NSRRC) with a wavelength of 1.3223 Å. The powder samples were charged in
Lindemann capillary tubes (80 mm long and 0.01 mm thick) from Charles Supper Co. with an
inner diameter of 1.0 mm.
4.2 3, 3'-Dinitrobiphenyl-4, 4'-diol
To a solution of biphenyl-4,4'-diol (9.3 g, 0.05 mol) dissolved in 70 mL of dichloromethane,
70% HNO3 (9.9 g, 0.11 mol) was slowly added. The mixture was kept at 0 °C and stirred for 3
h. The solids were filtered, and washed several time with saturated aqueous solution of
NaHCO3. The products isolated as pale yellow solids was obtained after recrystallization from
acetone. Yield 53%. 1H NMR (300 MHz, DMSO
= 4.4 Hz, Ar
(d, = 4.3 Hz, Ar H, 2H), 8.15 (d, = 1.2 Hz, Ar−H, 2H), 11.12 (s, Ar−
OH, 2H). 13C NMR
−d6):
δ
7.20 (d,
J
−H, 2H), 7.87
J
−
J
20

ACCEPTED MANUSCRIPT
119.82, 122.59, 129.29, 132.94, 137.51, 151.45.
(75 MHz, DMSO
−d6):
δ
4.3 3, 3'-Diaminobiphenyl-4, 4'-diol
A solution of 3, 3'-dinitrobiphenyl-4,4'-diol (3.0 g, 11 mmol), hydrazine monohydrate (9.0 mL,
0.18 mol) and Pd/C (0.3 g) dissolved in 25 mL of absolute ethanol was stirred for 4 h. The
crude products were filtered. The solids were dissolved in hot DMF and then was filtered
through fresh Celite. The filtrate was poured into cold water and the precipitates were filtered.
The product isolated as gray powders was obtained after recrystallization from acetone. Yield
85%. 1H NMR (300 MHz, DMSO
2H), 6.63 (d, = 4.05 Hz, Ar H, 2H), 6.74 (s, Ar
(75 MHz, DMSO d6): 112.36, 114.18, 114.51, 132.82, 136.53, 142.90.
4.4 6, 6'-(1E, 1'E)-hydrazine-1, 2-diylidenebis(methan-1-yl-1-ylidene)bis(3-propoxy
phenol) 1a (n = 3
−d6):
δ
4.46 (bs,
−NH2, 4H), 6.52 (d,
J
= 4.05 Hz, Ar
−H,
J
−
−H, 2H), 8.88 (bs, Ar
−
OH, 2H). 13C NMR
−
δ
)
A solution of 2-hydroxy-4-propoxybenzaldehyde (1.0 g, 5.6 mmol), hydrazine
dihydrochloride (1.14 g, 11 mmol), catalytic amount of solids I2 disolved in 30 mL of dry
DMSO was stirred for 30 mins. The solution was then poured into ice water then the crude
products were filtered. The light brown solid was passed through a short column of silica gel.
The products isolated as pale yellow solids was obtained after crystallization from
THF/Ethanol. Yield: 51%. 1H NMR (300 MHz, CDCl3):
δ 1.02 (t, J = 7.5 Hz, −CH3, 6H),
1.76
6.51 (s, Ar
CDCl3):
−
1.83 (m,
−
CH2, 4H), 3.93 (t,
J
= 6.3 Hz,
−
OCH2, 4H), 6.48 (d,
J
= 1.65 Hz, Ar
−H, 2H),
−H, 2H), 7.20 (d,
J
= 4.05 Hz, Ar
−H, 2H), 8.55 (s,
−
CHN, 2H). 13C NMR (75 MHz,
δ
10.44, 22.38, 69.74, 101.62, 108.03, 110.74, 133.51, 161.79, 162.55, 163.61. Anal.
Calcd. for C20H24N2O4: C, 67.40; H, 6.79; N, 7.86. Found: C, 67.21; H, 6.83; N, 7.83. MS
(LRFAB): M+ (m/z) = 356.34.
4.4.1 6, 6'-(1E, 1'E)-hydrazine-1, 2-diylidenebis(methan-1-yl-1-ylidene)bis(3-hexoxy
phenol) 1a (n = 6)
Pale yellow solids, yield 63%. 1H NMR (300 MHz, CDCl3):
1.29 1.48 (m, CH2, 12H), 1.71 1.80 (m, CH2, 4H), 3.96 (t,
δ
0.91 (t,
J
= 4.2 Hz,
−CH3, 6H),
−
−
−
−
J
= 6.6 Hz, −
OCH2, 4H), 6.47
21

ACCEPTED MANUSCRIPT
(d,
J
= 3 Hz, Ar
−H, 2H), 6.49 (s, Ar
−
H, 2H), 7.17 (d,
J
= 8.6 Hz, Ar
−H, 2H), 8.53 (s,
−CHN,
2H) , 11.36 (bs, Ar
−
OH, 2H). 13C NMR (75 MHz, CDCl3)):
δ 14.00, 22.56, 25.62, 29.00,
31.51, 68.26, 101.61, 107.95, 110.80, 133.43, 161.73, 162.58, 163.51. MS (LRFAB): M+ (m/z)
= 440.42. Anal. Calcd. for C26H36N2O4: C, 70.88; H, 8.24; N, 6.36. Found: C, 70.93; H, 8.26;
N, 6.27.
4.4.2 6, 6'-(1E, 1'E)-hydrazine-1, 2-diylidenebis(methan-1-yl-1-ylidene)bis(3-octyloxy
phenol) 1a (n = 8)
Pale yellow solids, yield 59%. 1H NMR (300 MHz, CDCl3):
1.27 1.43 (m, CH2, 20H), 1.74 1.79 (m, CH2, 4H), 3.96 (t,
(m, Hz, Ar
11.11 (bs, Ar
δ
0.87 (t,
J
= 6.9 Hz,
−CH3, 6H),
−
−
−
−
J
= 6.6 Hz, −
OCH2, 4H), 6.47
−
H, 2H), 6.50 (s, Ar
−H, 2H), 7.20 (d, J = 7.8 Hz, Ar−H, 2H), 8.55 (s, −CHN, 2H) ,
−
OH, 2H). 13C NMR (75 MHz, CDCl3): 14.08, 22.63, 25.96, 29.04, 29.20, 29.30,
31.78, 68.32, 101.64, 108.08, 110.71, 133.53, 161.83, 162.51, 163.68. MS (LRFAB): M+ (m/z)
= 496.56. Anal. Calcd. for C30H44N2O4: C, 72.55; H, 8.93; N, 5.64. Found: C, 72.18; H, 8.92;
N, 5.54.
4.4.3 6, 6'-(1E, 1'E)-hydrazine-1, 2-diylidenebis(methan-1-yl-1-ylidene)bis(3-decyloxy
phenol) 1a (n = 10)
Pale yellow solids, yield 66%. 1H NMR (300 MHz, CDCl3):
1.26 1.43 (m, CH2, 28H), 1.74 1.83(m, CH2, 4H), 3.97 (t,
(m, Hz, Ar
11.46 (bs, Ar
δ
0.88 (t,
= 6.6 Hz,
H, 2H), 8.56 (s,
δ 14.0, 22.67, 25.96, 29.04, 29.30, 29.54,
J
= 6 Hz,
OCH2, 4H), 6.48
CHN, 2H) ,
−CH3, 6H),
−
−
−
−
J
−
−
H, 2H), 6.52 (s, Ar
−
H, 2H), 7.21 (d,
J
= 8.1 Hz, Ar
−
−
−
OH, 2H). 13C NMR (75 MHz, CDCl3):
31.88, 68.37, 101.67, 108.20, 110.60, 133.60, 161.92, 162,38, 163.87. MS (LRFAB): M+ (m/z)
= 552.57. Anal. Calcd. for C34H52N2O4: C, 73.87; H, 9.48; N, 5.07. Found: C, 73.51; H, 9.49;
N, 4.99.
4.4.4 6, 6'-(1E,1'E)-hydrazine-1, 2-diylidenebis(methan-1-yl-1-ylidene)bis(3-dodecyloxy
phenol) 1a (n = 12)
Pale yellow solids, yield 57%. 1H NMR (300 MHz, CDCl3):
1.25 1.43 (m, CH2, 36H), 1.74 1.79 (m, CH2, 4H), 3.96 (t,
δ
0.87 (t,
J
= 6.9 Hz,
−CH3, 6H),
−
−
−
−
J
= 6.6 Hz, −
OCH2, 4H), 6.47
22

ACCEPTED MANUSCRIPT
(d,
J
= 2.4 Hz, Ar
−H, 2H), 6.50 (s, Ar
−
H, 2H), 7.18 (d,
J
= 9 Hz, Ar
−H, 2H), 8.54 (s, −CHN,
2H), 11.46 (bs, Ar
−
OH, 2H). 13C NMR (75 MHz, CDCl3):
δ
14.11, 22.68, 25.96, 29.05, 29.34,
29.58, 29.63, 31.91, 68.29, 101.62, 108.00, 110.79, 133.46, 161.77, 162.58, 163.57. MS
(LRFAB): M+ (m/z) = 608.60. Anal. Calcd. for C38H60N2O4: C, 74.96; H, 9.93; N, 4.60. Found:
C, 75.07; H, 10.12; N, 4.28.
4.4.5 6, 6'-(1E, 1'E)-hydrazine-1, 2-diylidenebis(methan-1-yl-1-ylidene)bis(3-tetra
decyloxyphenol) 1a (n = 14)
Pale yellow solids, yield 61%. 1H NMR (300 MHz, CDCl3):
1.24 1.43 (m, CH2, 44H), 1.73 1.82 (m, CH2, 4H), 3.97 (t,
(d, = 3.6 Hz, Ar
2H), 11.71 (bs, Ar
δ
0.86 (t,
= 6.6 Hz,
= 9.3 Hz, Ar H, 2H), 8.55 (s,
14.12, 22.69, 25.97, 29.05, 29.35,
J
= 6.9 Hz,
OCH2, 4H), 6.48
CHN,
−CH3, 6H),
−
−
−
−
J
−
J
−
H, 2H), 6.50 (s, Ar
−
H, 2H), 7.18 (d,
J
−
−
−
OH, 2H). 13C NMR (75 MHz, CDCl3):
δ
29.58, 29.66, 31.92, 68.38, 101.67, 108.23, 110.59, 133.61 161.94, 162.35, 163.91. MS
(LRFAB): M+ (m/z) = 664.68. Anal. Calcd. for C42H68N2O4: C, 75.86; H, 10.31; N, 4.21.
Found: C, 74.37; H, 10.31; N, 3.96.
4.4.6. 6, 6'-(1E, 1'E)-hydrazine-1, 2-diylidenebis(methan-1-yl-1-ylidene)bis(3-hexa
decyloxyphenol) 1a (n = 16)
Pale yellow solids, yield 62%. 1H NMR (300 MHz, CDCl3):
δ
0.86 (t,
= 6.6 Hz,
H, 2H), 8.55 (s, −
J
= 6.6 Hz,
OCH2, 4H), 6.48
CHN, 2H).
−CH3, 6H),
1.24
−1.43 (m,
−CH2, 52H), 1.73-1.79 (m,
−CH2, 4H), 3.97 (t,
J
−
(m, Hz, Ar
−H, 2H), 6.51 (s, Ar
−H, 2H), 7.20 (d,
J
= 8.4 Hz, Ar
−
13C NMR (75 MHz, CDCl3):
δ
14.11, 22.68, 25.96, 29.04, 29.35, 29.55, 29.67, 31.92, 68.34,
101.67, 108.08, 110.76, 133.54, 161.84, 162.58, 163.67. MS (LRFAB): M+ (m/z) = 720.87.
Anal. Calcd. for C46H76N2O4: C, 76.62; H, 10.62; N, 3.88. Found: C, 76.52; H, 10.65; N, 3.89.
4.5. 6, 6'-(1E, 1'E)-1, 1'-(hydrazine-1, 2-diylidene)bis(ethan-1-yl-1-ylidene)bis(3-propoxy
phenol) 1b (n = 3)
Pale yellow solids, yield 64%. 1H NMR (300 MHz, DMSO
−
d6):
= 6.6 Hz, OCH2, 4H),
H, 2H), 13.81 (s, Ar−
OH, 2H). 13C NMR
δ 1.03 (t, J= 7.5 Hz, −CH3,
6H), 1.75
−1.87 (m,
−CH2, 4H), 2.50 (s,
−CH3, 6H), 3.94 (t,
J
−
6.45 6.49 (m, Ar
−
−H, 4H), 7.50 (d,
J
= 9.3 Hz, Ar
−
23

ACCEPTED MANUSCRIPT
10.46, 14.62, 22.42, 69.60, 101.96, 107.14, 112.52, 130.05, 162.75,
(75 MHz, DMSO
162.83, 166.80.
−d6):
δ
4.5.1. 6,6'-(1E,1'E)-1,1'-(hydrazine-1,2-diylidene)bis(ethan-1-yl-1-ylidene)bis(3-
(dodecyloxy)phenol) 1b (n = 12)
Pale yellow solids, yield 63%. 1H NMR (300 MHz, DMSO
−
d6):
CH2, 4H), 2.66 (s, CH3, 6H), 4.01 (t,
H, 2H), 7.56 (d, = 9.9 Hz, Ar−
δ
0.86 (t,
J
= 6.9 Hz,
= 8.4 Hz,
H,
−CH3,
6H), 1.25 (m,
−CH2, 36H), 1.41
−1.43 (m,
−
−
J
−OCH2, 4H), 6.55 (d,
J
= 8.7 Hz, Ar
−H, 2H), 6.84 (s, Ar
−
J
2H). 13C NMR (75 MHz, DMSO
−d6): δ 14.11, 14.62, 22.68, 25.97, 29.07, 29.34, 29.62, 31.90,
68.15, 101.93, 107.16, 112.50, 130.05, 162.74, 162.84, 166.79.
4.6. 6, 6'-(1E, 1'E)-(1, 4-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)bis
(3-propoxyphenol) 2 (n = 3
)
A solution of 2-hydroxy-4-propoxybenzaldehyde (0.2 g, 1.0 mmol) and benzene-1,4-diamine
(0.06 g, 0.5 mmol) dissolved in 15 mL of absolute ethanol was stirred for 12 h. After cooling
to room temperature, the crude solids were filtered. The products isolated as orange
−yellow
solids were obtained after crystallization from ethanol/acetone. Yield: 75%. 1H NMR (300
MHz, CDCl3):
δ
1.03 (t,
J
= 7.2 Hz,
−
CH3, 6H), 1.78
−
1.85 (m,
7.29 (m, Ar H, 6H), 8.54 (s,
10.45, 22.42, 69.71, 101.59, 107.68, 113.01,
−
CH2, 4H), 3.96 (t,
J = 6.6 Hz,
−OCH2, 4H), 6.46
−6.49 (m, Ar
−H, 4H), 7.15
−
−
−CHN, 2H), 13.70
(s, Ar−
OH, 2H). 13C NMR (75 MHz, CDCl3)):
δ
121.97, 133.50, 146.62, 160.94, 163.67, 163.91. MS (LRFAB): M+ (m/z) = 431.40. Anal.
Calcd. for C26H28N2O4: C, 72.20; H, 6.53; N, 6.48. Found: C, 72.36; H, 6.72; N, 6.24.
4.6.1 6, 6'-(1E, 1'E)-(1, 4-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)
bis(3-(octyloxy)phenol) 2 (n = 8)
Orange
−
yellow solids, yield 76%. 1H NMR (300 MHz, CDCl3):
δ
0.87 (t,
CH2, 4H), 3.98 (t, = 6.9 Hz,
CHN, 2H), 13.70 (s, Ar−
J
= 6.3 Hz,
OCH2, 4H),
OH,
−CH3,
6H), 1.27
−1.44 (m,
−CH2, 20H), 1.74
−1.83 (m,
−
J
−
6.46
−6.49 (m, Ar
−H, 4H), 7.21
−7.29 (m, Ar
−H, 6H), 8.54 (s,
−
2H). 13C NMR (75 MHz, CDCl3):
δ
14.11, 22.67, 26.00, 29.08, 29.23, 29.34, 29.71, 31.82,
68.33, 101.58, 101.97, 107.82, 112.88, 121.98, 133.59, 146.44, 160.91, 163.85, 163.99. MS
24

ACCEPTED MANUSCRIPT
(LRFAB): M+ (m/z) = 571.56. Anal. Calcd. for C36H48N2O4: C, 75.49; H, 8.45; N, 4.89. Found:
C, 75.66; H, 8.75; N, 4.50.
4.6.2. 6, 6'-(1E, 1'E)-(1,4-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)
bis(3-tetradodecyloxyphenol) 2 (n = 14)
Orange
6H), 1.24
6.46 6.51 (m, Ar
−
yellow solids, yield 78%. 1H NMR (300 MHz, CDCl3):
δ
0.86 (t,
CH2, 4H), 3.99 (t, = 6.6 Hz,
CHN, 2H), 13.64 (s, Ar−
J
= 7.2 Hz,
OCH2, 4H),
OH,
−CH3,
−1.44 (m,
−CH2, 44H), 1.75
−1.78 (m,
−
J
−
−
−H, 4H), 7.21
−7.30 (m, Ar
−H, 6H), 8.53 (s,
−
2H). MS (LRFAB): M+ (m/z) = 739.80. Anal. Calcd. for C48H72N2O4: C, 77.79; H, 9.79; N,
3.78. Found: C, 77.86; H, 9.86; N, 3.68.
4.7. 4, 4'-Bis((E)-2-hydroxy-4-propoxybenzylideneamino)biphenyl-3, 3'-diol 3 (n = 3
)
A mixture of 2-hydroxy-4-propoxybenzaldehyde (0.2 g, 1.11 mmol), 4,4'-diaminobiphenyl-
3,3'-diol (0.12 g, 0.55 mmol) and catalytic amount of I2 dissolved in 10 mL of DMSO was
stirred under nitrogen for 24 h. The solution was poured into ice water then the crude solids
was filtered, washed with methanol. The products isolated as orange solids was obtained after
recrystallization from THF. Yield: 77%. 1H NMR (300 MHz, DMSO
CH3, 6H), 1.70-1.77 (m, CH2, 4H), 3.97 (t, = 6.3 Hz, OCH2, 4H), 6.38 (s, Ar
6.47(d, = 4.35 Hz, Ar
CHN, 2H), 9.92 (bs, Ar
−
d6):
δ
0.98 (t,
H, 2H),
−H, 4H), 7.45 (d, J = 2.85 Hz, Ar−H, 4H), 8.90 (s,
J = 7.5 Hz,
−
−
J
−
−
J
−
H, 2H), 7.12 (m, Ar
−
−
OH, 2H). MS (LRFAB): M+ (m/z) = 523.69. Anal. Calcd. for
C32H32N2O6: C, 71.09; H, 5.97; N, 5.18. Found: C, 69.32; H, 6.01; N, 4.89.
4.7.1. 4, 4'-Bis((E)-2-hydroxy-4-(octyloxy)benzylideneamino)biphenyl-3, 3'-diol 3 (n = 8)
Orange solids, yield 76%. 1H NMR (300 MHz, DMSO
−
d6):
= 5.4 Hz,
OH, 2H). Anal. Calcd. for C42H52N2O6: C,
δ
0.85 (t,
J
= 6.9 Hz,
−
CH3, 6H),
1.23
−
1.45 (m,
−
CH2, 20H), 1.71 (m,
−
CH2, 4H), 4.00 (t,
J
−OCH2, 4H), 6.37−7.62
(m, Ar
−H, 12H), 8.90 (s,
−CHN, 2H), 9.98 (bs, Ar
−
74.09; H, 7.70; N, 4.11. Found: C, 73.28; H, 7.66; N, 3.98.
4.7.2. 4, 4'-Bis((E)-2-hydroxy-4-(tetradecyloxy)benzylideneamino)biphenyl-3, 3'-diol
3 (n = 14)
Orange solids, yield 75%. 1H NMR (300 MHz, DMSO-d6):
δ 0.85 (t, J = 6.9 Hz, −CH3, 6H),
25

ACCEPTED MANUSCRIPT
1.24 (m,
−CH2, 44H), 1.68
−1.72 (m,
−
CH2, 4H), 4.02 (t,
J
= 5.7 Hz,
−OCH2, 4H), 6.37
−7.62
(m, Ar H, 12H), 8.87 (s,
−
−CHN, 2H), 9.99 (bs, Ar
−OH, 2H), 14.51 (bs, Ar−OH, 2H). Anal.
Calcd. for C54H76N2O6: C, 76.38; H, 9.02; N, 3.30. Found: C, 75.73; H, 9.08; N, 3.22
4.8. 3, 3'-bis((E)-2-hydroxy-4-propoxybenzylideneamino)biphenyl-4, 4'-diol 4 (n = 3
)
A mixture of 2-hydroxy-4-propoxybenzaldehyde (0.2 g, 1.11 mmol), 3,3'-diaminobiphenyl-
4,4'-diol (0.12 g, 0.55 mmol) and catalytic amount of I2 dissolved in 10 mL of DMSO was
stirred under nitrogen for 24 h. The solution was poured into ice water then the crude product
was filtered, washed with acetone to afford yellow solid. Yield 33%. 1H NMR (300 MHz,
DMSO
OCH2, 4H), 6.39 (s, Ar
2H), 7.41 (d, =4.1 Hz, Ar = 4.35 Hz, Ar
(s, CHN, 2H), 9.78 (s, Ar−OH, 2H), 14.40 (s, Ar−
OH, 2H). 13C NMR (75 MHz, DMSO-d6):
−d6):
δ
0.98 (t,
J
= 7.2 Hz,
H, 2H), 6.48 (d,
H, 2H), 7.46 (d,
−
CH3, 6H), 1.68
−
1.78 (m,
−
CH2, 4H), 3.98 (t,
J
= 6.6 Hz,
−
−
J
= 4.35 Hz, Ar
−H, 4H),7.00 (d,
J
= 4.2 Hz, Ar−
H,
J
−
J
−H, 2H), 7.65 (s, Ar−H, 2H), 8.97
−
δ
10.40, 21.98, 69.23, 101.59, 106.95, 113.02, 116.70, 125.15, 131.74, 134.03, 134.24, 149.60,
160.23, 163.41, 165.94 MS (LRFAB): M+ (m/z) = 522.78. Anal. Calcd. for C32H32N2O6: C,
71.09; H, 5.97; N, 5.18. Found: C, 69.32; H, 6.01; N, 4.89.
4.8.1. 3, 3'-Bis((E)-2-hydroxy-4-octyloxybenzylideneamino)biphenyl-4, 4'-diol 4 (n = 8)
Yellow solids, yield: 38%. 1H NMR (300 MHz, DMSO
1.26 1.40 (m, CH2, 20H), 1.66 1.75(m, CH2, 4H), 4.00 (t,
Ar H, 2H), 6.46 (d, = 8.4 Hz, Ar H, 2H), 7.00 (d, = 8.4 Hz, Ar
Hz, Ar
(s, Ar
−
d6):
δ
0.86 (t,
= 6.6 Hz,
H, 2H), 7.41 (d,
CHN, 2H), 9.85
13.98, 22.11, 25.50,
J
= 6.9 Hz,
OCH2, 4H), 6.38 (s,
= 8.7
−CH3, 6H),
−
−
−
−
J
−
−
J
−
J
−
J
−
H, 2H), 7.45 (d,
J
= 8.7 Hz, Ar
−H, 2H), 7.66 (s, Ar−H, 2H), 8.97(s, −
−
OH, 2H), 14.44 (s, Ar
−
OH, 2H). 13C NMR (75 MHz, DMSO
−
d6):
δ
28.56, 28.68, 31.26, 67.72, 101.52, 106.92, 112.98, 116.66, 125.09, 131.67, 133.95, 134.25,
149.57, 160.25, 163.33, 165.76. Anal. Calcd. for C42H52N2O6: C, 74.09; H, 7.70; N, 4.11.
Found: C, 73.97; H, 7.73; N, 4.08.
4.8.2. 3, 3'-Bis((E)-2-hydroxy-4-tetradecyloxybenzylideneamino)biphenyl-4, 4'-diol
4 (n = 14)
Yellow solids, yield: 36%. 1H NMR (300 MHz, DMSO
−d6): δ 0.85 (t, J = 6.6 Hz, −CH3, 6H),
26

ACCEPTED MANUSCRIPT
1.23
(s, Ar
Ar H, 4H), 7.62 (s, Ar
−
1.38 (m,
−
CH2, 44H), 1.68
= 6.3 Hz, Ar
H, 2H), 8.94 (s,
−
1.72 (m,
H, 2H), 6.95 (d,
CHN, 2H), 9.99 (s, Ar
−
CH2, 4H), 4.00 (t,
= 8.4 Hz, Ar
OH, 2H), 14.42 (s, Ar−
J
= 6.3 Hz,
−
OCH2, 4H), 6.37
7.48(m,
OH,
−
H, 2H), 6.44 (d,
J
−
J
−H, 2H), 7.44
−
−
−
−
−
2H). Anal. Calcd. for C54H76N2O6: C, 76.38; H, 9.02; N, 3.30. Found: C, 75.90; H, 8.98; N,
3.24.
Acknowledgements
We thank the Ministry of Science and Technology, Taiwan (MOST 103−2113−M−008−002)
for generous support of this work. Also we deeply appreciated Prof. Hwo-Shuenn Sheu for
performing powder XRD experiments at the National Synchrotron Radiation Research Center.
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