Supporting Information (SI) Three Ring based Thermotropic Mesogens ...
Supporting Information (SI) Three Ring based Thermotropic Mesogens with a Dimethylamino Group: Structural Characterization, Photophysical Properties and Molecular Order M. Guruprasad Reddy,† E. Varathan,‡Nitin. P. Lobo,§S. Easwaramoorthi,‡ T.Narasimhaswamy*†and A. B. Mandal‡ †
Polymer Laboratory, ‡Chemical Laboratory, §Chemical Physics Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai 600020.
EXPERIMENTAL SECTION Materials N,N-Dimethylaminobenzoic acid, 4-Hydroxy benzaldehyde, 4-Dimethylamino pyridine (DMAP), Dicyclohexylcarbodiimide (DCC), 4-Hydroxy acetanilide, n-bromoalkanes (C2-C12, even carbons only) are used as received (Aldrich, USA). Tetrahydrofuran (THF), Dichloromechane (DCM), Diethyl ether, Potassium hydroxide, Ethanol, Isopropyl alcohol are used without further purification (MERCK, India). Instrumental details 1
H and 13C NMR spectra of the compounds in CDCl3 were run on a JEOL 500 MHz instrument
at room temperature using tetramethylsilane as an internal standard. The resonance frequencies of 1H and 13C were 500.15 and 125.76 MHz respectively. Synthesis of 4- formylphenyl 4-(dimethylamino)benzoate (1) In a representative experiment, 4-(Dimethylamino)benzoic acid (4 g, 0.0242 mol) and 4hydroxy benzaldehyde (2.25 g, 0.0242 mol) were placed in a 250 ml conical flask. To that 50 ml dichloromethane and 50 ml tetrahydrofuran were added and the solution was stirred with magnetic stirrer. After one hour, dicyclohexylcarbodiimide (4.9 g, 0.0242 mol) dissolved in 25
ml dichloromethane and catalytic amount of 4-dimethylamino pyridine (0.29 g, 0.0024 mol) were added to the reaction mixture.1 The stirring was continued for 10 hours, then the reaction mixture was filtered and filtrate was concentrated by evaporating the solvent. The semi solid obtained was re dissolved in dichloromethane and washed with 10% HCl followed by 5 % KOH solution. The solid obtained was purified by recrystallization in isopropanol. Yield: 68%, FT-IR (KBR, cm-1): 2928, 2851 (C-Hstr), 1718 (C=Ostr), 1692 (-HC=O), 1593, 1500 (C=Cstr aromatic), 1409, 1356 (C-H bend), 1261, 1206, (C-O-C
asym & sym str
of ester
and ether respectively); 1H NMR (400 MHz, CDCl3): δ 9.92 (s, 1H), 7.97 (d, J = 7.9 Hz, 2H), 7.87 (d, J = 8.2 Hz, 2H), 7.31 (d, J = 7.7 Hz, 2H), 6.63 (d, J = 8.7 Hz, 2H), 3.01 (s, 6H);
13
C
NMR (100 MHz, CDCl3): δ 191.16, 164.76, 156.37, 153.90, 133.61, 132.18, 131.20, 122.73, 115.16, 110.92, 40.13.
Synthesis of 4-dodecyloxy aniline (2,3).
Preparation of 4-dodecyloxy acetanilide (2a-f) In a typical experiment, 4-hydroxy acetanilide (2.5 g, 0.0165 mol) was placed in a 500 ml three neck round bottom flask equipped with stirrer and thermometer. To that 170 ml DMF and potassium carbonate (6.8 g, 0.0496 mol) were added. The mixture was stirred while maintaining the temperature at 90°C. To this mixture, n-Bromododecane (4.1 ml, 0.0165 mol) was added through a pressure equalizing dropping funnel over a period of 30 minutes and the stirring was continued for additional 3 hours.2 Then the mixture was allowed to cool to room temperature, poured into a one liter beaker. The contents were diluted with water (500 ml) and then transferred to a 500 ml separating funnel and diethyl ether was added. The ether layer was washed with 10% potassium hydroxide, distilled water and then the organic layer was dried with
anhydrous sodium sulphate. Upon the evaporation of ether, the solid obtained was recrystallized from n-heptane. 4-dodecyloxy acetanilide (2f) Yield: 62.7%, FT-IR (KBr, cm-1): 3322 (NHstr), 2924, 2850 (C-Hstr), 1659 and 1510 (C=Cstr aromatic), 1412 (C-Hben), 1239, 1172 and 1152 (C-O-C
asym & sym str
of ester and ether
respectively); ); 1H NMR (500 MHz, CDCl3): δ 7.69 (s, 1H), 7.35 (d, J = 8.8 Hz, 2H), 6.80 (d, J = 8.9 Hz, 2H), 3.89 (t, J = 6.6 Hz, 2H), 1.76 (m, 2H), 1.45-1.29 (m, 18H), 0.91 (s, 3H); 13C NMR (126 MHz, CDCl3): δ 168.66, 156.06, 130.98, 122.07, 114.78, 68.71, 31.95, 29.70, 29.67, 29.64, 29.47, 29.39, 26.10, 22.73, 14.16. The above procedure was also followed for synthesizing other compounds namely 4ethoxy acetanilide, 4-butoxy acetanilide, 4-hexyloxy acetanilide, 4-octyloxy acetanilide and 4decyloxy acetanilide. Hydrolysis of 4-dodecyloxy acetanilide (3a-f) In an experiment, 4-Dodecyloxy acetanilide (1.2 g, 0.0037 mol) was dissolved in 150 ml of ethanol in a 500 ml two necked round bottom flask attached with reflux condenser. Then 25 ml Conc. HCl was added drop wise using a pressure equalizing dropping funnel over a period of 30 minutes while refluxing the solution.2 After 3 hours, the reaction mixture was allowed to cool to room temperature and then poured in to beaker, diluted with water. After neutralization with 10% NaOH, the solution was transferred to a 500 ml separating funnel and diethyl ether was added. The ether layer was washed twice with water and was dried with anhydrous sodium sulphate followed by evaporation. The solid thus obtained was purified by recrystallization in heptane.
The similar procedure was used for making other compounds homologues namely 4ethoxy aniline, 4-butoxy aniline, 4-hexyloxy aniline, 4-octyloxy aniline and 4-decyloxy aniline. 4-dodecyloxyaniline (3f) Yield: 62.7%, FT-IR (KBr, cm-1): 3412, 3311 (NH2str), 2925, 2854 (C-Hstr), 1623 and 1511 (C=Cstr aromatic), 1403 (C-Hben), 1236, 1175 and 1150 (C-O-C
asym & sym str
of ester and ether
respectively); 1H NMR (400 MHz, CDCl3): δ 6.77 (d, J = 7.6 Hz, 2H), 6.66 (d, J = 7.7 Hz, 2H), 3.90 (t, J = 6.0 Hz, 2H), 3.09 (s, 2H), 1.76 (m, 2H), 1.45-1.29 (m, 18H), 0.91 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 152.37, 139.77, 116.47, 115.66, 68.71, 31.95, 29.70, 29.67, 29.64, 29.47, 29.39, 26.10, 22.73, 14.16. (E)-4-(((4-dodecyloxyphenyl)imino)methyl)phenyl4-(dimethylamino)benzoate
(Dd
IMPDB) 4-formylphenyl4-(dimethylamino)benzoate (0.5 g, 0.0018 mol )
and 4-dodecyloxy
aniline (0.5 g, 0.0018 mol) were placed in 100 ml conical flask. A few drops of ethanol and a catalytic amount of acetic acid were added to it.4 The conical flask was placed in microwave oven (Power: 40W) for 15 minutes. Thus the target mesogen obtained was washed with methanol and recrystallized from n-propanol. (E)-4-(((4-dodecyloxyphenyl)imino)methyl)phenyl4-(dimethylamino)benzoate (Dd IMPDB) (4f) Yield: 62.7%, m.p-132.1°C, FT-IR (KBr, cm-1): 2953, 2870 (C-Hstr), 1714 (C=Ostr), 1615 (-C=Nstr), 1603 and 1574 (C=Cstr aromatic), 1472 (C-Hben), 1275, 1159 and 1157 (C-O-C sym str
asym &
of ester and ether respectively); 1H NMR (500 MHz, CDCl3): δ 8.47 (s, 1H), 8.06 (d, J =
9.0 Hz, 2H), 7.93 (d, J = 8.5 Hz, 2H), 7.31 (d, J = 8.5 Hz, 2H), 7.22 (d, J = 8.9 Hz, 2H), 6.92 (d, J = 8.6 Hz, 2H), 6.69 (d, J = 9.0 Hz, 2H), 3.96 (t, J = 6.6 Hz, 2H), 3.06 (s, 6H), 1.81 – 1.74 (m,
2H), 1.45 (m, 2H), 1.39 – 1.26 (m, 18H), 0.88 (t, J = 6.9 Hz, 3H); 13C NMR (125 MHz, CDCl3); δ 165.26, 157.98, 157.33, 153.89, 153.67, 144.72, 133.83, 132.17, 129.75, 122.44, 122.28, 115.64, 115.07, 110.88, 68.38, 40.15, 32.04, 29.79, 29.76, 29.73, 29.54, 29.47, 29.43, 26.17, 22.81, 14.26. Similar procedure was followed for synthesizing other homologs.
Figure S1: FT-IR spectra of synthesized mesogens {4(a-f)}
Figure S2: 1H NMR spectra of synthesized mesogens {4(a-f)}
Figure S3: Solution 13C NMR spectra of synthesized mesogens {4(a-f)}
Figure S4: DSC second heating scans of synthesized mesogens {4(a-f)}
Figure S5: Solution fluorescence spectra of DdPPB
Figure S6: SAMPI-44 pulse sequence used for obtaining the 2D-SLF spectrum in the mesophase. Here τ is cross-polarization (CP) contact time. During the t1 period, the heteronuclear
13
C-1H
dipolar couplings are evolved and the homonuclear 1H-1H dipolar couplings are suppressed by “magic sandwich” pulses. Finally
13
C signals acquired during t2 period with the heteronuclear
decoupling by SPINAL-645 pulse sequence. Here the darker boxes represent 90° pulses.
Figure S7: The variation of
13
C chemical shifts for 14 carbon resonances with the temperature
for the mesogen DdIMPDB. The verticle line indicates the phase transition temperature.
REFERENCES 1. Neubert, M. E.; Laskos, Jr. S. J.; Maurer, L. J,; Carlino, L. T.; Ferrato, J. P. Preparation of Liquid Crystal Intermediates: 4-Substituted Alkoxybenzenes. Mol. Cryst. Liq. Cryst. 1978, 44, 197-210. 2. Sudhakar, S.; Narasimhaswamy, T.; Srinivasan, K. S. V. Synthesis, Characterization and Thermal Properties of 4,4'-Bis(4-nalkoxybenzoyloxy)benzylideneanilines and Bis(4benzylidene-4'-n-alkoxyaniline)terephthalates. Liq. Cryst. 2000, 27, 1525-1532. 3. Kesava Reddy, M.; Subramanyam Reddy, K.; Phani Kumar, B. V. N.; Narasimhaswamy, T. Synthesis, Structural and Mesophase Characterization of Three Ring Based Thiophene Liquid Crystals. Mol. Cryst. Liq. Cryst. 2014, 593, 1–24. 4. Nevzorov, A. A.; Opella, S. J. Selective Averaging for High-Resolution Solid-State NMR Spectroscopy of Aligned Samples. J. Magn. Reson. 2007, 185, 59-70. 5. Fung, B. M.; Khitrin, A. K.; Ermolaev, K. An Improved Broad Band Decoupling Sequence for Liquid Crystals and Solids. J. Magn. Reson. 2000, 142, 97-101.
Polymer Laboratory, ‡Chemical Laboratory, §Chemical Physics Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai 600020.
EXPERIMENTAL SECTION Materials N,N-Dimethylaminobenzoic acid, 4-Hydroxy benzaldehyde, 4-Dimethylamino pyridine (DMAP), Dicyclohexylcarbodiimide (DCC), 4-Hydroxy acetanilide, n-bromoalkanes (C2-C12, even carbons only) are used as received (Aldrich, USA). Tetrahydrofuran (THF), Dichloromechane (DCM), Diethyl ether, Potassium hydroxide, Ethanol, Isopropyl alcohol are used without further purification (MERCK, India). Instrumental details 1
H and 13C NMR spectra of the compounds in CDCl3 were run on a JEOL 500 MHz instrument
at room temperature using tetramethylsilane as an internal standard. The resonance frequencies of 1H and 13C were 500.15 and 125.76 MHz respectively. Synthesis of 4- formylphenyl 4-(dimethylamino)benzoate (1) In a representative experiment, 4-(Dimethylamino)benzoic acid (4 g, 0.0242 mol) and 4hydroxy benzaldehyde (2.25 g, 0.0242 mol) were placed in a 250 ml conical flask. To that 50 ml dichloromethane and 50 ml tetrahydrofuran were added and the solution was stirred with magnetic stirrer. After one hour, dicyclohexylcarbodiimide (4.9 g, 0.0242 mol) dissolved in 25
ml dichloromethane and catalytic amount of 4-dimethylamino pyridine (0.29 g, 0.0024 mol) were added to the reaction mixture.1 The stirring was continued for 10 hours, then the reaction mixture was filtered and filtrate was concentrated by evaporating the solvent. The semi solid obtained was re dissolved in dichloromethane and washed with 10% HCl followed by 5 % KOH solution. The solid obtained was purified by recrystallization in isopropanol. Yield: 68%, FT-IR (KBR, cm-1): 2928, 2851 (C-Hstr), 1718 (C=Ostr), 1692 (-HC=O), 1593, 1500 (C=Cstr aromatic), 1409, 1356 (C-H bend), 1261, 1206, (C-O-C
asym & sym str
of ester
and ether respectively); 1H NMR (400 MHz, CDCl3): δ 9.92 (s, 1H), 7.97 (d, J = 7.9 Hz, 2H), 7.87 (d, J = 8.2 Hz, 2H), 7.31 (d, J = 7.7 Hz, 2H), 6.63 (d, J = 8.7 Hz, 2H), 3.01 (s, 6H);
13
C
NMR (100 MHz, CDCl3): δ 191.16, 164.76, 156.37, 153.90, 133.61, 132.18, 131.20, 122.73, 115.16, 110.92, 40.13.
Synthesis of 4-dodecyloxy aniline (2,3).
Preparation of 4-dodecyloxy acetanilide (2a-f) In a typical experiment, 4-hydroxy acetanilide (2.5 g, 0.0165 mol) was placed in a 500 ml three neck round bottom flask equipped with stirrer and thermometer. To that 170 ml DMF and potassium carbonate (6.8 g, 0.0496 mol) were added. The mixture was stirred while maintaining the temperature at 90°C. To this mixture, n-Bromododecane (4.1 ml, 0.0165 mol) was added through a pressure equalizing dropping funnel over a period of 30 minutes and the stirring was continued for additional 3 hours.2 Then the mixture was allowed to cool to room temperature, poured into a one liter beaker. The contents were diluted with water (500 ml) and then transferred to a 500 ml separating funnel and diethyl ether was added. The ether layer was washed with 10% potassium hydroxide, distilled water and then the organic layer was dried with
anhydrous sodium sulphate. Upon the evaporation of ether, the solid obtained was recrystallized from n-heptane. 4-dodecyloxy acetanilide (2f) Yield: 62.7%, FT-IR (KBr, cm-1): 3322 (NHstr), 2924, 2850 (C-Hstr), 1659 and 1510 (C=Cstr aromatic), 1412 (C-Hben), 1239, 1172 and 1152 (C-O-C
asym & sym str
of ester and ether
respectively); ); 1H NMR (500 MHz, CDCl3): δ 7.69 (s, 1H), 7.35 (d, J = 8.8 Hz, 2H), 6.80 (d, J = 8.9 Hz, 2H), 3.89 (t, J = 6.6 Hz, 2H), 1.76 (m, 2H), 1.45-1.29 (m, 18H), 0.91 (s, 3H); 13C NMR (126 MHz, CDCl3): δ 168.66, 156.06, 130.98, 122.07, 114.78, 68.71, 31.95, 29.70, 29.67, 29.64, 29.47, 29.39, 26.10, 22.73, 14.16. The above procedure was also followed for synthesizing other compounds namely 4ethoxy acetanilide, 4-butoxy acetanilide, 4-hexyloxy acetanilide, 4-octyloxy acetanilide and 4decyloxy acetanilide. Hydrolysis of 4-dodecyloxy acetanilide (3a-f) In an experiment, 4-Dodecyloxy acetanilide (1.2 g, 0.0037 mol) was dissolved in 150 ml of ethanol in a 500 ml two necked round bottom flask attached with reflux condenser. Then 25 ml Conc. HCl was added drop wise using a pressure equalizing dropping funnel over a period of 30 minutes while refluxing the solution.2 After 3 hours, the reaction mixture was allowed to cool to room temperature and then poured in to beaker, diluted with water. After neutralization with 10% NaOH, the solution was transferred to a 500 ml separating funnel and diethyl ether was added. The ether layer was washed twice with water and was dried with anhydrous sodium sulphate followed by evaporation. The solid thus obtained was purified by recrystallization in heptane.
The similar procedure was used for making other compounds homologues namely 4ethoxy aniline, 4-butoxy aniline, 4-hexyloxy aniline, 4-octyloxy aniline and 4-decyloxy aniline. 4-dodecyloxyaniline (3f) Yield: 62.7%, FT-IR (KBr, cm-1): 3412, 3311 (NH2str), 2925, 2854 (C-Hstr), 1623 and 1511 (C=Cstr aromatic), 1403 (C-Hben), 1236, 1175 and 1150 (C-O-C
asym & sym str
of ester and ether
respectively); 1H NMR (400 MHz, CDCl3): δ 6.77 (d, J = 7.6 Hz, 2H), 6.66 (d, J = 7.7 Hz, 2H), 3.90 (t, J = 6.0 Hz, 2H), 3.09 (s, 2H), 1.76 (m, 2H), 1.45-1.29 (m, 18H), 0.91 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 152.37, 139.77, 116.47, 115.66, 68.71, 31.95, 29.70, 29.67, 29.64, 29.47, 29.39, 26.10, 22.73, 14.16. (E)-4-(((4-dodecyloxyphenyl)imino)methyl)phenyl4-(dimethylamino)benzoate
(Dd
IMPDB) 4-formylphenyl4-(dimethylamino)benzoate (0.5 g, 0.0018 mol )
and 4-dodecyloxy
aniline (0.5 g, 0.0018 mol) were placed in 100 ml conical flask. A few drops of ethanol and a catalytic amount of acetic acid were added to it.4 The conical flask was placed in microwave oven (Power: 40W) for 15 minutes. Thus the target mesogen obtained was washed with methanol and recrystallized from n-propanol. (E)-4-(((4-dodecyloxyphenyl)imino)methyl)phenyl4-(dimethylamino)benzoate (Dd IMPDB) (4f) Yield: 62.7%, m.p-132.1°C, FT-IR (KBr, cm-1): 2953, 2870 (C-Hstr), 1714 (C=Ostr), 1615 (-C=Nstr), 1603 and 1574 (C=Cstr aromatic), 1472 (C-Hben), 1275, 1159 and 1157 (C-O-C sym str
asym &
of ester and ether respectively); 1H NMR (500 MHz, CDCl3): δ 8.47 (s, 1H), 8.06 (d, J =
9.0 Hz, 2H), 7.93 (d, J = 8.5 Hz, 2H), 7.31 (d, J = 8.5 Hz, 2H), 7.22 (d, J = 8.9 Hz, 2H), 6.92 (d, J = 8.6 Hz, 2H), 6.69 (d, J = 9.0 Hz, 2H), 3.96 (t, J = 6.6 Hz, 2H), 3.06 (s, 6H), 1.81 – 1.74 (m,
2H), 1.45 (m, 2H), 1.39 – 1.26 (m, 18H), 0.88 (t, J = 6.9 Hz, 3H); 13C NMR (125 MHz, CDCl3); δ 165.26, 157.98, 157.33, 153.89, 153.67, 144.72, 133.83, 132.17, 129.75, 122.44, 122.28, 115.64, 115.07, 110.88, 68.38, 40.15, 32.04, 29.79, 29.76, 29.73, 29.54, 29.47, 29.43, 26.17, 22.81, 14.26. Similar procedure was followed for synthesizing other homologs.
Figure S1: FT-IR spectra of synthesized mesogens {4(a-f)}
Figure S2: 1H NMR spectra of synthesized mesogens {4(a-f)}
Figure S3: Solution 13C NMR spectra of synthesized mesogens {4(a-f)}
Figure S4: DSC second heating scans of synthesized mesogens {4(a-f)}
Figure S5: Solution fluorescence spectra of DdPPB
Figure S6: SAMPI-44 pulse sequence used for obtaining the 2D-SLF spectrum in the mesophase. Here τ is cross-polarization (CP) contact time. During the t1 period, the heteronuclear
13
C-1H
dipolar couplings are evolved and the homonuclear 1H-1H dipolar couplings are suppressed by “magic sandwich” pulses. Finally
13
C signals acquired during t2 period with the heteronuclear
decoupling by SPINAL-645 pulse sequence. Here the darker boxes represent 90° pulses.
Figure S7: The variation of
13
C chemical shifts for 14 carbon resonances with the temperature
for the mesogen DdIMPDB. The verticle line indicates the phase transition temperature.
REFERENCES 1. Neubert, M. E.; Laskos, Jr. S. J.; Maurer, L. J,; Carlino, L. T.; Ferrato, J. P. Preparation of Liquid Crystal Intermediates: 4-Substituted Alkoxybenzenes. Mol. Cryst. Liq. Cryst. 1978, 44, 197-210. 2. Sudhakar, S.; Narasimhaswamy, T.; Srinivasan, K. S. V. Synthesis, Characterization and Thermal Properties of 4,4'-Bis(4-nalkoxybenzoyloxy)benzylideneanilines and Bis(4benzylidene-4'-n-alkoxyaniline)terephthalates. Liq. Cryst. 2000, 27, 1525-1532. 3. Kesava Reddy, M.; Subramanyam Reddy, K.; Phani Kumar, B. V. N.; Narasimhaswamy, T. Synthesis, Structural and Mesophase Characterization of Three Ring Based Thiophene Liquid Crystals. Mol. Cryst. Liq. Cryst. 2014, 593, 1–24. 4. Nevzorov, A. A.; Opella, S. J. Selective Averaging for High-Resolution Solid-State NMR Spectroscopy of Aligned Samples. J. Magn. Reson. 2007, 185, 59-70. 5. Fung, B. M.; Khitrin, A. K.; Ermolaev, K. An Improved Broad Band Decoupling Sequence for Liquid Crystals and Solids. J. Magn. Reson. 2000, 142, 97-101.
