T.V. Y et al. / Journal of Molecular Liquids 221 (2016) 1022–1028
1023
2
H-chromen-4-yl) methyl)-1H-1,2,3-triazol-4-yl)methyl 2-(((9H-
fluoren-9-yl)methoxy) cabonylamino)-3-phenylpropanoate [49],
cinchonidine and cinchonidine dications [50] using solvatochromic
shift method. We observed a large change in dipole moment of these
molecules in the excited state compared to the ground state.
There have been reports on the Solvatochromic and calculation of
the ground state and excited state dipole moment calculation of the
azo dyes [51–54], but there is no report on the Solvatochromic study
of the amino acid appended azobenzene derivatives. In the view of the
above discussion we here in report the synthesis of amino acid
appended azo dye hybrid (Gly-Azo-O7) and estimation of its ground
state and excited state dipole by the solvatochromic shift method
using Bakhshiev [55] and Bilot–Kawski [56,57] correlations and theoret-
ically using Density Function Theory (DFT).
Scheme 2. Synthesis of ethyl (E)-4-((4-heptyloxy)phenyl)diazenyl)benzoate.
reaction was monitored by TLC. After the completion of the reaction,
the reaction mixture concentrated under reduced pressure and water
(50 mL) was added. The formed precipitate was filtered under suction
to yield crude product which was recrystallized using ethanol to yield
pure product as orange solid (1.02 g, 84.2%).
1
3
H NMR (400 MHz, CDCl ) δ 8.20 (d, J = 8.7 Hz, 2H), 7.94 (dd, J =
1
5.6, 8.9 Hz, 4H), 7.04 (d, J = 9.0 Hz, 2H), 4.43 (q, J = 7.1 Hz, 2H),
2
. Experimental
4.07 (t, J = 6.6 Hz, 2H), 1.90–1.80 (m, 2H), 1.55–1.47 (m, 2H), 1.45 (t,
J = 7.1 Hz, 3H), 1.42–1.29 (m, 6H), 0.93 (t, J = 6.9 Hz, 3H). 13C NMR
2
.1. Materials
(101 MHz, CDCl
3
) δ 166.2, 162.3, 155.3, 146.8, 131.5, 130.5, 125.2,
1
22.3, 114.8, 68.4, 61.2, 31.8, 29.2, 29.1, 25.9, 22.6, 14.4, 14.1. FT-IR
−
1
All the chemicals were purchased from Sigma-Aldich, Alfa Aesar, and
(KBr, υ, cm ) 2916, 2847, 1713, 1504, 1466, 1295, 841.
Spectrochem India Pvt. Ltd. and used without further purification. All
the solvents used were HPLC grade or AR (purchased from Alfa Aesar).
Ethyl 4-aminobenzoate (1) and Phenol (2) were purchased from com-
mercial source and compound 3,was synthesized according to reported
2.3.2. Synthesis of (E)-(4-((4-(heptyloxy)phenyl)diazenyl)phenyl)methanol
(5, Scheme 3)
To a solution of LAH (0.154 mg, 4.07 mmol), in dry THF (20 mL) at 0 °
C, to this solution 4 (0.500 mg, 1.35 mmol). The reaction mixture was
stirred at room temperature for 2 h. after completion of the reaction,
the reaction was cooled to 0 °C and quenched by adding 1 N NaOH solu-
tion (30 mL). Subsequently ethyl acetate (20 mL) was added and the re-
action was filtered through celite and extracted using ethyl acetate
(20 mL × 2). The organic layer was dried over sodium sulfate and con-
centrated under reduced to give crude product which was recrystallized
1
13
protocol (Scheme 1) [58] and was characterized using H NMR and
C
NMR. (for the spectral data please see the supporting information).
2
.2. Instrumentation
1
Nuclear magnetic resonance spectra (NMR), the H NMR were re-
corded on Bruker 400 MHz spectrometer and 13C NMR spectrometer
was recorded on Bruker AMX 100 MHz solid state NMR spectrometer.
Melting points were determined on a capillary point apparatus
equipped with a digital thermometer and are uncorrected. Reactions
were monitored by using thin layer chromatography (TLC) on 0.2 mm
silica gel F254 plates (Merck). High resolution mass spectrometry
using ethanol to give pure product as orange solid (371 mg., 83.8%).
1
Mp: 118.5–119 °C H NMR (400 MHz, CDCl
3
) δ 7.88 (dd, J = 14.5,
8.6 Hz, 4H), 7.48 (d, J = 8.3 Hz, 2H), 6.99 (d, J = 9.0 Hz, 2H), 4.76 (s,
2H), 4.03 (t, J = 6.6 Hz, 2H), 1.84–1.78 (m, 2H), 1.51–1.41 (m, 2H),
1.37–1.27 (m, 7H), 0.89 (t, J = 6.8 Hz, 3H). 13C NMR (101 MHz, CDCl
3
)
(
HRMS) was performed with a waters synapt G2 HDMS instrument
δ 161.8, 152.3, 146.8, 143.1, 127.5, 124.8, 122.8, 114.7, 68.4, 64.9, 31.8,
29.4, 29.3, 26.0, 22.7, 14.1. FT-IR (KBr, υ, cm ) 3055, 2924, 2854,
1713, 1597, 1466, 1281, 1250, 1142, 841.
−
1
using time-of-flight (TOF-MS) with ESI/APCI- hybrid quadrupole. FT-IR
was taken on ABB Bomen MB 3000 FTIR for gelator and freeze dried
gels, using KBr disk technique. Absorption spectra were taken with the
help of dual beam JASCO V-570 UV/Vis/NIR spectrophotometer and
fluorescence spectra were recorded with the help of Shimadzu, RF-
2.3.3. Synthesis of (E)-4-((4-(heptyloxy)phenyl)diazenyl)benzyl
((benzyloxy)carbonyl)glycinate (Gly-Azo-O7, 7, Scheme 4)
5
301PC spectrofluorometer. The data were analyzed using related soft-
To the stirred solution of Cbz-glycine (6) (269 mg, 1.28 mmol) in
DCM (20 mL), DMAP (13.07 mg, 0.107 mmol) was added at 0 °C and
subsequently EDC.HCl (307.67 mg, 1.6605 mmol.) and HOBt
(163.86 mg, 1.07 mmol.) was added. The reaction mixture was stirred
for 15 min. at 0 °C, after which, 5 (350 mg, 1.07 mmol.) was added
and the reaction was stirred at room temperature for 6–8 h. The com-
pletion of the reaction was monitored by TLC. After the completion of
the reaction, the reaction mixture was diluted with water and extracted.
Organic layer was separated and dried over anhydrous sodium sulfate
and evaporated under reduced pressure to give crude product which
was recrystallized using ethanol to yield pure product 7 (442 mg,
78.8% ) as orange solid. Synthesis of Gly-Azo-O7, 7 is shown in
Scheme 1.
ware. The spectral shifts obtained with different sets of samples were
identical in most of the cases and values were within ± 1.0 nm. Data
were analyzed and were fitted to a straight line using Origin 6.1 soft-
ware. Density of the probe was estimated by ACD/Chemsketch software.
The concentration of Gly-Azo-O7 in all the solutions prepared in differ-
−
4
ent solvents was 10 M.
2
.3. Synthesis
2
.3.1. Synthesis of ethyl (E)-4-((4-(heptyloxy)phenyl)diazenyl)benzoate
(
4, Scheme 2)
2 3
To the stirred solution of 3 (1 g, 3.5 mmol) in acetone K CO (1.2 g,
.7 mmol) was added at 0 °C. the reaction mixture was stirred for
5mins at 0 °C after which 1-bromo heptane (0.75 g, 4.2 mmol) was
8
1
1H NMR (400 MHz, CDCl
3
) δ 7.91 (dd, J = 17.9, 8.7 Hz, 4H), 7.49 (d,
J = 8.3 Hz, 2H), 7.41–7.32 (m, 5H), 7.03 (d, J = 9.0 Hz, 2H), 5.36–5.27
(m, 1H), 5.27 (s, 2H), 5.16 (s, 2H), 4.07 (dd, J = 12.1, 5.9 Hz, 4H),
added and the reaction was refluxed for 16 h. The completion of the
1
.89–1.80 (m, 2H), 1.55–1.46 (m, 2H), 1.43–1.30 (m, 6H), 0.93 (t, J =
Scheme 1. Synthesis of (E)-4-((4(heptyloxy)phenyl)diazenyl)benzyl((benzyloxy)carbonyl)
glycinate (Gly-Azo-O7).
Scheme 3. Synthesis of (E)-(4-((4-(heptyloxy)phenyl)diazenyl)phenyl)methanol.