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A.K. Das et al. / Journal of Molecular Structure 1181 (2019) 329e337
Fig. 10. The comparable energy difference between involved frontier molecular orbital of BBCP as well as BBCQ.
azide was added to the reaction mixture and the reaction mixture
was kept stirring at the same temperature for 5 h. After completion
of the reaction (monitored by TLC), the whole mixture was poured
onto the ice cold water and a solid was precipitated out. After
filtration of the precipitate, the solid product compound 3 (800 mg,
77%) was purified by column chromatography by using 15% Ethyl
acetate in petroleum ether as solvent.
Elemental analysis: Calculated value: C, 75.64; H, 4.90; N,
12.38; Observed value: C, 75.68; H, 4.88; N, 12.36.
2.7.4. Synthesis of BBCQ
The compound BBCQ (500 mg, 48%) was prepared by the similar
procedure by using compound 3 (500 mg, 1.37 mmol) and com-
pound 5 (540 mg, 2.74 mmol).
1H NMR (CDCl3, 300 MHz):
d
(ppm): 8.012 (t, 3H, J ¼ 6.9 Hz),
1H NMR (CDCl3, 300 MHz):
d
(ppm): 7.969 (q, 3H, J ¼ 12.9 Hz),
7.859 (d, 1H), 7.463 (t, 1H), 7.338 (t, 1H), 6.761 (d, 2H, J ¼ 8.4 Hz),
7.819 (d, 2H, J ¼ 6.9 Hz), 7.675 (q, 2H, J ¼ 12.6 Hz), 7.427 (t, 5H,
J ¼ 11.4 Hz), 7.308 (t, 3H, J ¼ 12.6 Hz), 7.187 (m, 3H), 6.244 (s, 2H),
4.178 (d, 4H, J ¼ 5.4 Hz), 3.268 (d, 4H, J ¼ 5.4 Hz), 2.708 (d, 6H,
J ¼ 12.9 Hz), 2.027 (s, 4H).
3.829 (t, 4H, J ¼ 6.9 Hz), 3.675 (m, 4H).
MS (ESI-TOF): (m/z, %): M þ Calculated for C17H16N8S is
364.1219; Found: 365.15 (M þ H)þ;
MS (ESI-TOF): (m/z, %): M þ Calculated for C43H38N10O2S is
758.2900; Found: 759.2974 (M þ H)þ.
2.7.3. Synthesis of BBCP
To a mixture of compound 3 (500 mg, 1.37 mmol) and com-
pound 4 (740 mg, 2.74 mmol) in a solution of water and THF (v/
v ¼ 1:1, 8 mL), a catalytic amount of sodium ascorbate (4 equiv.)
was added followed by a catalytic amount of copper (II) sulphate
pentahydrate (2 equiv.). The heterogeneous mixture was stirred
vigorously overnight in the dark at room temperature. The
completion of the reaction was checked by TLC and the solvent was
removed under reduced pressure and extracted by DCM and water
several times; the combined organic part was evaporated to give
crude product which was then purified by column chromatography
by 1% MeOH in CHCl3 to yield the desired product BBCP (500 mg,
40%) as a white solid.
Elemental analysis: Calculated value: C, 68.05; H, 5.05; N,
18.46; Observed value: C, 68.02; H, 5.06; N, 18.48.
3. Conclusions
In summary, we have developed two click modified butterfly
molecules BBCP and BBCQ for the solvatochromic study depending
on aggregation induced excimer emission and ICT induced strong
hydrogen bonding effect. To our belief this is a rare example of such
click modified butter fly molecule having pyrene moiety which
shows ratiometric emission in solvatochromic analysis in H2O and
organic solvents which has been successfully supported by DFT and
TD-DFT study. The test strips based on BBCP and BBCQ in sol-
vatochromic analysis are fabricated, which can act as a convenient
and efficient test kits for the detection of various fluorescence
changes in solid phase without remedying for the time consuming
instrumental analysis.
1H NMR (DMSO‑d6, 300 MHz):
8.176 (d, 6H, J ¼ 7.8 Hz), 8.116 (d, 3H, J ¼ 6 Hz), 8.032 (d, 9H,
J ¼ 7.8 Hz), 7.453 (d, 1H), 7.354 (d, 1H), 6.804 (s, 2H), 5.134 (s, 4H),
4.677 (s, 4H), 4.538 (d, 4H), 3.778 (s, 4H).
d
(ppm): 8.277 (d, 6H, J ¼ 9 Hz),
MS (ESI-TOF): (m/z, %): M þ Calculated for C57H44N8O2S is
904.3308; Found: 905.40 (M þ H)þ.