T. Deng et al.
Dyes and Pigments 173 (2020) 107915
4
.4. Probe synthesis
J ¼ 5.8 Hz, 2H), 5.54 (s, 1H), 5.39 (s, 1H), 4.64 (s, 2H). HRMS (ESI) m/z
þ
To the stirred solution of fluorescein (1.0 mmol) in THF (4 mL),
according to general procedure B. The product was obtained as a brown
NaBH
4
(6.0 mmol) was added portion-wise. When the gas evolution
1
stopped, I
2
(3.0 mmol) was added slowly, where the reaction tempera-
solid (75% yield). H NMR (400 MHz, DMSO‑d
6
) δ 13.35 (s, 1H), 10.47
�
ture was then raised to 60 C. After 48 h, the reaction mixture was cooled
(s, 2H), 7.79–7.78 (m, 1H), 7.42–7.38 (m, 1H), 7.30–7.26 (m, 1H), 6.93
þ
to room temperature, followed by adding Na
S
2 2
O
3
⋅5H
2
O (1.0 eq to I
2
)
(d, J ¼ 10.2 Hz, 3H), 6.73 (s, 2H), 6.11 (s, 1H). ESI [MþH] m/z calcd.
þ
and then saturated NaHCO slowly. Then, the pH of the mixture was
3
for [C20H13Cl2O5] 403.01, found 402.99 [MþH] .
adjusted to pH 5 using 2 M AcOH, the aqueous layer was extracted with
Compound 6: Rhodamine B (1.0 mmol) was reacted according to
EtOAc (4 ꢁ 30 mL), the combined organic phase was washed with
general procedure A. The product was obtained as a purple solid (10%
saturated NaCl, dried over Na
2
SO
4
and concentrated under reduced
yield). 1H NMR (400 MHz, DMSO‑d
6
) δ 7.73 (d, J ¼ 7.4 Hz, 1H),
pressure, the residue was purified by column chromatography using
gradient MEOH/DCM as eluent (Scheme 2).
7.68–7.66 (m, 1H), 7.55–7.51 (m, 1H), 7.30–7.28 (m, 1H), 7.13–7.10
(m, 2H), 7.05 (s, 1H), 7.03 (s, 1H), 6.97 (d, J ¼ 2.3 Hz, 2H), 5.16 (s, 1H),
þ
Compound 2 (P1) was synthesized according to procedure A as a
4.21 (s, 2H), 3.68–3.63 (m, 8H), 1.24–1.22 (m, 12H). ESI [M À H] m/z
1
þ
white solid (90% yield). H NMR (400 MHz, DMSO‑d
6
) δ 9.51 (s, 2H),
calcd. for [C28H33N2O2] 429.26, found 429.30 [M À H] .
7
.37–7.35 (m, 1H), 7.13–7.11 (m, 2H), 6.95–6.93 (m, 1H), 6.77 (d,
Compound 7: Eosin Y disodium salt (1.0 mmol) was reacted ac-
J ¼ 8.5 Hz, 2H), 6.47 (d, J ¼ 2.4 Hz, 2H), 6.40–6.37 (m, 2H), 5.47 (s,
cording to general procedure A. The product was obtained as a white
1
3
solid (80% yield). 1H NMR (400 MHz, DMSO‑d
1
H), 5.26–5.23 (m, 1H), 4.58 (d, J ¼ 4.6 Hz, 2H). C NMR (100 MHz,
DMSO‑d
) δ 157.35, 151.24, 139.02, 130.83, 130.51, 128.31, 128.00,
26.35, 115.44, 111.58, 102.72, 61.55, 49.08. HRMS (ESI) m/z calcd for
6
) δ 10.15 (s, 2H),
6
7.40–7.38 (m, 1H), 7.23–7.18 (m, 4H), 6.90 (s, 1H), 5.72 (s, 1H), 5.47 (s,
þ
1
1H), 4.68 (s, 2H). ESI [MþH] m/z calcd. for [C20H13Br4O4] 636.74,
þ
þ
C20H16NaO4 [MþNa] 343.0941, found 343.0940.
found 636.73 [MþH] .
Fluorescein (1.0 mmol) dissolved in 4 mL THF, and then NaBH
4
The synthesis of compound 8 was described in Scheme 4 and the
(
6.0 mmol) was added. The mixture was allowed to stir at room tem-
supporting information. A mixture of 8 (1.0 mmol), NaBH
and I (3.0 mmol) was treated according general procedure A, giving
369 mg of compound 9 (P5) as a white solid (89% yield). H NMR
(400 MHz, DMSO‑d
4
(6.0 mmol)
perature for 96 h, the solvent was removed under vacuum and the res-
idue was purified by column chromatography using gradient MEOH/
DCM as eluent (Scheme 3).
2
1
6
) δ 9.52 (s, 2H), 7.24–7.22 (m, 1H), 7.15–7.06 (m,
Compound 3 (P2) was obtained according to procedure B as a light
2H), 6.89–6.81 (m, 3H), 6.75 (d, J ¼ 8.4 Hz, 2H), 6.40–6.37 (m, 2H),
yellow solid (89% yield). 1H NMR (400 MHz, DMSO‑d
) δ 7.73 (d,
5.55 (s, 1H), 3.71 (s, 2H), 2.89–2.84 (m, 2H), 2.74–2.66 (m, 4H),
6
þ
J ¼ 7.8 Hz, 1H), 7.35–7.31 (m, 1H), 7.21–7.18 (m, 1H), 6.90 (d,
J ¼ 7.9 Hz, 1H), 6.83 (d, J ¼ 8.4 Hz, 2H), 6.51 (d, J ¼ 1.3 Hz, 2H),
2.53–2.49 (m, 5H). HRMS (ESI) m/z calcd for C25H27N2O3 [MþH]
403.2016, found 403.2018.
6
.44–6.42 (m, 2H), 6.17 (s, 1H). HRMS (ESI) m/z calcd for C20H14NaO5
The synthesis of Compound 13 was described in supporting infor-
mation. HOBt (1.2 mmol) was added to the mixture of compound 1
(1.0 mmol), 13 (1.2 mmol) and TEA (2.0 mmol) in DMF (4 ml). Then,
EDC (2.0 mmol) was added portion-wise. Subsequently, the mixture was
stirred overnight at room temperature. Upon completion, the solvent
was removed by reduced pressure. The residue was purified by silica gel
þ
[
according to general procedure A. The product was obtained as a light
1
yellow solid (62% yield). H NMR (400 MHz, DMSO‑d
6
) δ 10.42 (s, 1H),
7
.39–7.37 (m, 1H), 7.20–7.16 (m, 2H), 6.95–6.92 (m, 3H), 6.72 (d,
column (MeOH:DCM ¼ 1:20), then compound 14 (red solid, 73% yield)
1
was collected (Scheme 4). H NMR (400 MHz, DMSO‑d
6
) δ 7.90–7.68
(
m, 19H), 6.93 (d, J ¼ 9.4 Hz, 2H), 6.60–6.58 (m, 4H), 3.57–3.54 (m,
þ
4
H), 3.25 (s, 6H), 2.55–2.51 (m, 2H), 1.70 (s, 2H). ESI [M À Br] m/z
þ
calcd. for [C46H40N2O5P] 731.27, found 731.30 [M À Br] .
Compound 15 (P6): A mixture of compound 14 (1.0 mmol), NaBH
4
(
8.0 mmol) and I
2
(4.0 mmol) was treated according general procedure
1
A, giving 648 mg of P6 as a white solid (83% yield). H NMR (400 MHz,
Scheme 3. Synthetic route of dihydrofluorescein acids (Procedure B).
Scheme 4. Synthetic route of P5 and P6
7