Page 5 of 9
Journal Name
Dalton Transactions
DOI: 10.1039/C5DT03627E
were added to the stirred solution. (4ꢀbromopyridinꢀ2ꢀyl)methanol
(752mg, 0.40 mmol) was added in and the mixture was heated to 70o
C for 12 h. After cooling, the formed precipitate of triethylamine
hydroiodide was filtered off and washed with THF. The combined
filtrates were evaporated under reduced pressure, and the crude
product was purified by silica column chromatography eluting with
1
PE:EA (10:1) to afford 2. (yield: 46%) H NMR (400 MHz, CDCl3)
δ 1.52 (s, 9H, CH3), δ 4.76 (s, 2H, CH2), 6.77 (s, 1H, NH), 7.27ꢀ7.48
(m, 6H, ArH), 8.51 (d, J=4.5, 1H, ArH) ppm; 13C NMR (100 MHz,
CDCl3) δ29.7, 65.4, 82.5, 87.5, 95.7, 117.5, 119.5, 123.7, 125.5,
133.9, 134.3, 140.9, 0149.8, 153.8, 160.7. MS (ESI). Calcd for
C19H20N2O3 [(M + 1)+] m/z 325.15. Found: m/z 325.07.
Figure 7. Luminescence intensity of EuL1 (10uM) in 10mM
HEPES (pH 7.4) on alternate addition of Cu (II)ꢀNaHS. Each
measurement was done after 60 min equilibrium from addition of
each Cu (II) ion /NaHS.
Synthesis of 3.
2 (113mg, 0.35mmol), PPh3 (99.6mg, 0.38mmol) were mixed
together and CBr4 (132mg, 0.4mmol) was added to the reaction
mixture and was allowed to stirred for three hours. The combined
filtrates were evaporated under reduced pressure, and the crude
product was purified by silica column chromatography eluting with
Conclusions
Detailed photophysical solution studies have been performed. EuL1
demonstrated a high selectivity and sensitivity for Cu (II) ion. The
binding constant was 74026 2899Mꢀ1 and corresponding detection
limit was 9.6 0.1ꢀM. Upon EuL1 binding with Cu (II) ion, it
becomes a selective responsive H2S probe. The detection limit was
2.7 0.1ꢀM. The reversible binding between EuL1 and Cu (II) ion or
EuL1Cu and H2S showed the onꢀoffꢀon type luminescence which
can allow this probe to be used as a monitoring system.
1
PE:EA (20:1) to afford 3. (yield: 37%) H NMR (400 MHz, CDCl3)
δ 1.52 (s, 9H, CH3), δ 4.53 (s, 2H, CH2), 7.09 (s, 1H, NH), 7.27 (d,
J= 5.4Hz, 1H, ArH), 7.41ꢀ7.51 (m, 5H, ArH), 8.53 (d, J=5.1, 1H,
ArH) ppm; 13C NMR (100 MHz, CDCl3) δ28.3, 33.3, 80.9, 85.7,
94.9, 115.8, 118.1, 124.6, 125.2, 132.9, 132.9, 139.7, 149.46, 152.4,
156.8. MS (ESI). Calcd for C19H19BrN2O2 [(M + 1)+] m/z 387.06.
Found: m/z 387.13.
Experimental
General Methods.
Synthesis of 4.
3 (108mg, 0.28 mmol), 8 (133mg, 0.28 mmol) and K2CO3 (77mg,
0.56mmol) were stirred in ACN (15ml) under reflux overnight .The
reaction mixture was filtered and purified by silica column
chromatography eluting with DCM:MeOH (20:1) to afford 4.
(yield:37%) 1H NMR (400 MHz, CDCl3) δ 1.23ꢀ1.29 (m, 9H, CH3),
1.52 (s, 9H, OCH3), 2.40ꢀ2.98 (m, br, 22H, CH2), 3.25ꢀ3.81 (m, 4H,
CH2), 4.12ꢀ4.18 (m, 8H, CH2), 7.23 (d, J= 4.9Hz, 1H, ArH), 7.28 (s,
1H, ArH), 7.44ꢀ7.47 (m, 3H, ArH), 7.56ꢀ7.58 (m, 2H, ArH), 8.28 (d,
J=5.04, 1H, ArH) ppm; 13C NMR (100 MHz, CDCl3) δ14.1, 28.3,
49.6, 50.3, 52.0, 55.9, 58.90, 60.9, 61.2, 67.6, 68.4, 80.6, 85.4, 95.5,
115.2, 118.3, 123.9, 125.4, 132.7, 132.9, 140.2, 149.1, 152.6, 158.3,
170.2, 172.9. MS (ESI). Calcd for C41H60N6O9 [(M + 1)+] m/z
781.44. Found: m/z 781.33.
Unless otherwise noted, all reagents were obtained from commercial
suppliers and used without further purification. Acetonitrile (ACN)
and dichloromethane (DCM) were distilled from calcium hydride.
NMR spectra were recorded with a Bruker Ultrashield 400 Plus
NMR spectrometer. All reactions were monitored using thinꢀlayer
chromatography (TLC) on Merck silica gel plates (Merck, Kieselgel
60, 0.25 mm thickness) with F254 indicator. 1H NMR chemical shifts
were referenced to internal CDCl3 and then reꢀreferenced to TMS (δ
= 0.00 ppm). Mass spectra, reported as m/z, were obtained with The
Micromass® QꢀToF 2 mass spectrometer.
Synthesis of 1.
4ꢀEthylaniline (936mg, 0.8 mmol), (Boc)2O (2.18g, 1 mmol) were
stirred in THF (10ml).The reaction mixture was filtered and purified
by silica column chromatography eluting with PE:EA (15:1) to
Synthesis of 5.
1
afford 1. (yield:62%) H NMR (400 MHz, CDCl3) δ 1.52 (m, 9H,
4 (68mg, 0.1 mmol) and TFA (1ml) were stirred in DCM (2ml)
overnight. The reaction mixture was filtered and washed by
DCM:diethyl ether (1:1) to afford 5. (yield:80%) 1H NMR (400
MHz, CDCl3) δ 1.18ꢀ1.25 (m, 9H, CH3), 2.15ꢀ2.90 (s, 22H, CH2),
3.20ꢀ3.50 (m, 4H, CH2), 4.07ꢀ4.18 (m, 8H, CH2), 4.51 (s, br, 2H,
NH2),7.14 (ms, 1H, NH), 7.23ꢀ7.29 (m, 2H, ArH), 7.45ꢀ7.53 (m, 5H,
ArH), 8.28 (d, 1H, ArH)ppm; 13C NMR (100 MHz, CDCl3) 14.1,
49.6, 50.3, 51.2, 52.8, 56.0,57.1, 60.7, 60.8, 61.2, 67.9, 80.74, 86.4,
95.9,114.6, 124.2, 125.2, 125.9, 133.4, 149.0, 158.1, 170.7. MS
(ESI). Calcd for C36H52N6O7 [(M + 1)+] m/z 681.39. Found: m/z
681.43.
OCH3), 3.01 (s, 1H, CH), 6.51 (s, br, 1H, NH) , 7.32 (m, J=8.6, 1H,
ArH), 7.41ꢀ7.43 (m, 2H, ArH), ppm; 13C NMR (100 MHz, CDCl3)
δ28.3, 80.9, 83.5, 116.2, 117.9, 132.9, 138.9, 152.3.MS (ESI). Calcd
for C13H15NO2Na [(M + 22)+] m/z 240.10. Found: m/z 240.13.
Synthesis of 2.
1 (1.29g, 0.40 mmol) was dissolved in dry triethylamine (8 mL) and
dry THF (4 mL) under an atmosphere of nitrogen. Copper(I) iodide
(9.8mg, 0.005 mmol), triphenylphosphine (52mg, 0.02 mmol) and
dichlorobis(triphenylphosphine)palladium(II) (35mg, 0.005 mmol)
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