J. Fan, D. Zhou, X. Peng et al.
stock solution of PdCl2 with MeOH was performed to prepare the
1.0 mm and 100.0 mm stock solutions. A 5.0 mm solution of Pd(OAc)2
(5.61 mg, 0.025 mmol) was prepared in acetone (5 mL). A 2.0 mm solu-
tion of [Pd(PPh3)4] (11.6 mg, 0.01 mmol, freshly synthesized from PdCl2,
light-yellow color) was prepared in THF (5 mL, deoxidized). A 100 mm
solution of PPh3 (262.3 mg, 1.00 mmol) was prepared in DMSO (10 mL).
Synthesis of RPd4: Rhodamine-6G hydrazine (2, 500.0 mg, 1.2 mmol)
was dissolved in EtOH (150 mL) in a 250 mL flask. Next, 2-diphenyl-
phosphinobenzaldehyde (DPPBde, 377.4 mg, 1.3 mmol) was added to the
boiling solution with vigorous stirring and the mixture was heated at
reflux for 48 h. After the removal of EtOH under vacuum, the residue
was purified by column chromatography on silica gel (CH2Cl2/EtOAc,
3:1) to give RPd4 as a light-pink powder (655.3 mg, yield: 77.9%). M.p.
256.8–257.58C; 1H NMR (400 MHz, CDCl3): d=9.17 (d, J(PH)=3.6 Hz,
1H; NNCH), 8.11 (s, 1H; C6H4), 7.99 (d, 1H; C6H4), 7.39 (s, 2H; C6H4),
7.25 (d, J=7.2 Hz, 3H; C6H4), 7.19 (d, J=7.6 Hz, 4H; C6H4), 7.10 (t, J=
7.2 Hz, 1H; C6H4), 7.01 (t, J=6.4 Hz, 5H; C6H4), 6.79 (s, 1H; C6H4), 6.37
(s, 2H; xanthene-H), 6.30 (s, 2H; xanthene-H), 3.15 (q, J=6.8 Hz, 4H;
CH2), 2.05 (s, 6H; CH3), 1.26 ppm (t, J=6.4 Hz, 6H; CH3); 13C NMR
(100 MHz, CDCl3): d=165.70, 153.20, 151.16, 147.46, 144.66, 139.91,
137.40, 135.31, 133.75, 129.64, 129.08, 128.30, 127.78, 126.41, 125.15,
123.59, 118.06, 105.87, 97.38, 65.75, 60.50, 38.44, 32.32, 29.81, 26.52, 23.56,
21.16, 16.81, 14.90, 14.32 ppm; 31P NMR (162 MHz): d=ꢀ18.058 ppm;
MS (Q-TOF, ESI): m/z calcd for C45H41N4O2P: 701.3045 [M+H]+; found:
701.3033.
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
A 2.0 mm solution of [Pd
in H2O (5 mL). A 2.0 mm solution of [Pd
diene, 2.85 mg, 0.01 mmol) was prepared in CH2Cl2 (5 mL). A 2.0 mm sol-
ution of [Pd(PPh3)2Cl2] (7.02 mg, 0.01 mmol) was prepared in DMSO
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
(5 mL). Sodium salts, such as NaBr, NaCl, Na2CO3, NaHCO3, Na2HPO4,
NaH2PO4, NaHSO3, NaNO2, NaNO3, NaOAc, Na3PO4, NaSCN, Na2SO3,
and Na2SO4, were separately dissolved in distilled water to prepare the
stock solutions of different anions (10.0 mm for each). A 10.0 mm solution
of RPd4 (26.8 mg, 0.05 mmol) was prepared in DMSO (5 mL) and stored
in a refrigerator before use. Measurements were done after the addition
of different cations to solutions of RPd4 after a balance time of 5 s.
1H NMR and 13C NMR spectra were recorded on a Varian Inova-400
spectrometer and chemical shifts are reported as ppm (CDCl3, TMS was
used as an internal standard). MS was performed on an Agilent
HP1100 LC/MSD mass spectrometer and an Agilent LC/Q-TOF mass
spectrometer. Fluorescence measurements were performed on a Varian
Synthesis of L: Methyl benzoate (1.36 g, 10.0 mmol) was dissolved in
CH3CN (50 mL) in a 100 mL flask. Excess hydrazine hydrate (10 mL)
was added dropwise to the boiling solution under vigorous stirring and
the mixture was heated at reflux for 5 h. After the removal of CH3CN
under vacuum, the residue was recrystalized from CH2Cl2 to give com-
pound 3 as a white powder (1.02 g, 75%). Compound 3 (136.1 mg,
1.0 mmol) was dissolved in EtOH (20 mL) in a 50 mL flask. Then, 2-di-
phenylphosphinobenzaldehyde (DPPBde, 290.2 mg, 1.0 mmol) was added
to the boiling solution under vigorous stirring and the mixture was
heated at reflux for 8 h. After the removal of EtOH under vacuum, the
residue was purified by column chromatography on silica gel (CH2Cl2/
EtOAc, 10:1) to give the white ligand L (318.6 mg, yield: 78.0%). M.p.
216.8–217.38C; 1H NMR (400 MHz, CDCl3): d=8.41 (s, 1H; NCH), 8.17
(d, J=7.2 Hz, 2H; C6H4), 7.56 (m, 2H; C6H4), 7.36 (m, 1H; C6H4), 7.72–
7.29 ppm (15H; C6H4 on PPh3); 31P NMR (162 MHz): d=ꢀ15.180 ppm;
HRMS (Q-TOF, ESI): m/z calcd for C26H21N2OP: 431.1289 [M+Na]+;
found: 431.1305.
Synthesis of L-Pd2+: L-Pd2+ was prepared by adding a stoichiometric
amount of NEt3 and (cod)Cl2 (142.6 mg, 0.5 mmol) to a solution of ligand
L (204.2 mg, 0.5 mmol) in CH2Cl2 (15 mL). The mixture was stirred at
RT for 3 h and then concentrated under reduced pressure to half of its
original volume. The addition of Et2O caused the precipitation of a
yellow complex, which was filtered off, dried in air, and recrystallized
from CH2Cl2/Et2O to give L-Pd2+ (125.7 mg, yield: 45.9%). M.p. 264.9–
265.58C; 31P NMR (162 MHz): d=33.178 ppm; HRMS (Q-TOF, ESI):
m/z calcd for C26H20ClN2OPPd: 549.0115 [M+H]+; found: 549.0126.
Cary
Eclipse
Fluorescence
Spectrophotometer
(Serial
No.
FL0812 M018). All pH measurements were made on a Model PHS-3C
meter.
Proof-of-concept experiments—Pd analysis in reaction vessels: K2CO3
(10 mg) and THF (3 mL) were added to three round-bottomed flasks
(10 mL). Next, PdCl2 and PdACHTUNTRGNE(NUG AcO)2 (10 mg in both cases) were added to
two of the three flasks. The mixtures were stirred at RT for 1 h and then
all of the chemicals were removed. The flasks were brushed with deter-
gent solution then washed with water and acetone three times each. To
these washed flasks were added a 10 mm solution of RPd4 in EtOH
(10 mL). These solutions were stirred at RT for 1 h, after which fluores-
cence measurements were performed. For the residual-PdCl2 reaction
vessel, the EtOH was removed under vacuum. The residue was dissolved
in aqua regia then diluted with water and used directly in ICP-AES anal-
ysis.
Pd analysis in drug compounds: A tablet of paracetamol (500 mg) was
dissolved in MeOH by stirring overnight. After filtration, the solvent was
evaporated and the residue was dissolved in EtOH (50 mL) to prepare a
10 mgmLꢀ1 sample of the drug compound. This sample was “spiked”
with solutions of PdCl2 ([Pd]final =0–1.0 mm, which was equal to 0–
10.64 ppm). Then, a solution of RPd4 was added to the different samples
of the Pd-contaminated drug compounds ([RPd4]final =10 mm). Fluores-
cence measurements were performed after several minutes.
Fluorescence quantum yields: The fluorescence quantum yields of RPd4,
RPd4-Pd2+, and RPd4-Pd0 were determined according to Equation (1),
where f is the fluorescence quantum yield, FA is the integrated area
under the corrected emission spectrum, A is the absorbance at the excita-
tion wavelength, lex is the excitation wavelength, and h is the refractive
index of the solution; subscripts u and s refer to the unknown and the
standard samples, respectively.
Pd analysis in soil: Soil was heated in an oven at 1338C for 24 h. Next, it
was suspended in EtOH to prepare a 10 mgmLꢀ1 sample, which was
spiked with solutions of PdCl2 ([Pd]final =0–1.0 mm, which was equal to 0–
10.64 ppm). After filtering to remove any insoluble materials, a solution
of RPd4 was added to the Pd-contaminated soil samples ([RPd4]final
=
10 mm). Fluorescence measurements were performed after several mi-
nutes.
Pd analysis in water: The water samples (sea-, pool-, and tap water) were
spiked with solutions of PdCl2 ([Pd]final =0–10 mm, which was equal to 0–
1.06 ppm). EtOH was added to prepare water/EtOH (1:1) solutions.
After filtering to remove any insoluble materials, a solution of RPd4 was
added to each Pd-contaminated sample ([RPd4]final =10 mm). Fluores-
cence measurements were performed after several minutes.
ðfsÞðFAuÞðAsÞðlexsÞðh2uÞ
ð1Þ
fu
¼
ðFAsÞðAuÞðlexuÞðh2s Þ
We chose Rhodamine B as a standard, which has a fluorescence quantum
yield of 0.49 in EtOH.[18]
Reversibility experiments: To a solution of RPd4 in CH2Cl2 was added
1.0 equiv of Pd2+ ions to obtain the complexed species RPd4-Pd2+ and
the UV/Vis spectrum was recorded. The solution of the complex in
CH2Cl2 was treated with a solution of Na2S, following which, the color of
the solution changed from deep pink to colorless. The organic layer was
washed several times with water, after which the optical spectrum was re-
corded and was found to be the same as that of free RPd4. Afterwards,
another 1.0 equiv of Pd2+ ions was added to that solution and the initial
UV/Vis spectrum of the RPd4-Pd2+ complex was largely restored, as was
the deep-pink color. This experiment was repeated over several cycles.
Theoretical calculations: The geometry optimizations were performed by
using density functional theory (DFT)[19] with the B3LYP functional and
the 6-31 g* basis set for H, C, N, O, and P atoms. For Pd, the standard
LanL2DZ basis set and the corresponding effective core potentials
(ECPs) were adopted.[20] The excited states were calculated by using
time-dependent DFT (TDDFT) with the same functional and basis set as
for the ground-state calculations. All calculations were carried out by
using the Gaussian 09W program package.[21]
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ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
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These are not the final page numbers!
Li, Honglin
