Inorganic Chemistry
Article
was effective in inducing an Eu(III) emission quenching
(99.8%) were purchased from Kanto Chemical Co., Inc. Tetrahy-
drofuran (THF), super dehydrated, with a stabilizer (for organic
synthesis), hydrogen peroxide (30%), potassium acetate, europium-
2
4−30
(
LMCT) state
the photosensitized energy transfer efficiency from the tmh
(III) acetate n-hydrate (99.9%), gadolinium acetate tetrahydrate
ligands was quite low (<1%). We used Eu(hfa)3 with
3
1,32
(99.9%), chrysene (95+%), and chloroform (spectroscopic grade)
were purchased from Wako Pure Chemical Industries, Ltd. N-
Bromosuccinimide (>98.0%), palladium(II) acetate (>98.0%), and
chlorodiphenylphosphine (>97.0%) were purchased from Tokyo
Chemical Industry Co., Ltd.
phosphine oxide ligands with a chrysene framework
diphenylphosphorylchrysene (DPCO)) to construct a highly
luminescent molecular thermometer using LMCT quenching
(
Preparation of Eu(hfa) (TPPO) . We prepared Eu-
3
2
33
(
hfa) (TPPO) according to a method previously reported.
3 2
Anal. calcd for C H EuF O P : C, 46.07, H, 2.50. Found: C,
6.03, H, 2.51.
5
1
33
18
8 2
4
Preparation of 6-Bromochrysene. We prepared 6-bromochry-
35
sene according to a previous report. A solution of chrysene (1.02 g,
.45 mmol) and N-bromosuccinimide (796 mg, 4.47 mmol) were
4
stirred for 20 h at 60 °C. The distilled water was added to a reactant
solution, and the obtained powder was filtrated. The solid powder is
washed with distilled water, methanol, and hexane.
1
Yield: 77% (1.05 g). H NMR (400 MHz, CDCl /TMS) δ/ppm =
3
9
.07 (s, 1H), 8.80 (d, 1H, J = 7.2 Hz), 8.71 (dd, 2H, J = 9.6 Hz, 10
Hz), 8.45 (d, 1H, J = 9.6 Hz), 8.02 (dd, 2H, J = 9.2 Hz, 6.0 Hz),
Figure 1. (a) Molecular design concept and molecular structures of
b) Eu(hfa) (DPCO) and (c) Eu(hfa) (TPPO) .
7
.79−7.72 (m, 3H), 7.68−7.65 (m, 1H)
(
3
2
3
2
Preparation of 6-Diphenylphosphorylchrysene (DPCO). A
solution of potassium acetate (481 mg, 4.90 mmol) and palladium
−2
acetate (8.8 mg, 3.91 × 10 mmol) were added dropwise to a
molecular orbital (HOMO) energy of the DPCO ligand
solution of 6-bromochrysene (1.22 g, 3.97 mmol) in dry DMA (14
(
EHOMO = −5.68 eV, Figure S1) was similar to that of the tmh
36
mL). Diphenylphosphine (0.7 mL, 4.03 mmol) was then added to
ligand and could induce low-energy LMCT states for
temperature-sensitive quenching. In the Eu(III) complex, hfa
ligands also contributed to intramolecular CH−F interactions
to construct a rigid coordination structure. The previously
reported luminescent Eu(III) complex (Figure 1c, Eu-
the solution, which was subsequently stirred for 24 h at 60 °C. Then,
2
00 mL of water was added to the solution, and the powder obtained
was filtrated. The product was extracted using CH Cl and washed
2
2
22
with distilled water before being dried over anhydrous MgSO4.
Following evaporation, the powder was dissolved in CHCl (30 mL),
3
33,34
and the resulting solution was cooled before the addition of a 30%
H O aqueous solution (3 mL). The reaction mixture was stirred for 3
(
hfa) (TPPO) , TPPO: triphenylphosphine oxide)
and
3
2
Gd(hfa) (DPCO) were also prepared for comparison of the
2
2
3
2
h. The product was extracted using CHCl and washed with distilled
3
photophysical data. In this study, we demonstrated a brilliant
red-luminescent thermometer based on π−f interactions. Our
findings could open up a new frontier in the field of lanthanide
photophysics and molecular materials chemistry.
water before being dried over anhydrous MgSO . The solvent was
4
then evaporated to produce a white powder whose compounds were
separated by silica gel chromatography (ethyl acetate: CH Cl = 1:4).
2
2
Recrystallization from CH Cl produced transparent crystals of the
2
2
title compound.
1
EXPERIMENTAL SECTION
Yield: 40% (733 mg). H NMR (400 MHz, CDCl /TMS) δ/ppm
■
3
General Methods. Electrospray ionization (ESI) mass spectrom-
etry was performed using a JEOL JMS-T100 LP instrument. H NMR
= 8.83 (d, 1H, J = 8.0 Hz), 8.73 (dd, 2H, J = 6.0 Hz, 3.2 Hz), 8.63 (d,
1H, J = 17 Hz), 8.11 (d, 1H, J = 9.2 Hz), 8.05 (d, 1H, J = 8.0 Hz),
8.98 (d, 1H, J = 8.0 Hz), 7.79 (dd, 4H, J = 6.8 Hz, 5.2 Hz), 7.71 (t,
1
spectra were recorded in CDCl on a JEOL ECS-400 (400 MHz)
spectrometer; CHCl (δH = 7.26 ppm) was used as the internal
reference. Elemental analyses were performed using a Micro Corder
JM10. Electronic absorption spectra were measured using a JASCO V-
3
1H, J = 8.0 Hz, 7.6 Hz), 7.65−7.50 (m, 9H); ESI-MS: m/z calcd for
3
+
C
H
30
21OP, [M + H] = 429.14; found, 429.14. Elemental analysis
calcd (%) for [DPCO + 0.5 CH
77.66, H 4.53.
Cl ]: C 77.79, H 4.71; found C
2
2
670 spectrophotometer. Diffuse-reflection spectra were recorded with
a JASCO V-670 spectrophotometer equipped with an integrating-
sphere unit (JASCO ISN-723). Emission spectra, excitation spectra,
and emission lifetimes (λex = 356 nm) for Eu(hfa) (TPPO)
Preparation of Gd(hfa)
(DPCO) . Dichloromethane (12 mL)
3 2
containing Gd(hfa) (H O) (181 mg, 0.300 mmol) and DPCO (257
3
2
2
mg, 0.599 mmol) was stirred for 12 h. The reaction mixture was
concentrated using a rotary evaporator. Recrystallization from
3
2
−
3
(
emission spectrum in CHCl : 1.0 × 10 M, λex = 380 nm;
3
−
4
excitation spectrum in CHCl : 1.0 × 10 M, λem = 613 nm; emission
spectrum in the solid state: λ = 365 nm; excitation spectrum in the
CH
Yield: 68% (334 mg). ESI-MS: m/z calcd for C70H44GdF12O P ,
6 2
2 2
Cl /hexane solution gave transparent crystals.
3
ex
3
3,34
+
solid state: λem = 613 nm)
and Eu(hfa) (DPCO) (emission
ex
[M − hfa] = 1428.17; found 1428.08. Elemental analysis calcd (%)
for C75 : C 55.08, H 2.77; found C 55.21, H 2.61. IR
(ATR) = 1653 (st, CO), 1251 (st, CF), 1143 (st, PO) cm .
Preparation of Eu(hfa) (DPCO) . Dichloromethane (15 mL)
containing Eu(hfa) (H O) (531 mg, 0.656 mmol) and DPCO (180
3
2
−
4
spectrum in CHCl : 1.0 × 10 M, λ = 380 nm; excitation spectrum
H45GdF18O P
8 2
3
−5
−1
in CHCl : 1.0 × 10 M, λem = 610 nm; emission spectrum in the
3
solid state: λ = 380 nm; excitation spectrum in the solid state: λ
=
3
2
ex
em
3
610 nm) were measured using a Horiba FluoroLog spectrofluor-
3
2
2
ometer. Emission quantum yields were measured using a FP-6300
mg, 0.419 mmol) was stirred for 12 h. The reaction mixture was
concentrated using a rotary evaporator. Recrystallization from
CH Cl /hexane solution gave transparent crystals.
spectrofluorometer with an integration sphere (ILF-533). Emission
1
2
spectra and emission lifetimes for Gd(hfa) (TPPO)2 and Gd-
3
2
2
(
hfa) (DPCO) were measured using a FP-6300 spectrofluorometer
Yield: 36% (251 mg). ESI-MS: m/z calcd for C H EuF O P ,
3
2
70 44 12 6 2
+
with a cryostat (Thermal Block Company SA-SB245T) and a
temperature controller (Oxford Instruments ITC-502S). Thermogra-
vimetric analyses (TGA) were performed using an EXSTAR 6000
TG/DTA 6300 instrument (Seiko Instruments Inc.).
[M − hfa] = 1421.15; found 1421.16. Elemental analysis calcd (%)
for C H EuF O P Cl [M + CH Cl ]: C 53.23, H 2.76; found C
7
6
47
18
8
2
2
2
2
53.52, H 2.52. IR (ATR) = 1653 (st, CO), 1251 (st, CF), 1133
−
1
(st, PO) cm .
Materials. Magnesium sulfate, anhydrous (>98.0% (titration)), n-
Single-Crystal X-ray Structure Determination. X-ray crystal
structure and crystallographic data for DPCO, Eu(hfa) (DPCO) ,
butyllithium in hexane (for organic synthesis), and chloroform-d1
3
2
B
Inorg. Chem. XXXX, XXX, XXX−XXX