Lanthanide complexes assembled from 3-fluorophthalate and 1,10-phenanthroline: Syntheses, crystal structure, photoluminescence, and white-light emission

Article abstract of DOI:10.1002/ejic.201402099

Two different crystal forms, [Ln₄(Fpht)₆(phen) ₆(H₂O)₄]·nH₂O (Ln = Eu 1, n = 14; Tb 2, n = 12) and [Ln(Fpht)(HFpht)(phen)(H₂O)] (Ln = La 3, Eu 4, Tb 5) were obtained from the one-pot reaction of Ln^III ions with 3-fluorophthalic acid (H₂Fpht) and 1,10-phenanthroline (phen). Complexes 1 and 2 are centrosymmetric tetranuclear molecules with two crystallographically different Ln^III ion environments, [Ln(1)O ₆N₂] and [Ln(2)O₄N₄]. The complexes have a tridentate bridging Fpht ligand and a bidentate terminal Fpht ligand. Complexes 3-5 show 2D networks with [LnO₇N₂] polyhedra. There are two kinds of ligands, Fpht and HFpht, which adopt chelating-bridging/ monodentate and bidentate-bridging coordination modes, respectively. The La ^III complex shows ligand-centered fluorescence. Eu^III and Tb^III complexes display red ⁵D₀→ ⁷F_0-4 and green ⁵D₄→ ⁷F_6-2 characteristic luminescence, respectively. Intriguingly, white-light emission was produced when Eu^III and Tb^III were codoped into the 2D La^III complex. Copyright

Full text of DOI:10.1002/ejic.201402099

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DOI:10.1002/ejic.201402099
Lanthanide Complexes Assembled from 3-Fluorophthalate
and 1,10-Phenanthroline: Syntheses, Crystal Structure,
Photoluminescence, and White-Light Emission
Yu-E Cha,[a,b] Xia Li,*[a] Dou Ma,[a] and Rui Huo[a]
Keywords: Metal-organic frameworks / Luminescence / Lanthanides / Bridging ligands / Doping
Two different crystal forms, [Ln4(Fpht)6(phen)6(H2O)4]·nH2O
(Ln = Eu 1, n = 14; Tb 2, n = 12) and [Ln(Fpht)(HFpht)(phen)-
(H2O)] (Ln = La 3, Eu 4, Tb 5) were obtained from the one-
pot reaction of LnIII ions with 3-fluorophthalic acid (H2Fpht)
show 2D networks with [LnO7N2] polyhedra. There are two
kinds of ligands, Fpht and HFpht, which adopt chelating-
bridging/monodentate and bidentate-bridging coordination
modes, respectively. The LaIII complex shows ligand-cen-
and 1,10-phenanthroline (phen). Complexes 1 and 2 are cen- tered fluorescence. EuIII and TbIII complexes display red
trosymmetric tetranuclear molecules with two crystallo-
graphically different LnIII ion environments, [Ln(1)O6N2] and
[Ln(2)O4N4]. The complexes have a tridentate bridging Fpht
ligand and a bidentate terminal Fpht ligand. Complexes 3–5
5D0 Ǟ7F0–4 and green 5D4 Ǟ7F6–2 characteristic lumines-
cence, respectively. Intriguingly, white-light emission was
produced when EuIII and TbIII were codoped into the 2D LaIII
complex.
Introduction
oxylates are sensitizing ligands for the emission of lantha-
nide complexes and they have been commonly used as link-
ers for the preparation of LnOFs that exhibit unique photo-
physical properties and intriguing structural features.[21] It
has also been well-documented that the π-conjugated 1,10-
phenanthroline (phen) ligand is an efficient sensitizer for
both EuIII and TbIII, and is usually inserted into lanthanide
carboxylate complexes.[10,22–24] 3-Fluorophthalic acid
(H2Fpht) is a suitable ligand for the preparation of lumines-
cent lanthanide complexes.[25] Because fluorinated organic
ligands have low-vibrational frequency of C–F (1220 cm–1),
the luminescence intensity of complexes can be remarkably
improved by reducing the fluorescence quenching effect of
the vibrational C–H bond (the energy level C–H
2950 cm–1).[26–30] However, much less work has been carried
out on coordination polymers of H2Fpht.[25,31,32] Therefore,
the complexes [Ln4(Fpht)6(phen)6(H2O)4]·nH2O (Ln = Eu
1, n = 14; Tb 2, n = 12) and [Ln(Fpht)(HFpht)(phen)(H2O)]
(Ln = La 3, Eu 4, Tb 5) were synthesized. Interestingly, 1
and 4, and 2 and 5 were obtained from a one-pot reaction
system, respectively. The complexes display different struc-
tural motifs: tetranuclear molecules (1 and 2) and 2D struc-
tures (3 and 4). The crystal structures and photophysical
properties were investigated. Notably, through doping of
the 2D frameworks, white-light emission was achieved when
excited with a UV wavelength.
In the past two decades, metal-organic frameworks
(MOFs) have received intense interest due to their novel
architectures and potential applications as functional materi-
als in fields such as gas storage, magnetism, catalysis, and
sensors.[1–4] Currently, there is increasing interest in white-
light emitting materials based on MOFs.[5–15] The interest
in such materials stems from their promising applications in
lighting light-emitting diodes and backlight sources.[16–20]
Lanthanide-containing MOFs (LnOFs) have received the
most attention for constructing white-light emitting materials
because they exhibit intense luminescence.[5–13] Furthermore,
it is possible to design isostructural compounds involving dif-
ferent lanthanide ions due to lanthanide contraction.
Red, green, and blue are the “primary” colors of white
light and their combination can produce a white-light emis-
sion. Thus, EuIII (red) and TbIII (green) are promising can-
didates for white-light emitting materials based on the lan-
thanide complexes.[5–11] It is important to design appropri-
ate lanthanide complexes with chromophoric antenna li-
gands for efficient emission. In general, aromatic-conju-
gated systems have highly efficient light absorption and
high efficiencies of intersystem crossing and energy transfer
processes. Investigations have revealed that aromatic carb-
[a] Beijing Key Laboratory for Optical Materials and Photonic
Devices, Deparment of Chemistry, Capital Normal University,
Beijing 100048, China
E-mail: xiali@mail.cnu.edu.cn
http://www.cnu.edu.cn/
Results and Discussion
Description of the Structures
[b] National Center for Rural Water Supply Technical
Guidance,Chinese Center for Disease Control and Prevention,
Beijing 102200, P. R. China
Complexes 1–2 and 3–5 are isostructural, respectively,
hence, only the structures of 2 and 3 will be discussed in
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201402099.
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detail. A summary of the crystallographic data and details one chelating-bridging carboxylate group (Scheme S1a). The
of the structure refinements are listed in Table 1. Selected bidentate Fpht anion as terminal ligand chelates with one
bond lengths and bond angles are listed in Table S1.
TbIII ion by two unidentate carboxylate oxygen atoms
The structure of 2 consists of a tetranuclear molecule (Scheme S1b). Tb(1) is eight-coordinated by four O atoms
[Tb4(Fpht)6(phen)6(H2O)4] and crystallization water mol- from three Fpht ligands, two N atoms from one phen li-
ecules. The [Tb4(Fpht)6(phen)6(H2O)4] molecule has a tetra- gand, and two water molecules, whereas Tb(2) is eight-coor-
nuclear centrosymmetry with two equivalent Tb2(Fpht)3- dinated by four O atoms from two Fpht ligands, and four
(phen)3(H2O)2 moieties linked by two bridged COO groups N atoms from two phen ligands. The phen ligand forms a
of the two Fpht ligands (Figure 1, a). In each of two equiva- five-membered chelate ring with each TbIII ion by means of
lent Tb2(Fpht)3(phen)3(H2O)2 moieties, two TbIII (Tb(1) its two N atoms, where phen acts as terminal blocking li-
and Tb(2)) ions with different coordination environments gand that prevents further polymerization because of the
are linked by one bridged COO group of the Fpht ligand. steric hindrance of the terminal ligands. The two terminal
There are two crystallographically distinct Fpht ligands. phen planes are ca. 78.38° apart. The distances of Tb1–O-
The tridentate Fpht anions bridging ligand bridges two (carboxyl), Tb1–O(water) and Tb1–N range from 2.307(3)
TbIII ions through one unidentate carboxylate group and to 2.367(3) Å, 2.430(4) to 2.435(4) Å, and 2.535(4) to
Table 1. Crystallographic data and structure refinement of complexes 1–5.
1
2
3
4
5
Empirical formula
Formula weight
T [K]
C
60H49Eu2F3N6O21 C60H47F3N6O20Tb2 C28H17LaF2N2O9
C28H17EuF2N2O9 C28H17F2N2O9Tb
1550.99
296(2)
1546.88
702.35
715.40
722.36
296(2)
293(2)
298(2)
293(2)
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
0.71073
monoclinic
P21/n
11.8530(6)
22.6293(10)
22.6381(11)
99.542(2)
5988.1(5)
4
0.71073
monoclinic
P21/n
11.8348(2)
22.4499(3)
23.6199(3)
109.7910(10)
5904.90(15)
4
0.71073
monoclinic
P21/c
12.6078(17)
16.171(2)
12.9635(18)
102.747(2)
2577.8(6)
4
0.71073
monoclinic
P21/c
12.9319(14)
16.4498(17)
13.2232(15)
101.670(2)
2754.8(5)
4
0.71073
monoclinic
P21/c
12.541(3)
15.909(4)
12.774(3)
101.462(4)
2497.7(10)
4
β [°]
V [Å3]
Z
Dcalcd. [Mgm–3
F(000)
]
1.713
3060
1.740
3064
1.810
1384
1.725
1408
1.921
1416
Limiting indices
–15ՅhՅ14,
–29ՅkՅ29,
–27ՅlՅ29
14400/10410
[R(int) = 0.0368]
14400/0/828
0.923
–15ՅhՅ15,
–29ՅkՅ29,
–30ՅlՅ31
14107/9616
[R(int) = 0.0468]
14107/0/820
1.050
–14ՅhՅ15,
–17ՅkՅ19,
–15ՅlՅ13
12892/4667
[R(int) = 0.0338]
4667/3/388
1.032
–15ՅhՅ14,
–19ՅkՅ19,
–7ՅlՅ15
13510/4857
[R(int) = 0.1348]
4857/0/379
0.899
–15ՅhՅ14,
–19ՅkՅ16,
–12ՅlՅ15
11684/4509
[R(int) = 0.0395]
4509/3/386
1.001
Reflections collected/unique
Data/restraints/parameters
Goodness-of-fit on F2
Final R indexes [IϾ2σ(I)]
R1 = 0.0395,
wR2 = 0.1177
R1 = 0.0627,
wR2 = 0.1390
0.887 and –0.791
R1 = 0.0417,
wR2 = 0.1019
R1 = 0.0714,
wR2 = 0.1185
0.823 and –1.363
R1 = 0.0262,
wR2 = 0.0597
R1 = 0.0324,
wR2 = 0.0625
0.473 and –0.468
R1 = 0.0550,
wR2 = 0.0755
R1 = 0.1194,
wR2 = 0.0891
1.561 and –1.046
R1 = 0.0309,
wR2 = 0.0685
R1 = 0.0492,
wR2 = 0.0771
1.027 and –1.008
R indexes [all data]
Largest diff. peak and hole [eÅ–3
]
Figure 1. (a) Molecular structure of 2 and the structural formula of the ligands. All hydrogen atoms and uncoordinated water molecules
are omitted for clarity; symmetry code: A: –x, –y, –z. (b) 3D supramolecular architecture.
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Figure 2. View of the structure of 3. (a) The coordination environment of the LaIII ion; free water molecules and H atoms are omitted
for clarity; symmetry code: A: –x + 1, –y, –z + 1; B: x, –y + 0.5, z + 0.5. (b) 2D structure. (c) 3D supramolecular architecture and
C–H···F hydrogen bonds; symmetry code: A: x – 1, y, z.
2.588(6) Å, respectively. The distances Tb2–O(carboxyl) uncoordinated (Scheme S1d). The carboxylate groups of
and Tb2–N range from 2.289(4) to 2.395(3) Å, and 2.527(4) Fpht and HFpht are twisted relative to their respective aro-
to 2.605(4) Å, respectively. Tb1 and Tb1A ions are inter- matic ring planes by 38.3°/86.6° and 33.1°/80.4°, respec-
connected by two COO groups from two tridentate Fpht tively. The adjacent LaIII ions are bridged by two chelating-
anions, whereas Tb2 and Tb1, and Tb1A and Tb2A are bridging carboxylate groups from two Fpht anions and two
together linked by one COO group from one tridentate bidentate-bridging carboxylate groups from two HFpht
Fpht anion, respectively, to form a tetranuclear molecule. anions to afford the [La2(COO)4] dimeric units with a
For the tetranuclear Tb(2)···Tb(1)···Tb(1A)···Tb(2A), the La···La distance of 4.198 Å. The [La2(COO)4] unit can be
distance Tb(1)···Tb(1A) of 5.751(2) Å is slightly shorter viewed as a basic building block for the whole structure;
than that of Tb(1)···Tb(2) [or Tb(1A)···Tb(2A)], which is such blocks are connected through Fpht ligands in two dif-
5.822(2) Å. The four TbIII ions are strictly coplanar. The ferent directions, giving rise to a layer structure with a
tetranuclear molecules are linked together by hydrogen La···La distance of 8.602 Å (Figure 2, b). The [La2(COO)4]
bonds involving lattice water, coordination water, and carb- unit can be viewed as four-connected nodes, and then the
oxylate oxygen atoms, giving rise to a 3D array (Figure 1, layer can be simplified as a (4,4) net with the Schläfli sym-
b; Table S2). The crystallization water molecules are tightly bol of (44). A 3D supramolecular architecture is formed
H-bonded to the tetranuclear molecule in the crystal pack- through hydrogen bonds between the C–H portions of the
ing. The observed distances of Ln–O, Ln–N, and Ln···Ln phen ligand and the F atoms of Fpht ligands from neigh-
in 1 and 2 decrease from Eu to Tb, respectively. Tetra- boring layers, C25–H25···F1A [H25···F1 2.537 Å, C12···F1
nuclear LnIII complexes are very rare and, to the best of 3.428 Å, C12–H12···F1, 160.31°] (Figure 2, c).
our knowledge, only two examples of such complexes have
A comparison of the average Ln–O, Ln–N, and Ln···Ln
distances for complexes 3, 4 and 5, reveals that the corre-
been reported.[33,34]
sponding distances decrease in the order LaIII Ͼ EuIII
Ͼ
Structure of [Ln(Fpht)(HFpht)(phen)(H2O)] (Ln = La 3,
Eu 4, Tb 5)
TbIII, respectively, which is in agreement with the lantha-
nide contraction along the row of trivalent lanthanide ions.
The crystal structures of complexes 3–5 consist of 2D
polymeric networks. The asymmetric unit of 3 comprises
one LaIII ion, one Fpht, one HFpht, one phen, and one
water molecule. There is only one LaIII environment in 3,
as shown in Figure 2 (a). Each LaIII ion is bound to four O
Thermogravimetric Analysis (TGA)
The thermal stabilities of all complexes were explored by
atoms from three Fpht anions, two O atoms from two means of TGA in the temperature range from room tem-
HFpht anions, one water molecule, and two N atoms from perature to 800 °C. The TGA curves of 1 and 2 exhibit sim-
a chelating phen molecule, thus resulting in a nine-coordi- ilar features (Figure 3). The first weight loss of 7.77% for 1
nate environment. The distances of La–O(carboxyl) range and 7.99% for 2 occurs in the range of 38–148 °C for 1 and
from 2.415(2) to 2.799(2) Å and those of La–N are 2.714(3) 35–155 °C for 2, which is equivalent to the release of free
and 2.735(3) Å. The distance of La–O(water) is 2.611(2) Å. water molecules (calcd. 8.12% for 1 and 7.09% for 2). The
The Ln–O and Ln–N distances are similar to those found anhydrous compounds decompose up to 250 °C for 1 and
in complexes 1–2. There are two kinds of anions, Fpht and 257 °C for 2, and completely decompose at 517 °C for 1
HFpht. The Fpht ligand adopts a chelating-bridging/mono- and 546 °C for 2. The complexes 2–4 do not contain guest
dentate coordination mode (Scheme S1, c). One carboxylate molecules, the TGA curve presents thermal stability up to
group of HFpht ligand adopts a bidentate-bridging coordi- 254 °C for 3, 258 °C for 4 and 269 °C for 5, at which point
nation mode and the protonated carboxylate group remains the complexes begin decomposition with mass loss corre-
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sponding to the organic ligands; this process persists up to of 5 (Figure 5). The excitation spectra exhibit large broad
525 °C for 3, 515 °C for 4, and 574 °C for 5. The remaining bands centered at 350 nm ascribed to the organic ligand
weight corresponds to the formation of lanthanide oxide and narrow bands at 394 nm attributed to the transition
(observed: 23.96% for 1, 26.68% for 2, 26.41% for 3, 7F0 Ǟ5L6 for the EuIII ion in 4 and at 379 nm for the
27.59% for 4 and 29.10% for 5; calculated: 21.91% for 1, 7F6 Ǟ5D3 transition of the TbIII ion in 5. However, the nar-
24.62% for 2, 23.26% for 3, 24.60% for 4 and 26.42% for row bands are weaker than the absorption of the organic
5).
ligand, which proves that luminescence sensitization
through excitation of the ligand is much more efficient than
direct excitation of the EuIII or TbIII ions absorption levels.
The emission spectra of 4 and 5 were recorded under the
maximum excitation wavelength at 350 nm. The emission
5
spectrum of 4 is composed of the first excited state, D0,
7
and the ground septet, FJ (J = 0–4) of EuIII (Figure 6, a).
The hypersensitive transition 5D0 Ǟ7F2 splits into two
peaks at 613 and 617 nm and is the strongest emission, re-
sulting in red fluorescence. The magnetic transition
5D0 Ǟ7F1 centers at 590 nm and is relatively weak. The in-
tensity ratio of 1.47 for I(5D0 Ǟ7F2)/I(5D0 Ǟ7F1) indicates
a low symmetry of the EuIII site in 4. The very weak peaks
at 579, 650 and 698 nm correspond to the transitions
5D0 Ǟ7F0, 5D0 Ǟ7F3, and 5D0 Ǟ7F4, respectively. Complex
5 shows emission bands at 488, 543, 586, and 618 nm,
which correspond to the characteristic transitions 5D4 Ǟ7FJ
(J = 6–3) of the TbIII ion (Figure 6, b). The most intense
Figure 3. The TGA curves of 1–5.
5
emission at 543 nm, corresponding to the D4 Ǟ7F5 transi-
Luminescent Properties
tion, results in green fluorescence. For 4 and 5, the absence
of emission from the ligand triplet states points out the
presence of an efficient ligand-to-EuIII/TbIII ions energy-
transfer mechanism, which demonstrates that the ligands
are suitable for sensitizing the EuIII/TbIII luminescence. In
addition, complexes 4 and 5 were also investigated by excit-
ing at f–f absorption of the EuIII and TbIII ions, respectively.
At excitation wavelength 394 nm for 4 and 379 nm for 5,
the emission intensity of the 5D0 Ǟ7FJ (J = 0–4) transitions
for 4 and 5D4 Ǟ7FJ (J = 6–3) transitions for 5 is lower than
that at the ligand excitation maxima (350 nm). This indi-
cates that ligand-to-LnIII energy transfer is effective in 4
and 5. The complex 4 has a luminescent quantum yield of
12.2% and a lifetime value of 0.595 ms, whereas complex 5
exhibits a higher quantum yield of 60.29% and longer a
lifetime of 1.041 ms, indicating the superior match of the
triplet energy level of ligands to that of the TbIII emitting
level. Because the lowest emitting level (around 20,
Photoluminescence measurements of the ligands and
complexes were acquired at room temperature. Under exci-
tation at 377 nm, the ligands display broad emission bands
centered at 439 nm for H2Fpht and 436 nm for phen, which
can be attributed to intraligand π*–π transition. Under ex-
citation at 400 nm, complex 3 presents a blue emission band
centered at 432 nm, which is similar to fluorescence of the
free ligands. An enhancement in the intensity is observed
compared with that of the free ligands (Figure 4). The lumi-
nescence lifetime value is 0.011 ms (Figure S1). Thus, we
assume that the emission may be attributed to the fluores-
cence of ligands. This is in accordance with the fact that
there is no f–f transition for the LaIII ion. The excitation
spectra were recorded in the range from 200 to 400 nm with
a wavelength monitored for the EuIII 5D0 Ǟ7F2 transition
(613 nm) of 4 and the TbIII 5D4 Ǟ7F5 transition (544 nm)
Figure 4. Emission spectra of H2Fpht, phen and complex 3 in the
solid state at room temperature.
Figure 5. Excitation spectra of 4 and 5 in the solid state at room
temperature.
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500 cm–1) of TbIII is higher than that (around 17, 500 cm–1) change from (x, y) A (0.329, 0.336) to B (0.273, 0.253) fall-
of EuIII ion, the energy transfer from the ligand to the TbIII ing within the white light region. The coordinate A (0.329,
ion is more efficient than that to the EuIII ion The observed 0.336) excited at 370 nm is very close to the standard white
luminescence decay profiles (Figure 6, inset) correspond to light (0.333, 0.333) according to 1931 CIE coordinate dia-
single exponential functions, thus implying the presence of gram.[35] The color rendering index (CRI) and correlated
only one emissive EuIII or TbIII center. The photolumines- color temperature (CCT) are 88 and 5658 K, respectively.
cence spectra of complexes 1 and 2 show similar character- CRI values up to 80 correspond to a warm-white light that
istic emissions to those of the corresponding EuIII ion in 4 is appropriate for solid-state light applications. However,
and TbIII ion in 5, respectively (Figure S2).
the CIE coordinates change from C (0.377, 0.395) to D
(0.433, 0.480) with a decrease in the excitation wavelength
from 365 to 350 nm, falling within the yellow-light region,
whereas the CIE coordinates change from E (0.241, 0.208)
to F (0.192, 0.135) with an increase in the excitation wave-
length from 380 to 390 nm, falling within the blue-light re-
gion (Figure 8). Therefore, the doped material provides a
promising and convenient approach to obtain uniform
white light emitting or tunable luminescent MOFs. Because
simultaneous luminescence of TbIII and EuIII occurs in the
LaIII complex to give green and red emission under UV
excitation, this system therefore provides an approach with
which to explore tunable white-light luminescence of
LnOFs.
Figure 6. Emission spectra of 4 (a) and 5 (b) in the solid state at
room temperature. Inset: decay profile of the complexes.
Figure 7. Emission spectra of the La18Eu2Tb80-doped material ex-
cited at 370 nm.
Considering that complexes 3, 4, and 5 emit the primary
colors (blue, red, and green), it is therefore possible to con-
struct white-light MOFs through doping of EuIII and TbIII
into the LaIII complex. Thus, the La18Eu2Tb80-doped mate-
rial was produced and its phase purity was verified by pow-
der X-ray diffraction (PXRD) analysis (Figure S3). The
emission spectrum of the La18Eu2Tb80-doped material is
composed of a broad band and a series of sharp lines (Fig-
ure 7). The broad emission band between 400 and 470 nm
is ascribed to the ligands in 3. The narrow emission bands
at 492 and 546 nm, and at 590 and 613 nm arise from the
characteristic transitions of TbIII and EuIII ion, respectively.
The bands at 586 and 618 nm of the TbIII ion overlap with
the bands at 590 and 613 nm of the EuIII ion. Upon exci-
tation from 370 to 375 nm, the Commission International
Figure 8. The CIE chromaticity diagram of the La18Eu2Tb80-doped
material excited at 370 nm (A), 375 nm (B), 350 nm (D), 365 nm
de I’Eclairage (CIE) chromaticity coordinates (Table S3) (C), 380 nm (E), and 390 nm (F).
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then cooled to room temperature and colorless crystals of 3, 4 and
5 were collected. The resulting solution was filtered and the filtrate
Conclusions
Tetranuclear molecules [Ln4(Fpht)6(phen)6(H2O)4]·nH2O was allowed to stand at room temperature without further disturb-
ance for two weeks to give colorless crystals of 1 and 2.
(Ln = Eu 1, Tb 2) and 2D frameworks [Ln(Fpht)(HFpht)-
(phen)(H2O)] (Ln = La 3, Eu 4, Tb 5) were synthesized in a
one-pot reaction system. The two types of complexes show
different thermal stabilities and luminescence properties be-
cause they involve different LnIII coordination geometry.
The LaIII complex shows ligand-centered luminescence in
the blue light. The EuIII- and TbIII-containing complexes
exhibit typical intra-4f narrow line-emission in red and
green light, respectively. Complexes 4 and 5 exhibit high
quantum yield and longer lifetime and can be good candi-
dates for light-emitting applications. In particular, Tb-con-
taining complex 5 has a high quantum yield of 60%. The
combination of LaIII, EuIII, and TbIII ions for isomorphic
2D complexes 3–5 allows fine-tuning of the photolumines-
cence by changing the excitation wavelength, and the emis-
sion can be tuned from yellow to white. Finally, white-light
emission was successfully realized. The different composi-
tions of La/Eu/Tb-doped complexes can be used for tunable
and white-light emitting materials, which have potential ap-
plications in the fields of labeling, sensing, and color dis-
plays.
Complex 1: Yield 20% based on EuIII. C120H98Eu4F6N12O40
(3069.98): calcd. C 46.40, H 3.18, N 5.40; found C 46.69, H 2.98,
N 5.50. IR (KBr pellet): ν = 3411 (s, br), 1600 (s), 1563 (s), 1519
˜
(m), 1463 (m), 1424 (m), 1399 (s), 1382 (s), 1240 (m), 847 (m), 772
(m), 730 (m), 465 (w) cm–1.
Complex 2: Yield 20% based on TbIII. C120H94F6N12O40Tb4
(3093.81): calcd. C 46.59, H 3.06, N 5.40; found C 46.74, H 3.28,
N 5.39. IR (KBr pellet): ν = 3410 (s, br), 1601 (s), 1563 (s), 1518
˜
(m), 1463 (m), 1424 (m), 1400 (s), 1381 (s), 1240 (m), 847 (m), 772
(m), 730 (m), 464 (w) cm–1.
Complex 3: Yield 49% based on LaIII. C28H15F2LaN2O9 (700.34):
calcd. C 48.02, H 2.16, N 4.00; found C 48.07, H 2.20, N 3.95. IR
(KBr pellet): ν = 3430 (m, br), 1733 (m), 1626 (s), 1602 (s), 1546
˜
(s), 1519 (m), 1476 (m), 1454 (m), 1402 (s), 1251 (m), 962 (m), 862
(m), 779 (m), 725 (m), 677 (w), 581 (w), 463 (w) cm–1.
Complex 4: Yield 43% based on EuIII. C28H17EuF2N2O9 (715.41):
calcd. C 47.00, H 2.40, N 3.92; found C 46.86, H 2.28, N 3.66. IR
(KBr pellet): ν = 3540 (m, br), 1734 (m), 1636 (s), 1605 (s), 1547
˜
(s), 1519 (m), 1478 (m), 1455 (m), 1398 (s), 1250 (m), 962 (m), 863
(m), 781 (m), 724 (m), 677 (w), 584 (w), 464 (w) cm–1.
Complex 5: Yield 48% based on TbIII. C28H17F2N2O9Tb (722.37):
calcd. C 46.56, H 2.37, N 3.88; found C 46.32, H 2.24, N 3.96. IR
(KBr pellet): ν = 3434 (m, br), 1734 (m), 1624 (s), 1606 (s), 1546
˜
Experimental Section
(s), 1519 (m), 1480 (m), 1453 (m), 1405 (s), 1248 (m), 963 (m), 863
Experimental Details and Physical Measurements: All reagents were
commercially available and were used without further purification.
Elemental analyses (C, H, and N) were determined with an Ele-
mentar Vario EL analyzer. IR spectra were recorded with a Nicolet
Magna 750 FT/IR spectrometer using the KBr pellet technique in
the range of 400–4000 cm–1. X-ray diffraction was performed with
a PANaytical XЈPert PRO MPD diffractometer for Cu-Kα radia-
tion (λ = 1.5406 Å), with a scan speed of 2 °min–1 and a step size
of 0.02° in 2θ. The simulated PXRD patterns were obtained from
the single-crystal X-ray diffraction data. The experimental PXRD
patterns are identical with the calculated spectra obtained from the
single-crystal structures, confirming the phase purity of the bulk
samples. The fluorescence spectra were recorded with an FL4500
fluorescence spectrophotometer (Japan Hitachi company) at room
temperature. The lifetimes were measured at room temperature
with a Life Spec-Red Picosecond lifetime spectrometer (Edinburgh
Instruments). The emission quantum yields were measured at room
temperature by using a quantum yield measurement system (Fluo-
rolog-3; HORIBA company) with a 450 W Xe lamp coupled to a
monochromator for wavelength discrimination, an integrating
sphere as sample chamber, and an analyzer R928P for signal detec-
tion. The CIE color coordinates were calculated based on inter-
national CIE standards.[35] Thermogravimetric analyses (TGA)
were carried out with a Shimadzu DTG-60AH thermal analyzer
(Japan) under air from room temperature to 800 °C with a heating
rate of 10 °C/min.
(m), 781 (m), 725 (m), 695 (w), 584 (w), 465 (w) cm–1.
La18Eu2Tb80 Doped Complex: Anal. Calc. for La18Eu2Tb80-doped
complex: C, 47.25; H, 2.20, N, 4.09%. IR (KBr pellet): ν = 3426
˜
(m, br), 1734 (m), 1625 (s), 1602 (s), 1576 (s), 1545 (s), 1519 (m),
1477 (m), 1456 (m), 1400 (s), 1241 (m), 962 (m), 862 (m), 779 (m),
727 (m), 695 (w), 581 (w), 483 (w) cm–1.
X-ray Crystallography Study: The X-ray single-crystal data collec-
tions for the five complexes were performed with a Bruker SMART
CCD diffractometer using graphite monochromatized Mo-Kα radi-
ation (λ = 0.71073 Å). Semiempirical absorption corrections were
applied. The structures were solved by direct methods and refined
by full-matrix least-squares method on F2 using the SHELXS-97
and SHELXL-97 programs.[36,37] All non-hydrogen atoms in the
complexes were refined anisotropically. The hydrogen atoms were
generated geometrically and treated by a mixture of independent
and constrained refinement. A summary of the crystallographic
data and details of the structure refinements is listed in Table 1.
Selected bond lengths and bond angles are listed in Table S1.
CCDC-917459 (for 1), -917460 (for 2), -917462 (for 3), -917463 (for
4), and -917464 (for 5) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
Supporting Information (see footnote on the first page of this arti-
cle): X-ray crystallographic files in CIF format, selected bond
lengths and bond angles (Tables S1) and H-bonds for 2 (Tables S2).
The PXRD patterns for complexes and the codoped complex (Fig-
ure S1). The coordination modes of Fpht and HFpht ligands
Synthesis of Complexes: Preparation of [Ln4(Fpht)6(phen)6(H2O)4]·
nH2O (Ln = Eu 1, n = 14; Tb 2, n = 12) and [Ln(Fpht)(HFpht)-
(phen)(H2O)] (Ln = La 3, Eu 4, Tb 5): A mixture of Ln(NO3)3·
6H2O (Ln = La, Eu, Tb) (0.1 mmol), 3-fluorophthalic acid
(0.2 mmol), phen (0.2 mmol), H2O (8.0 mL), C2H5OH (2.0 mL), (Scheme S1). Emission spectra of complexes 1(a) and 2 (b) in the
and 2 mol/L NaOH (2 mL) was sealed in a 25 mL stainless-steel
reactor with Teflon liner and heated to 170 °C. The system was
solid state at room temperature (Figure S3). CIE chromaticity co-
ordinates for the codoped complexes(Table S3).
Eur. J. Inorg. Chem. 2014, 2969–2975
2974
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
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Received: February 24, 2014
Published Online: May 27, 2014
Eur. J. Inorg. Chem. 2014, 2969–2975
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© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim