Hydrothermal synthesis, crystal structure, and luminescence of lanthanide(III) coordination polymers with tetrafluorosuccinate and 1,10-phenanthroline

Article abstract of DOI:10.1016/j.molstruc.2008.09.017

Three new coordination polymers [Nd₂(TFSA)₃(phen)₂]_n (1) and {[Ln(TFSA)(phen)(H₂O)₄]·0.5(TFSA)·2(phen) H₂O}_n (Ln = Sm, 2 and Dy, 3; TFSA = tetrafluorosuccinate; phen =

Full text of DOI:10.1016/j.molstruc.2008.09.017

Journal of Molecular Structure 919 (2009) 277–283
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Hydrothermal synthesis, crystal structure, and luminescence of lanthanide(III)
coordination polymers with tetrafluorosuccinate and 1,10-phenanthroline
a
b
Xia Li a, , Yan-Bin Zhang , Ying-Quan Zou
*
a Department of Chemistry, Capital Normal University, 105 Xisanhuan North, Beijing 100048, PR China
b Department of Chemistry, Beijing Normal University, Beijing 100875, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 14 June 2008
Received in revised form 9 September 2008
Accepted 15 September 2008
Available online 30 September 2008
Three new coordination polymers [Nd2(TFSA)3(phen)2]n (1) and {[Ln(TFSA)(phen)(H2O)4]Á0.5(TFSA)Á
2(phen) H2O}n (Ln = Sm, 2 and Dy, 3; TFSA = tetrafluorosuccinate; phen = 1,10-phenanthroline) were
synthesized and characterized using X-ray structure analyses and luminescence spectroscopy. The 1
has a 2-D network structure through TFSA ligands via bridging/chelating-bridging pentadentate and
bridging/bridging tetradentate coordination modes. The 2 and 3 have novel 1-D chain structures, in
which adjacent Ln(III) ions are linked though the single
sion spectrum in the NIR of 1 corresponds to the F3/2
emission spectra of 2 and 3 indicate the typical luminescence characteristics of the Sm(III) and Dy(III)
ions, respectively.
l
?
2-bridging TFSA ligands as linkages. The emis-
Keywords:
4
4I9/2
,
,
transitions of Nd(III) ion. The
11/2 13/2
Lanthanide coordination polymer
Tetrafluorosuccinate
Hydrothermal synthesis
Crystal structure
Ó 2008 Elsevier B.V. All rights reserved.
Luminescence
1. Introduction
quench the metal excited states nonradiatively, leading to de-
creased luminescence intensities [9]. Furthermore, the complexes
Luminescent lanthanide complexes have attracted attention due
to their potential applications in fluorescence materials, electrolumi-
nescent devices, bioassays, and luminescent probes [1–5]. Some tri-
valent lanthanide ions exhibit good emission, such as in the visible
region emitting Sm(III), Eu(III), Tb(III), and Dy(III), and in the near-
infrared (NIR) emitting Nd(III), Er(III), and Yb(III). Over the past two
decades, many studies have focused on lanthanide complexes with
carboxylic acid ligands, which have been used to excite lanthanide
ions. In particular lanthanide coordination polymers constructed by
multicarboxylate ligands show fascinating structure, and the one-,
two- and three-dimension polymers consisting of lanthanide and
multicarboxylate have been reported [2–17]. In the field of lantha-
nide carboxylates complexes, the rigid benzene-multicarboxylates
[2–11] and the flexible carboxylate ligands are employed [12–17].
In this work, we use a flexible ligand, namely tetrafluorosucci-
nic acid (H2TFSA) to construct lanthanide coordination polymers.
The H2TFSA ligand has advantages compared to other ligands: (i)
the flexible ligand can adopt various conformations due to the con-
formational freedom of the carbon skeleton leading to coordination
polymers with novel structures; (ii) its steric hindrance is much
smaller than benzene-multicarboxylates; (iii) its two carboxylate
groups locate on the relative orientation; (iv) it is a fully fluori-
nated aliphatic ligand. Fluorinated organic ligands can enhance
luminescence intensities of complexes, because of the species con-
taining high-energy C–H, N–H, and/or O–H oscillators significantly
of H2TFSA with metals were relatively less reported [18–21]. In
addition, 1,10-phenanthroline (phen) molecule is a good ligand
for Ln(III) ions, it is helpful to increase the rigidity and the thermal
stability of complexes, and it can also enhance the luminescent
properties of lanthanide complexes due to the antenna effect. In
the context, we synthesized three new lanthanide coordination
polymers, [Nd2(TFSA)3(phen)2]n (1) and {[Ln(TFSA)(phen)(H2O)4]Á
0.5(TFSA)Á2(phen) H2O}n (Ln = Sm, 2 and Dy, 3). Herein, the synthe-
ses, structural characteristics, and luminescence of the three com-
plexes were reported.
2. Experimental
2.1. Synthesis of the complexes
All reagents used for synthesis were of analytical grade and
used without further purification, except that the hydrated lantha-
nide chlorides were prepared by reaction of lanthanide oxides
Ln2O3 (Ln = Nd, Sm, and Dy) and hydrochloric acid.
Synthesis of [Nd2(TFSA)3(phen)2]n (1): a mixture of NdCl3ÁH2O
(0.0717 g, 0.2 mmol), tetrafluorosuccinic acid (0.0570 g, 0.3 mmol),
1,10-phenanthroline (0.0769 g, 0.4 mmol), deioned water (7 ml),
and sodium hydroxide aqueous solution (2 mol LÀ1, 0.40 ml) was
placed in a 25 ml Teflon-lined stainless steel autoclave. After stir-
red, the mixture was sealed and heated at 110 °C for 5 days under
autogenous pressure and then slowly cooled to room temperature.
After filtration, the product was washed with water, and then
* Corresponding author. Tel./fax: +86 10 68902320.
E-mail address: xiali@mail.cnu.edu.cn (X. Li).
0022-2860/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2008.09.017

278
X. Li et al. / Journal of Molecular Structure 919 (2009) 277–283
colorless block-like single crystals suitable for X-ray diffraction
were obtained in 58% yield (based on Nd). Anal. Calcd (%) for
C36H16F12N4O12Nd2 (1213.00): C, 35.65; H, 1.33; N, 4.79. Found:
C, 35.61; H, 1.32; N, 4.62. Selected IR (KBr pellet,
vs (masCOOÀ), 1421 s (msCOOÀ), 1384 s ( phen), 1232 m (msCOOÀ), 1128
vs ( phen), 848 m, 727 s (dphen(C–H)), 634 m, 541 m, 412 w ( Nd–O).
m
/cmÀ1): 1658
m
m
m
Synthesis of {[Sm(TFSA)(phen)(H2O)4]Á0.5(TFSA)Á2(phen)H2O}n
(2): The synthetic procedure of 2 was similar to that of 1 except
NdCl3ÁH2O was replaced by SmCl3Á6H2O (0.0729 g, 0.2 mmol) and
Table 1
Crystallographic data and structure refinement for complexes 1–3
the amount of sodium hydroxide aqueous solution (2 mol LÀ1
,
Complexes
1
2
3
0.33 ml). Colorless block-like crystals of 2 were obtained in 43%
yield (based on Sm). Anal. Calcd (%) for C42H34F6N6O11Sm
(1063.11): C, 47.45; H, 3.22; N, 7.90. Found: C, 47.21; H, 3.45; N,
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
a (Å)
C36H16F12N4O12Nd2 C42H34F6N6O11Sm C42H34F6N6O11Dy
1213.00
294(2)
1063.11
273(2)
1075.25
273(2)
Monoclinic
C2/c
Triclinic
P1
Triclinic
P1
8.26. Selected IR (KBr pellet,
1624 s (masCOOÀ), 1425 m (msCOOÀ), 1375 m, 1120 vs (
729 m (dphen(C–H)), 636 m, 540 w, 414 w ( Sm–O).
m
/cmÀ1): 3386 br (
m
O–H), 1677 vs,
ꢀ
ꢀ
m
phen), 844 m,
23.939(3)
9.441(11)
17.866(2)
90.00
101.598(2)
90.00
7.758(3)
14.383(5)
20.295(8)
100.227(2)
98.622(2)
105.514(2)
2100.3(14)
2
7.747(3)
14.343(5)
20.210(7)
100.417(2)
98.540(2)
105.377(2)
2083.4(13)
2
m
b (Å)
c (Å)
Synthesis of {[Dy(TFSA)(phen)(H2O)4]Á0.5(TFSA)Á2(phen)H2O}n
(3): The synthetic procedure of 3 was similar to that of 1 except
NdCl3ÁH2O was replaced by DyCl3ÁH2O (0.0754 g, 0.2 mmol)
a
(°)
b (°)
c
(°)
and the amount of sodium hydroxide aqueous solution (2 mol LÀ1
,
V (Å3)
3955.2(8)
8
0.24 ml). Colorless block-like crystals of 3 were obtained in 48.3%
yield (based on Dy). Anal. Calcd (%) for C42H34F6N6O11Dy
(1075.25): C, 46.92; H, 3.19; N, 7.81. Found: C, 46.65; H, 3.01; N,
Z
Dc (mg/m3)
Absorption
coefficient
2.037
1.681
1.714
2.722
1.494
1.890
7.99. Selected IR (KBr pellet,
m mO–H), 1681 vs,
/cmÀ1): 3386 br (
(mmÀ1
)
1631 s (masCOOÀ), 1425 m (msCOOÀ), 1375 m, 1122 m (
m
phen), 852 m,
F (000)
2336
1064
1072
Crystal size (mm)
h range for data
collection (o)
0.22 Â 0.18 Â 0.12 0.38 Â 0.26 Â 0.20 0.36 Â 0.22 Â 0.18
727 m (dphen(C–H)), 632 m, 539 w, 418 w (mDy–O).
1.74–26.39
1.04–28.39
1.05–28.30
Limiting indices
À29 6 h 6 29
À9 6 k P 11
À22 6 l 6 22
À10 6 h 6 10
À19 6 k 6 19
À27 6 l 6 27
30928/10535
À10 6 h 6 10
18 6 k 6 19
À26 6 l 6 26
29857/10365
Table 3
Selected bond lengths (Å) and angles (°) for complex 2
Reflections collected/ 10989/4041
unique
Sm(1)–O(5)
Sm(1)–O(8)#1
Sm(1)–O(1)
2.322(3)
2.378(3)
2.450(3)
Sm(1)–O(2)
Sm(1)–O(4)
Sm(1)–O(3)
2.373(3)
2.411(2)
2.473(3)
[Rint = 0.0300]
99.6%
[Rint = 0.0271]
96.5 %
[Rint = 0.0308]
90.1 %
Completeness
to h = 28.31°
Data/restraints/
parameters
Sm(1)–N(1)
2.600(3)
Sm(1)–N(2)
2.608(3)
4041/54/326
1.033
10535/6/635
1.034
10365/0/635
1.044
O(5)–Sm(1)–O(2)
O(2)–Sm(1)–O(8)#1
O(2)–Sm(1)–O(4)
O(5)–Sm(1)–O(1)
O(8)#1–Sm(1)–O(1)
O(5)–Sm(1)–O(3)
O(8)#1–Sm(1)–O(3)
O(1)–Sm(1)–O(3)
O(2)–Sm(1)–N(1)
O(4)–Sm(1)–N(1)
O(3)–Sm(1)–N(1)
O(2)–Sm(1)–N(2)
O(4)–Sm(1)–N(2)
O(3)–Sm(1)–N(2)
107.37(12)
145.10(10)
73.29(10)
73.15(10)
139.01(9)
151.75(11)
81.56(10)
133.83(10)
140.18(10)
146.52(10)
107.71(11)
83.81(10)
140.83(9)
70.83(10)
O(5)–Sm(1)–O(8)#1
O(5)–Sm(1)–O(4)
O(8)#1–Sm(1)–O(4)
O(2)–Sm(1)–O(1)
O(4)–Sm(1)–O(1)
O(2)–Sm(1)–O(3)
O(4)–Sm(1)–O(3)
O(5)–Sm(1)–N(1)
O(8)#1–Sm(1)–N(1)
O(1)–Sm(1)–N(1)
O(5)–Sm(1)–N(2)
O(8)#1–Sm(1)–N(2)
O(1)–Sm(1)–N(2)
N(1)–Sm(1)–N(2)
78.05(10)
81.67(11)
73.53(10)
72.74(10)
128.60(10)
79.20(11)
73.89(11)
85.10(11)
73.69(10)
75.34(10)
136.34(10)
116.65(10)
70.34(10)
63.25(9)
Goodness-of-fit
on F2
Final R indices
[I > 2r(I)]
R1 = 0.0204
R1 = 0.0360
R1 = 0.0273
wR2 = 0.0443
R1 = 0.0277
wR2 = 0.0467
0.521 and À0.649
wR2 = 0.0962
R1 = 0.0415
wR2 = 0.1014
0.877 and À0.699 0.621 and À0.579
wR2 = 0.0594
R1 = 0.0347
wR2 = 0.0696
R indices (all data)
Largest diff. peak
and hole (e/Å3)
Table 2
Symmetry transformations used to generate equivalent atoms: #1 x À 1, y, z.
Selected bond lengths (Å) and angles (°) for complex 1
Nd(1)–O(1)
Nd(1)–O(3)
Nd(1)–O(5)
Nd(1)–O(1)#2
2.411(19)
2.435(18)
2.453(18)
2.790(19)
2.627(2)
94.70(7)
71.82(7)
75.34(6)
76.44(6)
74.77(7)
118.84(6)
140.12(7)
72.70(7)
140.05(6)
64.84(6)
48.12(5)
94.72(7)
144.00(7)
153.86(7)
120.90(7)
126.34(7)
75.52(6)
102.94(6)
Nd(1)–O(4)#1
Nd(1)–O(6)
Nd(1)–O(2)#2
Nd(1)–N(1)
2.416(18)
2.444(18)
2.614(19)
2.602(2)
Table 4
Nd(1)–N(2)
Selected bond lengths (Å) and angles (°) for complex 3
O(1)–Nd(1)–O(4)#1
O(4)#1–Nd(1)–O(3)
O(4)#1–Nd(1)–O(6)
O(1)–Nd(1)–O(5)
O(3)–Nd(1)–O(5)
O(1)–Nd(1)–O(2)#2
O(3)–Nd(1)–O(2)#2
O(5)–Nd(1)–O(2)#2
O(4)#1–Nd(1)–O(1)#2
O(6)–Nd(1)–O(1)#2
O(2)#2–Nd(1)–O(1)#2
O(4)#1–Nd(1)–N(1)
O(6)–Nd(1)–N(1)
O(1)–Nd(1)–N(2)
O(3)–Nd(1)–N(2)
O(5)–Nd(1)–N(2)
N(1)–Nd(1)–O(2)#2
N(2)–Nd(1)–O(1)#2
O(1)–Nd(1)–O(3)
O(1)–Nd(1)–O(6)
O(3)–Nd(1)–O(6)
O(4)#1–Nd(1)–O(5)
O(6)–Nd(1)–O(5)
O(4)#1–Nd(1)–O(2)#2
O(6)–Nd(1)–O(2)#2
O(1)–Nd(1)–O(1)#2
O(3)–Nd(1)–O(1)#2
O(5)–Nd(1)–O(1)#2
O(1)–Nd(1)–N(1)
O(3)–Nd(1)–N(1)
O(5)–Nd(1)–N(1)
O(4)#1–Nd(1)–N(2)
O(6)–Nd(1)–N(2)
O(2)#2–Nd(1)–N(2)
N(1)–Nd(1)–O(1)#2
N(1)–Nd(1)–N(2)
74.09(6)
73.38(6)
130.93(7)
146.59(7)
129.89(6)
136.69(7)
88.16(7)
71.68(7)
134.06(6)
68.15(6)
142.55(7)
74.67(7)
75.85(7)
72.78(7)
81.16(7)
65.17(6)
119.19(6)
62.89(8)
Dy(1)–O(8)#1
Dy(1)–O(5)
Dy(1)–O(4)
Dy(1)–N(1)
2.284(2)
2.331(2)
2.390(3)
2.547(2)
Dy(1)–O(2)
Dy(1)–O(3)
Dy(1)–O(1)
Dy(1)–N(2)
2.319(2)
2.356(3)
2.418(2)
2.560(2)
78.31(8)
81.35(9)
73.26(9)
73.26(10)
127.99(10)
79.66(9)
74.70(10)
83.19(8)
73.52(8)
75.17(9)
135.79(8)
116.41(8)
70.60(9)
64.30(8)
O(8)#1–Dy(1)–O(2)
O(2)–Dy(1)–O(5)
O(2)–Dy(1)–O(3)
O(8)#1–Dy(1)–O(4)
O(5)–Dy(1)–O(4)
O(8)#1–Dy(1)–O(1)
O(5)–Dy(1)–O(1)
O(4)–Dy(1)–O(1)
O(2)–Dy(1)–N(1)
O(3)–Dy(1)–N(1)
O(1)–Dy(1)–N(1)
O(2)–Dy(1)–N(2)
O(3)–Dy(1)–N(2)
O(1)–Dy(1)–N(2)
107.86(9)
144.33(9)
73.11(10)
72.72(9)
139.29(9)
151.63(10)
80.39(8)
134.68(10)
141.25(9)
145.52(9)
108.39(9)
84.25(9)
O(8)#1–Dy(1)–O(5)
O(8)#1–Dy(1)–O(3)
O(5)–Dy(1)–O(3)
O(2)–Dy(1)–O(4)
O(3)–Dy(1)–O(4)
O(2)–Dy(1)–O(1)
O(3)–Dy(1)–O(1)
O(8)#1–Dy(1)–N(1)
O(5)–Dy(1)–N(1)
O(4)–Dy(1)–N(1)
O(8)#1–Dy(1)–N(2)
O(5)–Dy(1)–N(2)
O(4)–Dy(1)–N(2)
N(1)–Dy(1)–N(2)
141.76(8)
71.14(10)
Symmetry transformations used to generate equivalent atoms: #1 Àx + 2, Ày,
Àz + 2; #2 Àx + 2, y, Àz + 3/2.
Symmetry transformations used to generate equivalent atoms: #1 x + 1, y, z.

X. Li et al. / Journal of Molecular Structure 919 (2009) 277–283
279
2.2. X-ray crystallography
atoms were fixed at their ideal positions. Summary of the
crystallographic data and details of the structure refinements
are listed in Table 1. The selected bond lengths and bond an-
The X-ray single crystal data collections for three complexes
were performed on
a
Bruker SMART CCD diffractometer
radiation
gles of complexes 1, 2, and 3 are listed in Tables 2–4,
respectively.
equipped with graphite monochromated Mo
a
Ka
(k = 0.71073 Å). Semiempirical absorption corrections were
applied. The structures were solved by direct method and
refined by full-matrix least-squares method on F2 using the
SHELXTL-97 software package [22,23]. All non-hydrogen atoms
in the complexes were refined anisotropically. The hydrogen
CCDC-668403, 655772, and 655774 for complexes 1, 2, and 3,
respectively, contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK; fax: +44(0)1223–
336033; email: deposit@ccdc.cam.ac.uk
a
b
Fig. 1. View of the structure of 1: (a) coordination geometry of the dimer building block and coordination environment of Nd(III) ion at the 30% probability displacement
ellipsoids. (b) 2-D network. All hydrogen atoms are omitted for clarity.

280
X. Li et al. / Journal of Molecular Structure 919 (2009) 277–283
2.3. Physical measurements
Nd
CF2
Nd
CF2
a
b
C
O
O
Elemental analyses (C, H, N) were performed using an Elemen-
tar Vario EL analyzer. IR spectra were recorded with a Bruker
EQUINOX-55 spectrometer using the KBr pellet technique. The
steady-state near-infrared emission spectra were measured on an
Edinburgh FLS920 fluorescence spectrometer equipped with a
Hamamatsu R5509-72 supercooled photomultiplier tube at 193 K
and a TM300 emission monochromator. Near-IR emission spectra
were corrected via a calibration curve supplied with the instru-
ment. Solid-state luminescence spectra were recorded on an
F-4500 fluorescence spectrophotometer at room temperature.
C
C
O
O
O
O
CF2
Nd
Nd
Nd
CF2
C
O
O
Nd
Nd
c
CF2
CF2
3. Results and discussion
C
C
3.1. Structural description of [Nd2(TFSA)3(phen)2]n (1)
O
O
O
O
The complex 1 consists of a 2-D network, as shown in Fig. 1. The
Nd1(III) ion is nine coordinated by seven oxygen atoms of TFSA
groups and two nitrogen atoms from phen molecule (Fig. 1a).
The Nd1(III) ion is in a distorted monocapped square-antiprism
coordination sphere. Atoms O1, O2A, O5, O6 and O3, O4B, N1, N2
form the upper and lower square with mean deviations of 0.1176
and 0.2250 Å, respectively, and the dihedral angle between them
is 2.9°. Atom O1A caps the upper plane. The Nd1–O bond lengths
vary from 2.411(19) to 2.790(19) Å with the average distance of
2.509 Å. The Nd1–N bond lengths are 2.602(2) and 2.627(2) Å with
the average distance of 2.615 Å.
Sm
Sm
Scheme 1. The coordination modes of TFSA ligands in 1 and 2.
age bond distance of 2.472 Å. The Sm1–N bond distances are
2.600(3) and 2.608(3) Å, respectively, with the average bond dis-
tance of 2.604 Å.
Adjacent Sm(III) ions are connected through single TFSA ligand
to form a 1-D coordination polymer chain (Fig. 2b). Both carboxyl-
ate groups of each TFSA ligand coordinate the Sm(III) ion in the rare
monodentate fashion (Scheme 1c), and thereby TFSA ligand acts as
All H2TFSA ligands deprotonate completely and participate in
the coordination to Nd(III) ions in two coordination modes. (i) TFSA
ligand coordinates three different Nd(III) ions to form a pentaden-
tate bridge, namely, one carboxylate group of TFSA ligand is in
bidentate-bridging mode and another is in bridging-chelating
mode (Scheme 1a). (ii) TFSA ligand coordinates four different
Nd(III) ions to form a tetradentate bridge, namely, two carboxylate
groups of TFSA ligand are in bidentate-bridging mode (Scheme 1b).
The two neighboring Nd(III) ions are linked through four COOÀ
groups of TFSA ligands via bidentate-bridging (e.g., O5-C17-O5A
and O6-C19-O6A) and bridging-chelating (e.g., O1-C1-O2 and
O1A-C1A-O2A) modes to form a dimeric unit with the distance
Nd1(III). . .Nd1A(III) ions of 4.220(5) Å. The dimeric units as build-
ing blocks are connected to a 1-D chains through pentadentate
TFSA ligands along c-axis with the distance between two neighbor-
ing Nd(III) ions of 6.142(5) Å. These dimeric units are connected to
a another 1-D chains through tetradentate TFSA ligands along b-
axis with the distance between two neighboring Nd(III) ions of
9.441(5) Å. The two types of 1-D chains are further cross-linked
to a 2-D network structure (Fig. 1b).
a l2-bridging ligand. Namely, 1-D chain is formed through the infi-
nite extension Sm–OOCCF2CF2COO–Sm. This is a rare example of
lanthanide carboxylate coordination polymers. Many coordination
polymers consisting of the assembly of metal centers through mul-
ticarboxylate linker show higher dimensional structures, 2-D and
3-D networks [1–9,13–17], 1-D chains are less in lanthanide mul-
ticarboxylate complexes [10–12]. However, monodentate coordi-
nation mode of carboxylate group and the 1-D chain as 2 formed
through single ligand as linker are rare.
In the chain of 2, TFSA ligand as long bridge links two Sm (III)
ions, leading a long Sm(III). . .Sm(III) distance of 7.758(3) Å, which
is larger than Sm. . .Sm distances in other reported samarium car-
boxylate complexes [10,14,17]. Coordinated phen molecules paral-
lel to each other, and the distance of face-to-face is 7.71 Å.
Uncoordinated phen molecules are almost parallel with the dihe-
dral angle of 1.1° and the distance of face-to-face between them
is 3.24 Å, which indicates
p–p stacking interactions of aromatic
rings between the uncoordinated phen molecules.
Interestingly, the intermolecular hydrogen bonds are formed
between uncoordinated molecules and 1-D coordination polymer
chain. Uncoordinated TFSA ligands form hydrogen bonds with
coordinated water molecules in the 1-D chain, resulting in a dou-
ble-chains supramolecular structure (Fig. 2c). Uncoordinated phen
molecules are connected to 1-D chain through three kinds of
hydrogen bonds, which are formed between coordinated water
molecules and uncoordinated phen molecules, O–H. . .N; uncoordi-
nated water molecules and uncoordinated phen molecules,
O–H. . .N; and uncoordinated water molecules and coordinated
water molecules, O–H. . .O. Distances of the hydrogen bonds are
in the range of 2.707(5)–2.919(5) Å (Table 5). Uncoordinated TFSA
ligands, phen and water molecules are connected with the 1-D
coordination polymer chain through intermolecular hydrogen
bonds, which further increases the stability of the structure.
The structural characteristics of 3 are similar to that of 2. So, the
details will not be further discussed in here. The comparison of
crystal data between 3 and 2 shows that the average distances of
Dy1–O(carboxylate) (2.308 Å), Dy1–O(water) (2.371 Å), Dy1–N
3.2. Structural description of {[Ln(TFSA)(phen)(H2O)4]Á0.5(TFSA)Á
2(phen)H2O}n (Ln = Sm, 2 and Dy, 3)
The crystal structure of 2 is given in Fig. 2. The asymmetric unit
of 2 consists of [Sm(TFSA)ÁphenÁ(H2O)4] core (Fig. 2a), free half
TFSA ligand, two phen molecules, and a lattice water molecule.
The Sm1(III) ion is eight-coordinated by two oxygen atoms from
two TFSA ligands, two nitrogen atoms from phen molecule, and
the other from four water molecules. The coordination sphere of
the Sm(III) ion is a distorted square-antiprism, in which the top
square face is defined by O1, O2, O4, and O5, and the bottom one
is formed by O3, O8A, N1, and N2. The mean deviations from the
upper and lower planes are 0.1693 and 0.088 Å, respectively, and
the dihedral angle between the two planes is 6.4°. The Sm1–O(car-
boxylate) bond distances are 2.322(3) and 2.378(3) Å, respectively,
with the average bond distance of 2.35 Å. The Sm1–O (water) bond
distances vary in the range of 2.373(3)–2.473(2) Å with the aver-

X. Li et al. / Journal of Molecular Structure 919 (2009) 277–283
281
a
b
c
Fig. 2. View of the structure of 2: (a) coordination environment of Sm(III) ion at the 30% probability displacement ellipsoids. The free TFSA, phen, and H2O are omitted
for clarity (b) 1-D chain. (c) Packing diagram viewed along the a-axis showing the double-chains structure by hydrogen bonds. All hydrogen atoms are omitted for
clarity.

282
X. Li et al. / Journal of Molecular Structure 919 (2009) 277–283
Table 5
150
a
Hydrogen bond lengths (Å) and bond angles (°) for complex 2
D–H. . .A
d(D. . .A)
<(DHA)
100
50
0
O(11)–H(11A)...N(5)
O(3)–H(3A)...O(11)
O(1)–H(1B)...O(7)
O(1)–H(1A)...O(9)
O(4)–H(4B)...O(11)
O(4)–H(4A)...N(4)
O(2)–H(2B)...N(3)
O(2)–H(2A)...O(10)
O(11)–H(11B)...O(6)#1
O(3)–H(3B)...O(9)#1
2.822(5)
2.707(5)
2.721(4)
2.756(4)
2.717(5)
2.735(4)
2.761(4)
2.680(4)
2.803(5)
2.919(5)
154(6)
179(6)
158(5)
163(5)
156(6)
168(4)
158(5)
172(5)
155(5)
171(8)
5 00
5 5 0
600
65 0
Wavelength / nm
Symmetry transformations used to generate equivalent atoms: #1 x À 1, y, z.
300
250
200
150
100
50
b
(2.553 Å), and Dy1(III). . .Dy1A(III) (7.748(3) Å) in 3 are slightly
shorter than corresponding distances in 2, respectively, the reason
for that is the radius of the Dy(I) ion is shorter than that of the
Sm(I) ion, which is in accordance with the effect of the lanthanide
contraction.
3.3. Near-infrared luminescence of the complex 1
0
4 00
4 5 0
5 00
5 5 0
600
The emission spectrum is presented in Fig. 3. Three infrared
emission bands centered around 890, 1061, and 1335 nm, respec-
Wavelength / nm
tively, are assigned to 4F3/2 ? 4I9/2 4F3/2 ? 4I11/2, and 4F3/2 ? 4I13/2
,
Fig. 4. Emission spectra (a) for 2, kex = 403 nm; (b) for 3, kex = 309 nm.
transitions of Nd(III) ion. Among these emission bands, the
4F3/2 ? 4I11/2 transition is the most intense.
4. Conclusions
3.4. Visible photoluminescence of complexes 2 and 3
We have synthesized three lanthanide coordination polymers
under hydrothermal condition. The three complexes have two
types of crystal structures, in which TFSA ligands adopt the differ-
ent coordination modes to lanthanide ions. The complex 1 has a 2-
D network structure through pentadentate and tetradentate TFSA
ligands. The complexes 2 and 3 show novel 1-D structures, in
which Ln(III) ions are separated by long and single flexible TFSA
anions with its two monodentate carboxylate groups, and rela-
tively long Ln. . .Ln distances are seen in the 2 and 3. These struc-
tural features are rare in lanthanide carboxylate complexes. The
1 exhibits the near-infrared luminescence of Nd(III) ion. The 2
and 3 exhibit the visible region luminescence of Sm(III) and Dy(III)
ions, respectively.
The solid-state luminescent properties of 2 and 3 were investi-
gated at room temperature. The emission spectrum of 2 was re-
corded upon excitation wavelength of 345 nm (Fig. 4a). Three
emission bands are at 561, 595, and 642 nm, which are attributed
to 4G5/2 ? 6H5/2 4G5/2 ? 6H7/2, and 4G5/2 ? 6H9/2 transitions of
,
Sm(III) ion, respectively. The emission spectrum of 3 upon excita-
tion at 309 nm shows two emission bands at 482 and 571 nm
(Fig. 4b), respectively, corresponding to 4F9/2 ? 6H15/2 and
4F9/2 ? 6H13/2 transitions of Dy(III) ion. Further, in the emission
spectra of the two complexes, the fluorescent emission of ligands
is not observed, indicating an efficient energy transfer from the li-
gand to the Ln(III) ion. Thus, these observations of emission spectra
clearly indicate the typical luminescence characteristics of the
Sm(III) and Dy(III) ions caused by the intramolecular energy trans-
fer that consists of the absorption energy by organic ligands, and
energy transfer to the Ln(III) ions.
Acknowledgements
We are grateful to the Natural Science Foundation of Beijing
(No. 2073022) and the Science and Technology Program, Beijing
Municipal Education Commission (KM200510028007).
8000
7000
6000
5000
4000
3000
2000
1000
0
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.molstruc.2008.09.017.
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