1
86
Q. Shi et al. / Journal of Molecular Structure 837 (2007) 185–189
fashion and properties, we disclose our results on the syn-
thesis and characterization of a series of pydc-3,5 rare-earth
metal compounds. SpeciWcally, we are concerned with the
metal-organic frameworks of their rare-earth metal ana-
logues and the photoluminescent property of its europium
product.
Synthesis of [Eu (PDC) (H O) ] 3nH O (2). An iden-
2 3 2 9 n 2
tical procedure with 1 was followed to prepare 2 except
SmCl ·6H O was replaced by EuCl ·6H O and the amount
3
2
3
2
of pydc-3,5 (0.217 g, 1.3mmol), EuCl ·6H O (0.317 g,
3
2
0.87 mmol) (yield: 0.24 g, 52.3% based on Eu). Anal. Calcd
(%) for C H Eu N O : C, 23.90; H, 2.39; N, 3.98; Found:
2
1
25
2
3
27
¡
1
C, 24.22; H, 2.42; N, 4.05, FI-IR data (KBr, cm ): 3419
(m), 1653 (s), 1606 (s), 1557 (s), 1455 (s), 1376 (s), 1151 (m).
Synthesis of [Gd (PDC) (H O) ] 3nH O (3). An iden-
2
. Experimental section
2
3
2
9
n
2
2
.1. Materials and general methods
tical procedure with 1 was followed to prepare 3 except
SmCl ·6H O was replaced by GdCl ·6H O and the amount
3
2
3
2
All chemicals used were of reagent grade. The pyridine-
,5-dicarboxylic acid was prepared by oxidation reaction
of pydc-3,5 (0.2 g, 1.2 mmol), GdCl ·6H O (0.3g, 0.8 mmol)
3 2
3
(yield: 0.19g, 44.6% based on Gd). Anal. Calcd (%) for
C H Gd N O : C, 23.66; H, 2.36; N, 3.94; Found: C,
from 3,5-lutidine. Elemental analyses were carried out using
2
1
25
2
3
27
¡1
¡1
Flash EA1112 microanalyzer. IR spectra (4000–400cm
)
23.98; H, 2.41; N, 4.08; FI-IR data (KBr, cm ): 3451 (s),
1653 (s), 1610 (s), 1556 (s), 1448 (s), 1378 (s), 1316 (s), 1147
(m).
were recorded on Perkin-Elmer system FT-IR 2000 spec-
trometer using KBr disc. Melting points of the H PDC
2
were obtained on a Setaram DSC-131 instrument in the
standard DSC run mode. Solid-state luminescence spectra
were recorded on a Hitachi F-2500 Xuorescence spectro-
photometer.
Synthesis of [Dy (PDC) (H O) ] 3nH O (4). An iden-
tical procedure with 1 was followed to prepare 4 except
2
3
2
9
n
2
SmCl ·6H O was replaced by Dy(NO ) ·6H O and the
3
2
3 3
2
amount of pydc-3,5 (0.088 g, 0.52mmol), Dy(NO) ·6H O
3
2
(0.16 g, 0.35 mmol) in a 15 ml TeXon reactor (yield: 0.09 g,
2
.2. Synthetic procedure
47.9% based on Dy). Anal. Calcd (%) for C H Dy N O :
2
1
25
2
3
27
C, 23.34; H, 2.34; N, 3.90. Found: C, 23.45; H, 2.29; N, 4.10,
¡
1
Preparation of ligand. The pyridine- 3,5-dicarboxylic acid
FI-IR data (KBr, cm ): 3371(vs), 1672(s), 1610(s), 1559(s),
1390(s), 1148(m).
was prepared by oxidation reaction from 3,5-lutidine. Potas-
sium permanganate (53.2g, 0.34mol) was added in 500ml
water and heated to 80°C. When potassium permanganate
was dissolved, 3,5-lutidine (16.7g, 0.156mol) was slowly
added. After the addition, the temperature was raised to
2.3. Single-crystal X-ray diVraction
Single-crystal X-ray diVraction for complexes 2, 3, and
4 were performed on Rigaku R-AXIS Rapid IP diVrac-
tometer with graphite-monochromated Mo Kꢀ radiation
(ꢀ D 0.71073 Å) at 293(2) K. Intensity data for 1 were col-
lected on a Bruker P4 diVractometer with graphite-mono-
chromated Mo Kꢀ radiation (ꢀ D 0.71073 Å) at 293(2) K.
Cell parameters were obtained by global reWnement of
the positions of all collected reXections. Intensities were
corrected for Lorentz and polarization eVects and empiri-
cal absorption. The structures were solved by direct
methods and reWned by full-matrix least-squares on F2.
All non-hydrogen atoms were reWned anisotropically.
Structure solution and reWnement were performed by
using the SHELXL-97 package. Crystal data collection
and reWnement details for all compounds are given in
Table 1. Selected bond lengths and angles are listed in
Table 2.
1
00°C, the mixture was stirred until the purple color disap-
peared. When temperature came down to 80°C, another part
of potassium permanganate (53.2g, 0.34mol) was added
through a dropping funnel carefully. The mixture was heated
to 100°C. After 2h, the purple color disappeared again. The
reaction was cooled to room temperature. Filtration and
removal of solvent until the residual volume down to 200ml,
then concentrated sulfuric acid (98%, 18.7ml) was added
slowly, the precipitate was Wltered aVorded pyridine-3,5-
dicarboxylic acid as a white solid (18.2g, yield: 70%). Mp:
3
24°C Anal. Calcd for C H NO : C, 50.31; H, 3.02; N, 8.38.
7 5 4
¡1
Found: C, 50.18; H, 2.99; N, 8.51. FT-IR (KBr, cm ) 3091
(
vs), 1722 (vs), 1466 (w), 1165 (s), 895 (m), 752 (s).
Synthesis of [Sm (PDC) (H O) ] 3nH O (1). pydc-3,5
2
3
2
9
n
2
(
0.11 g, 0.66 mmol) was dissolved in the appropriate amount
of water. The pH of the solution was controlled in the range
–7 by addition of 1 M NaOH solution. A hydrotropic
solution of SmCl ·6H O (0.16 g, 0.44 mmol) was then added
6
3. Results and discussion
3
2
dropwise. The mixture was then transferred to a 23ml
TeXon reactor and kept at 140°C for 5 days under autoge-
nous pressure, then cooled to room temperature. On allow-
ing the Wltrate to evaporate at room temperature for a
week, colorless crystals of compound 1 were obtained
3.1. Structure description
As a typical example, the samarium compound has one-
dimensional double-stranded chains which contains two
kinds of units. The Wrst one contains a nine-oxygen-bonded
Sm atom through coordinated with three carboxylate
groups (in which two are didentate and one is monoden-
tate) and four coordinated water molecules (Fig. 1a), while
(
yield: 0.11 g, 47.8% based on Sm). Anal. Calcd (%) for
C H Sm N O : C, 23.97; H, 2.39; N, 3.99; Found: C,
2
1
25
2
3
27
¡1
2
1
3.82; H, 2.40; N, 4.12, FI-IR data (KBr, cm ): 3371 (vs),
666 (s), 1612 (s), 1550 (s), 1389 (s), 1297 (w), 1148 (m).