Inorganic Chemistry
Article
a
recognition of C H over C H via the C−H···F hydrogen
Table 1. Crystallographic Data for JXNU-6
3
4
3
6
bond based on the fluorous organic ligand.
formula
fw
C H F O Tb
42 14 12 13 2
1272.37
293(2)
tetragonal
EXPERIMENTAL SECTION
H -TFBPDC, which was prepared as given in Scheme S1.
■
temp (K)
cryst syst
space group
Z
2
P4 22
1
Gas Sorption Studies. The gas sorption experiments were
performed on a Micromeritics ASAP2020 HD88 surface area analyzer.
N (99.999%), C H (99.95%), and C H (99.999%) were used. The
4
a (Å)
b (Å)
c (Å)
15.8993(2)
15.8993(2)
27.5708(7)
90
2
3
4
3
6
as-prepared JXNU-6 samples were washed with DMF five times and
then soaked with dichloromethane for 8 days. The dichloromethane-
exchanged JXNU-6 was first vacuumed for 3 h at 30 °C and then
immediately vacuumed for 27 h at 98 °C to yield the activated sample
of JXNU-6a.
α (deg)
β (deg)
γ (deg)
90
90
V (Å3)
6969.6(2)
1.213
2.085
38062
7126
6660
Adsorption Selectivity and Isosteric Heat of Adsorption
Calculations. The adsorption selectivity was calculated with the ideal
adsorbed solution theory (IAST). The experimental pure-component
gas adsorption isotherms at 273 and 298 K were fitted by a single-site
Dcalcd (g cm−3
μ (mm−1)
)
10
no. of reflns collected
no. of indep reflns
no. of obsd reflns [I > 2σ(I)]
F(000)
Langmuir−Freundlich model. The isosteric heat of adsorption was
calculated from the fitting parameters of the adsorption isotherms
11
using the virial method.
2432
Column-Breakthrough-Separation Experiments. Gas separa-
tion experiments were performed on our previously reported
R
R
int
0.0382
0.0332
12
apparatus for gas mixtures. A gas chromatograph with a thermal
conductivity detector was used for monitoring the effluent gas from
the adsorption column. The separation experiments were carried out
at 298 K and 1 atm. The adsorption column has a length of 100 mm
and an inner diameter of 4 mm and was loaded with 0.347 g of
[I > 2σ(I)]
1
wR (all data)
2
CCDC number
a
2
2 2
R1 = ∑||F | − |F ||/∑|F | and wR = {∑[w(Fo − F ) ]/
o
c
o
2
c
2
2
1/2
−
1
∑[w(F ) ]} .
o
sample. The mixed gas with a total flow rate of 2 mL min was
continuously fed into the adsorption column.
Synthesis of {[Tb (TFBPDC) (H O)]·4.5DMF·0.5H O} (JXNU-
2
3
2
2
n
6
(
). A mixture of TbCl ·6H O (7.46 mg, 0.02 mmol), H -TFBPDC
3
2
2
2
1
2
1
1
1
3.12 mg, 0.01 mmol), and 2-fluorobenzoic acid (7 mg, 0.05 mmol)
in 2 mL of DMF was screw-capped in a 10 mL vial and heated at 100
C for 24 h. After cooling to room temperature, colorless crystals were
2
2
carboxylate groups (Figure S1). The dihedral angles between
the benzene planes and their attached carboxylate moieties are
44.3 and 88.7°. In contrast to its analogue, the benzene rings
with their attached carboxylate groups in the biphenyl-4,4′-
dicarboxylate ligand are nearly coplanar. Such large torsion
°
obtained. Yield: 48% based on H -TFBPDC. Elem anal. Calcd/found
2
for JXNU-6 (1610.31): C, 41.39/41.13; H, 2.91/2.78; N, 3.91/3.81.
IR spectrum (cm ): 3415 (w), 1633 (s), 1589 (s), 1398 (s), 1280
−1
(
(
w), 1251 (w), 1147 (w), 1111 (w), 1035 (s), 858 (s), 845 (s), 804
w), 723 (m), 681 (m), 585 (s), 522 (w), 422 (m).
Crystallographic Study. Single-crystal X-ray diffraction experi-
2−
angles in the TFBPDC ligand result from the large size of the
F atoms and the electrostatic repulsion between carboxylate O
atoms and F atoms with negative charge. As displayed in
ments were carried out with a Rigaku Oxford SuperNova
diffractometer equipped with an EOS detector (Mo Kα radiation; λ
III
Figure 1b, Tb ions are bridged by the carboxylate groups to
=
0.71073 Å). Absorption correction and data reduction were handled
generate a 1D right-handed helical chain propagating along the
13
14
15
with a CrysAlisPro package. SHELXT and SHELXTL were
applied to structure solution and refinement. All H atoms were
modeled geometrically and refined with a riding model. Non-H atoms
c axis. Within the helix, the Tb1 and Tb2 atoms are alternately
III
arranged and the separation between the neighboring Tb
atoms is 4.07 Å. The pitch length of 27.2 Å for the helix is
identical with the c-axis length. Such a helical chain is
were refined anisotropically. The guest H O and DMF molecules
2
−
(
3549 Å and 741 e per unit cell) are highly disordered and treated by
16
1
S2), which is consistent with a P4 22 space group for JXNU-6.
1
Table 1, and the important bonds are presented in Table S1.
Each helix is connected to four adjacent helixes with the same
handedness through tetrafluorobiphenyl moieties to generate a
3D structure (Figure 1c). The 3D framework has 1D square
channels extending to the c axis, with the inner wall full of F
atoms, which generates the fluorine-lined channels. The 1D
RESULTS AND DISCUSSION
■
Structural Description. JXNU-6 exhibits a 3D framework
featuring the 1D terbium carboxylate helical chains and 1D
fluorine-lined channels. One and a half TFBPDC ligands,
2−
channels are occupied by the disordered DMF and H O
2
III
half a coordinated H O molecule, and two Tb ions with half-
molecules, which are accounted for 50.5% of the unit cell
2
16
occupation compose the asymmetric unit of JXNU-6. Both
Tb1 and Tb2 atoms are located at 2-fold axes but display
different coordination geometries. The Tb1 atom is nine-
coordinated by eight O atoms from six carboxylate groups of
volume. The PXRD pattern of the bulk materials was close to
(TGA) curve showed that the loss of DMF and H O
2
2−
six TFBPDC ligands and one O atom of an aqua ligand
Figure 1a), while Tb2 is bound to eight carboxylate O atoms
molecules occurred between 30 and 185 °C (weight loss:
curve of the dichloromethane-exchanged sample showed that
(
2−
from six TFBPDC ligands. The Tb−O bond distances fall
into the typical range varying from 2.336(5) to 2.623(5) Å.
The two crystallographically unique TFBPDC2 ligands exhibit
two coordination modes binding four metal ions with two μ2-
2
−
successfully exchanged by dichloromethane (Figure S4).
Thus, the dichloromethane-exchanged sample was degassed
B
Inorg. Chem. XXXX, XXX, XXX−XXX
He, Chun-Ting
