Inorganic Chemistry
Communication
−
i
2
4
oriented μ -OH ions (O3 and O3 ) and four carboxyl oxygen
L-1 is finally a 4-connected chiral umy net with (4 ·6 )
2
ii
i
iii
1
33−35
atoms (O1, O1 , O2 , and O2 ) from four different L ligands
topology (Figure 2e).
To our knowledge, the present 4-
connected chiral network with a umy topology has not yet
ii
to form a distorted [InO ] octahedron where O1, O1 , O3,
and O3 are in the equatorial plane, while O2 and O2 sit in
6
i
i
iii
exist (Table S5). Furthermore, when the large dimethylamino
1
groups in the H L were changed to two smaller ones
2
2
3
(
methoxy in H L and methyl in H L ), while the cis-[InO (μ -
2 2 4 2
OH) ] SBU remained, the same chiral umy net can still be
2
obtained, revealing that self-assembly of the cis-[InO (μ -
4
2
OH) ] SBU with the nonchiral 2,2′-bisubstituted BPDC is an
2
effective strategy for the construction of uninodal chiral 3D
MOFs.
The experimental powder X-ray diffraction (PXRD) patterns
of 1−3 are basically identical with the respective simulated
1
in H O for 1 month, their PXRD peaks are in good agreement
2
with the simulated ones, revealing that 1 is highly water-stable.
Moreover, the framework of 1 can also be retained in a pH = 2
aqueous solution for 1 day (Figure S10), which is very unusual
18,36−38
in the carboxylate-based 3D InOFs.
In the thermogra-
vimetric analysis (TGA) curve of 1, the first observed weight
H O and two DMF molecules (calcd 26.4%; Figure S13). The
2
framework of 1 collapses above 673 K, and the final residue is
Figure 1. cis-[InO (μ -OH) ] octahedron in L-1 (a) and D-1 (b).
4
2
2
In O at 813 K (the observed loss of 22.1% and calcd 22.3%).
2
3
S14 and S15), further supporting the isostructural nature of 1−
i
O2 distances are 2.150(2) and 2.154(3) Å, respectively. Each
−
3+
3.
2
iv
The 55.9% solvent-accessible volume of 2 is smaller than
2
S2). All In−O bond lengths are comparable to the related
58.7% of 3 because the size of methoxy in H
that of methyl in H L . To confirm the permanent porosities of
L is larger than
2
1
7−19
3+
−
3
InOFs.
Each adjacent In ion is bridged by a μ -OH ion
2
2
and two carboxylic groups to produce a 1D helical [In(μ -
1−3, the N adsorption isotherm at 77 K is determined, and
2
2
i
OH)(COO) ] chain with an In1···In1 (i, 1 + x − y, 1 + x, z −
the results show that all InOFs exhibit a reversible type I
S16−S18). The Brunauer−Emmett−Teller (BET)/Langmuir
surface areas of 1−3 are 1167/1196, 1460/1524, and 1694/
2
1
/
6
) distance of 3.5878(2) Å (Figure 2a). Along the c axis,
there is a pitch of 17.7236(9) Å, which is exactly equal to the c
dimension of the unit cell. Each 1D helical chain as a chiral
source is further connected to six peripheral ones through the
biphenyl groups to form a 3D homochiral framework (Figure
2
1829 m /g, respectively, and the corresponding porosities are
3
0.46, 0.56, and 0.65 cm /g, respectively (Table 1). Because 3
2
possesses the biggest BET area and porosity among 1−3, the
edge of 9 Å along the c axis (Figure S3). The channels are
gas adsorption properties of 3 are studied in detail. The CO ,
2
occupied by one H O and two DMF molecules, accounting for
CH
measured at 273 and 298 K, respectively (Figure 3). The
saturated CO , CH , C , C , and C adsorption of 3 at
273 K are 87.5, 32.2, 134.4, 122.5, and 125 cm /g, respectively
4 2 2 2 4 2 6
, C H , C H , and C H adsorption isotherms were
2
32
the 48.4% solvent-accessible voids of the L-1 framework.
Notably, the chirality of L-1 may come from the axially chiral
2
4
H
2
2
2
H
4
H
2 6
1
3
conformation of the H L ligand owing to the existence of two
2
3
large dimethylamino groups on the 2 and 2′ positions of the
biphenyl ring. This hypothesis can be confirmed by the
spectra (Figure S4). The present InOFs 1−3 are good
examples of chirality transfer from an achiral ligand to the
K, the CO , CH , C , C
decrease to 48.9, 21.0, 85.6, 80.2, and 92.5 cm /g, respectively,
2
adsorption is only 7.1 cm /g. At 298
H
H
2
, and C uptake capacities of 3
H
2 6
2
4
2
2
4
3
3
while the N
adsorption is merely 2.9 cm /g. Thus, 3 shows
2
2
3
1
D helical chain and finally to the homochiral lattices. This
adsorption value of 3 at 273 K is larger than that (64 cm /
result may originate from two elements of chirality: (1) the
g) found in a related InOF (FJI-C1) with a similar BET area
2
3
2
,2′-bisubstituted BPDC ligand is locked into an atropisomeric
(1726 m /g) but quite smaller than those (190.8 and 129 cm /
g) in two related InOFs (CPM-200-In/Mg and JLU-Liu18)
−
conformation, and (2) the rare cis-coordinated μ -OH ions
2
39−41
can induce 1D [In(μ -OH)(COO) ] chains to form a helix,
with the same porosity.
However, the C H and C H
2
2 n
2 2 2 6
thus promoting the transfer of chirality and a spontaneous
adsorption values of 3 at 273 K are almost equal to the
corresponding ones (135.9 and 123.6 cm /g) found in FJI-C1,
2
0
3
resolution.
−
Topologically, if we neglect the μ -OH ions and connect all
while the C H adsorption value of 3 is larger than that (85.2
2
2
4
3
carboxylate carbon atoms in the same way as that shown in
Figure 2d, it will give a helical ladder with the carbon atoms at
the vertices. In this case, each cis-[InO (μ -OH) ] octahedron
cm /g) in FJI-C1. Notably, 2 shows the highest CO
adsorption capacity of 111.2 cm /g at 273 K, which is
comparable to the known InOF (JLU-Liu7, 113 cm /g) with a
smaller BET area (879 m /g). The better affinity of 2 with
2
3
3
4
2
2
2
38
can be simplified as a 4-connected node, and the framework of
B
Inorg. Chem. XXXX, XXX, XXX−XXX
He, Xin
