Structure characterization
The synthesized
[Zn2(bpy)(btec)(H2O)2]·2H2O
has a two-dimensional structure, each layer is formed by Zn coordinated
with bpy and btec, and H2O molecules between layers
provide multiple hydrogen bonding sites to connect the two
layers28. In this work, we investigated the rapid
synthesis and large-scale synthesis processes of these materials, the
PXRD patterns of these samples were matched well with the simulated one,
and the SEM images show that the samples have relatively high
crystallinity (Figure S1 and S2). After guest removal,
Zn2(bpy)(btec) still
shows porosity with the pore cavities of 3.6 Å×3.8 Å×6.6
Å (Figure 2a, b). These cavities
match well with the size and shape of
C2H2 (3.3 Å×3.3 Å×5.7 Å), suggesting a
potential application for C2H2separation.
The porosity in Zn2(bpy)(btec) was established by
CO2 sorption at 273 K. As shown in Figure S3, the
CO2 adsorption isotherms slowly increase with increasing
pressure. By using the Dubinin-Radushkevich equation, the surface area
of Zn2(bpy)(btec) was calculated to be 397
m2/g, and its pore-size is around 3.6 Å (Figure S3).
The pore cavity between two layers is
about 3.6 Å×3.8 Å×6.6 Å, which is slightly larger than the size of
C2H2, CO2 and smaller
than C2H4, thus could be used for
C2H2/C2H4and
C2H2/CO2 separation.