MIL-100(Fe, Cr) and MIL-101(Cr) were synthesized by the hydrothermal method and applied to the adsorptions of five aromatic amines from aqueous solutions. These three metal-organic frameworks (MOFs) were well characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and surface area analysis. The adsorption mechanism of three MOFs and the effects of the structures of MOFs on the adsorption of aromatic amines were discussed. The results show that the cavity system and suitable hydrogen bond acceptor were important factors for the adsorption for five aromatic amines of aniline, 1-naphthalamine, o-toluidine, 2-amino-4-nitrotoluene and 2-nitroaniline: (a) the saturated adsorption capacity of aniline, 1-naphthylamine and o-toluidine on MIL-100(Fe) were 52.0, 53.4 and 49.6 mg/g, respectively, which can be attributed to the intermolecular hydrogen bond interaction and cavity system diffusion. (b) The adsorption capacity of 2-nitroaniline and 2-amino-4-nitrotoluene on MIL-101(Cr) were 54.3 and 25.0 mg/g, respectively, which can be attributed to the more suitable pore size of MIL-101(Cr) than that of MIL-100(Fe, Cr). The MOFs of MIL-100(Fe) and MIL-101(Cr) can be potential materials for removing aromatic amines from aqueous solutions.
Recently,
researchers found the abilities of cepharanthine (CEP)
to prevent and treat coronavirus. However, the study about CEP solid
forms has been rarely reported. In this study, the crystal structure
of CEP form I was first solved, and eight solvates were screened and
discovered based on the conductor-like screening model for real solvents.
The crystal structures of five solvates of CEP with methanol (SMeOH), acetonitrile (SACN), methyl acetate (SMA), ethyl acetate (SEA), and butyl acetate (SBA) were solved. The results showed that five solvates belonged
to isolated-site solvates. Hydrogen bonding between the solvent molecule
and the active pharmaceutical ingredient molecule was present only
in SMeOH. The remaining four solvates formed C–H···O
weak hydrogen bonds and C–H···π interactions
between the host and guest. The mechanism of solvate formation was
explained by calculating the packing coefficients, and it was proved
that the introduction of solvent molecules mainly made the crystal
structure packed more effectively. In addition, the desolvation of
the five solvates were studied and found that the desolvation of SMeOH followed a cooperative mechanism, while SACN, SMA, SEA, and SBA conformed to
a destruction-collapse mechanism.
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