The preparation of zeolite utilizing commercially available organic compounds instead of complex and expensive ones is of practical significance. Herein, we report the synthesis of germanosilicate zeolite with UOS framework by utilizing a simple and commercially available compound 3-diethylamino-1-propanol (DEAP) as organic structure-directing agent (OSDA) under fluoride condition. The synthesis has been optimized by rational modification of the variables, including the Si/Ge molar ratios, the amount of DEAP and F− anions, the concentration of the synthesis gel and crystallization temperature. UOS zeolite materials were prepared with Si/Ge ratio in the range of 1–4. The physicochemical properties, including crystallinity, crystal morphology, chemical environment of framework elements, textural properties and acidity were characterized by multiple techniques. Ge atoms are proved to preferentially occupy the T sites in the double-four-ring (D4Rs) units. Compared to the isostructural IM-16 zeolite, the UOS zeolites prepared herein are of similar textural properties, such as specific surface area and micropore volume. The simple structure and commercial availability of DEAP endow this synthesis with a cost advantage over the conventional preparation of UOS zeolite, where an expensive imidazolium derivative is employed.
The photocatalytic CO2 cycloaddition to prepare high value-added chemicals, such as cyclic carbonates (CCs) under mild conditions is an effective strategy to realize carbon neutrality. Herein, through a three-step reaction, the porphyrin-based covalent organic polymer with bimetallic active sites (Fe-COP-Zr) is successfully obtained by coordinating Fe2+ and Zr4+ with porphyrin and bipyridine (Bpy), respectively. Owing to excellent photosensitivity of porphyrin moieties, Fe-COP-Zr exhibits outstanding visible light absorption, which is very important for the production of photogenerated carriers. Consequently, Fe-COP-Zr shows high photocatalytic performance towards CO2 cycloaddition with a yield of 12.1 mmol/h, which is 6 times higher than that of pure covalent organic polymer (COP) and 3 times higher than that of monometallic Fe-COP. The reason for this excellent photocatalytic CO2 cycloaddition performance may be ascribed to the synergistic effect of Fe and Zr sites. The photogenerated electrons are easily injected into epichlorohydrin (ECH) through Fe—O bonds to form affluent electron transition state, and interact with Zr4+ as Lewis acid sites for the ring-opening of ECH, which is the rate-determining step for the visible light boosted chemical fixation of CO2 into CCs. This work might provide some insights for design and preparation of COPs with multiple active sites to modulate their photocatalytic activities.
In this study, Pepsin@AuNPs (Pep@AuNPs) and Trypsin@AuNPs (Try@AuNPs) were synthesized by a microfluidic droplet system using Pepsin and Trypsin as protection reagents and NaOH as reducing reagents. Compared to the synthesis method in a flask, the AuNPs synthesized by the microfluidic droplet system demonstrated uniform nucleation, superior ultraviolet absorption performance, high stability and short preparation cycles (15 min). The detection range of Cu(II) by Pep@AuNPs was 1.0–100.0 µmol/L and the detection limit was 0.3 µmol/L. The detection range of L-Cysteine by Try@AuNPs was 0.3–250.0 mmol/L and the detection limit was 0.1 mmol/L. This universal method provides an effective strategy for the detection of bioactive molecules, such as metal ions and amino acids by AuNPs with protein as a protective agent.
Farnesoid X receptor (FXR) is a ligand-activated nuclear receptor and plays important roles in the regulation of metabolism and homeostasis of several important physiological substances, such as bile acids, glucose, and lipids. As such, FXR has become a promising therapeutic target for the treatment of several metabolic diseases and liver disorders. Recently, fargesone A (FA), a natural product from Magnolia fargesii was identified to be a novel, potent FXR agonist that demonstrated good in vitro and in vivo activities. However, the detailed interaction mechanism of FA with FXR remains unclear. In this study, we employed multiple computational approaches including molecular docking, molecular dynamics simulation, and binding free energy calculation to address the issue. By comparisons of the structural dynamics and binding free energies, an optimal binding mode was identified, in which FA interacts with FXR via a direct hydrogen bond with His447 and hydrophobic interactions with multiple residues, such as Leu287, Met290, Met328, Ile352, and Trp454. Two mutants, namely, H447F and L287N, were further constructed to validate the importance of the identified residues. We anticipate that these findings could be helpful for future rational design of new FA analogues targeting FXR.