The synthesis of discrete polyoxometalate clusters composed of more than 3 metallic elements has always been attractive but seldom successful. For the first time, we have developed a de novo synthetic route to quinary Cu–Ni–Co–Mn–Zn Keplerate clusters with a nuclearity of 20. Seven single-crystalline quinary Keplerates in a medium-entropy state with various compositions have been obtained. A systematic study reveals that the different ions’ ability to be incorporated into the Keplerates is governed by the Irving–Williams series, and they are stabilized in a medium entropy state. More intriguingly, these quinary Keplerate clusters represent an analogue of the Ship of Theseus at the molecular level, i.e., the global features of the {M20} Keplerates are intact, while the constitution can be altered by tuning the synthesis conditions. Our further investigation reveals that the quinary elements {M20} compared to mono-component and binary Keplerate clusters exhibit much superior electrochemical performance, therefore shedding light on the design of multimetallic clusters in high-entropy states as novel electrocatalysts.
Functional oligopeptides derived from natural proteins are often used as targeting groups or therapeutic drugs but always suffer from a dramatic bioaffinity decrease due to the loss of conformational restriction in proteins, which increases their entropy state. It is worth noting that the linear Cys-Arg-Gly-Asp-Ser (CRGDS) oligopeptide can spontaneously restore its natural conformation by anchoring one terminus and forming hydrogen bonds on another terminus, on protein-like zwitterionic fifth-generation polyamide-amine (G5 PAMAM) nanocarriers, thus exhibiting high bioaffinity. However, the different physicochemical properties of nanocarriers have an impact on the bioaffinity recovery of linear CRGDS. In this work, it is found that the bioaffinity decreases with the reduction of generation of PAMAM and zwitterionic G3 PAMAM is a turning point for bioaffinity recovery via a series of in vitro experiments. This indicates that the spontaneous restoration of the native conformation of the RGD segment requires proper surface group density and structural rigidity of the zwitterionic nanocarrier for reducing the entropic energy of CRGDS peptides before binding. This approach paves a way for functional reproduction of protein molecules using low-cost synthetic polymers for extensive biomedical applications.
危险品化学品经营许可证（带存储）