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Academician Zhang Xi's speech
? Academician Zhang Xi went to Fudan to give an academic report, and it was a great honor to listen to the master's lecture. The topic of the lecture is super amphiphilic molecules: from molecular construction to functional assembly. Let's briefly summarize the contents and feelings.

What is a super hermaphrodite?

Super-amphiphiles refer to amphiphiles constructed by non-valence bonds such as electrostatic interaction, π-π interaction, charge transfer interaction, hydrogen bond, host-guest interaction, etc. Some dynamic valence bonds, such as imine bonds and disulfide bonds, can be reversibly broken and formed under certain conditions, which have similar properties to non-valence bonds and can also be used to construct super-amphiphilic molecules. Amphoteric molecules can easily introduce various functional groups, which can be small molecules or high polymers. Amphiphility is one of the foundations of self-assembly.

Examples are given to illustrate the details of the method of constructing supramolecules, as well as some properties and structural characterization of constructing supraamphiphilic molecules, including TEM. From the interaction between molecules, including the very important interaction between electron-deficient and electron-rich, electrostatic interaction, what is the reason for this property?

? For superhydrophilic molecules, a response group is introduced. It is mentioned that the molecules that react to PH and enzymes are mainly caused by the charge repulsion of phenolic hydroxyl groups. What is the driving force for each molecule to have such a structure? Do they form stoichiometric supramolecules? Through nuclear magnetic resonance, we can see that they have face-to-face charge transfer interaction, and through single crystal, we can see the structural basis of this force. The teacher mentioned the method of microcalorimetry ITC, and we can know the type and size of force by dropping quantitative heat. The structure of enzymatic reaction was realized by atp, and its structure was determined by cryo-TEM, and it was quickly frozen with liquid propane or ethane.

Choosing different building blocks, super parents and different driving forces to build will get different results. This is the research mode.

On the other hand, some functional progress has been made with the aid of polymers. For example, by using CB as the head of the building block, the quenching of molecules with fluorescence can be weakened, and the stoichiometric ratio can be maintained due to the interaction between host and guest. At the same time, the fluorescence can be quenched by replacing CB7 in other ways, and spermine can be detected with this material. Examples of solving problems in other disciplines with super amphiphiles.

? Photodynamic therapy is carried out by photochemistry. Under illumination, the energy gap between the ground state and the excited state of porphyrin is transferred to the triplet porphyrin. If there is a lot of oxygen in the solution, it will transfer energy to singlet oxygen. However, porphyrin is easy to polymerize, and the use of sterically hindered organic groups may produce toxicity. Increasing the energy gap with CB7 can greatly increase the appearance of singlet oxygen, and the increase of singlet oxygen can be obtained by fluorescence and paramagnetism. At the same time, the bactericidal effect was tested by Escherichia coli. The bactericidal effect reached 100%.

? The other part is supramolecular radical, which can be stabilized by supramolecular. Stabilizing anionic radical with CB7 (containing 7 carbonyl groups) reduces the energy levels of lumo and humo, and reduces the energy level by 0.47eV through measurement and calculation. At the same time, through further ultraviolet absorption and paramagnetism, it is determined to be a stable free radical, and supramolecular free radicals have a fast life because of their stability. At the same time, this material may also be used as a near infrared material, and the photothermal conversion efficiency reaches 3 1%. At the same time, CB7 can be used to activate free radicals, which greatly accelerates this reaction.

After listening to Mr. Zhang's explanation, although there are many theoretical problems I don't understand, I found that their scientific research ideas are very clear and the results obtained are explained by various means. At the same time, they are not satisfied with the existing model (they could have published many similar but different papers) and have done a lot of pioneering work, which is very detailed and systematic. I feel that scientific research should do this. If they imitate others blindly, they will get good grades and papers. At the same time, Professor Zhang also specifically mentioned that mutual communication in scientific research is very important. Everyone can't be all-rounder. Only by communicating with each other can the sparks of thinking collide.