I Have a Research Support System

At noon, Xu Qiu and Wu Shengnan had an in-depth exchange in the cafeteria.

Mainly, the postdoctoral sister talked about her scientific research experience in these years:

"When I was a master's degree, there were not many research groups in the school to choose from. I didn't understand anything at the time, so I randomly chose an associate professor with a good reputation. It took three years to publish a Chinese core article, and An article in the three districts of SCI is worthy of graduating..."

"Because the master's school is an ordinary 211, and there are no articles, it is difficult to find a doctoral program. Finally, I found a professor who is a photoluminescent material across the field, and then there is no funding in the group, and it is difficult to apply for a general project. , I can only take some projects in the province, which add up to 100,000 yuan in a few years. The first thing to consider before doing an experiment is whether the material is cheap, and then a disposable glove needs to be used for two weeks..."

Xu Qiu nodded approvingly, no matter what field it is, a good platform is indeed very important.

Now, in Mr. Wei's research group, although the equipment cannot be bought casually, the cost of materials is still sufficient. Most of the materials you want can be purchased directly, and experimental consumables are also available at will.

Just like people who like to get together to go to big factories after graduation and like to join the "Party A" unit, in the academic circle, if there is no "hat" and no backstage, there will be no funding and students will not be recruited. Without the results of the article, it is difficult to apply for the project without the results of the article, which eventually forms a vicious circle.

This is also the bitter daily life of green pepper scholars who have been staying in China. Unless they have hard power or luck, they can publish two or three top journals such as AM and JACS to improve the status quo, otherwise it will be difficult to break out of this cycle, and some The school is still in the "up or go" mode, and the pressure is even greater.

The main reason is that there are too many people pouring into the scientific research circle every year. Although there is always a shortage of high-end talents, most of the scientific research personnel, accounting for more than 90%, are ordinary people.

For these ordinary scientific researchers, the scientific research circle has long been a red ocean, and the annual funding is only so much. Except for a few top-notch talents, everyone else has similar strengths. Naturally, "hats" and contacts are given priority.

The "hat" is the performance of historical achievements, and the network represents the background. Usually, those who have connections are the children of famous teachers. Whether it is a "hat" or connections, ordinary scientific researchers who have either of these two are not necessarily good, but there is a high probability that they will be better than others. The Sanwu scholars who have nothing are even stronger.

"Sister Wu Shengnan, what are your future plans?" Xu Qiu asked.

"After that..." Wu Shengnan thought for a while, and said, "First post a few more articles here, then find a college to deal with associate professors, and then go abroad as a visiting scholar. It’s a bit difficult to leave the station and stay directly at this school, which is Shanghai’s comprehensive university.”

"It should be very difficult." Xu Qiu understood this, and explained: "There are no teachers who have stayed in the Department of Materials for a few years after entering the school. They are all hired from outside, and most of them have 'hats', such as Teacher Wei is "Qingqian", maybe ten years ago, he could graduate with a Ph.D. and stay in school after his doctorate to become a lecturer directly, but now it is not so easy to get a teaching position in a domestic TOP5 university."

In the afternoon, Xu Qiu introduced the overall structure of the next experiment to Wu Shengnan, which was the PPT shown to Teacher Wei before.

The experiment is still in progress and cannot be processed for the time being. Xu Qiu did not paddle, took out the documents he had accumulated before, and began to read the documents.

Recently, many articles have emerged in the field of non-fullerenes, and both PDI systems and ADA-type molecules are relatively active.

The PDI system, the Zang Chaojun research group of Qingbei University who first proposed the concept of 3D-PDI on JACS, published a new work in the AM journal. They reported a new type of 3D-PDI molecule, which did not collide with Xu Qiu and Han Jiaying. The central core unit used is tetraphenylsilane, and the highest efficiency of the device is 7.8%.

In the ADA system, there is a work of Zang Chaojun's research group of Qingbei University and Lu Changjun's research group of the Chinese Academy of Sciences, which was also published on AM. On the basis of IDTBR, they synthesized several IDTBR derivatives with fluorine atoms, and the photoelectric efficiency of the device It reached 9%, which is not bad, although it has not broken a new high.

In addition, there were several scattered works published in journals such as JMCA and ACSAMI. Xu Qiu simply glanced at them and memorized the molecular structures they reported.

At four o'clock in the afternoon, the first synthesis reaction of ICIN-2F has reached 6 hours. Xu Qiu took Wu Shengnan to the laboratory for post-reaction processing.

The reactant A suspended on the surface of acetic anhydride at the initial stage of the reaction has disappeared, and a pot of red solution was obtained. After the reaction vessel was slowly lowered to room temperature, the product gradually precipitated from the acetic anhydride. Xu Qiu filtered the product, and then used petroleum ether Wash to obtain crude product.

This time, Xu Qiu did not choose to use the column method to purify the reaction product. The main reason is that the product is too much, about 20 grams. After passing through the column, it will be a waste of solvent. Before the PDI was a few grams. The product used a liter or two of solvent.

He intends to refer to the conditions in the literature and use the method of recrystallization of acetic anhydride.

In fact, Xu Qiu did not use recrystallization often during the experiment. He had planned to recrystallize and purify the purchased monomers before, but later found that the purity was up to the standard, so he did not recrystallize and directly put it into the reaction.

The so-called recrystallization is a means of purifying substances by utilizing the large difference in the solubility of solutes in solvents at different temperatures.

The solubility of most substances increases with temperature, so choose a solvent that makes the solubility of the solute very low at room temperature, but very high at high temperature, and forms a saturated solution of the solute at the reflux temperature, and then slowly cools down, so that The solute is precipitated, and a small amount of impurities will be dissolved in the solvent to obtain a pure solute.

The recrystallization device is relatively simple, just a flask and a spherical condenser, Xu Qiu quickly set it up.

He added all the reaction products, initially only a small amount of acetic anhydride, then stirred and raised the temperature to 160 degrees Celsius, and refluxed for a period of time. According to the remaining fixed amount, he judged the amount of acetic anhydride to be added next until all the solid products were just completely absorbed. until dissolved.

This is a technical task. Xu Qiu remembered that when he was doing "Organic Chemistry Experiments", it involved recrystallization experiments. At that time, the solvent used was ethanol, and he forgot the solute.

A classmate was impatient. He added too much ethanol solvent, and the solute did not precipitate even when the temperature was lowered... Then he chose to add more solute, and as a result, more solute was added... Then add more solvent, and the solvent was added again. The solute... Repeatedly cycled, originally expected to get 1 gram of recrystallized product, but he made more than 5 grams...

At that time, the raw materials were unlimited, and the solute could be supplemented by adding more solvents, but now Xu Qiu’s products are limited. The method is to remove the solvent. This is acetic anhydride with a boiling point of 140 degrees Celsius. The key is the smell, which is too troublesome.

The vinegar smell of acetic anhydride is really strong, Xu Qiu can still smell it through the fume hood and disposable mask.

Xu Qiu also knew that this kind of disposable mask in the laboratory was more symbolic. Except for large particles of dust, most of the solvents were basically unable to protect it. However, it seemed unnecessary to directly put on the gas mask for acetic anhydride, so he just Continue to experiment.

After Xu Qiu's very careful operation, there was no problem with the recrystallization. After working hard for an hour, he finally obtained the product of the first step reaction, a pale red solid powder. Weighed it with a balance, it was about 17.2 grams, converted , which is a yield of 79%.

Wu Shengnan also completed the recrystallization of her product, and obtained 16.3 grams of the product, with a yield of about 76%.

At this time, the liquids in the Soxhlet extraction tubes of Han Jiaying's two products H21 and H22 have become colorless and transparent, indicating that the Soxhlet extraction has been completed, and the small molecular impurities, oligomers, catalysts, etc. in the products have been basically washed away. .

Xu Qiu and Wu Shengnan took out the products of the junior girls and put them in a vacuum oven to dry.

Next, the two continued to vote for the second step of the ICIN system.

Wu Shengnan’s material only needs three steps to directly obtain the final ICIN-DM product; while Xu Qiu needs to undergo an additional step of reaction to obtain ICIN-2F, which is to replace the two chlorine (Cl) atoms on the benzene ring of ICIN Becoming a fluorine (F) atom involves a fluorination reaction, which requires a total of four steps to complete.

Therefore, Xu Qiu explained the reaction steps he extracted from the literature to Wu Shengnan, and then the two began to submit their reactions respectively.

Xu Qiu’s additional reaction is the reaction of phthalic anhydride (reactant B) substituted by dichloro at the 3 and 4 positions on the benzene ring with potassium fluoride to generate phthalic anhydride substituted by difluorine at the 3 and 4 positions on the benzene ring. formic anhydride.

The reaction solvent used this time is sulfolane, which is an excellent aprotic polar solvent with a boiling point of 285 degrees Celsius, but it will slowly decompose when heated above 220 degrees Celsius.

Although fluoride sounds scary, the danger of this kind of solid powdered potassium fluoride is not high. As long as it is not swallowed by yourself, it will be fine. The highly toxic ones are generally volatile, such as hydrofluoric acid. Kind of, direct skin contact or breathing will be recruited, and it is hard to prevent.

Xu Qiu accurately weighed reactant B, potassium fluoride, and polyethylene glycol methyl ether, and dissolved them together in sulfolane solvent. Under the condition of nitrogen protection, the temperature was raised to 185 degrees Celsius to start the reaction. The reaction time was 3 hours.

This time, he did not throw away all the reaction products directly, but left half of the reactant B, which happened to be able to proceed directly to the third and fourth steps of the subsequent reaction to obtain the ICIN-2Cl unit, which is equivalent to throwing once reaction, two structures ICIN-2Cl and ICIN-2F were obtained simultaneously.

Before dinner, Xu Qiu and Wu Shengnan took Han Jiaying's product out of the vacuum oven and started Soxhlet extraction with chloroform.