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 told her research experience over the years:

"At the time of the master's degree, there were not many research groups to choose from. At that time, I didn't understand anything, so I just chose an associate professor with a good reputation. It took three years to produce a Chinese core article. An SCI three district, worthy of graduation..."

"Because the master's school is a normal 211, and there are no articles, it is difficult to find a doctoral degree. Finally, I found a professor who specializes in photoluminescence materials in a cross-field. Then there was no funding in the group, and it was difficult to apply for a general project. , I can only take some projects in the province, and a few years add up to 100,000 yuan. Before doing experiments, the first thing to consider is whether the materials are cheap, and then a disposable glove needs two weeks..."

Xu Qiushen nodded in agreement, no matter what field it is, a good platform is indeed very important.

Now Teacher Wei’s research group, although the equipment cannot be bought casually, the material cost is still sufficient. Most materials you want can be purchased directly, and experimental consumables are also casually collected.

Just like people like to get together to run to the big factory after graduation, like to enter the "Party A" unit, in the academic circle, if there is no "hat", no backstage, there will be no funding, no students, no funding, no students. Without article achievements, it is difficult to apply for the project without article achievements, which will eventually form a vicious circle.

This is also the daily life of the green pepper scholars who have been staying in China. Unless they have hard power or luck, they can publish two or three top publications 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 a "promote or go" model, 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 a shortage of high-end talents at any time, most scientific researchers, accounting for more than 90%, are ordinary people.

For these ordinary scientific researchers, the scientific research circle has long been the Red Sea, and the annual funding is so much. Except for some top-notch abilities, the strength of others is similar. Naturally, "hats" and connections are first.

"Hat" is a manifestation of historical achievements. Personal connections represent the foundation. Usually, the people who have connections are the children of famous teachers. Whether it is a "hat" or a network, ordinary researchers who have one of the two are not necessarily good, but the probability is higher. The three-no scholars who have nothing are stronger.

"Sister Wu Sheng, what are your plans for the future?" Xu Qiu asked.

"After..." Wu Shengnan thought for a while, and said: "First post a few more articles here, then find a college to solve the associate professor, and then go abroad as a visiting scholar, exchange for two years and return to China. I guess I want a postdoc It’s a bit difficult to leave the station and stay directly at our school, that is, Mordu University."

"It should be very difficult," Xu Qiu understood this and explained: "In the past few years, there have been no teachers in the Department of Materials who have been directly in school. Teacher Wei is a "Qing Qian". He may have graduated with a Ph.D. ten years ago and stayed as a lecturer directly after his post-doctorate degree. Now, the teaching position of the top 5 universities in China is not so easy to enter."

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

The experiment was still in progress and could not be processed for the time being. Xu Qiu didn't draw the water, took out the literature accumulated before, and began to read the literature.

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 3D-PDI concept 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%.

For the ADA system, there is an article of cooperation between the Zang Chaojun research group of Qingbei University and the Lu Changjun 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%. Although it did not break a new high, it is not bad.

In addition, there are several scattered works published in journals such as JMCA and ACSAMI. Xu Qiu just glanced at it and remembered the molecular structure they reported.

At around four 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.

At the beginning of the reaction, the reactant A suspended on the surface of acetic anhydride has disappeared, and a pot of red solution is obtained. After the reaction vessel is slowly reduced to room temperature, the product gradually precipitates out of acetic anhydride. Xu Qiu filters the product and then uses petroleum ether Washing to obtain a crude product.

This time, Xu Qiu did not choose to use the column method to purify the reaction product, mainly because the product was too much, about 20 grams, after the column and waited until the year of the monkey to go, and also used the solvent, the previous PDI a few grams The product uses one or two liters of solvent.

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

In fact, Xu Qiu didn't use many recrystallizations during his experiment. Previously, he planned to recrystallize and purify the purchased monomers. Later, it was found that the purity was up to the standard, so there was no recrystallization and direct reaction.

The so-called recrystallization is a means of purifying substances by using the large difference in the solubility of the solute in the solvent at different temperatures.

The solubility of most substances increases with increasing temperature, so choose a solvent to make the solubility of the solute at room temperature very low, but very high at high temperature, and form a saturated solution of the solute at the reflux temperature, and then slowly cool down to make The solute is precipitated, and a small amount of impurities will be dissolved in the solvent, and a pure solute can be obtained.

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

He added all the reaction products. At first, only a small amount of acetic anhydride was added, and then stirred and heated 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 removed. Until it dissolves.

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

A classmate was rather impatient. The ethanol solvent was added too much, and the solute did not precipitate out... Then he chose to add a little more solute, and the solute increased again... Then add more solvent, and the solvent was increased again, and then added The solute... repeated cycles, originally expected to get 1 gram of recrystallized product, he was surprised to make more than 5 grams...

At that time, the raw materials were unlimited. If you add more solvents, you can supplement the solute, but now Xu Qiu’s products are limited. Once you add more, you will either re-synthesize a pot to supplement the amount of product, or you can only use distillation. The method removes the solvent. This is acetic anhydride with a boiling point of 140 degrees Celsius. The key is the smell, which is too troublesome.

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

Xu Qiu also knows that this disposable mask in the laboratory is more symbolic. Except for large particles of dust, most solvents are basically incapable of protection, but it is unnecessary to put on the gas mask directly for acetic anhydride. Continue the experiment.

After Xu Qiu's very careful operation, there was no problem with the recrystallization. After working for an hour, he finally obtained the product of the first step reaction, a pale red solid powder, which was converted by weighing on a balance, which was 79%. Yield.

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

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

Xu Qiu and Wu Shengnan took out the products of the school girl and put them in a vacuum oven for drying.

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

Wu Shengnan’s material requires only two steps to directly obtain the final ICIN-DM product; 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 ICIN benzene ring. Becoming a fluorine (F) atom involves a fluorination reaction, which requires a total of three steps to complete.

Therefore, Xu Qiu explained the reaction steps he extracted from the literature to Wu Shengnan, and the two began to react separately.

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 produce phthalic difluoride substituted at the 3 and 4 positions on the benzene ring. Formic anhydride~www.ltnovel.com~ 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 terrible, this kind of solid powdery potassium fluoride is not dangerous, as long as it is not swallowed by yourself, it will be fine.

Highly toxic ones are generally volatile, such as hydrofluoric acid, which can be attacked by direct contact with the skin or by breathing.

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

This time, instead of throwing out all the reaction products directly, he left half of the reactant B, which happened to be able to proceed directly to the third step of the subsequent reaction to obtain the ICIN-2Cl unit, which is equivalent to a single reaction. Two structures ICIN-2Cl and ICIN-2F were obtained.

Before dinner, Xu Qiu and Wu Shengmen took out the products of Han Jiaying from the vacuum oven and started the Soxhlet extraction of chloroform.