Chapter 228: 100% yield, but...

Returning to the office, Xu Qiu washed his hands and walked directly to sit down at Han Jiaying's desk.
The A501 has three desks, and the three of them were all sitting separately.
But now that the elder sister already knew their relationship, the two of them didn't bother to conceal it, and got together in an upright manner.
After playing around with the school girl for a while, Xu Qiu continued to write a review.
The classification of the second part of this review is based on the type of material, and the third part is the three main factors affecting the photoelectric performance of the device. The references cited in the two parts are essentially the same.
"The taboo in writing a review is to repeat the description. Therefore, in the second part, it is important to focus on the cited documents, and in the third part, do not repeat the large description." Xu Qiu reminded the school girl next to it.
"That's it," Han Jiaying thoughtfully, "then the content of the third part will be less."
"Yes," Xu Qiu nodded, "Grasp the main point, just write a few paragraphs to summarize the current situation, and quote one or two typical articles for each paragraph."
Han Jiaying was not polite with Xu Qiu, and asked directly: "Then what are the main points of the part of the "blended film morphology" that I am responsible for?"
"Well..." Xu Qiu thought for a moment, and said: "The morphology of the blended film itself involves factors such as crystallinity, compatibility, phase separation between the receptors, etc., which can be described directly in words; the corresponding characterization means, Including transmission electron microscope, atomic force microscope, wide-angle grazing incidence X-ray diffraction, etc., each of these characterization methods can be equipped with a picture."
"Okay." Han Jiaying smiled sweetly. During Xu Qiu's speech, her fingers did not stop all the way, and she recorded all the content he said on a new note on the desktop.
After that, the two entered the working state, Han Jiaying asked some questions from time to time, and Xu Qiujun answered them patiently.
For Xu Qiu, although the current work efficiency has been slightly reduced, because the two communicated in time, the time spent on changing the article will definitely be reduced later, and the overall work efficiency may be higher.
The senior sister didn't show up all afternoon, it seemed that she was trapped by the liquid chromatograph.
It was not until five o'clock that Chen Wanqing opened the door of A501.
She saw Xu Qiu and Han Jiaying sitting in a row, gently "tsk tsk", then turned to say while washing their hands:
"go for meal?"
"Good, good."
"Walk."
After dinner, Xu Qiu went directly to the laboratory.
His three Suzuki reactions are almost up to time, and one nitration reaction will not end until nine o'clock in the evening.
Click the plates one by one to confirm that the yield of the product is not low, then directly shut down the reaction and start the post-processing.
Liquid separation, washing, sample mixing, rotary steaming, loading sample column.
Next is a fortified station. It's just after six o'clock. Today, the products of the four reactions have to pass through the column, and maybe it will be early in the morning.
After installing the sample column, Xu Qiu found that a box of disposable blank silica gel columns presented by the liquid chromatograph manufacturer was almost used up, and only five were left, which was enough for this use.
After that, you have to install the columns yourself, or find old disposable columns for reuse.
Most disposable blank chromatographic columns will have some raw materials "dead adsorbed" in the column after use, forming a red mark. Of course, if it is not a PDI raw material, it may also be a blue mark or a colorless mark.
The so-called "dead adsorption" is also well understood, that is, sample molecules that are firmly absorbed by the silica gel column and cannot be easily desorbed, but no one can guarantee that they will never desorb. If you use an old column, there is a risk of sample contamination.
Set up the sample column and the blank silica gel column, arrange the test tube rack, insert the A/B solvent tube and the waste liquid bucket, and Xu Qiu turns on the liquid chromatograph.
The familiar sounds of "duang" and "duang" came, and the experimental platform began to vibrate slightly.
Recently, there are no less columns in the group. Solvents are used very fiercely, especially the low-polarity petroleum ether. The 16 liters of the four large barrels I bought before have been used up, and then four more barrels have been replenished, but the highly polar ethyl acetate Ester is used less.
The dichloromethane, 4 liters, also used nearly three barrels. The main solvent can not only be used to wash the column, it is very good for washing the bottle, especially the PDI material, which can be washed with a little dichloromethane. Clean.
That is, although its toxicity is not high among commonly used solvents, it is not low. Its boiling point is only 40 degrees Celsius. It is extremely volatile and can penetrate rubber gloves. If it is dropped on the hand, it will penetrate into the skin if it is not handled quickly.
Xu Qiu accidentally got his hand once. At first, it was isolated by gloves. It didn't feel much. After a few seconds, the hand felt cold. This was because the dichloromethane volatilized and took away the heat. After contaminated gloves, the skin will become red due to the infiltration of methylene chloride irritating the skin.
However, there were no other special adverse reactions.
In fact, the waste liquid collected through the column can also be recycled and reused by rotary evaporation.
However, all the solvents used in the group are mixed solvents. It is difficult to figure out the specific ratio. It can not be used indiscriminately. At most, it can only be used to wash bottles. The key point is that tens of liters of solvents are very laborious. Therefore, no one takes care of this work, and it is simply treated as waste liquid.
Xu Qiu looked at the waste liquid area in the shade under the next window. The waste liquid buckets were lined up. Most of them looked red. Most of them were PDI-related waste liquid. You need to go to the School of Pharmacy to deal with it when you have time. a bit.
In the middle of the experiment, Han Jiaying and Chen Wanqing went to the laboratory separately to deal with their reactions, and each cast a new reaction.
Because Xu Qiu’s three reactions were all 500 mg samples, not too much, he HOLD lived, so he didn’t let his schoolgirls help. He also went through the column and steamed at the same time, and took time to save some dirty bottles, The test tube is taken out of the alkali tank, rinsed and thrown into the ultrasonic cleaner for cleaning.
By about nine ten ten, the two systems PDI3-B-5 and PDI3-B-6 had been separated and purified.
Xu Qiu was planning to go to the fume hood to check the progress of the nitration reaction. Han Jiaying suddenly ran in and said, "Brother, we are going back to Handan. Be careful when you do the experiment alone, or... I will stay with you tonight. you?"
Xu Qiu was taken aback, just about to say something, the school girl smiled slyly, "What about you, I'm leaving, send me a message when it's over."
"Okay, bye." Xu Qiu had no choice but to smile, and then waved to the senior sister who was waiting at the door of the laboratory.
Seeing the back of the two of them leaving, Xu Qiuqing sighed, "They are all gone, we must speed up the progress."
Afterwards, he walked quickly towards the fume hood, dipped the capillary tube into the reaction solution and spotted the plate.
"Fucking?" Xu Qiu was stunned when he saw the results of the click.
There is no raw material point in the climbing board result, indicating that the raw material reaction is complete and the yield is close to 100%, but there are three product points, which are close together, stacked together.
These three products are very dark in color, it is difficult to judge which is the main product, and the polarity difference between each other is very small, and they will definitely be inseparable after passing the column.
Xu Qiu frowned, feeling that things were not simple.
His brain is spinning fast...
Not long after, a light bulb suddenly appeared next to Xu Qiu's head.
I understand!
3D-PDI molecules, each PDI has two reactive sites, which can be numbered (1, 2), (3, 4), (5, 6), each molecule can only be substituted by one nitro group , That is, take a number from each of the three brackets.
Since the molecule is centrally symmetric, there are only three cases: 135, 136, and 145.
In these three cases, there are slight changes in the positions of the three nitro groups in the molecule, which have an impact on the polarity of the molecule, but the effect is not large, so the three product points are almost overlapped.
Thinking of this step, the problem will be solved.
100% yield, no need to go through the column, directly use the anti-solvent to precipitate the solid product, and then dry it.
Just say nothing, Xu Qiu took about 150 ml of methanol in a disposable PE cup, and directly dropped the solution in the reaction flask into the methanol with a disposable dropper.
With the addition of the solution, a dark red solid precipitated out.
After all the reaction solution was dripped, Xu Qiu started to install the Buchner funnel.
The main body is a ceramic funnel, the name is Buchner funnel, there are many small holes on it, which can be used for filtering, but to use with filter paper, you need to cut the filter paper into a circular shape with scissors, and spread it inside the funnel to cover all the small holes. hole;
Below is a liquid contact flask, the shape of a triangular flask, with a branch pipe mouth, the branch pipe mouth is connected with a water pump, can be used to vacuum;
In addition, there is a rubber gasket, which is placed between the Buchner funnel and the wetted bottle, to ensure the high air tightness of the system.
Next, Xu Qiu turned on the water pump, fixed the Buchner funnel, and poured the methanol solution mixed with the product into the Buchner funnel for vacuum filtration.
During this process, repeated washing with water is used to remove possible residual nitric acid, and the pH of the filtrate is continuously checked with pH test paper until the pH of the filtrate is maintained at about 7.
Finally, scrape the product on the Buchner funnel with a stainless steel spatula, wrap it in filter paper, and transfer it to a vacuum oven at 70 degrees Celsius and high vacuum for drying.
"It's done." Xu Qiu tried to snap his fingers, but found that he was wearing multiple gloves.
Looking around, UU reading www.uukanshu.com laboratory is empty.
Xu Qiu couldn't help singing a song, "The only thing left is the oven to talk with me for a day, the sleeping liquid chromatography..."
After a while, continue the experiment.
It took more than an hour to complete the separation and purification of PDI3-B-8.
Counting the products, it was a bumper harvest this time. The three first-generation 3D-PDI molecules all obtained 300-400 mg of products, and the average yield was about 70%.
Copy the three to the simulation laboratory, allowing simulation experimenters to traverse different donor materials and explore the photoelectric properties of the three acceptor molecules.
Although there are two molecules that have been tried once before, after all, the batches are different, and there may be differences. Also, considering the fixed cost of device preparation, the more systems you explore, the higher the cost performance. Xu Qiu put them also Give it to the simulation experimenter.
The focus of this research is whether increasing the length of the side chain at the position of the nitrogen atom of the PDI molecule can improve its photoelectric performance.