When preparing Pd@MOFs catalysts via wet impregnation, I added carbon-dots solutions (synthesized from citric acid and ethylenediamine) into MOFs suspension in an attempt to facilitate the reduction of Pd(II) to Pd(0) in the following step. However, after hours of magnetic stirring, the MOFs particles dissolved, forming a clear solution, and I couldn't separate them by centrifugation. I wonder what has caused MOFs to dissolve, and does it necessarily mean that the original crystal structure, along with the coordination environment, has been damaged? (Typically, MOFs would form a suspension during the wet impregnation step, and could easily be separated by subsequent centrifugation. )
According to my knowledge and experience related to MOF, i think it should retain its crystal structure and should easily be centrifuged. I recommend you this article, please have a look at it. 'Imparting functionality to a metal–organic
framework material by controlled nanoparticle
encapsulation'. Thank you
I agree, usually, the crystal structure is not destroyed by stirring - of course, you will always reduce the crystal size to some extent, especially when vigorously stirring with high rpm. For separation, you could try high rpm for long time (e.g., 3500 rpm, 30 mins).
Dear Israt Ali :
Thank you for your kind suggestion! Actually I had read that article before. In this case, however, I wonder whether the effect of carbon dots could cause the mofs to dissolve, but I can't see why. Like you said, usually it can be easily centrifuged. Besides, with carbon dots added I got a clear solution instead of a suspension, which is why I found it hard to separate.
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