I was thinking about adding a special M3+ metal ion in a Tetraphenylporphyrin (TPP) ring.
What will happen if we add bases like NaOC(CH3)3 to a solution contains Tetraphenylporphyrin (TPP)? Can this leads to detaching of the hydrogens from nitrogens (on NH sites of the porphyrin ring) and making the ring capable of bonding with our metal ion or the base might just be add to a part of the ring?
What about using a normal weak base like ethanolamine? Can this do what we want for us?
Do you think this method will work for synthesizing metal-porphyrins? And would you mind please let me know if there is any other bases which can do the same for us?
Can This method followed by a hydrothermal reaction in a autoclave reactor for synthesizing metal-porphyrin nanoclusters?
Hi Ramin,
There is no need for a strong base, such as tBuOK, in this reaction. Pyrrolic NH will be readily deprotonated with an amine.
For metal insertion to porphyrin, triethylamine is most commonly used. However, choice of a base depend on the metal you wish to introduce. Certain M3+ ions can be reduced upon treatment with organic amine, especially if the procedure requires heating.
I suggest you can use pyridine as a solvent. In this case no need to add a base.
Dear Ramin,
I agree with Mikhail A Filatov.
In order to obtain metalloporphyrins, a basic medium is needed, because in acid medium the inserted metal is liberated from the porphyrin core.
The issue that you raised up of the bulky tert- butyl, may be a problem , but I consider
that porphyrin will lose its planar architecture, will distort and became ruffed-like and be able to be metallated. Tert - butyllithium is the best for this action, but the Na derivative is OK too.
But be cautious, this type of organic compounds , might react vigorously, with large heat formation, so I think you will need argon or at least nitrogen protection and to conduct the reaction at low temperatures. Di-sodium organoreagents can be formed as secondary products.
Why don't you use the normal way (to use anorganic salts in large excess) in a mixture of DMF/water???
Best regards and Success!
Eugenia
The insertion of a M3+ metal into a porphyrin is not a matter of overcoming the thermodynamics of the system, etc. They are most likely on your side. So the issue is kinetics, as Eugenia already eluded to. I, like her, would also use t-BuLi under rigorously anhydrous conditions, to prepare the Li2 salt (check out John Arnold's work), followed by your metal salt. This said it all depends on the M3+ metal you like to insert. Do not hesitate to be specific about it, all metalloporphyrins that could be readily made have been prepared already.
No idea about the hydrothermal method you like to follow the metal insertion with.
Good luck, Christian
Dear Dr.Filatov, Thank you so much. The idea of using pyridine as a solvent seems really interesting to me, do you think adding pyridine in v/v ratios in solvent solution might do the same for us?
Dear Dr.Fagadar-Cosma, thanks a lot. That was a great point that production of di-sodium organoreagents will cause a big decrease in the yield of our reaction, I was thinking about normal ways, but I'm not sure if that works well with lanthanide and actinide metals which I'm going to work with.
Dear Dr.Brueckner, Thank you, too. Mentioning the Li salts cause me actually thinking about using dilithiotetraphenylporphyrin instead of TPP as the first reagent. I know so many metalloporphyrins have been prepared yet, but I think the yields of those reaction were low, plus synthesizing some of nano-metalloporphyrins is still a challenge.
Raman, you asked me via RG message - however, I can not add anything valuable better than what the previous experts commented.
Yes Dr.Wessling, I want to know your idea about usability of my theory which was about using hydrothermal methods to synthesis metal-porphyrin NCs.
I am not very familiar with porphyrin chemistry; using (strong) bases seems to be the usual way, but are bases like NaOC(CH3)3 strong enough? I doubt it. Maybe if applied under hydrothermal conditions?
My expertise is more with Polyaniline / metal complexes which spontaneously form under suitable dispersion / room (or elevated) temperature conditions because of the redox potential of Polyaniline.
Usually metallation of free porphyrin with transition metal salt does not require external base and good yield can be obtained. Refluxing in a suitable solvent is a common practice.
In some minor cases, work up with dilute HCl to introduce the axial Cl- ligand is needed.
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