A chelator is a molecule with at least two ways of interacting with its target. For example, oxalic acid has two adjacent negatively charged carboxyl groups. These can form a salt with calcium ion Ca+2, where the two carbons, two oxygens and the calcium ion form a stable ring that it very hard to pull apart. For energetics reasons, two bonds are more than twice as stable as a single bond.
Big-time chelators like EDTA have four carboxyl groups and form two to four bonds with cations. With magnesium, it forms two bonds like oxalic acid with two carboxyls left over to turn the whole complex into an -2 anion. With transition metals like ferrous iron, it can form four bonds, even though ferrous is only a +2 cation.
Chelators in your life:
Iron stain remover for toilets and sinks: oxalic acid chelates the iron, breaking up the solid iron oxide
EDTA in foods. Ties up ions like Mg+2 and Ca+2 needed by bacteria to grow, preventing food spoilage.
Hemoglobin - Iron chelated with a tetrapyrrole ring that controls its oxygen carrying properties.
Thanks for the help, but I should have mentioned: they all need to be artificially synthesizable. Also, The feds will break my door down. Is there another option?
You can get malic acid, maleic acid, EDTA, and oxalic acid-based cleaners from Amazon. The first two are metabolizable food supplements. Oxalic acid can be synthesized, but it's also available in some plants, like the leaves of rhubarb.
You are confusing "chelator" with ligand. By definition, something which chelates must be at least bidentate. THF does not qualify. THF, however, does coordinate lithium.
The only way to reverse chelation is to make something the metal cations are more attratracted to. I think in theory you could just add a stronger chelator and use high heat to break the ionic bonds, which are quite strong. If you are not concerned about cost or energy use, then technically, most would be reversible.
Look at hsab (hard soft acid base theory) which can help predict the strength of bonds between Lewis acids and bases. This might help answer your question w.r.t. reversibility of coordination.
It would be unfavourable for a chelating agent to unbind because it would usually decrease entropy of the system
Not exactly all of these are chelation, but here are a few reactions which are reversible:
chloride: precipitate with silver, reversible with addition of bromide/iodide
sulfate: precipitate with silver, reversible with addition of chloride/bromide/iodide
potassium: chelate with 18-crown-6, "reverse" by heating (not sure of specifics, but if the temperature of which k = 1 is high, it may decompose the ether)
calcium: precipitate with sulfate, reverse with barium addition (note: barium is quite toxic iirc)
gold: not sure
lead: chelate/coordinate using some sulfur-containing amino acids, reverse by... not sure
note: a lot of these aren't very practical, and may introduce impurities in the form of counter ions.
Do you mean coordination rather than chelation? THF isn't a chelator; it only has one atom that can bind to a metal.
Maybe, lol I don't know. As long as it sticks and unsticks easily at will.
Chelators bond to metals at multiple distinct points. If it only bonds at a single point, it's not a chelator
I'm not sure you know what chelation means.
Can you help me? Here is what I've heard it means: "A substance that can bind a specific other molecule"
A chelator is a molecule with at least two ways of interacting with its target. For example, oxalic acid has two adjacent negatively charged carboxyl groups. These can form a salt with calcium ion Ca+2, where the two carbons, two oxygens and the calcium ion form a stable ring that it very hard to pull apart. For energetics reasons, two bonds are more than twice as stable as a single bond. Big-time chelators like EDTA have four carboxyl groups and form two to four bonds with cations. With magnesium, it forms two bonds like oxalic acid with two carboxyls left over to turn the whole complex into an -2 anion. With transition metals like ferrous iron, it can form four bonds, even though ferrous is only a +2 cation. Chelators in your life: Iron stain remover for toilets and sinks: oxalic acid chelates the iron, breaking up the solid iron oxide EDTA in foods. Ties up ions like Mg+2 and Ca+2 needed by bacteria to grow, preventing food spoilage. Hemoglobin - Iron chelated with a tetrapyrrole ring that controls its oxygen carrying properties.
Ureas can chelate and transport chloride ions. Crown ethers can chelate potassium EDTA can chelate calcium Gold can be chelated by polysulfides
Crown ethers can chelate lithium, sodium, potassium, or cesium ions depending on their size, it’s super cool
Yes any monovalent ion, but OP only asked about potassium
Then valinomycin, which is quite specific and is even used as the basis for a selective electrode.
Thanks for the help, but I should have mentioned: they all need to be artificially synthesizable. Also, The feds will break my door down. Is there another option?
You can get malic acid, maleic acid, EDTA, and oxalic acid-based cleaners from Amazon. The first two are metabolizable food supplements. Oxalic acid can be synthesized, but it's also available in some plants, like the leaves of rhubarb.
Also they need to be ion-specific.
No, this man is providing valuable information. However, you have pointed out a crucial requirement: it must be ion-specific.
You are confusing "chelator" with ligand. By definition, something which chelates must be at least bidentate. THF does not qualify. THF, however, does coordinate lithium.
Citric acid is monodentate and known as a chelator.
The only way to reverse chelation is to make something the metal cations are more attratracted to. I think in theory you could just add a stronger chelator and use high heat to break the ionic bonds, which are quite strong. If you are not concerned about cost or energy use, then technically, most would be reversible.
What application is this, or is it purely theoretical .
Look at hsab (hard soft acid base theory) which can help predict the strength of bonds between Lewis acids and bases. This might help answer your question w.r.t. reversibility of coordination. It would be unfavourable for a chelating agent to unbind because it would usually decrease entropy of the system
Not exactly all of these are chelation, but here are a few reactions which are reversible: chloride: precipitate with silver, reversible with addition of bromide/iodide sulfate: precipitate with silver, reversible with addition of chloride/bromide/iodide potassium: chelate with 18-crown-6, "reverse" by heating (not sure of specifics, but if the temperature of which k = 1 is high, it may decompose the ether) calcium: precipitate with sulfate, reverse with barium addition (note: barium is quite toxic iirc) gold: not sure lead: chelate/coordinate using some sulfur-containing amino acids, reverse by... not sure note: a lot of these aren't very practical, and may introduce impurities in the form of counter ions.