There's iridium-based blood called Chloro-carbonyl-bis(triphenylphosphine)-iridium that's effective at transporting hydrogen alongside oxygen.

What I want to know is that, are there other metal-based blood types that can be used/be effective at transporting other non-oxygen-based gases? Such as a metal-based blood type that's effective at transporting methane for example.

And what color would the blood be when they're saturated with these non-oxygen-based gases?

To clarify, the gases I want to know that can be transported effectively by certain blood types are:

Methane. Chlorine. Sulfur. Ammonia. Noble gases.

In terms of what metal-based blood types, I'm not sure, there isn't much information on how none oxygen-based gases can be transported by blood types I can find, and it's why I'm asking.

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    $\begingroup$ Welcome to Worldbuilding! We're glad you could join us! When you have a moment, please click here to learn more about our culture and take our tour. An admittedly rapid Google search does not identify that compound as a blood, or usable as a blood, but apparently a rather toxic substance nicknamed "Vaska's Complex" that can reversibly bind oxygen. Are you sure that compound is what you think it is? $\endgroup$
    – JBH
    Sep 22, 2019 at 1:22
  • $\begingroup$ @JBH Yes, that's the compound, and here's a link to where I've heard about it reversibly binding to hydrogen daviddarling.info/encyclopedia/B/blood.html However, as I stated before in my post, I would like to know if there are blood types that can be used to reversibly bind other none oxygen-based gases besides hydrogen. $\endgroup$ Sep 22, 2019 at 1:46
  • $\begingroup$ Ah. Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization by Robert A. Freitas, Jr. is very well educated fiction. Keep in mind that we know of no alien life forms. It's all a guess. You're reading a possibility/suggestion as if it's real. It's not. Better informed people on this website can offer greater clarification, but I suspect there aren't any comparables to work with. In other words, if you start with a fictional possibility, you shouldn't be surprised that there isn't realistic plausibility. Fair warning. $\endgroup$
    – JBH
    Sep 22, 2019 at 1:56
  • $\begingroup$ Also, please keep in mind that the compound you're referring to, reversibly binds oxygen. It doesn't do what you think it does, at least not according to the factual literature about the synthetic compound. Despite Mr. Freitas' suppositions, I'd be hard pressed to believe this compound could ever act as blood for any creature. $\endgroup$
    – JBH
    Sep 22, 2019 at 1:58
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    $\begingroup$ You need to decide which gasses you want to transport a list of every possible gas/transport combination is way to broad. $\endgroup$
    – John
    Sep 22, 2019 at 4:32

1 Answer 1


Fluorine, chlorine, and hydrogen could be transported simply by a reaction with graphene. The resulting graphene fluoride and chloride are reactive, so they could be decomposed back into graphene and gaseous F2 and Cl2. Ammonia, sulfur dioxide, and carbon monoxide could be transported by various metal conplexes; the color would vary based on the metal. Hydrogen sulfide can react with silver to make silver sulfide and hydrogen which could be reversed by an enzyme. Hydrogen could theoretically be carried via a metal hydride complex, but I'm not sure how feasible that is evolutionarily. Methane....I don't know; most of the research I could find on methane-metal complexes was on the activation of methane for natural gas.

Please note: I am no expert in this. I just wanted to put my thoughts on this here, and honestly, I am also interested in this topic.

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    $\begingroup$ Huh, I didn't know that about graphene and the reaction fluorine and chlorine had with it, thank you. Can you give some examples of these metal complexes that can transport ammonia, sulfur dioxide, and carbon monoxide? $\endgroup$ Sep 22, 2019 at 5:24
  • $\begingroup$ Not really how it works... $\endgroup$
    – AlexP
    Sep 22, 2019 at 6:59
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    $\begingroup$ I never said I was an expert, but here are some quick examples. It's 3am here, and I need sleep. Ammonia:pubs.rsc.org/en/content/articlelanding/2019/dt/… CO:chemistry.stackexchange.com/questions/95303/… SO2: researchgate.net/publication/… $\endgroup$
    – Aezyc
    Sep 22, 2019 at 7:10
  • $\begingroup$ The key here is why blood is red in the first place. And that's basically because it contains rusted iron. $\endgroup$
    – Ton Day
    Sep 24, 2019 at 4:58
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    $\begingroup$ @Dayton Williams Not Really that simple...I wish it was though. The oxidation color of the metal involved does play a role in the complex's color, but it is also influenced by the complex itself and some weird electrical phenomena that even I don't understand! Just compare Cobalt complexes and their colors. And look at hemoglobin and phycoerythrin, both use Iron but are completely different looking! The colors of metal complexes are hard to determine to say the least. Again...I'm no expert. $\endgroup$
    – Aezyc
    Dec 24, 2019 at 7:37

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