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When I search for catalysts other than chlorophyll on Google, I only get references to artificial photosynthesis. When I look up photosynthesis, I see accessory pigments mentioned, but it appears that the chlorophyll family is crucial.

These chlorophyll variants all have the chlorin (not to be confused with chlorine) ring in common.

Are there any photosynthetic organisms that do not use a chlorin derivative? Why is chlorin so predominant?

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There are photosynthetic organisms that use retinal-rhodopsin complex. However, the mechanism of photosynthesis is different in these organisms than those that employ chlorophyll dependent photosystems. In these organisms, the light causes the rhodopsin-like membrane proteins to pump proton out of the cell and create a proton gradient which in turn is used by the ATP synthase to make ATP.

See this post too Why are there no known photosynthetic archaea?

This mechanism of "photosynthesis" is not as efficient as the chlorophyll dependent one (page 22, Baltscheffsky, 1997†). Moreover, it does not produce NADPH.

† Baltscheffsky, Herrick. Origin and evolution of biological energy conversion. New York etc: VCH, 1996. Print. ISBN: 978-0-471-18581-9

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  • $\begingroup$ What is the efficiency of that process, compared to chlorophyll photosynthesis? $\endgroup$
    – David Jonsson
    Sep 25, 2020 at 8:47
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    $\begingroup$ I think you would do better to ask that as a separate question, rather than commenting on a four-year old answer. $\endgroup$
    – David
    Sep 25, 2020 at 18:35
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I would say even photolyase counts since it uses light to change chemical bonds in DNA repair.

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