porphyrin
noun
por·phy·rin ˈpȯr-fə-rən 
: any of various compounds with a macrocyclic structure that consists essentially of four pyrrole rings joined by four =CH− groups
especially : one (such as chlorophyll or hemoglobin) containing a central metal atom and usually exhibiting biological activity
Example Sentences
Recent Examples on the Web The researchers’ gold-scrubber is based on an organic compound called a porphyrin. 
Scott K. Johnson, Ars Technica, 28 June 2020 The compounds, called porphyrins, had previously been shown to be adept at absorbing light and using that energy to convert oxygen molecules in the air to a reactive form known as singlet oxygen. Robert F. Service, Science | AAAS, 3 Sep. 2019
Scott K. Johnson, Ars Technica, 28 June 2020 The compounds, called porphyrins, had previously been shown to be adept at absorbing light and using that energy to convert oxygen molecules in the air to a reactive form known as singlet oxygen. Robert F. Service, Science | AAAS, 3 Sep. 2019 Word History
Etymology
International Scientific Vocabulary, from Greek porphyra purple
First Known Use
1910, in the meaning defined above
Medical Definition
porphyrin
noun
por·phy·rin ˈpȯr-fə-rən
: any of various compounds with a structure that consists essentially of four pyrrole rings joined by four =CH− groups
especially : one (as chlorophyll or hemoglobin) containing a central metal atom and usually having biological activity