In organic chemistry, chlorins are tetrapyrrole pigments that are partially hydrogenated porphyrins.[1] The parent chlorin is an unstable compound which undergoes air oxidation to porphine.[2] The name chlorin derives from chlorophyll. Chlorophylls are magnesium-containing chlorins and occur as photosynthetic pigments in chloroplasts. The term "chlorin" strictly speaking refers to only compounds with the same ring oxidation state as chlorophyll.
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| Other names
2,3-Dihydroporphine
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3D model (JSmol)
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C20H16N4 | |
| Molar mass | 312.36784 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Chlorins are excellent photosensitizing agents. Various synthetic chlorins analogues such as m-tetrahydroxyphenylchlorin (mTHPC) and mono-L-aspartyl chlorin e6 are effectively employed in experimental photodynamic therapy as photosensitizer.[3]
Chlorophylls
editThe most abundant chlorin is the photosynthetic pigment chlorophyll. Chlorophylls have a fifth, ketone-containing ring unlike the chlorins. Diverse chlorophylls exists, such as chlorophyll a, chlorophyll b, chlorophyll d, chlorophyll e, chlorophyll f, and chlorophyll g. Chlorophylls usually feature magnesium as a central metal atom, replacing the two NH centers in the parent.[4]
Variation
editMicrobes produce two reduced variants of chlorin, bacteriochlorins and isobacteriochlorins. Bacteriochlorins are found in some bacteriochlorophylls; the ring structure is produced by Chlorophyllide a reductase (COR) reducing a chlorin ring at the C7-8 double boud.[5] Isobacteriochlorins are found in nature mostly as sirohydrochlorin, a biosynthetic intermediate of vitamin B12, produced without going through a chlorin. In living organisms, both are ultimately derived from uroporphyrinogen III, a near-universal intermediate in tetrapyrrole biosynthesis.[6]
Synthetic chlorins
editNumerous synthetic chlorins with different functional groups and/or ring modifications have been examined.[7]
Contracted chlorins can be synthesised by reduction of B(III)subporphyrin or by oxidation of corresponding B(III)subbacteriochlorin.[8] The B(III)subchlorins were directly synthesized as meso-ester B(III)subchlorin from meso-diester tripyrromethane, these class of compound showed very good fluorescence quantum yield and singlet oxygen producing efficiency[9][10]
See also
editFurther reading
edit- Juse´lius, Jonas; Sundholm, Dage (2000). "The aromatic pathways of porphins, chlorins and bacteriochlorins". Physical Chemistry Chemical Physics. 2 (10): 2145–2151. Bibcode:2000PCCP....2.2145J. doi:10.1039/b000260g.
References
edit- ^ Gerard P. Moss (1988). "Nomenclature of Tetrapyrroles. Recommendations 1986". European Journal of Biochemistry. 178 (2): 277–328. doi:10.1111/j.1432-1033.1988.tb14453.x. PMID 3208761.
- ^ Battersby, Alan R. (2000). "Tetrapyrroles: The pigments of life". Natural Product Reports. 17 (6): 507–526. doi:10.1039/b002635m. PMID 11152419.
- ^ Spikes, John D. (July 1990). "New trends in photobiology". Journal of Photochemistry and Photobiology B: Biology. 6 (3): 259–274. doi:10.1016/1011-1344(90)85096-F. PMID 2120404.
- ^ K. Eszter, Borbas. Handbook of Porphyrin Science: 181: Chlorins. worldscientific. doi:10.1142/9789813149564_0001. ISBN 9814322326.
- ^ Chew, Aline Gomez Maqueo; Bryant, Donald A. (2007). "Chlorophyll Biosynthesis in Bacteria: The Origins of Structural and Functional Diversity". Annual Review of Microbiology. 61: 113–129. doi:10.1146/annurev.micro.61.080706.093242. PMID 17506685.
- ^ Battersby, Alan R. (2000). "Tetrapyrroles: The pigments of life: A Millennium review". Natural Product Reports. 17 (6): 507–526. doi:10.1039/B002635M. PMID 11152419.
- ^ Taniguchi, Masahiko; Lindsey, Jonathan S. (2017). "Synthetic Chlorins, Possible Surrogates for Chlorophylls, Prepared by Derivatization of Porphyrins". Chemical Reviews. 117 (2): 344–535. doi:10.1021/acs.chemrev.5b00696. OSTI 1534468. PMID 27498781.
- ^ Osuka, Atsuhiro; Kim, Dongho (2008). "Synthesis and Characterization of meso-Aryl-Substituted Subchlorins". Journal of the American Chemical Society. 130 (2): 438–439. doi:10.1021/ja078042b. PMID 18095693.
- ^ Chandra, Brijesh; Soman, Rahul; Sathish Kumar, B.; Jose, K. V. Jovan; Panda, Pradeepta K. (3 Dec 2020). "Meso-Free Boron(III)subchlorin and Its μ-Oxo Dimer with Interacting Chromophores". Organic Letters. 22 (24): 9735–9739. doi:10.1021/acs.orglett.0c03813. PMID 33270460. S2CID 227282229.
- ^ Soman, Rahul; Chandra, Brijesh; Bhat, Ishfaq A.; Kumar, B. Sathish; Hossain, Sk Saddam; Nandy, Sridatri; Jose, K. V. Jovan; Panda, Pradeepta K. (15 Jul 2021). "A2B- and A3-Type Boron(III)Subchlorins Derived from meso-Diethoxycarbonyltripyrrane: Synthesis and Photophysical Exploration". The Journal of Organic Chemistry. 86 (15): 10280–10287. doi:10.1021/acs.joc.1c01001. PMID 34264670. S2CID 235959639.