Fluorescein

Fluorescein
Names
Pronunciation	/flʊəˈrɛsi.ɪn, flʊəˈrɛsiːn/
	IUPAC name 3′,6′-dihydroxyspiro[isobenzofuran-1(3H),9′-[9H]xanthen]-3-one
	Other names Resorcinolphthalein, C.I. 45350, solvent yellow 94, D&C yellow no. 7, angiofluor, Japan yellow 201, soap yellow
Identifiers
CAS Number	2321-07-5 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:31624 ;
ChEMBL	ChEMBL177756 ;
ChemSpider	15968 ;
DrugBank	DB00693 ;
ECHA InfoCard	100.017.302
EC Number	219-031-8;
KEGG	D01261 ;
MeSH	Fluorescein
PubChem CID	16850;
UNII	TPY09G7XIR ;
CompTox Dashboard (EPA)	DTXSID0038887 ;
	InChI InChI=1S/C20H12O5/c21-11-5-7-15-17(9-11)24-18-10-12(22)6-8-16(18)20(15)14-4-2-1-3-13(14)19(23)25-20/h1-10,21-22H Key: GNBHRKFJIUUOQI-UHFFFAOYSA-N ; InChI=1/C20H12O5/c21-11-5-7-15-17(9-11)24-18-10-12(22)6-8-16(18)20(15)14-4-2-1-3-13(14)19(23)25-20/h1-10,21-22H Key: GNBHRKFJIUUOQI-UHFFFAOYAZ;
	SMILES c1ccc2c(c1)C(=O)OC23c4ccc(cc4Oc5c3ccc(c5)O)O;
Properties
Chemical formula	C20H12O5
Molar mass	332.311 g·mol−1
Melting point	314 to 316 °C (597 to 601 °F; 587 to 589 K)
Solubility in water	Slightly
Pharmacology
ATC code	S01JA01 (WHO)
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H319
Precautionary statements	P305, P338, P351
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Fluorescein is an organic compound and dye based on the xanthene tricyclic structural motif, formally belonging to triarylmethine dyes family. It is available as a dark orange/red powder slightly soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications.^[1]

The color of its aqueous solutions is green by reflection and orange by transmission (its spectral properties are dependent on pH of the solution),^[2] as can be noticed in bubble levels, for example, in which fluorescein is added as a colorant to the alcohol filling the tube in order to increase the visibility of the air bubble contained within. More concentrated solutions of fluorescein can even appear red (because under these conditions nearly all incident emission is re-absorbed by the solution).

It is on the World Health Organization's List of Essential Medicines.^[3]

^ Gessner, Thomas; Mayer, Udo (2000). "Triarylmethane and Diarylmethane Dyes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a27_179. ISBN 978-3527306732.
^ Sjöback, Robert; Nygren, Jan; Kubista, Mikael (1995-06-01). "Absorption and fluorescence properties of fluorescein". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 51 (6): L7–L21. Bibcode:1995AcSpA..51L...7S. doi:10.1016/0584-8539(95)01421-P. ISSN 1386-1425.
^ World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.

[Ull-1] Gessner, Thomas; Mayer, Udo (2000). "Triarylmethane and Diarylmethane Dyes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a27_179. ISBN 978-3527306732.

[dx.doi.org-2] Sjöback, Robert; Nygren, Jan; Kubista, Mikael (1995-06-01). "Absorption and fluorescence properties of fluorescein". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 51 (6): L7–L21. Bibcode:1995AcSpA..51L...7S. doi:10.1016/0584-8539(95)01421-P. ISSN 1386-1425.

[WHO21st-3] World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.

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