Rhodamine B

Rhodamine B /ˈroʊdəmiːn/ is a chemical compound and a dye. It is often used as a tracer dye within water to determine the rate and direction of flow and transport. Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with fluorometers.

Rhodamine B

Names
IUPAC name [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-diethylammonium chloride
Other names Rhodamine 610, C.I. Pigment Violet 1, Basic Violet 10, C.I. 45170
Identifiers
CAS Number	81-88-9
3D model (JSmol)	Interactive image
ChEBI	CHEBI:52334
ChEMBL	ChEMBL428971
ChemSpider	6439
ECHA InfoCard	100.001.259
KEGG	C19517
PubChem CID	6694
UNII	K7G5SCF8IL
CompTox Dashboard (EPA)	DTXSID6042369
InChI InChI=1S/C28H30N2O3.ClH/c1-5-29(6-2)19-13-15-23-25(17-19)33-26-18-20(30(7-3)8-4)14-16-24(26)27(23)21-11-9-10-12-22(21)28(31)32;/h9-18H,5-8H2,1-4H3;1H Key: PYWVYCXTNDRMGF-UHFFFAOYSA-N
SMILES CCN(CC)C1=CC2=C(C=C1)C(=C3C=CC(=[N+](CC)CC)C=C3O2)C4=CC=CC=C4C(=O)O.[Cl-]
Properties
Chemical formula	C28H31ClN2O3
Molar mass	479.02
Appearance	red to violet powder
Melting point	210 to 211 °C (410 to 412 °F; 483 to 484 K) (Decomposes)
Solubility in water	8 to 15 g/L (20 °C)[1][nt 1]
Hazards
Safety data sheet	MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Rhodamine B is used in biology as a staining fluorescent dye, sometimes in combination with auramine O, as the auramine-rhodamine stain to demonstrate acid-fast organisms, notably Mycobacterium. Rhodamine dyes are also used extensively in biotechnology applications such as fluorescence microscopy, flow cytometry, fluorescence correlation spectroscopy and ELISA. It is also used in rose milk, a popular Indian beverage.

Other uses

Rhodamine B solution in water

Rhodamine B is often mixed with herbicides to show where they have been used.[2]

It is also being tested for use as a biomarker in oral rabies vaccines for wildlife, such as raccoons, to identify animals that have eaten a vaccine bait. The rhodamine is incorporated into the animal's whiskers and teeth.[3]

Rhodamine B (BV10) is mixed with quinacridone magenta (PR122) to make the bright pink watercolor known as Opera Rose.[4]

Properties

Rhodamine B closed form (A) and open form (B)

Rhodamine B can exist in equilibrium between two forms: an "open"/fluorescent form and a "closed"/nonfluorescent spirolactam form. The "open" form dominates in acidic condition while the "closed" form is colorless in basic condition.[5]

The fluorescence intensity of rhodamine B will decrease as temperature increases.[6]

The solubility of rhodamine B in water varies by manufacturer, and has been reported as 8 g/l and ~15 g/L,[1] while solubility in alcohol (presumably ethanol) has been reported as 15 g/L.[nt 1] Chlorinated tap water decomposes rhodamine B. Rhodamine B solutions adsorb to plastics and should be kept in glass.[7] Rhodamine B is tunable around 610 nm when used as a laser dye.[8] Its luminescence quantum yield is 0.65 in basic ethanol,[9] 0.49 in ethanol,[10] 1.0,[11] and 0.68 in 94% ethanol.[12] The fluorescence yield is temperature dependent;[13] the compound is fluxional in that its excitability is in thermal equilibrium at room temperature.[14]

Synthesis

Safety and health

In California, rhodamine B is suspected to be carcinogenic and thus products containing it must contain a warning on its label.[15] Cases of economically motivated adulteration, where it has been illegally used to impart a red color to chili powder, have come to the attention of food safety regulators.[16]

See also

• Dye laser
• Laser dyes
• Rhodamine
• Rhodamine 6G

References

1. "Safety data sheet" (PDF). Roth. 2013.
2. Cai SS, Stark JD (November 1997). "Evaluation of five fluorescent dyes and triethyl phosphate as atmospheric tracers of agricultural sprays". Journal of Environmental Science & Health Part B. 32 (6): 969–83. doi:10.1080/03601239709373123.
3. Slate D, Algeo TP, Nelson KM, Chipman RB, Donovan D, Blanton JD, et al. (December 2009). Bethony JM (ed.). "Oral rabies vaccination in north america: opportunities, complexities, and challenges". PLOS Neglected Tropical Diseases. 3 (12): e549. doi:10.1371/journal.pntd.0000549. PMC 2791170. PMID 20027214.
4. MacEvoy B. "Handprint: color making attributes". www.handprint.com.
5. Birtalan E, Rudat B, Kölmel DK, Fritz D, Vollrath SB, Schepers U, Bräse S (2011). "Investigating rhodamine B-labeled peptoids: scopes and limitations of its applications". Biopolymers. 96 (5): 694–701. doi:10.1002/bip.21617. PMID 22180914.
6. Chauhan VM, Hopper RH, Ali SZ, King EM, Udrea F, Oxley CH, Aylott JW (March 2014). "Thermo-optical characterization of fluorescent rhodamine B based temperature-sensitive nanosensors using a CMOS MEMS micro-hotplate". Sensors and Actuators. B, Chemical. 192: 126–133. doi:10.1016/j.snb.2013.10.042. PMC 4376176. PMID 25844025.
7. Bedmar AP, Araguás LA (2002). Detection and Prevention of Leaks from Dams. Taylor & Francis. ISBN 90-5809-355-7.
8. Prahl S. "Rhodamine B". OMLC.
9. Kubin R (1982). "Fluorescence quantum yields of some rhodamine dyes" (PDF). Journal of Luminescence. 27 (4): 455–462. Bibcode:1982JLum...27..455K. doi:10.1016/0022-2313(82)90045-X.
10. Casey KG, Quitevis EL (1988). "Effect of solvent polarity on nonradiative processes in xanthene dyes: Rhodamine B in normal alcohols". The Journal of Physical Chemistry. 92 (23): 6590–6594. doi:10.1021/j100334a023.
11. Kellogg RE, Bennett RG (1964). "Radiationless Intermolecular Energy Transfer. III. Determination of Phosphorescence Efficiencies". The Journal of Chemical Physics. 41 (10): 3042–3045. Bibcode:1964JChPh..41.3042K. doi:10.1063/1.1725672.
12. Snare M (1982). "The photophysics of rhodamine B". Journal of Photochemistry. 18 (4): 335–346. doi:10.1016/0047-2670(82)87023-8.
13. Karstens T, Kobs K (1980). "Rhodamine B and rhodamine 101 as reference substances for fluorescence quantum yield measurements". The Journal of Physical Chemistry. 84 (14): 1871–1872. doi:10.1021/j100451a030.
14. Strack R (May 2019). "Bypassing bleaching with fluxional fluorophores". Nature Methods (Paper). 16 (5): 357. doi:10.1038/s41592-019-0402-2. PMID 31040423.(subscription required)
15. "Naval Jelly MSDS with Rhodamine B" (PDF). Locite Corporation. 20 October 1998. Archived from the original (PDF) on 2010-04-15.
16. Lin S (2015). "Rapid and sensitive SERS method for determination of Rhodamine B in chili powder with paper-based substrates". Analytical Methods. 7 (12): 5289. doi:10.1039/c5ay00028a. Retrieved 1 February 2018.

Notes

1. Ellis RC (November 16, 2015). "Reagent and Dye Solubility Chart". IHCWorld. Retrieved 9 February 2020. This is to be used as a guide only as solubility data varies between manufacturers for the same product, especially for dyes. Note that most sources simply indicate that the compound is water soluble without providing a g/l value.