Fluorescein

Introduction

In 1871 fluorescein (1) was firstly synthesized by A. von Baeyer via a Friedel–Crafts acylation of phthalic anhydride (2) and resorcinol (3).[ ¹ ] Fluorescein is a dark red powder which when dissolved displays excellent fluorescent properties (λ_ex = 494 nm and λ_em = 521 nm in water) making it widely used in applications ranging from molecular sensing to labeling. It has a high quantum yield, is water soluble, can be excited with the readily available argon ion laser, is prepared in a short synthetic route and is non-toxic [LD₅₀ = 6.7 g/kg (rat)].[ ² ] A large number of ­fluorescein derivatives are commercially available while the properties can be modified to tune its fluorescent properties and widen its range of applications.

Scheme 1 Synthesis of fluorescein

• References

• 1 Baeyer A. Ber. Dtsch. Chem. Ges. 1871; 4: 555
• 2a Chen X, Pradhan T, Wang F, Kim JS, Yoon J. Chem. Rev. 2012; 112: 1910
• 2b Sjöback R, Nygren J, Kubista M. Spectrochim. Acta A 1995; 51: L7
• 2c Yankell SL, Loux JJ. J. Periodontol. 1977; 48: 228
• 3 Seo S, Lee HY, Park M, Lim JM, Kang D, Yoon J, Jung JH. Eur. J. Inorg. Chem. 2010; 843
• 4 Unciti-Broceta A, Yusop MR, Richardson PR, Walton JG. A, Bradley M. Tetrahedron Lett. 2009; 50: 3713
• 5 Miller EW, Bian SX, Chang CJ. J. Am. Chem. Soc. 2007; 129: 3458
• 6 Terai T, Urano Y, Izumi S, Kojima H, Nagano T. Chem. Commun. 2012; 48: 2840
• 7 Tanaka K, Kitamura N, Chujo Y. Macromolecules 2010; 43: 6180
• 8 Li N, Lim RK. V, Edwardraja S, Lin Q. J. Am. Chem. Soc. 2011; 133: 15316
• 9 Thielbeer F, Chankeshwara SV, Bradley M. Biomacromolecules 2011; 12: 4386