A new fluorescent pH probe for extremely acidic conditions

Ratiometric Emission Fluorescent pH Probe for Imaging of Living Cells in Extreme Acidity

“…More recently, a turn-off fluorescent probe based on coumarin and imidazole derivative has been developed for detection of extreme acidity (pK a = 2.1) in bacteria. 23 However, the probe required ultraviolet excitation and may somewhat cause cellular damage due to lengthy irradiation. Meanwhile, it showed blue fluorescence emission where cells may have strong autofluorescence interference.…”

FRET-based rhodamine–coumarin conjugate as a Fe3+ selective ratiometric fluorescent sensor in aqueous media

“…As shown in Figure 1, in the absence of Fe 3+ , the receptor only exhibited a maximum absorption wavelength at 439 nm which corresponded to the absorption band of coumarin moiety. [32][33][34] Moreover, the characteristic absorption band of Rhodamine 6G at about 530 nm was not observed, demonstrating its existence in spirolactam form. 35,36 However, upon addition of Fe 3+ to an aqueous solution of HL, the absorption band at 425 nm slightly decreased while the absorption intensity exhibited significantly increased in the range of 385-475 nm.…”

Design of a novel coumarin-based multifunctional fluorescent probe for Zn2+/Cu2+/S2− in aqueous solution

“…1. The free receptor showed maximum absorption wavelength at 450 nm which might be assigned to the coumarin group [30][31][32][33]. Upon addition of Zn 2 + , the absorption band at 450 nm exhibited a slightly bathochromic shift along with certain increasing intensity, the absorption band at 280 nm gradually decreased while a new absorption band appeared at 350 nm.…”

“…Compared to single-ion responsive molecular sensors, the multifunctional sensors have been actively developed because of the advantages such as analytical time reduction [27][28][29]. Coumarin is a kind of compound with great fluorescent intensity, high quantum yield, and is very suitable to act as fluorescent chromophores [30][31][32][33]. In addition, Schiff bases are well known to be good ligands which provide an electron-rich environment, which made it easy to bind with metal ions [34][35][36].…”