Lysosome-targeted near-infrared fluorescent dye and its application in designing of probe for sensitive detection of cysteine in living cells

Rational design of a large Stokes shift xanthene–benzothiozolium dyad for probing cysteine in mitochondria

“…S1, ESI †). In general, compared with the previously reported dyes, 27,28,31 PhCy-OH exhibited longer emission wavelengths and larger Stokes shifts, confirming that the simultaneous expansion of molecular p-conjugated system and heteroatomic substitution was an effective strategy to commendably improve the Stokes shift of xanthene-benzothiozolium fluorophores.…”

“…As displayed in Scheme 1b, the LUMO of PhCy-OH was calculated to be À5.49 eV, which is lower than the LUMO of other fluorescent dyes that have been reported. 28,31 On the other hand, the energy level gap of PhCy-OH was calculated to be 2.21 eV, which has been significantly reduced, and is lower than those of other reported fluorescent dyes. 27,28,31 The above DFT calculation results showed that the molecule PhCy-OH designed in this paper theoretically has a longer emission wavelength and a wider Stokes shift than other dyes listed in Scheme 1a.…”

“…28,31 On the other hand, the energy level gap of PhCy-OH was calculated to be 2.21 eV, which has been significantly reduced, and is lower than those of other reported fluorescent dyes. 27,28,31 The above DFT calculation results showed that the molecule PhCy-OH designed in this paper theoretically has a longer emission wavelength and a wider Stokes shift than other dyes listed in Scheme 1a. Surprisingly, the results of the spectroscopic experiment showed that the fluorescence emission wavelength of PhCy-OH was extended to 803 nm, and the Stokes shift was improved to 68 nm.…”

“…In order to solve this dilemma, our group has been committed to developing new strategies for a long time to improve the Stokes shift of xanthene-benzothiozolium fluorophores. 27,28 In our previous work, the heteroatom replacement strategy was mainly used to reduce the LUMO energy level and reduce the energy level gap ( f ) of the molecule to extend the emission wavelength and broaden the Stokes shift of xanthene-benzothiozolium fluorophores (Scheme 1a). 27,28 Although the emission wavelength and Stokes shift of the modified dye have been improved to a certain extent, there is still a certain gap from the excellent level.…”

A highly selective quinolizinium-based fluorescent probe for cysteine detection

“…Align with literature reports, [54][55][56][57][58][59] we proposed the reaction mechanism of probe 1 with Cys was based on the nucleophilic addition reaction of Cys with C]C bond of acrylate, followed by the cyclization-cleavage reaction and resulting in the formation of 2 with a hydroxyl group (Scheme 2). HRMS analysis of the crude reaction mixture showed the presence of peak with m/z 394.16, which revealed the formation of 2 aer the reaction (Fig.…”