Design Strategies for High-Efficiency Ratiometric Two-Photon-Excited Fluorescent and Room-Temperature Phosphorescent Probes for Hypochlorous Acid

Abstract

Hypochlorous acid (HOCL) plays a critical role in the natural defense system, but excessive production of HOCL leads to many diseases. It is very essential to monitor the distribution and level of endogenous HOCL. However, the applicable two-photon-excited fluorescent (TPEF) and phosphorescent probes for biological imaging and quantitative detection is rare due to low efficiency and vague mechanism. Therefore, we thoroughly researched the electron structures and luminous mechanisms of turn-on and ratiometric TPEF probe compounds and provide design strategies for high-efficient ratiometric TPEF probes. The designed ratiometric TPEF probe benza1-COCL and product benza1-CO have quite large two-photon absorption (TPA) cross sections (143 GM/898 nm, 168 GM/988 nm), high fluorescence efficiencies (0.15, 0.28), and spectral resolution, contributing to the real-time monitoring level of HOCL in vivo. Besides, a long-lived two-photon-excited room-temperature phosphorescent probe benza2-COCL is provided first, which possesses a large TPA cross section (144 GM/838 nm) and time-resolved biological imaging (1.09 ms).

Theoretical characterization of two-photon fluorescent probes for nitric oxide detection: sensing mechanism, photophysical properties and protonation effects

“…The same TD-B3LYP level was adopted for the TPA simulations, which has been shown to give consistent TPA cross sections with the experimental trends for various large chromophores. 41,[50][51][52][53] The accurate description of double excitations deserves future investigations. [32][33][34] All the above calculations were performed in the Gaussian 16 54 package, except for the TPA simulation performed in the Dalton 55,56 program.…”

Excellent ratiometric two-photon fluorescent probes for hydrogen sulfide detection based on the fluorescence resonance energy transfer mechanism

“…Apart from electron donors and acceptors, isomerism also plays an important role in TPA [34][35][36][37] and fluorescence. 38,39 It is well known that the fluorescence quantum yield (0.13) of phenanthrene is lower than that (0.30) of anthracene. 40 They found that a benzo[h]coumarin derivative exhibited high fluorescence quantum yield (0.37), while its corresponding benzo[ f ]coumarin derivative induced fluorescence quenching (0.08).…”

“…Apart from electron donors and acceptors, isomerism also plays an important role in TPA 34–37 and fluorescence. 38,39 It is well known that the fluorescence quantum yield (0.13) of phenanthrene is lower than that (0.30) of anthracene. 40 Hao et al recently designed a series of benzocoumarin-based fluorescent probes for H 2 O 2 detection.…”

Theoretical Studies and Design Strategies of Highly Efficient Two-Photon Excited Fluorescent Probes for Hydrogen Sulfide Detection through Simulation of Excited-State Dynamics

“…Moreover, the reaction product (DCM-OH) also possesses a two-photon absorption feature. To date, most of the fluorescent probes still are one-photon excited with a relatively shorter excitation wavelength, and thus the inevitable interference of background fluorescence and shallow depth of tissue penetration limit their application in living systems. − In contrast, two-photon excited fluorescent (TPEF) probes, simultaneously absorbing two photons with low energy, have the advantages of deep tissue penetration, high spatial resolution, and less photodamage to tissues. − But the practical application of the TPEF probe leaves much to be desired, due to their rather small two-photon absorption (TPA) efficiency and unclear internal mechanisms. − Therefore, it is still necessary to research and develop a novel TPEF probe with large TPA cross section and high luminous efficiency.…”