π-Extended Coumarins Derived with Nonhydrolyzable Iminophosphoranes as Two-Photon-Excited Fluorophores

Hsia, Liang-Yu; Chen, Hsin-Ni; Chiang, C. C.; Hung, Ming-Yang; Wei, Hao-Keng; Luo, Chih‐Wei; Kuo, Ming‐Yu; Luo, Shun‐Yuan; Chu, Chih-Chien

doi:10.1021/acs.joc.0c00901

Cited by 8 publications

(7 citation statements)

References 22 publications

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“…The fluorescence quantum yield, measured against emission standards of C153 in ethanol, ϕ em =0.53, [21] and C151, ϕ em =0.57, [22] along with corresponding 2PEF brightness values, are collected in Table 2. The values of quantum yield and 2PEF brightness for C1‐C4 in the neutral solvents are relatively high, ϕ em =0.6–0.7, and, σ 2PA ⋅ ϕ em =10–13 GM, making them comparable to yields observed by Luo et al [23] . for similar phosphazene‐modified coumarin compounds, although this emission drops upon protonation.…”

Section: Resultssupporting

confidence: 74%

Novel Lipophilic Fluorophores with Highly Acidity‐Dependent Two‐Photon Response

Rammo

Trummal

Uudsemaa

et al. 2022

Chemistry A European J

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Lipophilic fluorophores are widely implemented in nonlinear microscopy; however, few existing membrane‐specific probes combine the high brightness of two‐photon excited fluorescence (2PEF) with pH sensitivity. Herein we describe four novel two‐photon excited fluorophores, based on a coumarin 151 core structure, where lipophilicity is induced by a covalently attached phosphazene moiety. Changing the environmental acidity using trifluoromethanesulfonic (triflic) acid leads to profound changes in the linear fluorescence and 2PEF characteristics, due to chromophores’ switching between neutral‐ and protonated forms. We characterize this dependence by measuring the two‐photon absorption (2PA) spectra over the region λ2PA=550–1000 nm, observing 2PA cross sections of σ2PA=10–20 GM, with an associated 2PEF brightness of 10–13 GM, in neutral solutions of both acetonitrile and n‐octanol. Although quantum chemical modelling and NMR measurements show that, at high chromophore concentrations, protonation may be accompanied by a dimerization process, these dimers likely do not form at the lower concentrations used in optical spectroscopy.

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Section: Resultssupporting

confidence: 74%

Novel Lipophilic Fluorophores with Highly Acidity‐Dependent Two‐Photon Response

Rammo

Trummal

Uudsemaa

et al. 2022

Chemistry A European J

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“…Likewise, other azaylides NPPh3′ and NPAni3′ show similar tendencies in comparison with those of non‐chlorinated ones (Figures S82–84). Thus, the decrease in LUMO around the phosphorus atom, owing to electron‐withdrawing chlorine atoms, stabilized the azaylide moiety because nucleophilic addition of water to the phosphorus atom is a rate‐determining step (Scheme S1) [35, 36] . A steric protection effect may also be present in this system.…”

Section: Figurementioning

confidence: 97%

Synthesis of Azaylide‐Based Amphiphiles by the Staudinger Reaction

et al. 2021

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Catalyst‐ and reagent‐free reactions are powerful tools creating various functional molecules and materials. However, such chemical bonds are usually hydrolysable or require specific functional groups, which limits their use in aqueous media. Herein, we report the development of new amphiphiles through the Staudinger reaction. Simple mixing of chlorinated aryl azide with a hydrophilic moiety and various triarylphosphines (PAr3) gave rise to azaylide‐based amphiphiles NPAr3, rapidly and quantitatively. The obtained NPAr3 formed ca. 2 nm‐sized spherical aggregates (NPAr3)n in water. The hydrolysis of NPAr3 was significantly suppressed as compared with those of non‐chlorinated amphiphiles nNPAr3. Computational studies revealed that the stability is mainly governed by the decrease in LUMO around the phosphorus atom owing to the o‐substituted halogen groups. Furthermore, hydrophobic dyes such as Nile red and BODIPY were encapsulated by the spherical aggregates (NPAr3)n in water.

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“…Optical microscopy analysis was performed on Olympus BFXM microscope modules equipped with a U-RFL-T power supply and fluorescence filter cubes and a cooling CCD camera (Model: MTR3CCD06000KPA, Touptek, P. R. China). The coumarin–TPIPP was synthesized following our published procedure …”

Section: Experimental Sectionmentioning

confidence: 99%

“…The amphiphiles could form spherical aggregates with a size of approximately 2 nm through a self-assembly process. Our group has used the NSR concept to synthesize a series of coumarin–triphenyliminophosphorane (TPIPP) derivatives . The electron-withdrawing 2-pyranone ring and the CN group at C-3 position at the coumarin structure help in stabilizing the aza-ylide intermediate through mesomeric effects.…”

Section: Introductionmentioning

confidence: 99%

Polymer-Bound Coumarin–Triphenyliminophosphorane Derivatives as Turn-On Fluorescence Sensors for Water Content Detection via Non-Hydrolytic Staudinger Reaction

Lin

Chen

et al. 2022

ACS Appl. Polym. Mater.

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Fluorometric optical sensors have recently been developed for analyzing environmental humidity and solvents' water content. Our group has demonstrated a series of coumarin−triphenyliminophosphorane (TPIPP) derivatives that exhibit a remarkable fluorescence efficiency under photoexcitation. We speculated that these derivatives could be developed into turn-on fluorescent probes suitable for the analysis of water content and humidity. First, the non-hydrolytic Staudinger reaction (NSR) was employed to modify the side chain of a styrene−4-diphenylphosphino styrene (DPPS) copolymer with coumarin−TPIPP fluorophores. When the DPPS content of the copolymer was higher, the fluorophores' fluorescence was weaker because of their dense packing, causing self-quenching. When the fluorophoremodified copolymer was placed in tetrahydrofuran containing water and a small amount of AcOH, hydrolysis occurred, and highly fluorescent 7-amino-3-cyanocoumarin (coumarin 1) was released in the solvent following the general Staudinger reduction route. The release of some fluorophores from the copolymer also resulted in less self-quenching, thus enhancing the fluorescence intensity. To take full advantage of this emission, we prepared polymer beads with crosslinked poly (styrene) and poly(DPPS) and coumarin fluorophores that were covalently linked to the beads through an efficient NSR. Compared with the nonbead form, the polymer beads required a much lower acid concentration for hydrolysis to occur and solvents' fluorescence turned on more quickly. The water content in three common solvents, tetrahydrofuran, acetonitrile, and methanol, was analyzed by immersing the modified beads for 5 min (AcOH concentration = 0.5%); the respective quantitation limits were 0.067, 0.013, and 0.057%, respectively. The proposed polymer material is a promising platform for moisture detection in the chemical refinery industry.

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π-Extended Coumarins Derived with Nonhydrolyzable Iminophosphoranes as Two-Photon-Excited Fluorophores

Cited by 8 publications

References 22 publications

Novel Lipophilic Fluorophores with Highly Acidity‐Dependent Two‐Photon Response

Novel Lipophilic Fluorophores with Highly Acidity‐Dependent Two‐Photon Response

Synthesis of Azaylide‐Based Amphiphiles by the Staudinger Reaction

Polymer-Bound Coumarin–Triphenyliminophosphorane Derivatives as Turn-On Fluorescence Sensors for Water Content Detection via Non-Hydrolytic Staudinger Reaction

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