Synthesis and photophysics of a series of lipophilic phosphazene‐based fluorescent indicators

Selberg, Sigrid; Pagano, Todd; Tshepelevitsh, Sofja; Haljasorg, Tõiv; Vahur, Signe; Luik, Juhan; Saame, Jaan; Leito, Ivo

doi:10.1002/poc.3950

Cited by 14 publications

(14 citation statements)

References 39 publications

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“…The newly obtained values are generally in good agreement with those published earlier , , . For 78 % of bases the differences are less than 0.03 p K a units and for 98 % of bases less than 0.1 p K a units.…”

Section: Resultssupporting

confidence: 91%

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On the Basicity of Organic Bases in Different Media

et al. 2019

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The basicities of simple organic bases – aliphatic and aromatic amines, amidines, phosphazenes, as well as saturated and unsaturated nitrogen heterocycles – are examined in acetonitrile, dimethyl sulfoxide, tetrahydrofuran, water and the gas phase. The basicities (pKaH values) of conjugate acids of a large variety of bases in these media are presented and discussed. Equations employing easily usable structural descriptors have been derived for approximately converting basicities from acetonitrile to other solvents. Recommendations are given on their practical use and a number of pKaH values that are experimentally unavailable are estimated from these relationships. An important part of the minireview is a large compilation of pKaH and GB values of the compounds in solvents and the gas phase, respectively, as well as the revised basicity scale in acetonitrile, now containing more than 270 pKaH values.

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Section: Resultssupporting

confidence: 91%

“…The revised basicity scale (Table ) is composed of previously published data, , and unpublished results for 9‐chloroacridine and 2‐aminoacridine (experimental conditions as in ref …”

Section: Methodsmentioning

confidence: 99%

On the Basicity of Organic Bases in Different Media

et al. 2019

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“…Imaging applications will be addressed in an upcoming study. To further accommodate potential applications, these molecular probes may be tailored via modifications of the phosphazene substituent groups or coumarin motif, which have been shown to affect the pKa [6] or 2PEF brightness, [22] respectively.…”

Section: Discussionmentioning

confidence: 99%

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

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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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“…General information: 1 H, 13 C, 19 F, and 31 P NMR spectra were measured using a Bruker Biospin AVANCE II 600 or III 300 spectrometer using CDCl 3 as the solvent. Infrared spectra (IR) were obtained for samples in KBr disks and recorded using a JASCO Fourier transform (FT)-IR spectrometer.…”

Section: Methodsmentioning

confidence: 99%

π‐Extended Push‐Pull‐Type Bicyclic Fluorophores Based on Quinoline and Naphthyridine Frameworks with an Iminophosphorane Fragment

2021

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Emissive quinoline and naphthyridine derivatives, bearing an iminophosphorane (IPP) fragment as an electrondonating group and two trifluoromethyl groups as electronwithdrawing groups, were prepared as electron push-pulltype bicyclic fluorophores: quinoline-IPP (1) and naphthyridine-IPP (2). Compared to those of the precursor bicyclic amines without the IPP moiety, the fluorescence quantum yields (Φ f ) of 1 and 2 were considerably higher, not only in low polarity solvents but also polar solvents. Moreover, the molar absorption coefficients (ɛ) were enhanced; thus, 1 and 2 are fluorophores with relatively high brightness (Φ f × ɛ). Using density functional theory calculations, the t indices were calculated, and these reveal that locally excited character is dominant in both molecules. Because of the sterically bulky IPP fragments, 1 and 2 emitted with moderate Φ f values, even in the solid state. Further, by exploiting the low crystallinity of 1 and 2, emissive amorphous thin films were prepared.

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Synthesis and photophysics of a series of lipophilic phosphazene‐based fluorescent indicators

Cited by 14 publications

References 39 publications

On the Basicity of Organic Bases in Different Media

On the Basicity of Organic Bases in Different Media

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

π‐Extended Push‐Pull‐Type Bicyclic Fluorophores Based on Quinoline and Naphthyridine Frameworks with an Iminophosphorane Fragment

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