New fluorescent quinolinium dyes — applications in nanometre particle sizing

Geddes, Chris D.; Apperson, Kathleen; Birch, David J. S.

doi:10.1016/s0143-7208(99)00079-0

Cited by 27 publications

(25 citation statements)

References 15 publications

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“…They are similar to the emission spectra of protonated 6-methoxyquinoline, where l emmax % 445 nm [12]. Dyes also based on the 6-methoxyquinoline nucleus have recently been reported with similar absorption and emission wavelength maxima as well as similar¯uorescence lifetimes [13]. An interesting feature of the SPQ molecule and in fact an important factor in this work is the large Stokes shift in the¯uorescence emission spectrum with respect to the excitation, %100 nm.…”

Section: Resultssupporting

confidence: 77%

“…At pH %1, protonated 6-methoxyquinoline, shows mono-exponential¯uorescence decay kinetics with t % 20 ns [12], whilst, SPQ is bi-exponential with lifetimes, t 1 and t 2 solvent dependent, in the range %14±32 ns, Table 3. The bi-exponential nature of the 6-methoxyquinoline nucleus and some of its quaternary salts has been reported by several authors previously [12,13].…”

Section: Resultsmentioning

confidence: 57%

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Halide sensing using the SPQ molecule

Geddes

2001

Sensors and Actuators B: Chemical

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The¯uorescent and halide sensitive 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ) molecule has been synthesised and incorporated into a hydrophilic copolymer to produce a halide sensor ®lm. The sensor ®lm typically swells in aqueous media allowing dye¯uorescence to be quenched by the diffusion of aqueous halide ions at high pH. , respectively. The reduction in K SV values of the immobilised dye is discussed and are compared to K SV values for SPQ immobilised in a hydrophobic copolymer. Fluorescence lifetime data, obtained using the single photon counting technique, of SPQ sensor ®lms is also presented. The sensor ®lms are reversibly capable of determining aqueous iodide, bromide and chloride with %1.5, 2.5 and 5% accuracy, respectively, at concentrations around 0.001 mol dm 3 , where chloride concentrations in blood, sweat and some photographic processes are typically in the range 0.1±0.001 mol dm 3 . The hydrophilic sensor ®lms 90% response time to molar halide solution was typically 30 s. The sensor ®lms were found to have a shelf life in excess of 2 years. #

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 57%

Halide sensing using the SPQ molecule

Geddes

2001

Sensors and Actuators B: Chemical

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“…22 The concentration of C 1 MQ was determined spectrophotometrically on the basis of the molar absorption coefficients of 5500…”

Section: Methodsmentioning

confidence: 99%

Effect of torsional isomerization and inclusion complex formation with cucurbit[7]uril on the fluorescence of 6-methoxy-1-methylquinolinium

Miskolczy

Harangozó

Biczók

et al. 2014

Photochem Photobiol Sci

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Inclusion of 6-methoxy-1-methylquinolinium (C 1 MQ) in the cavity of cucurbit [7]uril (CB7) was studied by absorption, fluorescence, NMR and isothermal calorimetric methods in aqueous solution at 298 K. The free C 1 MQ exhibited dual-exponential fluorescence decay kinetics due to the two torsional isomers differing in the orientation of the methoxy moiety relative to the heterocyclic ring. The enthalpy-driven encapsulation of the heterocycle in CB7 led to very stable 1:1 complex with a binding constant of (2.0±0.4)×10 6 M −1. The rate of C 1 MQ−CB7 complex dissociation was found to be comparable to the NMR timescale.Because the methoxy moiety is oriented outward from the host, its s-cis−s-trans isomerization is slightly affected by the confinement. Inclusion complex formation significantly slowed down the photoinduced electron transfer from I − and N 3 − to the singletexcited C 1 MQ, but did not preclude the reaction because long distance electron transfer occurred through the wall of CB7 macrocycle. Due to the large difference in the quenching rate constant for free and encapsulated forms, C 1 MQ is an excellent probe for the study of the inclusion of nonfluorescent compounds in CB7 in the presence of Cl − or Br − .

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“…Hydrogen transfers across a cleaved bond during the formation of some fragments are not shown in the chemical structures. (Adams et al, 1955) or 342 nm for 6-methoxy-1-methylquinolinium bromide/iodide in water (Geddes et al, 2000). Fluorescence spectroscopy of the quinolinium metabolites was not investigated, although quinolinium is known to have fluorescent excitation/emission.…”

Section: Discussionmentioning

confidence: 99%

Metabolic Aromatization ofN-Alkyl-1,2,3,4-Tetrahydroquinoline Substructures to Quinolinium by Human Liver Microsomes and Horseradish Peroxidase

Gu¹,

Collins²,

Holsworth³

et al. 2006

Drug Metab Dispos

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ABSTRACT:Metabolic aromatization of xenobiotics is an unusual reaction with some documented examples. For instance, the oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine to the neurotoxic pyridinium ion metabolite 1-methyl-4-phenylpyridinium by monoamine oxidase (MAO) B in the brain has been of interest to a number of investigators. It has also been reported that although the aromatization of N-methyl-tetrahydroisoquinoline occurs with MAO B, the metabolism does not proceed for its isomer, N-methyltetrahydroquinoline, by the same enzyme. The aromatization of an N-alkyl-tetrahydroquinoline substructure was identified during in vitro metabolite profiling of compound A, which was designed as a potent renin inhibitor for the treatment of hypertension. The Nalkylquinolinium metabolite of compound A was identified by liquid chromatography-tandem mass spectrometry of human liver microsomal incubates and proton NMR of the isolated metabolite.Further in vitro metabolism studies with a commercially available chemical (compound B), containing the same substructure, also generated an N-alkylquinolinium metabolite. In vitro cytochrome P450 (P450) reaction phenotyping of compound A revealed that the metabolism was catalyzed exclusively by CYP3A4. Although compound B was a substrate for several P450 isoforms, its quinolinium metabolite was also generated predominantly by CYP3A4. Neither compound A nor compound B was a substrate of MAOs. The quinolinium metabolites were readily produced by horseradish peroxidase, suggesting that aromatization of the N-alkyltetrahydroquinoline could occur via a mechanism involving single electron transfer from nitrogen. Although dihydro intermediates from the tetrahydroquinoline substrates were not observed in the formation of quinolinium metabolites, cyanide trapping results indicated the occurrence of iminium intermediates.Compound A (Scheme 1) was a lead compound, consisting of a novel nonpeptidic ketopiperazine-based scaffold, that was designed as a potent renin inhibitor for the treatment of hypertension (Holsworth et al., 2005(Holsworth et al., , 2006. The renin-angiotensin system (RAS) plays a key role in blood pressure regulation. Pharmacological blockade of the RAS cascade is usually achieved with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Renin inhibition has been sought for decades, as it would inhibit the initial and rate-limiting step of the RAS and hence might offer a therapeutic profile distinct from angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Recent progress shows new potential for the treatment of hypertension by renin inhibition (Fisher and Hollenberg, 2005;Wood et al., 2005).During in vitro metabolite profile studies on compound A, in support of lead optimization, an unusual metabolite was observed. It appeared to be derived from aromatization of the N-alkyltetrahydroquinoline ring, yielding an N-alkylquinolinium ion as a major metabolite in human liver microsomes. Similar metabolic oxidation of 1-methyl-4...

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New fluorescent quinolinium dyes — applications in nanometre particle sizing

Cited by 27 publications

References 15 publications

Halide sensing using the SPQ molecule

Halide sensing using the SPQ molecule

Effect of torsional isomerization and inclusion complex formation with cucurbit[7]uril on the fluorescence of 6-methoxy-1-methylquinolinium

Metabolic Aromatization ofN-Alkyl-1,2,3,4-Tetrahydroquinoline Substructures to Quinolinium by Human Liver Microsomes and Horseradish Peroxidase

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