Determination of micromolar concentrations of strong acids in chloroform by protonation of tetraphenylporphyrin

Harvey, Brent M.; Hoggard, Patrick E.

doi:10.1007/s00706-012-0784-7

Cited by 7 publications

(6 citation statements)

References 22 publications

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“…Tetraphenylporphyrin, which we used to detect HCl, can also be protonated by hydronium ion, 29 but the equilibrium between H 3 O + and H 2 TPP is much less favorable than that between HCl and H 2 TPP. The existence of eqn (16) as a reaction pathway can explain both the presence of chloroform and the low concentration of HCl, which appears to approach a steady state during irradiation.…”

Section: Mechanistic Considerationsmentioning

confidence: 99%

Photodecomposition of dichloromethane catalyzed by tetrachloroferrate(iii) supported on a Dowex anion exchange resin

Chan

Harvey

Hoggard

2013

Photochem Photobiol Sci

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The FeCl4(-) ion, heterogenized on a Dowex ion exchange resin, catalyzes the aerobic photodecomposition of neat CH2Cl2. Phosgene production was used to characterize the extent of decomposition, although it appears to be a secondary product from the decomposition of chloroform, which is suggested to arise from the reaction of dichloromethanol with hydrogen chloride. The yield of CHCl3 increases when the production of phosgene is suppressed by water or acetonitrile. CuCl4(2-), likewise heterogenized on Dowex, is photocatalytically inactive.

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Section: Mechanistic Considerationsmentioning

confidence: 99%

Photodecomposition of dichloromethane catalyzed by tetrachloroferrate(iii) supported on a Dowex anion exchange resin

Chan

Harvey

Hoggard

2013

Photochem Photobiol Sci

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“…[16] Free-base porphyrins (i.e. those not containing ac entral chelated metal cation) are known to exhibit chromic properties, includingh alochromism, due to protonation at the central imino nitrogen atoms, [17][18][19] and aggregachromism [20,21] (due to excitonic coupling interactions in stacked aggregates). Although typical free-base porphyrins (e.g.…”

Section: Introductionmentioning

confidence: 99%

Structural Modulation of Chromic Response: Effects of Binding‐Site Blocking in a Conjugated Calix[4]pyrrole Chromophore

et al. 2018

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Herein, we modulate the chromic response of a highly colored tetrapyrrole macrocycle, namely, tetrakis(3,5‐di‐tert‐butyl‐4‐oxocyclohexadien‐2,5‐yl)porphyrinogen (OxP) by structural modification. N‐Benzylation at the macrocyclic nitrogen atoms leads to stepwise elimination of the two calix[4]pyrrole‐type binding sites of OxP and serial variation of the chromic properties of the products, double N‐benzylated Bz2OxP and tetra N‐benzylated Bz4OxP. The halochromic (response to acidity) and solvatochromic (response to solvent polarity) properties were studied by using UV/Vis spectroscopy and NMR spectroscopy in nonpolar organic solvents. Titration experiments were used to generate binding isotherms to elucidate their binding properties with difluoroacetic acid. Differences in the halochromic properties of the compounds allowed construction of a colorimetric scale of acidity in nonpolar solvents, as the compounds in the series OxP, Bz2OxP, and Bz4OxP are increasingly difficult to protonate but maintain their propensity to change color upon protonation. The concurrent effects of binding‐site blocking and modulation of acidity sensitivity are important new aspects for the development of colorimetric indicators.

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“…The most explored case is the porphyrin's chemistry in the presence of protic species in organic solvents, usually described in terms of acid-base equilibrium [2][3][4][5]. The significance of protonated H 2 Por species follows from the fact that they may serve as convenient models which can be used to explore the strength and photochemistry of the chromophore in structurally different porphyrin units.…”

Section: Introductionmentioning

confidence: 99%

meso-Aryl-substituted free-base porphyrins: formation, structure and photostability of diprotonated species

et al. 2015

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Susceptibility to interact with trifluoroacetic acid (TFA) of selected freebase porphyrins, including a novel lipophilic 3-n-pentadecyl(phenoxy)-ethoxyphenyl-substituted porphyrin, and photostability of their diprotonated compounds was explored in benzene and N,N-dimethylformamide (DMF). Results have been discussed in terms of the commonly applied pK a -based procedure and confronted with a simple approach derived from experimentally-determined correlations reflecting the porphyrins affinity for TFA. Density functional theory (DFT) has proved the porphyrin moiety creates stable diprotonated species involving two TFA molecules, in which the fluorine atoms effectively contribute to the overall interaction of the acid with the porphyrin macrocycle. The relevance of the mesosubstituent and ambient medium to the reactivity and photostability of diverse porphyrin derivatives was emphasized and referred to structural features of the investigated diprotonated porphyrins.

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Determination of micromolar concentrations of strong acids in chloroform by protonation of tetraphenylporphyrin

Cited by 7 publications

References 22 publications

Photodecomposition of dichloromethane catalyzed by tetrachloroferrate(iii) supported on a Dowex anion exchange resin

Photodecomposition of dichloromethane catalyzed by tetrachloroferrate(iii) supported on a Dowex anion exchange resin

Structural Modulation of Chromic Response: Effects of Binding‐Site Blocking in a Conjugated Calix[4]pyrrole Chromophore

meso-Aryl-substituted free-base porphyrins: formation, structure and photostability of diprotonated species

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