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Spectroscopic study of porphyrin-caffeine interactions.

Makarska-Bialokoz M - J Fluoresc (2012)

Bottom Line: The association constants were calculated using curve-fitting procedure (K(AC) of the order of magnitude of 10(3) mol(-1)).Whereas the emission spectra point at the presence of the fluorescence quenching effect testifying for the partial inactivation of the porphyrin molecule.The fluorescence quenching constants were calculated from Stern-Volmer plots.

View Article: PubMed Central - PubMed

Affiliation: Department of Inorganic Chemistry, Maria Curie-Sklodowska University, Lublin, Poland. makarska@hektor.umcs.lublin.pl

ABSTRACT
The association between water-soluble porphyrins: 4,4',4″,4'''-(21 H,23 H-porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H(2)TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21 H,23 H-porphine (H(2)TPPS(4)), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21 H,23 H-porphine tetra-p-tosylate (H(2)TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21 H,23 H-porphine tetra-p-tosylate (H(2)TMePyP), the Cu(II) complexes of H(2)TTMePP and H(2)TMePyP, as well as chlorophyll a with caffeine (1,3,7-trimethylxanthine) has been studied analysing their absorption and emission spectra in aqueous (or acetone in case of chlorophyll a) solution. During the titration by caffeine the porphyrins absorption spectra undergo the evolution - the bathochromic effect can be observed as well as the hypochromicity of the Soret maximum. The association constants were calculated using curve-fitting procedure (K(AC) of the order of magnitude of 10(3) mol(-1)). Whereas the emission spectra point at the presence of the fluorescence quenching effect testifying for the partial inactivation of the porphyrin molecule. The fluorescence quenching constants were calculated from Stern-Volmer plots. The results obtained show that caffeine can interact with water-soluble porphyrins and through formation of stacking complexes is able to quench their ability to emission.

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Evolution of H2TTMePP emission spectrum during titration by caffeine. The dependence of fluorescence intensity versus porphyrin concentration for the process presented. All the concentrations as in Fig. 2
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Fig3: Evolution of H2TTMePP emission spectrum during titration by caffeine. The dependence of fluorescence intensity versus porphyrin concentration for the process presented. All the concentrations as in Fig. 2

Mentions: In emission spectra, which undergo the bathochromic effect as absorption spectra, the decrease of peak maximum is observed, what testifies for the interactions with caffeine influencing the partial inactivation of the porphyrin and faster decay of its luminescence properties. In the same manner react H2TTMePP (Fig. 3), H2TCPP and H2TPPS4 porphyrins. While H2TMePyP is the only porphyrin, which in these experimental conditions is shifted towards the ultraviolet and shows the initial increase of the emission intensity.Fig. 3


Spectroscopic study of porphyrin-caffeine interactions.

Makarska-Bialokoz M - J Fluoresc (2012)

Evolution of H2TTMePP emission spectrum during titration by caffeine. The dependence of fluorescence intensity versus porphyrin concentration for the process presented. All the concentrations as in Fig. 2
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3473192&req=5

Fig3: Evolution of H2TTMePP emission spectrum during titration by caffeine. The dependence of fluorescence intensity versus porphyrin concentration for the process presented. All the concentrations as in Fig. 2
Mentions: In emission spectra, which undergo the bathochromic effect as absorption spectra, the decrease of peak maximum is observed, what testifies for the interactions with caffeine influencing the partial inactivation of the porphyrin and faster decay of its luminescence properties. In the same manner react H2TTMePP (Fig. 3), H2TCPP and H2TPPS4 porphyrins. While H2TMePyP is the only porphyrin, which in these experimental conditions is shifted towards the ultraviolet and shows the initial increase of the emission intensity.Fig. 3

Bottom Line: The association constants were calculated using curve-fitting procedure (K(AC) of the order of magnitude of 10(3) mol(-1)).Whereas the emission spectra point at the presence of the fluorescence quenching effect testifying for the partial inactivation of the porphyrin molecule.The fluorescence quenching constants were calculated from Stern-Volmer plots.

View Article: PubMed Central - PubMed

Affiliation: Department of Inorganic Chemistry, Maria Curie-Sklodowska University, Lublin, Poland. makarska@hektor.umcs.lublin.pl

ABSTRACT
The association between water-soluble porphyrins: 4,4',4″,4'''-(21 H,23 H-porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H(2)TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21 H,23 H-porphine (H(2)TPPS(4)), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21 H,23 H-porphine tetra-p-tosylate (H(2)TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21 H,23 H-porphine tetra-p-tosylate (H(2)TMePyP), the Cu(II) complexes of H(2)TTMePP and H(2)TMePyP, as well as chlorophyll a with caffeine (1,3,7-trimethylxanthine) has been studied analysing their absorption and emission spectra in aqueous (or acetone in case of chlorophyll a) solution. During the titration by caffeine the porphyrins absorption spectra undergo the evolution - the bathochromic effect can be observed as well as the hypochromicity of the Soret maximum. The association constants were calculated using curve-fitting procedure (K(AC) of the order of magnitude of 10(3) mol(-1)). Whereas the emission spectra point at the presence of the fluorescence quenching effect testifying for the partial inactivation of the porphyrin molecule. The fluorescence quenching constants were calculated from Stern-Volmer plots. The results obtained show that caffeine can interact with water-soluble porphyrins and through formation of stacking complexes is able to quench their ability to emission.

Show MeSH
Related in: MedlinePlus