Limits...
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.

Show MeSH

Related in: MedlinePlus

Evolution of H2TTMePP absorption spectrum during titration by caffeine. The dependence of absorbance versus porphyrin concentration for the process presented. The concentrations of the porphyrin and caffeine in solution changed in the range 3.27 – 1.92 (× 10-7 mol dm-3) and 0–4.13 × 10-4 mol dm-3, respectively
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3473192&req=5

Fig2: Evolution of H2TTMePP absorption spectrum during titration by caffeine. The dependence of absorbance versus porphyrin concentration for the process presented. The concentrations of the porphyrin and caffeine in solution changed in the range 3.27 – 1.92 (× 10-7 mol dm-3) and 0–4.13 × 10-4 mol dm-3, respectively

Mentions: The evolution of absorption and emission spectra during the interactions between caffeine and a series of synthetic water-soluble porphyrins (H2TMePyP, CuTMePyP, H2TTMePP, CuTTMePP, H2TCPP, H2TPPS4) was recorded. In absorption spectra of H2TTMePP porphyrin the hypochromicity of the peak in Soret band and a shift towards the infrared (bathochromic effect, λmax = 412–417 nm) can be observed (Fig. 2). In Q band the similar changes proceed, apparent particularly for IV band component (λmax = 514–517 nm). For all the systems examined the dependence of absorbance vs. molar concentration of porphyrin shows the deviations from linearity confirming the existence of porphyrin – caffeine interactions.Fig. 2


Spectroscopic study of porphyrin-caffeine interactions.

Makarska-Bialokoz M - J Fluoresc (2012)

Evolution of H2TTMePP absorption spectrum during titration by caffeine. The dependence of absorbance versus porphyrin concentration for the process presented. The concentrations of the porphyrin and caffeine in solution changed in the range 3.27 – 1.92 (× 10-7 mol dm-3) and 0–4.13 × 10-4 mol dm-3, respectively
© Copyright Policy
Related In: Results  -  Collection

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

Fig2: Evolution of H2TTMePP absorption spectrum during titration by caffeine. The dependence of absorbance versus porphyrin concentration for the process presented. The concentrations of the porphyrin and caffeine in solution changed in the range 3.27 – 1.92 (× 10-7 mol dm-3) and 0–4.13 × 10-4 mol dm-3, respectively
Mentions: The evolution of absorption and emission spectra during the interactions between caffeine and a series of synthetic water-soluble porphyrins (H2TMePyP, CuTMePyP, H2TTMePP, CuTTMePP, H2TCPP, H2TPPS4) was recorded. In absorption spectra of H2TTMePP porphyrin the hypochromicity of the peak in Soret band and a shift towards the infrared (bathochromic effect, λmax = 412–417 nm) can be observed (Fig. 2). In Q band the similar changes proceed, apparent particularly for IV band component (λmax = 514–517 nm). For all the systems examined the dependence of absorbance vs. molar concentration of porphyrin shows the deviations from linearity confirming the existence of porphyrin – caffeine interactions.Fig. 2

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