TY  - JOUR
AU  - Cvijetić, Ilija
AU  - Pešić, Miloš P.
AU  - Todorov, Miljana D.
AU  - Drakulić, Branko
AU  - Juranić, Ivan
AU  - Verbić, Tatjana
AU  - Zloh, Mire
PY  - 2018
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2693
AB  - Aryldiketo acids (ADKs) exhibit the variety of biological activities, mainly due to large affinity toward divalent metal ions. Metal complexation ability of ADKs, as well as interactions with proteins, depend on tautomeric form present in solution. The main aim of this study was to fully explore the tautomeric preferences of 4-phenyl-2,4-dioxobutanoic acid (4PDA), as ADKs representative, in aqueous media at different pH values. 1D and 2D NMR spectroscopy in combination with quantum chemical calculations was applied in order to better understand the tautomeric preferences of 4PDA. The data in highly acidic media are especially interesting since there are no such findings in the literature due to low solubility of ADKs in molecular form. At low pH values, where 4PDA is unionized, the most abundant tautomeric form is enol with keto group closer to phenyl ring. At higher pH values, mixture of two 4PDA ionic forms coexists in solution. Their ratio calculated according to NMR data fits the values predicted using two experimentally determined pK (a) values. Based on the complexity of H-1 NMR spectrum of monoanionic 4PDA form, coexistence of two stable rotamers was assumed. In an alkaline media, 4PDA is mostly present in dianionic form. As pi-electrons of dianion are delocalized over an entire keto-enol moiety, spectral distinction between tautomers was not possible. Quantum chemical calculations were used to predict relative stability of tautomers. The predictions were in good accordance with experimental results only in case when explicit water molecule was included in calculations.
PB  - Springer/Plenum Publishers, New York
T2  - Structural Chemistry
T1  - Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations
VL  - 29
IS  - 2
SP  - 423
EP  - 434
DO  - 10.1007/s11224-017-1039-3
ER  - 

@article{
author = "Cvijetić, Ilija and Pešić, Miloš P. and Todorov, Miljana D. and Drakulić, Branko and Juranić, Ivan and Verbić, Tatjana and Zloh, Mire",
year = "2018",
abstract = "Aryldiketo acids (ADKs) exhibit the variety of biological activities, mainly due to large affinity toward divalent metal ions. Metal complexation ability of ADKs, as well as interactions with proteins, depend on tautomeric form present in solution. The main aim of this study was to fully explore the tautomeric preferences of 4-phenyl-2,4-dioxobutanoic acid (4PDA), as ADKs representative, in aqueous media at different pH values. 1D and 2D NMR spectroscopy in combination with quantum chemical calculations was applied in order to better understand the tautomeric preferences of 4PDA. The data in highly acidic media are especially interesting since there are no such findings in the literature due to low solubility of ADKs in molecular form. At low pH values, where 4PDA is unionized, the most abundant tautomeric form is enol with keto group closer to phenyl ring. At higher pH values, mixture of two 4PDA ionic forms coexists in solution. Their ratio calculated according to NMR data fits the values predicted using two experimentally determined pK (a) values. Based on the complexity of H-1 NMR spectrum of monoanionic 4PDA form, coexistence of two stable rotamers was assumed. In an alkaline media, 4PDA is mostly present in dianionic form. As pi-electrons of dianion are delocalized over an entire keto-enol moiety, spectral distinction between tautomers was not possible. Quantum chemical calculations were used to predict relative stability of tautomers. The predictions were in good accordance with experimental results only in case when explicit water molecule was included in calculations.",
publisher = "Springer/Plenum Publishers, New York",
journal = "Structural Chemistry",
title = "Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations",
volume = "29",
number = "2",
pages = "423-434",
doi = "10.1007/s11224-017-1039-3"
}

Cvijetić, I., Pešić, M. P., Todorov, M. D., Drakulić, B., Juranić, I., Verbić, T.,& Zloh, M.. (2018). Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations. in Structural Chemistry
Springer/Plenum Publishers, New York., 29(2), 423-434.
https://doi.org/10.1007/s11224-017-1039-3

Cvijetić I, Pešić MP, Todorov MD, Drakulić B, Juranić I, Verbić T, Zloh M. Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations. in Structural Chemistry. 2018;29(2):423-434.
doi:10.1007/s11224-017-1039-3 .

Cvijetić, Ilija, Pešić, Miloš P., Todorov, Miljana D., Drakulić, Branko, Juranić, Ivan, Verbić, Tatjana, Zloh, Mire, "Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations" in Structural Chemistry, 29, no. 2 (2018):423-434,
https://doi.org/10.1007/s11224-017-1039-3 . .

TY  - JOUR
AU  - Cvijetić, Ilija
AU  - Pešić, Miloš P.
AU  - Todorov, Miljana D.
AU  - Drakulić, Branko
AU  - Juranić, Ivan
AU  - Verbić, Tatjana
AU  - Zloh, Mire
PY  - 2018
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2694
AB  - Aryldiketo acids (ADKs) exhibit the variety of biological activities, mainly due to large affinity toward divalent metal ions. Metal complexation ability of ADKs, as well as interactions with proteins, depend on tautomeric form present in solution. The main aim of this study was to fully explore the tautomeric preferences of 4-phenyl-2,4-dioxobutanoic acid (4PDA), as ADKs representative, in aqueous media at different pH values. 1D and 2D NMR spectroscopy in combination with quantum chemical calculations was applied in order to better understand the tautomeric preferences of 4PDA. The data in highly acidic media are especially interesting since there are no such findings in the literature due to low solubility of ADKs in molecular form. At low pH values, where 4PDA is unionized, the most abundant tautomeric form is enol with keto group closer to phenyl ring. At higher pH values, mixture of two 4PDA ionic forms coexists in solution. Their ratio calculated according to NMR data fits the values predicted using two experimentally determined pK (a) values. Based on the complexity of H-1 NMR spectrum of monoanionic 4PDA form, coexistence of two stable rotamers was assumed. In an alkaline media, 4PDA is mostly present in dianionic form. As pi-electrons of dianion are delocalized over an entire keto-enol moiety, spectral distinction between tautomers was not possible. Quantum chemical calculations were used to predict relative stability of tautomers. The predictions were in good accordance with experimental results only in case when explicit water molecule was included in calculations.
PB  - Springer/Plenum Publishers, New York
T2  - Structural Chemistry
T1  - Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations
VL  - 29
IS  - 2
SP  - 423
EP  - 434
DO  - 10.1007/s11224-017-1039-3
ER  - 

@article{
author = "Cvijetić, Ilija and Pešić, Miloš P. and Todorov, Miljana D. and Drakulić, Branko and Juranić, Ivan and Verbić, Tatjana and Zloh, Mire",
year = "2018",
abstract = "Aryldiketo acids (ADKs) exhibit the variety of biological activities, mainly due to large affinity toward divalent metal ions. Metal complexation ability of ADKs, as well as interactions with proteins, depend on tautomeric form present in solution. The main aim of this study was to fully explore the tautomeric preferences of 4-phenyl-2,4-dioxobutanoic acid (4PDA), as ADKs representative, in aqueous media at different pH values. 1D and 2D NMR spectroscopy in combination with quantum chemical calculations was applied in order to better understand the tautomeric preferences of 4PDA. The data in highly acidic media are especially interesting since there are no such findings in the literature due to low solubility of ADKs in molecular form. At low pH values, where 4PDA is unionized, the most abundant tautomeric form is enol with keto group closer to phenyl ring. At higher pH values, mixture of two 4PDA ionic forms coexists in solution. Their ratio calculated according to NMR data fits the values predicted using two experimentally determined pK (a) values. Based on the complexity of H-1 NMR spectrum of monoanionic 4PDA form, coexistence of two stable rotamers was assumed. In an alkaline media, 4PDA is mostly present in dianionic form. As pi-electrons of dianion are delocalized over an entire keto-enol moiety, spectral distinction between tautomers was not possible. Quantum chemical calculations were used to predict relative stability of tautomers. The predictions were in good accordance with experimental results only in case when explicit water molecule was included in calculations.",
publisher = "Springer/Plenum Publishers, New York",
journal = "Structural Chemistry",
title = "Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations",
volume = "29",
number = "2",
pages = "423-434",
doi = "10.1007/s11224-017-1039-3"
}

Cvijetić, I., Pešić, M. P., Todorov, M. D., Drakulić, B., Juranić, I., Verbić, T.,& Zloh, M.. (2018). Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations. in Structural Chemistry
Springer/Plenum Publishers, New York., 29(2), 423-434.
https://doi.org/10.1007/s11224-017-1039-3

Cvijetić I, Pešić MP, Todorov MD, Drakulić B, Juranić I, Verbić T, Zloh M. Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations. in Structural Chemistry. 2018;29(2):423-434.
doi:10.1007/s11224-017-1039-3 .

Cvijetić, Ilija, Pešić, Miloš P., Todorov, Miljana D., Drakulić, Branko, Juranić, Ivan, Verbić, Tatjana, Zloh, Mire, "Tautomerism of 4-phenyl-2,4-dioxobutanoic acid. Insights from pH ramping NMR study and quantum chemical calculations" in Structural Chemistry, 29, no. 2 (2018):423-434,
https://doi.org/10.1007/s11224-017-1039-3 . .

TY  - JOUR
AU  - Cvijetić, Ilija
AU  - Verbić, Tatjana
AU  - de Resende, Pedro Ernesto
AU  - Stapleton, Paul
AU  - Gibbons, Simon
AU  - Juranić, Ivan
AU  - Drakulić, Branko
AU  - Zloh, Mire
PY  - 2018
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2690
AB  - Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents. (C) 2017 Elsevier Masson SAS. All rights reserved.
PB  - Elsevier
T2  - European Journal of Medicinal Chemistry
T1  - Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains
VL  - 143
SP  - 1474
EP  - 1488
DO  - 10.1016/j.ejmech.2017.10.045
ER  - 

@article{
author = "Cvijetić, Ilija and Verbić, Tatjana and de Resende, Pedro Ernesto and Stapleton, Paul and Gibbons, Simon and Juranić, Ivan and Drakulić, Branko and Zloh, Mire",
year = "2018",
abstract = "Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents. (C) 2017 Elsevier Masson SAS. All rights reserved.",
publisher = "Elsevier",
journal = "European Journal of Medicinal Chemistry",
title = "Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains",
volume = "143",
pages = "1474-1488",
doi = "10.1016/j.ejmech.2017.10.045"
}

Cvijetić, I., Verbić, T., de Resende, P. E., Stapleton, P., Gibbons, S., Juranić, I., Drakulić, B.,& Zloh, M.. (2018). Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains. in European Journal of Medicinal Chemistry
Elsevier., 143, 1474-1488.
https://doi.org/10.1016/j.ejmech.2017.10.045

Cvijetić I, Verbić T, de Resende PE, Stapleton P, Gibbons S, Juranić I, Drakulić B, Zloh M. Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains. in European Journal of Medicinal Chemistry. 2018;143:1474-1488.
doi:10.1016/j.ejmech.2017.10.045 .

Cvijetić, Ilija, Verbić, Tatjana, de Resende, Pedro Ernesto, Stapleton, Paul, Gibbons, Simon, Juranić, Ivan, Drakulić, Branko, Zloh, Mire, "Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains" in European Journal of Medicinal Chemistry, 143 (2018):1474-1488,
https://doi.org/10.1016/j.ejmech.2017.10.045 . .

TY  - JOUR
AU  - Cvijetić, Ilija
AU  - Verbić, Tatjana
AU  - de Resende, Pedro Ernesto
AU  - Stapleton, Paul
AU  - Gibbons, Simon
AU  - Juranić, Ivan
AU  - Drakulić, Branko
AU  - Zloh, Mire
PY  - 2018
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2690
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2691
AB  - Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents. (C) 2017 Elsevier Masson SAS. All rights reserved.
PB  - Elsevier France-Editions Scientifiques Medicales Elsevier, Issy-Les-Moulineaux
T2  - European Journal of Medicinal Chemistry
T1  - Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains
VL  - 143
SP  - 1474
EP  - 1488
DO  - 10.1016/j.ejmech.2017.10.045
ER  - 

@article{
author = "Cvijetić, Ilija and Verbić, Tatjana and de Resende, Pedro Ernesto and Stapleton, Paul and Gibbons, Simon and Juranić, Ivan and Drakulić, Branko and Zloh, Mire",
year = "2018",
abstract = "Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents. (C) 2017 Elsevier Masson SAS. All rights reserved.",
publisher = "Elsevier France-Editions Scientifiques Medicales Elsevier, Issy-Les-Moulineaux",
journal = "European Journal of Medicinal Chemistry",
title = "Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains",
volume = "143",
pages = "1474-1488",
doi = "10.1016/j.ejmech.2017.10.045"
}

Cvijetić, I., Verbić, T., de Resende, P. E., Stapleton, P., Gibbons, S., Juranić, I., Drakulić, B.,& Zloh, M.. (2018). Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains. in European Journal of Medicinal Chemistry
Elsevier France-Editions Scientifiques Medicales Elsevier, Issy-Les-Moulineaux., 143, 1474-1488.
https://doi.org/10.1016/j.ejmech.2017.10.045

Cvijetić I, Verbić T, de Resende PE, Stapleton P, Gibbons S, Juranić I, Drakulić B, Zloh M. Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains. in European Journal of Medicinal Chemistry. 2018;143:1474-1488.
doi:10.1016/j.ejmech.2017.10.045 .

Cvijetić, Ilija, Verbić, Tatjana, de Resende, Pedro Ernesto, Stapleton, Paul, Gibbons, Simon, Juranić, Ivan, Drakulić, Branko, Zloh, Mire, "Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains" in European Journal of Medicinal Chemistry, 143 (2018):1474-1488,
https://doi.org/10.1016/j.ejmech.2017.10.045 . .

TY  - JOUR
AU  - Drakulić, Branko
AU  - Juranić, Ivan
AU  - Erić, Slavica
AU  - Zloh, Mire
PY  - 2008
UR  - http://farfar.pharmacy.bg.ac.rs/handle/123456789/1029
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/3512
AB  - The use of chemical penetration enhancers (CPE) is growing due to their ability to improve drug delivery through the skin. A possible mechanism of penetration enhancement could involve the complex formation between drug and components in the pharmaceutical formulation, thus altering the physicochemical properties of the active substance. Here, modelling studies indicate that hydrocarbon and oxygen-containing terpenes (penetration enhancers) could form complexes with drugs. Satisfactory correlations have been obtained between the predicted molecular properties of enhancers and their enhancement effects. Crown Copyright
PB  - Elsevier
T2  - International Journal of Pharmaceutics
T1  - Role of complexes formation between drugs and penetration enhancers in transdermal delivery
VL  - 363
IS  - 1-2
SP  - 40
EP  - 49
DO  - 10.1016/j.ijpharm.2008.06.032
ER  - 

@article{
author = "Drakulić, Branko and Juranić, Ivan and Erić, Slavica and Zloh, Mire",
year = "2008",
abstract = "The use of chemical penetration enhancers (CPE) is growing due to their ability to improve drug delivery through the skin. A possible mechanism of penetration enhancement could involve the complex formation between drug and components in the pharmaceutical formulation, thus altering the physicochemical properties of the active substance. Here, modelling studies indicate that hydrocarbon and oxygen-containing terpenes (penetration enhancers) could form complexes with drugs. Satisfactory correlations have been obtained between the predicted molecular properties of enhancers and their enhancement effects. Crown Copyright",
publisher = "Elsevier",
journal = "International Journal of Pharmaceutics",
title = "Role of complexes formation between drugs and penetration enhancers in transdermal delivery",
volume = "363",
number = "1-2",
pages = "40-49",
doi = "10.1016/j.ijpharm.2008.06.032"
}

Drakulić, B., Juranić, I., Erić, S.,& Zloh, M.. (2008). Role of complexes formation between drugs and penetration enhancers in transdermal delivery. in International Journal of Pharmaceutics
Elsevier., 363(1-2), 40-49.
https://doi.org/10.1016/j.ijpharm.2008.06.032

Drakulić B, Juranić I, Erić S, Zloh M. Role of complexes formation between drugs and penetration enhancers in transdermal delivery. in International Journal of Pharmaceutics. 2008;363(1-2):40-49.
doi:10.1016/j.ijpharm.2008.06.032 .

Drakulić, Branko, Juranić, Ivan, Erić, Slavica, Zloh, Mire, "Role of complexes formation between drugs and penetration enhancers in transdermal delivery" in International Journal of Pharmaceutics, 363, no. 1-2 (2008):40-49,
https://doi.org/10.1016/j.ijpharm.2008.06.032 . .

TY  - JOUR
AU  - Verbić, Tatjana
AU  - Drakulić, Branko
AU  - Zloh, Mire
AU  - Pecelj, Jovana R.
AU  - Popović, Gordana
AU  - Juranić, Ivan
PY  - 2007
UR  - http://farfar.pharmacy.bg.ac.rs/handle/123456789/997
UR  - http://cherry.chem.bg.ac.rs/handle/123456789/902
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/3513
AB  - The protolytic equilibria of 13 4-aryl-2,4-dioxobutanoic acids (ADKs) were spectrophotometrically studied in aqueous solutions in the pH range 1-9 at 25±1 °C and an ionic strength of 0.1 mol l-1 (NaCl), with the exception of the 4-OH-derivative which was also potentiometrically studied in the pH range 7-10 at 25±1 °C and an ionic strength of 0.1 mol l-1 (NaCl). In solution, the compounds simultaneously exist in one diketo and two enolic forms; therefore, the determined acidity constants (pKa1 1.87-2.29, pKa2 6.63-8.13 and pKa3(4-OH-) 9.52) represent system macro constants. The 1H-NMR spectrum of the parent compound (4-phenyl- -2,4-dioxobutanoic acid) (25 °C, pD 5.0) proved the existence of all tautomeric forms. Using the extended Hammett relation, the determined pKa values were correlated with literature σ values. The predicted pKa values were in fair accordance with the experimentally observed ones. Molecular, monoanionic and dianionic forms of the parent compound were optimized by the semi-empirical molecular orbital PM6 method using the implicit water solvation model (COSMO). The obtained geometries were used to explain the quality of the LFER models.
AB  - Protolitičke ravnoteže 13 jedinjenja iz klase 4-aril-2,4-dioksobutanskih kiselina (ADK) spektrofotometrijski su proučavane u vodenim rastvorima u pH intervalu 1-9 pri temperaturi 25±1 °C i jonskoj jačini rastvora 0.1 mol l-1 (NaCl), sa izuzetkom 4-OH-derivata koji je proučavan i potenciometrijski u pH intervalu 7-10 pri istim uslovima. Kako ADK u vodenom rastvoru podležu keto-enolnoj tautomeriji i istovremeno postoje u diketo i dva enolna oblika, to određene kiselinske konstante (pKa1 1.87-2.29, pKa2 6.63-8.13 i pKa3(4-OH-) 9.52) predstavljaju makro konstante za dati sistem. 1H-NMR spektar osnovne supstance (4-fenil-2,4-dioksobutanska kiselina) (25 °C, pD 5.0) potvrđuje prisustvo svih tautomernih oblika. Upotrebom proširene Hametove korelacije, određene pKa vrednosti korelisane su sa literaturnim σ vrednostima. Predviđene pKa vrednosti dobro se slažu sa eksperimentalno dobijenim. Molekulski, monoanjonski i dianjonski oblici osnovne supstance su optimizovani semiempirijskom molekulsko-orbitalnom PM6 metodom sa implicitnim modelom solvatacije u vodi (COSMO). Dobijene geometrije su upotrebljene za objašnjenje kvaliteta LFER modela.
PB  - Srpsko hemijsko društvo, Beograd
T2  - Journal of the Serbian Chemical Society
T1  - An LFER study of the protolytic equilibria of 4-aryl-2,4-dioxobutanoic acids in aqueous solutions
T1  - Linearne korelacije slobodne energije (LFER) protolitičkih ravnoteža 4-aril-2,4-dioksobutanskih kiselina u vodenim rastvorima
VL  - 72
IS  - 12
SP  - 1201
EP  - 1216
DO  - 10.2298/JSC0712201V
ER  - 

@article{
author = "Verbić, Tatjana and Drakulić, Branko and Zloh, Mire and Pecelj, Jovana R. and Popović, Gordana and Juranić, Ivan",
year = "2007",
abstract = "The protolytic equilibria of 13 4-aryl-2,4-dioxobutanoic acids (ADKs) were spectrophotometrically studied in aqueous solutions in the pH range 1-9 at 25±1 °C and an ionic strength of 0.1 mol l-1 (NaCl), with the exception of the 4-OH-derivative which was also potentiometrically studied in the pH range 7-10 at 25±1 °C and an ionic strength of 0.1 mol l-1 (NaCl). In solution, the compounds simultaneously exist in one diketo and two enolic forms; therefore, the determined acidity constants (pKa1 1.87-2.29, pKa2 6.63-8.13 and pKa3(4-OH-) 9.52) represent system macro constants. The 1H-NMR spectrum of the parent compound (4-phenyl- -2,4-dioxobutanoic acid) (25 °C, pD 5.0) proved the existence of all tautomeric forms. Using the extended Hammett relation, the determined pKa values were correlated with literature σ values. The predicted pKa values were in fair accordance with the experimentally observed ones. Molecular, monoanionic and dianionic forms of the parent compound were optimized by the semi-empirical molecular orbital PM6 method using the implicit water solvation model (COSMO). The obtained geometries were used to explain the quality of the LFER models., Protolitičke ravnoteže 13 jedinjenja iz klase 4-aril-2,4-dioksobutanskih kiselina (ADK) spektrofotometrijski su proučavane u vodenim rastvorima u pH intervalu 1-9 pri temperaturi 25±1 °C i jonskoj jačini rastvora 0.1 mol l-1 (NaCl), sa izuzetkom 4-OH-derivata koji je proučavan i potenciometrijski u pH intervalu 7-10 pri istim uslovima. Kako ADK u vodenom rastvoru podležu keto-enolnoj tautomeriji i istovremeno postoje u diketo i dva enolna oblika, to određene kiselinske konstante (pKa1 1.87-2.29, pKa2 6.63-8.13 i pKa3(4-OH-) 9.52) predstavljaju makro konstante za dati sistem. 1H-NMR spektar osnovne supstance (4-fenil-2,4-dioksobutanska kiselina) (25 °C, pD 5.0) potvrđuje prisustvo svih tautomernih oblika. Upotrebom proširene Hametove korelacije, određene pKa vrednosti korelisane su sa literaturnim σ vrednostima. Predviđene pKa vrednosti dobro se slažu sa eksperimentalno dobijenim. Molekulski, monoanjonski i dianjonski oblici osnovne supstance su optimizovani semiempirijskom molekulsko-orbitalnom PM6 metodom sa implicitnim modelom solvatacije u vodi (COSMO). Dobijene geometrije su upotrebljene za objašnjenje kvaliteta LFER modela.",
publisher = "Srpsko hemijsko društvo, Beograd",
journal = "Journal of the Serbian Chemical Society",
title = "An LFER study of the protolytic equilibria of 4-aryl-2,4-dioxobutanoic acids in aqueous solutions, Linearne korelacije slobodne energije (LFER) protolitičkih ravnoteža 4-aril-2,4-dioksobutanskih kiselina u vodenim rastvorima",
volume = "72",
number = "12",
pages = "1201-1216",
doi = "10.2298/JSC0712201V"
}

Verbić, T., Drakulić, B., Zloh, M., Pecelj, J. R., Popović, G.,& Juranić, I.. (2007). An LFER study of the protolytic equilibria of 4-aryl-2,4-dioxobutanoic acids in aqueous solutions. in Journal of the Serbian Chemical Society
Srpsko hemijsko društvo, Beograd., 72(12), 1201-1216.
https://doi.org/10.2298/JSC0712201V

Verbić T, Drakulić B, Zloh M, Pecelj JR, Popović G, Juranić I. An LFER study of the protolytic equilibria of 4-aryl-2,4-dioxobutanoic acids in aqueous solutions. in Journal of the Serbian Chemical Society. 2007;72(12):1201-1216.
doi:10.2298/JSC0712201V .

Verbić, Tatjana, Drakulić, Branko, Zloh, Mire, Pecelj, Jovana R., Popović, Gordana, Juranić, Ivan, "An LFER study of the protolytic equilibria of 4-aryl-2,4-dioxobutanoic acids in aqueous solutions" in Journal of the Serbian Chemical Society, 72, no. 12 (2007):1201-1216,
https://doi.org/10.2298/JSC0712201V . .