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Papers by Daniela Nedeltcheva
Molecules
The chemical composition and aroma profile of industrial essential oils (EOs) from species of ros... more The chemical composition and aroma profile of industrial essential oils (EOs) from species of rose grown in China, including the native Kushui rose (R. sertata × R. rugosa) and R. rugosa Thunb. cv. Plena, and the recently introduced Damask rose (R. damascena Mill.), were studied in comparison by means of GC/MS and GC-FID. More than 150 individual compounds were detected in Chinese rose samples, of which 112 were identified and their quantitative content determined, representing 88.7%, 96.7% and 97.9% of the total EO content, respectively. It was found that the main constituents of the Chinese rose EOs were representatives of terpenoid compounds (mono- and sesquiterpenoids, predominantly) and aliphatic hydrocarbons. Comparative chemical profiling revealed different chemical composition and aroma profiles: while the R. damascena oil showed a balance between the eleoptene and stearoptene fractions of the oil (the average ratio between the main terpene alcohols and paraffins was 2.65), ...
Plants
Lavender (L. angustifolia Mill.) is an important essential oil-bearing and medicinal plant with h... more Lavender (L. angustifolia Mill.) is an important essential oil-bearing and medicinal plant with high commercial value. Lavender scent components can be derived not only as an essential oil but also as lavender concrete or absolute. The development of reliable analytical methods for origin assessment and quality assurance is of significant fundamental importance and high practical interest. Therefore, a comprehensive chemical profiling of seven industrial samples of Bulgarian lavender absolute (L. angustifolia Mill.) was performed by means of gas chromatography–mass spectrometry (GC/MS) and gas chromatography with flame ionization detection (GC-FID). As a result, 111 individual compounds were identified by GC/MS, and their quantitative content was simultaneously determined by GC-FID, representing 94.28–97.43% of the total contents of the lavender absolute. According to our results, the main constituents of lavender absolute (LA) are representatives of the terpene compounds (with the ...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Physical Chemistry Chemical Physics, 2021
A new rotary switch, showing anti-Kasha excited state intra-molecular proton transfer.
The concept for sensing systems using the tautomerism as elementary signaling process has been fu... more The concept for sensing systems using the tautomerism as elementary signaling process has been further developed by synthesizing a ligand containing 4-(phenyldiazenyl)naphthalene-1-ol as a tautomeric block and an amide group as metal capturing antenna. Although it has been expected, that the intramolecular hydrogen bonding (between the tautomeric hydroxyl group and the nitrogen atom from the amide group), could stabilize the pure enol form in some solvents, the keto tautomer is also observed. This is a result from formation of intramolecular associates in some solvents. Strong bathochromic and hyperchromic effects on the visible spectra accompany the complex 1:1 formation with some alkaline earth metal ions.
Journal of Molecular Liquids, 2019
Foods, 2018
The possibility of applying near-infrared (NIR) spectroscopy to monitor 13 active components (phe... more The possibility of applying near-infrared (NIR) spectroscopy to monitor 13 active components (phenolic acids, flavonoids, and sesquiterpene lactones) in Arnicae flos was studied. The preprocessing of the spectra were performed by using the conventional Golay-Savitzky procedure and the newly developed step-by-step filter. The results obtained show that the step-by-step filter derivatives provide a better signal-to-noise ratio at a lower convolution window. Better calibration for the content of protocatechuic acid, chlorogenic acid, caffeic acid, p-cumaric acid, ferulic acid, isoquercitrin, and quercetin were obtained by step-by-step filter derivatives, compared to the direct raw spectra processing and the Golay-Savitzky approach. Although the step-by-step filter substantially reduces the spectral distortion, the convolution procedure leads to loss of spectral points in the red end of the spectral curve. Probably for this reason this approach shows better calibration only in seven of ...
RSC Advances, 2015
Proton transfer in HBQ and modified compounds was investigated experimentally (steady state absor... more Proton transfer in HBQ and modified compounds was investigated experimentally (steady state absorption and emission spectroscopy, NMR and chemometrics) and theoretically (DFT and TD-DFT M06-2X/TZVP calculations) in ground and excited singlet state.
RSC Advances, 2015
Piroxicam tautomerism was studied in solution. Enol-amide tautomer is presented mainly as a sandw... more Piroxicam tautomerism was studied in solution. Enol-amide tautomer is presented mainly as a sandwich type dimer in ethanol and DMSO. The addition of water leads to gradual shift of the equilibrium towards the zwitterionic tautomer.
![Research paper thumbnail of [PDF]Chemical Characterisation Of Maltese Propolis In Relation](https://attachments.academia-assets.com/120781620/thumbnails/1.jpg)
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The Journal of Physical Chemistry A, 2004
Rapid Communications in Mass Spectrometry, 2009
Gas‐phase tautomerism in 1‐phenylazonaphthalene‐4‐ol (1) was studied by using electron ionization... more Gas‐phase tautomerism in 1‐phenylazonaphthalene‐4‐ol (1) was studied by using electron ionization (EI) mass spectrometry on the basis of the fragmentations of the model enol and keto tautomers, where the movable proton is replaced by a methyl group. These fixed tautomers were obtained as an easy separable mixture by simple methylation of the cheap and easily accessible diazene (1). It was found that their EI mass spectral fragmentations are in full congruence with the already published theoretical predictions. The relative energies required for bond cleavage in 1 and its fixed tautomers were estimated by stepwise increasing of the electron energy of the ion source of the mass spectrometer. A simple equation for the approximate estimation of the molar fractions of the individual tautomers was suggested. It was shown that the enol form is dominant in the temperature range of 200–300°C. Copyright © 2009 John Wiley & Sons, Ltd.
Journal of Photochemistry and Photobiology A: Chemistry, 2006
Linear (one-photon) and nonlinear (two-photon) spectral properties of 4-N,N-dimethylamino-4′-amin... more Linear (one-photon) and nonlinear (two-photon) spectral properties of 4-N,N-dimethylamino-4′-aminoazobenzene have been investigated under protonation in DMSO/water solvent mixtures. Observed spectral changes have been discussed in terms of ammonium–azonium tautomerism. The corresponding tautomeric constants have been determined for the first time for such kind of tautomeric equilibria. The process of protonation leads to changes of the two-photon absorption properties, suggesting that
Journal of Molecular Structure, 2005
Molecules
The chemical composition and aroma profile of industrial essential oils (EOs) from species of ros... more The chemical composition and aroma profile of industrial essential oils (EOs) from species of rose grown in China, including the native Kushui rose (R. sertata × R. rugosa) and R. rugosa Thunb. cv. Plena, and the recently introduced Damask rose (R. damascena Mill.), were studied in comparison by means of GC/MS and GC-FID. More than 150 individual compounds were detected in Chinese rose samples, of which 112 were identified and their quantitative content determined, representing 88.7%, 96.7% and 97.9% of the total EO content, respectively. It was found that the main constituents of the Chinese rose EOs were representatives of terpenoid compounds (mono- and sesquiterpenoids, predominantly) and aliphatic hydrocarbons. Comparative chemical profiling revealed different chemical composition and aroma profiles: while the R. damascena oil showed a balance between the eleoptene and stearoptene fractions of the oil (the average ratio between the main terpene alcohols and paraffins was 2.65), ...
Plants
Lavender (L. angustifolia Mill.) is an important essential oil-bearing and medicinal plant with h... more Lavender (L. angustifolia Mill.) is an important essential oil-bearing and medicinal plant with high commercial value. Lavender scent components can be derived not only as an essential oil but also as lavender concrete or absolute. The development of reliable analytical methods for origin assessment and quality assurance is of significant fundamental importance and high practical interest. Therefore, a comprehensive chemical profiling of seven industrial samples of Bulgarian lavender absolute (L. angustifolia Mill.) was performed by means of gas chromatography–mass spectrometry (GC/MS) and gas chromatography with flame ionization detection (GC-FID). As a result, 111 individual compounds were identified by GC/MS, and their quantitative content was simultaneously determined by GC-FID, representing 94.28–97.43% of the total contents of the lavender absolute. According to our results, the main constituents of lavender absolute (LA) are representatives of the terpene compounds (with the ...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Physical Chemistry Chemical Physics, 2021
A new rotary switch, showing anti-Kasha excited state intra-molecular proton transfer.
The concept for sensing systems using the tautomerism as elementary signaling process has been fu... more The concept for sensing systems using the tautomerism as elementary signaling process has been further developed by synthesizing a ligand containing 4-(phenyldiazenyl)naphthalene-1-ol as a tautomeric block and an amide group as metal capturing antenna. Although it has been expected, that the intramolecular hydrogen bonding (between the tautomeric hydroxyl group and the nitrogen atom from the amide group), could stabilize the pure enol form in some solvents, the keto tautomer is also observed. This is a result from formation of intramolecular associates in some solvents. Strong bathochromic and hyperchromic effects on the visible spectra accompany the complex 1:1 formation with some alkaline earth metal ions.
Journal of Molecular Liquids, 2019
Foods, 2018
The possibility of applying near-infrared (NIR) spectroscopy to monitor 13 active components (phe... more The possibility of applying near-infrared (NIR) spectroscopy to monitor 13 active components (phenolic acids, flavonoids, and sesquiterpene lactones) in Arnicae flos was studied. The preprocessing of the spectra were performed by using the conventional Golay-Savitzky procedure and the newly developed step-by-step filter. The results obtained show that the step-by-step filter derivatives provide a better signal-to-noise ratio at a lower convolution window. Better calibration for the content of protocatechuic acid, chlorogenic acid, caffeic acid, p-cumaric acid, ferulic acid, isoquercitrin, and quercetin were obtained by step-by-step filter derivatives, compared to the direct raw spectra processing and the Golay-Savitzky approach. Although the step-by-step filter substantially reduces the spectral distortion, the convolution procedure leads to loss of spectral points in the red end of the spectral curve. Probably for this reason this approach shows better calibration only in seven of ...
RSC Advances, 2015
Proton transfer in HBQ and modified compounds was investigated experimentally (steady state absor... more Proton transfer in HBQ and modified compounds was investigated experimentally (steady state absorption and emission spectroscopy, NMR and chemometrics) and theoretically (DFT and TD-DFT M06-2X/TZVP calculations) in ground and excited singlet state.
RSC Advances, 2015
Piroxicam tautomerism was studied in solution. Enol-amide tautomer is presented mainly as a sandw... more Piroxicam tautomerism was studied in solution. Enol-amide tautomer is presented mainly as a sandwich type dimer in ethanol and DMSO. The addition of water leads to gradual shift of the equilibrium towards the zwitterionic tautomer.
The Journal of Physical Chemistry A, 2004
Rapid Communications in Mass Spectrometry, 2009
Gas‐phase tautomerism in 1‐phenylazonaphthalene‐4‐ol (1) was studied by using electron ionization... more Gas‐phase tautomerism in 1‐phenylazonaphthalene‐4‐ol (1) was studied by using electron ionization (EI) mass spectrometry on the basis of the fragmentations of the model enol and keto tautomers, where the movable proton is replaced by a methyl group. These fixed tautomers were obtained as an easy separable mixture by simple methylation of the cheap and easily accessible diazene (1). It was found that their EI mass spectral fragmentations are in full congruence with the already published theoretical predictions. The relative energies required for bond cleavage in 1 and its fixed tautomers were estimated by stepwise increasing of the electron energy of the ion source of the mass spectrometer. A simple equation for the approximate estimation of the molar fractions of the individual tautomers was suggested. It was shown that the enol form is dominant in the temperature range of 200–300°C. Copyright © 2009 John Wiley & Sons, Ltd.
Journal of Photochemistry and Photobiology A: Chemistry, 2006
Linear (one-photon) and nonlinear (two-photon) spectral properties of 4-N,N-dimethylamino-4′-amin... more Linear (one-photon) and nonlinear (two-photon) spectral properties of 4-N,N-dimethylamino-4′-aminoazobenzene have been investigated under protonation in DMSO/water solvent mixtures. Observed spectral changes have been discussed in terms of ammonium–azonium tautomerism. The corresponding tautomeric constants have been determined for the first time for such kind of tautomeric equilibria. The process of protonation leads to changes of the two-photon absorption properties, suggesting that
Journal of Molecular Structure, 2005