Solvatochromism and solvatofluorochromism of the intramolecular charge transfer band of 4-dimethylaminochalcone in the electronic spectra of its solutions

Bakhshiev, N. G.; Gularyan, S. K.; Dobretsov, G. E.; Kirillova, A. Yu.; Svetlichnyĭ, V. Yu.

doi:10.1134/s0030400x06050109

Cited by 23 publications

(11 citation statements)

References 4 publications

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“…These theories describe quite well the connection between the physical properties of the media surrounding the probe and the probe's optical properties. 5 With that knowledge one might look at a probe as a nanoscale physical sensor. The next equally important physical parameter which could be obtained from experiments with fluorescent probes is the quantum yield of their fluorescence.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8] Its optical properties are very sensitive to characteristics of surrounding media. 5 In different organic solvents a maximum of DMAC fluorescence spectrum can be shifted by more than 120 nm (depending on solvent polarity), and its fluorescence quantum yield varies by two orders of magnitude. Also, the quantum yield of DMAC in model biomembranes depends on their lipid composition and varies in different intracellular organelles of a living cell.…”

Section: Introductionmentioning

confidence: 99%

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Electronically excited states of membrane fluorescent probe 4-dimethylaminochalcone. Results of quantum chemical calculations

Romanov¹,

Gularyan

Polyak

et al. 2011

Phys. Chem. Chem. Phys.

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Quantum-chemical calculations of ground and excited states for membrane fluorescent probe 4-dimethylaminochalcone (DMAC) in vacuum were performed. Optimized geometries and dipole moments for lowest-lying singlet and triplet states were obtained. The nature of these electronic transitions and the relaxation path in the excited states were determined; changes in geometry and charge distribution were assessed. It was shown that in vacuum the lowest existed level is of (n, π*) nature, and the closest to it is the level of (π, π*) nature; the energy gap between them is narrow. This led to an effective (1)(π, π*) →(1)(n, π*) relaxation. After photoexcitation the molecule undergoes significant transformations, including changes in bond orders, pyramidalization angle of the dimethylamino group, and planarity of the molecule. Its dipole moment rises from 5.5 Debye in the ground state to 17.1 Debye in the (1)(π, π*) state, and then falls to 2 Debye in the (1)(n, π*) state. The excited (1)(n, π*) state is a short living state; it has a high probability of intersystem crossing into the (3)(π, π*) triplet state. This relaxation path explains the low quantum yield of DMAC fluorescence in non-polar media. It is possible that (3)(π, π*) is responsible for observed DMAC phosphorescence.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electronically excited states of membrane fluorescent probe 4-dimethylaminochalcone. Results of quantum chemical calculations

Romanov¹,

Gularyan

Polyak

et al. 2011

Phys. Chem. Chem. Phys.

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“…The results of calculations of the electronic absorption spectra of DMAC (Table 4) are in good agreement with the experimental data. 22, 23 We cal culated positions of the absorption bands corresponding to other possible conformations of the DMAC molecule at room temperature (see above) and found that this only leads to small variations in the position of the long wave length absorption band (at most 6 nm). Fig.…”

Section: Resultsmentioning

confidence: 99%

“…2), namely, µ g (DMAC) = 5.2 (vacuum), 5.9 (heptane), and 6.9 D (acetone). A spectroscopic study 23 of DMAC showed that µ g = 6.3±0.6 D in nonpolar solvents (hep tane, hexane, toluene) and increases to 7.0±0.7 D in acetone. This is in good agreement with the results of quantum chemical calculations.…”

Section: Resultsmentioning

confidence: 99%

4-Dimethylaminochalcone as a f luorescent probe: Quantum chemical calculations of its interaction with the environment

et al. 2006

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Ground state RHF/6 311G(d,p) and density functional B3LYP/6 311G(d,p) quantum chemical calculations of 4 dimethylaminochalcone (DMAC), a sensitive fluorescent probe, were carried out for vacuum and for solvents of different polarity. The effect of the medium was included by the SCRF method in the framework of the polarization continuum model. The DMAC fragment comprising the aniline and propenone groups has a nearly planar conforma tion. The phenyl group can lie in the same plane or rotate by an angle within the limits of ±20°w ith a low barrier at 293 K. The results of calculations were confirmed by the data of X ray study, according to which the phenyl group in the crystal is rotated by 20°. Calculations with allowance for solvation effects predict charge transfer from the dimethylamino group to the oxygen atom; the higher the medium polarity, the larger the degree of charge transfer (atomic charge of oxygen increases by 0.07 e in acetone). The calculated dipole moment of the DMAC molecule increases from 5.2 D (vacuum) to 5.9 D (heptane) and 6.9 D (acetone), which is in agreement with spectroscopic data. The energy of the DMAC-environment interaction was calculated. Due to large dipole moment of the DMAC molecule, the electrostatic component of this energy strongly depends on the environment polarity, which can be related to redistribu tion of the probe between the aqueous phase and cells and lipid structures of lipoproteins. The electronic absorption spectra of DMAC in solvents of different polarity were calculated; differences between the calculated and experimentally measured values are at most 15 nm.

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“…Binding of the probes to the bacterial surface and transition from an aquatic to a hydrophobic environment were proved by the blue shift of the fluorescence maxima registered for ANS (from 512 ± 1 to 490 ± 2nm) and for DMC (from 522 ± 1 nm to 499 ± 1 nm) in bacterial suspensions.…”

Section: Resultsmentioning

confidence: 99%

Neutrophil activation by Escherichia coli isolates from human intestine: effects of bacterial hydroperoxidase activity and surface hydrophobicity

et al. 2020

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Successful colonization of the intestine requires that bacteria interact with the innate immune system and, in particular, neutrophils. Progression of inflammatory bowel diseases (IBD) is associated with alterations in gut microbiota, and dysbiosis in Crohn’s disease (CD) patients is often associated with an expansion of Escherichia coli. Here, we investigated the ability of such E. coli isolates to avoid neutrophil activation and to utilize reactive oxygen species. Neutrophil activation was detected in vitro in normal human blood via luminol chemiluminescence (CL) induced by reactive oxygen and halogen species generated by neutrophils. No significant difference in neutrophil activation in vitro was detected between isolates from inflamed (23 isolates) vs healthy intestines (5 isolates), with 10‐fold variation within both groups (2.9–61.2 mV). CL activity of isolates from the same patient differed by 1.5–5 times. Twenty‐four isolates from ileal aspirate, biopsy, and feces of seven patients with CD and one patient with no intestine inflammation were tested for extracellular peroxidase and catalase activity and cell surface hydrophobicity. Average values between patients varied from 26 ± 3 to 73 ± 18 µmol·g−1 of air dry weight for peroxidase activity, from 15 ± 2 to 189 ± 56 mmol·g−1 of air dry weight for catalase activity, and from 5 ± 3 to 105 ± 9 a.u. for the hydrophobic probe fluorescence. Extracellular peroxidase activity and hydrophobicity of bacterial cell surface correlated negatively with stimulated neutrophil CL. The ability of some isolates to avoid neutrophil activation and to utilize reactive oxygen species may provide a strategy to survive assault by the innate immune system.

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Solvatochromism and solvatofluorochromism of the intramolecular charge transfer band of 4-dimethylaminochalcone in the electronic spectra of its solutions

Cited by 23 publications

References 4 publications

Electronically excited states of membrane fluorescent probe 4-dimethylaminochalcone. Results of quantum chemical calculations

Electronically excited states of membrane fluorescent probe 4-dimethylaminochalcone. Results of quantum chemical calculations

4-Dimethylaminochalcone as a f luorescent probe: Quantum chemical calculations of its interaction with the environment

Neutrophil activation by Escherichia coli isolates from human intestine: effects of bacterial hydroperoxidase activity and surface hydrophobicity

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