Study of the protonation of simple Schiff bases in solvents of various polarity by means of Raman spectroscopy

Alex, Serge; Turcotte, P.; Fournier, René; Vocelle, D.

doi:10.1139/v91-038

Cited by 12 publications

(10 citation statements)

References 32 publications

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“…, whereas the imine stretches at 1,613 and 1,591 cm −1 are broadened due to overlap with the C = C stretch of the enediyne functional group (39,40) (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

Metal-mediated diradical tuning for DNA replication arrest via template strand scission

Porter

Lindahl

Lietzke

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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) for Cu(PyED)·2Cl, indicating three nitrogens and a chloride in the psuedo-equatorial plane with the remaining pyridine nitrogen and solvent in axial positions. EPR spectra of the Cu(II) complexes exhibit an axially elongated octahedron. This spectroscopic evidence, together with density functional theory computed geometries, suggest six-coordinate structures for Cu(II) and Fe(II) complexes and a five-coordinate environment for Zn(II) analogs. Bergman cyclization via thermal activation of these constructs yields benzannulated product indicative of diradical generation in all complexes within 3 h at 37°C. A significant metal dependence on the rate of the reaction is observed [Cu(II) > Fe(II) > Zn(II)], which is mirrored in in vitro DNA-damaging outcomes. Whereas in situ chelation of PyED leads to considerable degradation in the presence of all metals within 1 h under hyperthermia conditions, Cu(II) activation produces >50% compromised DNA within 5 min. Additionally, Cu(II) chelated PyED outcompetes DNA polymerase I to successfully inhibit template strand extension. Exposure of HeLa cells to Cu(PyBD)·SO 4 (IC 50 = 10 μM) results in a G2/M arrest compared with untreated samples, indicating significant DNA damage. These results demonstrate metal-controlled radical generation for degradation of biopolymers under physiologically relevant temperatures on short timescales. metal-mediated radicals | DNA degradation | polymerase inhibition | enediyne | Bergman cyclization

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“…, whereas the imine stretches at 1,613 and 1,591 cm −1 are broadened due to overlap with the C = C stretch of the enediyne functional group (39,40) (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

Metal-mediated diradical tuning for DNA replication arrest via template strand scission

Porter

Lindahl

Lietzke

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…From Table 3 then, it must be concluded that chloroform is rather effective in shielding the PSB from water and only a small fraction of the molecules of water can hydrolyze the PSB. Chloroform is known to cause the formation of tight ion-pairs (thus favoring protonation) and this has been described before (20,24). Finally, the ratio of chloroform to dioxane was varied from 1 : 1 to 1 : 9 and the same results were obtained, that is, R was identical or greater than R obtained in pure dioxane.…”

Section: Addition Of Watermentioning

confidence: 67%

“…Several hypotheses have been advanced to explain this shift (2,16,18), but lately, the emphasis has been placed on the relationship between the protonated Schiff base and its counterion; visualize R~~CH=N(R)H+-..-OOCR, where Ret is the retinylidene portion of the Schiff base that could well explain totally or in part the opsin shift. Yet, model studies conducted in our laboratory (20)(21)(22)(23)(24)(25) have in- 'Author to whom correspondence may be addressed. 'Revision received July 1 1, 1992. or in methanol couid not be fully protonatedAby acids having pK,'s in the 3-5 region as measured in water, which is the region where Glu or Asp have their pK,'s (4.25 and 3.89 respectively).…”

Section: Introduction Dicated That a Retinylidene Schiff Base In Nonpmentioning

confidence: 99%

Studies of the role of water on some imine–acid complexes by means of Raman spectroscopy

Turcotte¹,

Alex²,

Vocelle³

1992

Can. J. Chem.

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The percentages of protonation were determined for a conjugated Schiff base trans, trans-2,4-heptadienylidene tertbutylamine in the presence of 3-chloropropionic acid (CPR) and dichloroacetic acid (DCA) in three solvents of different polarities. In dioxane, a solvent of low polarity, protonation is only important for the strong acid DCA (50-60%). By using solvents of higher polarities, protonation is seen to increase and is almost complete for DCA in ethanol. When water molecules are added to these systems, hydrolysis of the Schiff base, measured inside the time span of the experiments (10 min), occurs readily in dioxane, is very slow in a chloroform-dioxane mixture (9: l), and is totally absent in a mixture of ethanol-dioxane (1 :9). Results indicate that water does not mediate protonation in all three sets of solvent combinations. The results are also discussed in terms of the possible role that water molecules could have in the visual and bacterial pigments. Les pourcentages de protonation ont CtC determines pour le cas d'une base de Schiff conjuguke, la trans,trans-2,4-heptadiknylidkne tert-butylamine, en presence de l'acide 3-chloropropionique (CPR) et de l'acide dichloroacCtique (DCA) dans trois solvants de differentes polarites. Dans le dioxane, un solvant de faible polaritk, la protonation n'est importante que pour l'acide fort DCA (50-60%). En utilisant des solvants de polarit6 plus klevke, la protonation augmente et est B peu pres complkte pour le DCA dans I'ethanol. Quand de l'eau est ajoutCe a ces systemes, l'hydrolyse de la base de Schiff, mesuree 21 l'intkrieur du temps d'enregistrement des spectres (10 min), est rapide dans le dioxane, est beaucoup plus lente dans un melange de chloroforme-dioxane (9: 1) et est totalement absente dans un melange d'kthanoldioxane (1 :9). Les resultats indiquent que l'eau ne favorise aucunement la protonation et cela vaut pour les trois ensem-I

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“…The Raman spectrum of P(M1‐co‐Edot)/ZnO shows bands of carbon double bonds at 1567 cm −1 (asym CC), 1532 cm −1 (asym CC), 1432 cm −1 (sym CC), 1365 cm −1 (CC), 1260 cm −1 (C‐C inter‐ring) 21,31,32 . For aromatic compounds, the CH and OH stretching modes are usually observed in the region of approximately 2850‐3000 cm −1 and approximately 2700‐3800 cm −1 as seen in Figure 11.…”

Section: Resultsmentioning

confidence: 96%

Electropolymerizations of two novelEDOT‐BODIPYzincoxide nanocomposites andevaluation of their in vitro antibacterial activities

Kılavuz

Turaç

Torun

et al. 2020

Polymers for Advanced Techs

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Boron containing materials as novel classes of antibacterial agents have been widely used in coating or medical applications due to their excellent functionality against microorganisms. In this study, two different boron dipyrromethene (BODIPY)/zinc oxide based P(M1‐co‐Edot)/ZnO and P(M2‐co‐Edot)/ZnO nanocomposite copolymer materials were prepared. The BODIPY/ZnO nanocomposite films were synthesized using potentiostat. ZnO nanoparticles were used to increase the strength and conductivity of the obtained semiconducting materials. Spectroelectrochemical analysis show that the copolymers, P(M1‐co‐Edot)/ZnO and P(M2‐co‐Edot)/ZnO, have electronic band gaps at 1.56 and 2.51 eV and optical band gaps at 2.11 and 2.00 eV, respectively. The synthesized nanocomposite films were characterized by Raman, nuclear magnetic resonance (NMR) and FT‐IR spectroscopies. The optical properties of the synthesized monomers and their nanocomposite copolymers were demonstrated using UV‐Vis and fluorescence spectroscopy. SEM and AFM images show the surface morphologies of nanocomposite copolymer films and surface roughness of P(M1‐co‐Edot)/ZnO and P(M2‐co‐Edot)/ZnO were calculated as Ra = 84.6 nm Rq = 106 nm and 120 nm, respectively. Antibacterial activities of the obtained nanocomposite films prepared in ultrapure water with different concentrations (2.5‐0.25 mg/mL) were discovered against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria by using disc diffusion method. The antibacterial activities of obtained films were found to be higher against Gram negative bacteria compared to that of Gram positives. Obtained results show that synthesized nanocomposites with easy production and nontoxic properties can be used as functional bioengineering materials for antibacterial electrochromical materials.

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Study of the protonation of simple Schiff bases in solvents of various polarity by means of Raman spectroscopy

Cited by 12 publications

References 32 publications

Metal-mediated diradical tuning for DNA replication arrest via template strand scission

Metal-mediated diradical tuning for DNA replication arrest via template strand scission

Studies of the role of water on some imine–acid complexes by means of Raman spectroscopy

Electropolymerizations of two novelEDOT‐BODIPYzincoxide nanocomposites andevaluation of their in vitro antibacterial activities

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