The influence of pH on the stability of antazoline: kinetic analysis

RSC Advances ◽  
2015 ◽  
Vol 5 (83) ◽  
pp. 68179-68186 ◽  
Author(s):  
Kārlis Bērziņš ◽  
Ilze Grante ◽  
Ilva Nakurte ◽  
Andris Actiņš
Keyword(s):  
Aqueous Solutions ◽  
Kinetic Analysis ◽  
The Stability ◽  
Influence Of Ph

Degradation of the drug antazoline was studied in aqueous solutions by means of pH-rate profiling (pH 0–7.4).

scholarly journals The Influence of pH and Temperature on the Stability ofN-[(Piperidine)methylene]daunorubicin Hydrochloride and a Comparison of the Stability of Daunorubicin and Its Four New Amidine Derivatives in Aqueous Solutions

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mikołaj Piekarski ◽  
Agnieszka Dołhań ◽  
Judyta Cielecka-Piontek ◽  
Przemysław Zalewski ◽  
Witold Kycler ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Hplc Method ◽  
Base Catalysis ◽  
Spontaneous Hydrolysis ◽  
Influence Of Water ◽  
Enthalpy And Entropy ◽  
The Stability ◽  
Protonated Molecules ◽  
Influence Of Ph ◽  
Hydrolysis Of

The influence of pH and temperature on the stability ofN-[(piperidine)methylene]daunorubicin hydrochloride (PPD) was investigated. Degradation was studied using an HPLC method. Specific acid-base catalysis of PPD involves hydrolysis of protonated molecules of PPD catalyzed by hydrogen ions and spontaneous hydrolysis under the influence of water zwitterions, unprotonated molecules, and monoanions of PPD. The thermodynamic parameters of these reactions, energy, enthalpy, and entropy, were calculated. Also, the stability of daunorubicin and its new amidine derivatives (piperidine, morpholine, pyrrolidine, and hexahydroazepin-1-yl) in aqueous solutions was compared and discussed.

scholarly journals Influence of pH, temperature, and light on the stability of melatonin in aqueous solutions and fruit juices

Heliyon ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. e03648 ◽  
Author(s):  
Thorung Pranil ◽  
Anuchita Moongngarm ◽  
Patiwit Loypimai
Keyword(s):  
Aqueous Solutions ◽  
Fruit Juices ◽  
The Stability ◽  
Influence Of Ph

On the Structure of Lead(II) Complexes in Aqueous Solutions. I. Trinuclear Clusters

1995 ◽  
Vol 60 (4) ◽  
pp. 527-536 ◽  
Author(s):  
Martin Breza ◽  
Alena Manová
Keyword(s):  
Quantum Chemistry ◽  
Aqueous Solutions ◽  
Electronic Structures ◽  
Mndo Method ◽  
Model Systems ◽  
Trinuclear Clusters ◽  
The Stability ◽  
Semiempirical Mndo

Using semiempirical MNDO method of quantum chemistry the optimal geometries and corresponding electronic structures of [Pb3(OH)n]6-n model systems as well as of their hydrated [Pb3(OH)n(H2O)8-n]6-n analogues (n = 4, 5) are investigated. The most stable trinuclear lead(II) complexes present in aqueous solutions correspond to cyclo-(μ3-OH)(μ2-OH)3Pb32+, Pb(μ-OH)2Pb(μ-OH)2Pb2+, cyclo-(μ3-OH)2(μ2-OH)3Pb3+, Pb(OH)(μ-OH)2Pb(μ-OH)Pb(OH)+ and Pb(OH)(μ-OH)2Pb(μ-OH)2Pb+ systems. The key role of OH bridges (by vanishing direct Pb-Pb bonds) on the stability of individual isomers is discussed.

scholarly journals Effective replacement of cetyltrimethylammonium bromide (CTAB) by mercaptoalkanoic acids on gold nanorod (AuNR) surfaces in aqueous solutions

Nanoscale ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 658-668 ◽  
Author(s):  
Rafael del Caño ◽  
Jose M. Gisbert-González ◽  
Jose González-Rodríguez ◽  
Guadalupe Sánchez-Obrero ◽  
Rafael Madueño ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Gold Nanorods ◽  
Ligand Exchange ◽  
Cetyltrimethylammonium Bromide ◽  
Gold Nanorod ◽  
Experimental Conditions ◽  
Seed Mediated ◽  
The Stability

The highly packed cetyltrimethylammonium bromide bilayer on the surface of gold nanorods synthesized by the seed-mediated procedure hampers the complete ligand exchange under experimental conditions that preserves the stability of the dispersions.

scholarly journals Investigations of ternary complexes of Co(II) and Ni(II) with thiodiacetate anion and 1,10-phenanthroline or 2,2’-bipyridine in aqueous solutions

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Dariusz Wyrzykowski ◽  
Joanna Pranczk ◽  
Dagmara Jacewicz ◽  
Aleksandra Tesmar ◽  
Bogusław Pilarski ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Substitution Reactions ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Hydroxo Complexes ◽  
Binary Complexes ◽  
Vis Spectroscopy ◽  
Potentiometric Titration Method ◽  
The Stability ◽  
Ph Range

AbstractA potentiometric titration method (PT) and a stopped-flow kinetic technique monitored by a UV−Vis spectroscopy have been used to characterize the stability of series of Co(II)- and Ni(II)-thiodiacetato complexes, M(TDA), in the presence of 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) in aqueous solutions. The stability constants of the binary (1:1), ternary (1:1:1) as well as the resulting hydroxo complexes were evaluated and compared to the corresponding oxydiacetate complexes. Based on the species distribution as a function of pH the relative predominance of the species in the system over a pH range was discussed. Furthermore, the kinetic measurements of the substitution reactions of the aqua ligands to phen or bipy in the coordination sphere of the binary complexes M(TDA) were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (0.2–0.5 mM). The kinetic stability of the M(TDA) complexes was discussed in relation to the experimental conditions and the kind of the auxiliary ligands (phen/bipy). Moreover, the influence of the type of primary ligand (thiodiacetate/oxydiacetate) on the substitution rate of the auxiliary ligands was also compared.

Effect of pH and temperature on the infectivity of human coronavirus 229E

1989 ◽  
Vol 35 (10) ◽  
pp. 972-974 ◽  
Author(s):  
Alain Lamarre ◽  
Pierre J. Talbot
Keyword(s):  
Incubation Period ◽  
Storage Conditions ◽  
Viral Infectivity ◽  
Human Coronavirus ◽  
Virus Growth ◽  
The Stability ◽  
And Storage ◽  
Influence Of Ph ◽  
Human Coronavirus 229E

The stability of human coronavirus 229E infectivity was maximum at pH 6.0 when incubated at either 4 or 33 °C. However, the influence of pH was more pronounced at 33 °C. Viral infectivity was completely lost after a 14-day incubation period at 22, 33, or 37 °C but remained relatively constant at 4 °C for the same length of time. Finally, the infectious titer did not show any significant reduction when subjected to 25 cycles of thawing and freezing. These studies will contribute to optimize virus growth and storage conditions, which will facilitate the molecular characterization of this important pathogen.Key words: coronavirus, pH, temperature, infectivity, human coronavirus.

Addition of Aliphatic and Aromatic Amines to Catechol in Aqueous Solution Under Oxidizing Conditions

1989 ◽  
Vol 42 (3) ◽  
pp. 365 ◽  
Author(s):  
MK Manthey ◽  
SG Pyne ◽  
RJW Truscott
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Aromatic Amines ◽  
Aliphatic Amines ◽  
Substitution Pattern ◽  
Vinylogous Amides ◽  
The Stability

The oxidation of catechol in the presence of two aliphatic and aromatic amines has been investigated. In aqueous solutions of pH 7.0 and 11.7, the substitution pattern of the adduct was dependent on the type of amine used. Aromatic amines produced 4,5-disubstituted o-quinones, whereas aliphatic amines gave either 2,4,5-trisubstituted or 2,4-disubstituted o-quinone adducts. A rationale based upon the stability of vinylogous amides is presented to account for the observed substitution pattern.

scholarly journals Water confined in solutions of biological relevance

2020 ◽  
Vol 92 (10) ◽  
pp. 1563-1574
Author(s):  
Marie-Claire Bellissent-Funel
Keyword(s):  
Aqueous Solutions ◽  
Bulk Water ◽  
Biological Macromolecules ◽  
Organic Solutes ◽  
Confined Water ◽  
The Past ◽  
Structure And Dynamics ◽  
Biological Relevance ◽  
The Stability

AbstractIn many relevant situations, water is not in its bulk form but instead attached to some substrates or filling some cavities. We shall call water in the latter environment confined water as opposed to bulk water. It is known that the confined water is essential for the stability and the function of biological macromolecules. In this paper, we provide a review of the experimental and computational advances over the past decades concerning the understanding of the structure and dynamics of water confined in aqueous solutions of biological relevance. Examples involving water in solution of organic solutes (cryoprotectants such as dimethylsulfoxide (DMSO), sugars such as trehalose) are provided.

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