Infra-Red Study of Tautomerism in Some Schiff Bases.

Infra-Red spectra of a series of substituted salicylaldehyde and 2-hydroxy-naphthaldehyde Schiff bases were used to investigate enol-keto tautomeric equilibrium. Two model compounds, namely, salicylidinaniline and naphthylidinequinolineamine Schiff bases were used to represent the enol and keto forms, respectively. From the IR spectra of the model compounds it was possible to assign the IR absorption for the C=O and the C=N groups in both the keto and the enol form. It was also possible to assign other absorptions which were either specific to the keto or the enol forms. Specific pattern were observed for all the studied compounds.     

Oxidation of phenol and chlorophenols on platinized titanium anodes in an acidic medium

A comparative study of oxidation of phenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol on Pt/Ti and Ce,Pt/Ti electrocatalysts is performed via cyclic voltammetry. It is shown that the surface morphology and roughness of the anode do not change after modification with cerium. The formal kinetic orders of electrooxidation of all compounds are found to be less than one. It is shown that the β temperature coefficients of the rate of oxidation of chlorophenols grow by 10 to 50% when the Ce,Pt/Ti anode is used at a substrate concentration of 1 mM. A tenfold increase in concentration reduces the effect of cerium additive, except for 3-chlorophenol: the latter exhibits a 250% increase in the β value, compared to the Pt/Ti anode.     

Study of Interactions Between Sugammadex and Penicillins Using Affinity Capillary Electrophoresis

Sugammadex, a new modified gamma cyclodextrin, reverses the neuromuscular blockage induced by rocuronium by forming a strong complex with this muscle relaxant. To evaluate possible interactions with potentially co-administered drugs, interactions between sugammadex and penicillins were investigated using the affinity capillary electrophoresis method for the first time. Capillary electrophoresis coupled to an ultra violet detector was used as an analytical device for the analysis and detection of cyclodextrin inclusion complexes. Changes in the effective mobility of guest drugs (amoxicillin, ampicillin, oxacillin, dicloxacillin and azlocillin) were correlated with the increasing concentration of host molecules in background electrolyte, and successfully fitted into a non-linear curve equation; assuming 1:1 stoichiometric interaction. The calculated association constants (K _a) were: 383.44, 184.54, 265.34 and 95.06 M⁻¹ for amoxicillin, ampicillin, oxacillin and dicloxacillin, respectively. No complex formation with sugammadex could be detected for both penicillin G and piperacillin. The difference in the chemical structure of the penicillins, especially in the (R) side chains, is suggested to be responsible for the variety of binding strength between penicillins and sugammadex. The displacement study demonstrated that interactions between sugammadex and co-administered penicillins could reduce the pharmacological effects of both.

     

A theoretical evidence for cooperativity effects in fluorine-centered halogen bonds: linear (FCN)2–7 and (FNC)2–7 clusters

A theoretical investigation was performed to study cooperative effects in fluorine-centered halogen bond interactions. We investigated geometry, strength, and origin of the interactions in linear (FCN)_2–7 and (FNC)_2–7 clusters by means of MP2 and CCSD(T) methods. Our results strongly suggest that cooperative effects induced by fluorine-centered halogen bonds are significant in both linear FCN and FNC clusters. CCSD(T)/6-311++G** calculations reveal that for (FCN)_2–7 clusters, the average halogen-bonding energy per monomer increases from ?0.76 kcal/mol in dimer to ?0.92 kcal/mol in heptamer. The results of electron density analysis suggest that the capacity of the linear FCN and FNC clusters to concentrate electrons at the F···N and F···C BCPs enhance considerably with cluster size. The results also indicate that the magnitude of cooperative effects is more important for FCN than for FNC clusters. According to energy decomposition analysis, attractive electrostatic and dispersion components make the major contribution to the F···N and F···C halogen bond interactions. An acceptable correlation is found between different energy terms and total interaction energies, revealing the main role of these interactions for stability of linear (FCN) _n and (FNC) _n clusters.     

Comparative High-Performance Liquid Chromatographic and High-Performance Thin-Layer Chromatographic Study for the Simultaneous Determination of Dapagliflozin and Metformin Hydrochloride in Bulk and Pharmaceutical Formulation

JPC – Journal of Planar Chromatography – Modern TLC - The discovery of potent antidiabetic drugs is of necessity owing to the rapid prevalence of diabetes worldwide. The investigation...     

Improved Method for the Total Synthesis of Azaperone and Investigation of Its Electrochemical Behavior in Aqueous Solution

Azaperone, with anti-anxiety and anti-aggressive activities used in veterinary medicine, is a member of the butyrophenone class. It is ordinarily utilized for a wide range of indications, such as sedation, obstetrics, and anesthesia. In this research, an improved synthetic route is presented for azaperone using a phase-transfer catalyst(PTC). In general, it was synthesized as a dopamine antagonist in four steps. The bis(2-chloroethyl) amine intermediate is easily obtained after the conversion of the alcohol groups into the chloride leaving group using thionyl chloride(95% yields). The alkylation of commercially available 2-amino pyridine in the presence of PTC was then carried out, giving 1-(pyridin-2-yl) piperazine with 75% yield. 1-(Pyridin-2-yl) piperazine was finally alkylated using 4-chloro-1-(4-fluorophenyl) butan-1-one to achieve azaperone with 60% yield. The butyrophenone intermediate was obtained via the Friedel-Crafts reaction of fluorobenzene with 4-chlorobutyryl chloride in the presence of AlCl₃. High efficiency, gentle reaction conditions, and fast and simple procedure are the advantages of this method. Also, the electrochemical oxidation behaviour of azaperone was investigated using cyclic and differential pulse voltammetry techniques. Cyclic voltammetric studies indicated an irreversible process for azaperone electro-oxidation with a peak potential of 0.78 V in a phosphate buffer solution(pH=7.0) vs. Ag/AgCl(saturated KCl) electrode. The value of the peak current vs. the azaperone concentration was enhanced linearly in the range of 10―70 μmol/L, and the detection limit was found to be 3.33 μmol/L.     

Graphene and Carbon Nanotube-based Electrochemical Sensing Platforms for Dopamine

Dopamine (DA) is an important neurotransmitter, which is created and released from the central nervous system. It plays a crucial role in human activities, like cognition, emotions, and response to anything. Maladjustment of DA in human blood serum results in different neural diseases, like Parkinson's and Schizophrenia. Consequently, researchers have started working on DA detection in blood serum, which is undoubtedly a hot research area. Electrochemical sensing techniques are more promising to detect DA in real samples. However, utilizing conventional electrodes for selective determination of DA encounters numerous problems due to the coexistence of other materials, such as uric acid and ascorbic acid, which have an oxidation potential close to DA. To overcome such problems, researchers have put their focus on the modification of bare electrodes. The aim of this review is to present recent advances in modifications of most used bare electrodes with carbonaceous materials, especially graphene, its derivatives, and carbon nanotubes, for electrochemical detection of DA. A brief discussion about the mechanistic phenomena at the electrode interface has also been included in this review.     

A novel method for non-destructive Compton scatter imaging based on the genetic algorithm

Compton scattering tomography is widely used in numerous applications such as biomedical imaging, nondestructive industrial testing and environmental survey, etc. This paper proposes the use of the genetic algorithm (GA), which utilizes bio-inspired mathematical models, to construct an image of the insides of a test object via the scattered photons, from a voxel within the object. A NaI(Tl) scintillation detector and a 185 MBq ¹³⁷Cs gamma ray source were used in the experimental measurements. The obtained results show that the proposed GA based method performs well in constructing images of objects.