A comparative study of the thermodynamic properties at the air–water interface and in the bulk of structurally related phenothiazine drugs aqueous solutions

Surface tension, conductivity, density, and ultrasound velocity measurements have been performed in order to determine in a systematic manner some of the aggregation properties of the phenothiazine drugs promazine and triflupromazine hydrochlorides. Both drugs are structurally related, differing in an extra CF₃ group in the triflupromazine molecular structure. Surface tension data showed that the presence of an extra CF₃ in the molecular structure of triflupromazine involves a higher hydrophobicity of this drug and a restriction in the number of conformations molecules can adopt due to the presence of this bulkier atomic group. This involves a larger surface area in order to accommodate triflupromazine molecules at the interface. From conductivity measurements at different temperatures, the thermodynamic quantities of the micellization process of these drugs indicate that the aggregation is a spontaneous process, mainly enthalpic, where the London-dispersion forces play an active role. Using density and ultrasound velocity measurements, apparent molar volume and adiabatic compressibility of aqueous solutions of the amphiphilic cationic drugs have been determined. Positive deviations from the Debye–Hückel limiting law of the apparent molar volume were obtained from both drugs over the whole temperature range, which provides evidence of possible pre-association at concentrations below the critical concentration. Apparent molar adiabatic compressibility of the aggregates formed by these drugs was typical of those corresponding for an aggregate formed by a stacking process.     

Synthesis of bicyclo[2.2.2]octane-2,3,5,6,7,8 hexols (Bishomoinositols) as glycosidase inhibitors

For the construction of the bicyclo[2.2.2]octane skeleton, 2,2-dimethyl-3a,7a-dihydro-1,3-benzodioxole was reacted with vinylene carbonate to give two isomeric cycloadditon products having the bicyclo[2.2.2]octane skeleton. Hydrolysis of the ketal ring and the opening of the carbonate functionality, followed by hydroxylation of the remaining double bond resulted in the formation of a symmetrical hexol. Epoxidation of the double bond in the cycloaddition products and the subsequent ring-opening reactions produce two additional hexol derivatives. One of the synthesized molecules exhibited enzyme-specific inhibition against alpha-glycosidase.     

Synthesis,characterization, DNA binding,antibacterial, and antioxidant activity of new bis-phthalimides

New bis-phthalimides were synthesized by 2: 1 condensation of phthalic anhydride and tetrachlorophthalic anhydride with 1,2,4-triazole-3,5-diamine, pyridine-2,6-diamine, and 4-hydroxypyrimidine- 2,6-diamine. The synthesized compounds were characterized by elemental analyses and IR, ¹H NMR, and mass spectra. Their interaction with calf thymus DNA (ct-DNA) was studied by UV-Vis spectrophotometry, cyclic voltammetry, and viscosity measurements, which revealed intercalative mode of binding to ct-DNA. Antibacterial activity of the synthesized compounds against Escherichia coli and Streptococcus mutans was assessed in vitro by the agar well diffusion method. The antioxidant activity of these compounds was estimated by DPPH assay.     

Influence of the chelate ligand structure on the amide methanolysis reactivity of mononuclear zinc complexes

Zinc complexes of three new amide-appended ligands have been prepared and isolated. These complexes, [(dpppa)Zn](ClO4)2 (4(ClO4)2; dpppa = N-((N,N-diethylamino)ethyl)-N-((6-pivaloylamido-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine), [(bdppa)Zn](ClO4)2 (6(ClO4)2; bdppa = N,N-bis((N,N-diethylamino)ethyl)-N-((6-pivaloylamido-2-pyridyl)methyl)amine), and [(epppa)Zn](ClO4)2 (8(ClO4)2; epppa = N-((2-ethylthio)ethyl)-N-((6-pivaloylamido-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine), have been characterized by X-ray crystallography (4(ClO4)2 and 8(ClO4)2), 1H and 13C NMR, IR, and elemental analysis. Treatment of 4(ClO4)2 or 8(ClO4)2 with 1 equiv of Me4NOH.5H2O in methanol-acetonitrile (5:3) results in amide methanolysis, as determined by the recovery of primary amine-appended forms of the chelate ligand following removal of the zinc ion. These reactions proceed via the initial formation of a deprotonated amide intermediate ([(dpppa-)Zn]ClO4 (5) and [(epppa-)Zn]ClO4 (9)) which in each case has been isolated and characterized (1H and 13C NMR, IR, elemental analysis). Treatment of 6(ClO4)2 with Me4NOH.5H2O in methanol-acetonitrile results in the formation of a deprotonated amide complex, [(bdppa-)Zn]ClO4 (7), which was isolated and characterized. This complex does not undergo amide methanolysis after prolonged heating in a methanol-acetonitrile mixture. Kinetic studies and construction of Eyring plots for the amide methanolysis reactions of 4(ClO4)2 and 8(ClO4)2 yielded thermodynamic parameters that provide a rationale for the relative rates of the amide methanolysis reactions. Overall, we propose that the mechanistic pathway for these amide methanolysis reactions involves reaction of the deprotonated amide complex with methanol to produce a zinc methoxide species, the reactivity of which depends, at least in part, on the steric hindrance imparted by the supporting chelate ligand. Amide methanolysis involving a zinc complex supported by a N2S2 donor chelate ligand (3(ClO4)2) is more complicated, as in addition to the formation of a deprotonated amide intermediate free chelate ligand is present in the reaction mixture.     

Control of light in a quantized four level graphene atomic system via self and cross-Kerr nonlinearity

We investigate self and cross-Kerr nonlinearity in a four level quantized graphene atomic medium. The absorption, dispersion, transmission and subluminal/superluminal behaviors of a probe light field are studied. An amplification of the probe light field is observed in the absorption spectrum. The normal and anomalous slope of dispersion is also investigated at the positive/negative absorption region. It is shown that Kerr nonlinearity invert and enhance the subluminal/superluminal behaviors of the pulse and self-Kerr effect is found to be more subluminal/superluminal as compared to cross-Kerr effect. The results show significant applications in information storage, self and cross phase modulation and lasing without inversion.     

Analysis and use of fragment-occurrence data in similarity-based virtual screening

Current systems for similarity-based virtual screening use similarity measures in which all the fragments in a fingerprint contribute equally to the calculation of structural similarity. This paper discusses the weighting of fragments on the basis of their frequencies of occurrence in molecules. Extensive experiments with sets of active molecules from the MDL Drug Data Report and the World of Molecular Bioactivity databases, using fingerprints encoding Tripos holograms, Pipeline Pilot ECFC_4 circular substructures and Sunset Molecular keys, demonstrate clearly that frequency-based screening is generally more effective than conventional, unweighted screening. The results suggest that standardising the raw occurrence frequencies by taking the square root of the frequencies will maximise the effectiveness of virtual screening. An upper-bound analysis shows the complex interactions that can take place between representations, weighting schemes and similarity coefficients when similarity measures are computed, and provides a rationalisation of the relative performance of the various weighting schemes.     

On k-uniformly close-to-convex functions of complex order

In this paper, we define and study some subclasses of analytic functions by using fractional derivative operator. Some interesting properties, coefficients problems and inclusion results of these classes are investigated. It is also shown that these classes are closed under convolution with convex functions and some applications are given.