UV-VIS spectroscopic study of interaction and transformation of allyl alcohol on zeolites HZSM-5

Formation of alkenylcarbenium ions has been proved during transformation of allyl alcohol on zeolite HZSM-5.

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HZSM-5.

     

Mass-spectrometric investigation of the photoionization of diphenylmercury

Theoretical and Experimental Chemistry -     

Manifestation of oxygen desorption in photoluminescence spectra of ZnO

The influence of oxygen desorption on the photoluminescence of zinc oxide has been investigated. Photodesorption and thermal desorption of oxygen have been controlled using mass spectrometry. It has been found that the removal of oxygen from the ZnO surface leads to a manifold increase in the exciton photoluminescence intensity. The process has a reversible character. The mechanism of increase in the exciton luminescence intensity of ZnO during the oxygen desorption has been discussed.     

Synthesis of 1-(4-butoxyphenyl)-1-cyclohexyl-3-(4-arylpiperazin-1-yl)-2-phenylpropan-1-ols and their dihydrochlorides

Aminomethylation of 1-(4-butoxyphenyl)-2-phenylethanone with paraformaldehyde and substituted piperazines in ethanol medium results in 1-(4-butoxyphenyl)-3-(4-R-piperazin-1-yl)-2-phenylpropan-1-ones. The latter react with cyclohexylmagnesium halide to give 1-(4-butoxyphenyl)-1-cyclohexyl-3-(4-arylpiperazin-1-yl)-2-phenylpropan-1-ols. Reduction of the prepared β-aminoketones with lithium aluminum hydride in absolute diethyl ether leads to the secondary aminopropanols. The prepared compounds could be converted into the corresponding dihydrochlorides.     

Synthesis and Neurotropic Activity of New Heterocyclic Systems: Pyridofuro[3,2-d]pyrrolo[1,2-a]pyrimidines,Pyridofuro[3,2-d]pyrido[1,2-a]pyrimidines and Pyridofuro[3′,2′:4,5]pyrimido[1,2-a]azepines

Background: Neurotic disturbances, anxiety, neurosis-like disorders, and stress situations are widespread. Benzodiazepine tranquillizers have been found to be among the most effective antianxiety drugs. The pharmacological action of benzodiazepines is due to their interaction with the supra-molecular membrane GABA-a-benzodiazepine receptor complex, linked to the Cl-ionophore. Benzodiazepines enhance GABA-ergic transmission and this has led to a study of the role of GABA in anxiety. The search for anxiolytics and anticonvulsive agents has involved glutamate-ergic, 5HT-ergic substances and neuropeptides. However, each of these well-known anxiolytics, anticonvulsants and cognition enhancers (nootropics) has repeatedly been reported to have many adverse side effects, therefore there is an urgent need to search for new drugs able to restore damaged cognitive functions without causing significant adverse reactions. Objective: Considering the relevance of epilepsy diffusion in the world, we have addressed our attention to the discovery of new drugs in this field Thus our aim is the synthesis and study of new compounds with antiepileptic (anticonvulsant) and not only, activity. Methods: For the synthesis of compounds classical organic methods were used and developed. For the evaluation of biological activity some anticonvulsant and psychotropic methods were used. Results: As a result of multistep reactions 26 new, five-membered heterocyclic systems were obtained. PASS prediction of anticonvulsant activity was performed for the whole set of the designed molecules and probability to be active Pa values were ranging from 0.275 to 0.43. The studied compounds exhibit protection against pentylenetetrazole (PTZ) seizures, anti-thiosemicarbazides effect as well as some psychotropic effect. The biological assays evidenced that some of the studied compounds showed a high anticonvulsant activity by antagonism with pentylenetetrazole. The toxicity of compounds is low and they do not induce muscle relaxation in the studied doses. According to the study of psychotropic activity it was found that the selected compounds have an activating behavior and anxiolytic effects on the models of “open field” and “elevated plus maze” (EPM). The data obtained indicate the anxiolytic (anti-anxiety) activity of the derivatives of pyrimidines, especially pronounced in compounds 6n, 6b, and 7c. The studied compounds increase the latent time of first immobilization on the model of “forced swimming” (FST) and exhibit some antidepressant effect similarly to diazepam. Docking studies revealed that compound 6k bound tightly in the active site of GABA_A receptor with a value of the scoring function that estimates free energy of binding (ΔG) at −7.95 kcal/mol, while compound 6n showed the best docking score and seems to be dual inhibitor of SERT transporter as well as 5-HT_1A receptor. Conclusions: Тhe selected compounds have an anticonvulsant, activating behavior and anxiolytic effects, at the same time exhibit some antidepressant effect.     

Metastable modifications in mercury diiodide nanocrystals

The formation of the HgI₂ crystalline phase in pores of various porous matrices and on their surfaces was studied. Based on the analysis of the evolution of the HgI₂ optical spectra and electron and atomicforce microscopy data, it was shown that the formation of microcrystals of the stable red α modification is preceded by the formation and growth of particles of metastable yellow (β′) and orange modifications. The absorption edge of the β′ phase at T = 77 K is formed by excitonic transitions with an energy of ～2.7 eV. The Raman spectra of the β′ phase were compared to the spectra of known metastable yellow modifications.     

1-Vinyl-3- and 1-vinyl-5-pyrazolecarboxylic acids. Synthesis and anti-burn activity of their chitosan salts

The synthesis of 1-vinyl-3- and 1-vinyl-5-pyrazolcarboxylic acids is developed and the anti burn activity of the chitosan salts of 1-vinyl-3(5)-carboxylic acids is studied.     

Effects of Grape Polyphenols on the Life Span and Neuroinflammatory Alterations Related to Neurodegenerative Parkinson Disease-Like Disturbances in Mice

Functional nutrition is a valuable supplementation to dietary therapy. Functional foods are enriched with biologically active substances. Plant polyphenols attract particular attention due to multiple beneficial properties attributed to their high antioxidant and other biological activities. We assessed the effect of grape polyphenols on the life span of C57BL/6 mice and on behavioral and neuroinflammatory alterations in a transgenic mouse model of Parkinson disease (PD) with overexpression of the A53T-mutant human α-synuclein. C57BL/6 mice were given a dietary supplement containing grape polyphenol concentrate (GPC—1.5 mL/kg/day) with drinking water from the age of 6–8 weeks for life. Transgenic PD mice received GPC beginning at the age of 10 weeks for four months. GPC significantly influenced the cumulative proportion of surviving and substantially augmented the average life span in mice. In the transgenic PD model, the grape polyphenol (GP) diet enhanced memory reconsolidation and diminished memory extinction in a passive avoidance test. Behavioral effects of GP treatment were accompanied by a decrease in α-synuclein accumulation in the frontal cortex and a reduction in the expression of neuroinflammatory markers (IBA1 and CD54) in the frontal cortex and hippocampus. Thus, a GP-rich diet is recommended as promising functional nutrition for aging people and patients with neurodegenerative disorders.     

Stepwise ionization of the 2,4-dioxybenzaldehyde and 3,4-dimethoxypropiophenone vapors

The processes of stepwise ionization of the 2,4-dioxybenzaldehyde and 3,4-dimethoxypropiophenone vapors by radiation in the range of wavelengths down to 266 nm were studied using total-current spectroscopy, mass spectrometry, and photoelectron spectroscopy. The process of two-step ionization and the resulting generation of molecular ions are dominant if the laser-radiation intensity amounts to ≈10⁶ W/cm². These molecular ions have appreciable (up to 1.8 eV) energy of vibrational excitation. As the laser-radiation intensity increases, progressively more pronounced fragmentation occurs owing to dissociation of molecular (and, possibly, fragmentation) ions as a result of absorption of at least a single additional photon. The processes leading to fragmentation of ions are suggested. It is found that the dissociation-ionization mechanism is important for the dimethoxypropiophenone. Dissociation with a breakage of the α bond in the carbonyl group with subsequent two-photon ionization of the fragments occurs when the S ₂(¹ A′) state of the ππ* type is excited.     

Relaxation spectra in polymers

Methods of determining the continuous and discrete relaxation spectra are analyzed with the object of choosing a characteristic describing the actual relaxation processes. It is shown that the discrete spectrum is a physically sounder characteristic and makes it possible to distinguish the most probable elementary relaxation processes. Problems of predicting the relaxation processes in real polymers can be simplified by using the discrete relaxation spectrum.Leningrad Branch, Scientific-Research Institute of the Rubber Industry. Translated from Mekhanika Polimerov, No. 1, pp. 151–154, January–February, 1973.