A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery.     

Amount of sterols and triterpenoids in leaves and petioles of leaf-shedding and standard lines of cotton plant

The amount of free and bound sterols and triterpenoids in the leaf blades and petioles of the variety Tashkent-1 and the deciduous lines L-275 and L-470 in the budding-flowering, maturing, and leaf-fall phases have been compared. In the leaf blades, the maximum accumulation of free sterols in the deciduous lines is observed in an earlier phase than in the variety Tashkent-1, and this is most characteristic for sterols saturated in the C-17 side chain. The dynamics of the change in the content of unsaturated sterols is individual for each line. The nature of the change in the amount of free sterols in the petioles is typical for each line and does not depend on the nature of the sterol for the variety Tashkent-1 this index falls sharply in the leaf-fall phase while for L-275 the process is retarded between the second and third phases, and for L-470 in the same period the amount of these substances rises sharply. In the leaf blades, as a rule, the level of sterol esters changes in parallel with the levels of free sterols, and in the petioles in the antiparallel direction between the first and second phases. In all the samples free and bound amyrin was detected. The dynamics of the change in the amounts of these substances in the three lines were different. Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Institute of Experimental Plant Biology, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Vol. 6, pp. 796–805, November–December, 1989.     

Synthesis and structure of 6-bromo-4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline and its mixed crystal with 4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline

Bromination of the alkaloid 2,3-tetramethylene-3,4-dihydroquinazoline by N-bromosuccinimide was studied. It was shown that either 4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline or 6-bromo-4-hydroxy-2,3tetramethylene-3,4-dihydroquinazoline was formed depending on the ratio of reagents. Oxidation of 2,3tetramethylene-3,4-dihydroquinazoline by KMnO₄ produced 4-hydroxy-2,3-tetramethylene-3,4dihydroquinazoline. The crystal structures of 6-bromo-4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline and its mixed crystal with 4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline were studied by x-ray structure analysis. The enantiomeric molecules in all crystal structures formed associates owing to two opposing OH...N1 H-bonds.     

Quinazolines. 3*. synthesis of 6-bromo-8-chloro-sulfonylquinazoline-2,4(1h,3h)-dione and its interaction with nucleophilic reagents

6-Bromo-8-chlorosulfonylquinazoline-2,4(1H,3H)-dione was obtained from 6-bromoquinazoline-2,4(1H,3H)-dione and chlorosulfonic acid in place of the expected 6-bromo-7-chlorosulfonyl-quinazoline-2,4(1H,3H)-dione. Interaction of the product with water, alcohols, ammonia, aliphatic and heterocyclic amines gave 6-bromo-8X-quinazoline-2,4(1H,3H)-diones (X = SO₂OH, SO₂OAlk, SO₂NR¹R²), and, by reduction with SnCl₂·2H₂O in hydrochloric acid, 6-bromo-8-mercaptoquinazoline-2,4-dione was obtained.     

Formylation of deoxyvasicinone by alkylformates: synthesis and reaction of <Emphasis Type=Italic>α</Emphasis>-hydroxymethylidenedeoxyvasicinone with isomeric aminophenols and aminobenzoic acids

A new method for formylation of deoxyvasicinone (DOV) was developed. Nucleophilic substitution of α-hydroxy- and -dimethylaminomethylidene-DOV by isomeric aminophenols and benzoic acids to give α-arylaminomethylidene-DOV was studied.     

Quinazolines 1. Synthesis and chemical reactions of 6-chlorosulfonyl-quinazoline-2,4-diones

Treatment of quinazoline-2,4-dione and its symmetrical 1,3-dialkyl derivatives with chlorosulfonic acid gave the corresponding 6-chlorosulfonylquinazoline-2,4-diones. Reaction of the compounds obtained with nucleophilic agents (water, ammonia, aliphatic and cyclic amines) gave the corresponding free 2,4-dioxoquinazoline-6-sulfonic acids, 6-sulfamidoquinazoline-2,4-diones, and 2,4-dioxoquinazoline-6-sulfonic acid amides. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 420–427, March 2008.     

Effect of spatial heterogeneity on level of rejuvenation in Ni80P20 metallic glass

Understanding the relation between spatial heterogeneity and structural rejuvenation is one of the hottest topics in the field of metallic glasses (MGs). In this work, molecular dynamics (MD) simulation is implemented to discover the effects of initial spatial heterogeneity on the level of rejuvenation in the Ni$_{80}$P$_{20 }$MGs. For this purpose, the samples are prepared with cooling rates of $10^{10}$ K/s-$10^{12}$ K/s to make glassy alloys with different atomic configurations. Firstly, it is found that the increase in the cooling rate leads the Gaussian-type shear modulus distribution to widen, indicating the aggregations in both elastically soft and hard regions. After the primary evaluations, the elastostatic loading is also used to transform structural rejuvenation into the atomic configurations. The results indicate that the sample with intermediate structural heterogeneity prepared with 10$^{11}$ K/s exhibits the maximum structural rejuvenation which is due to the fact that the atomic configuration in an intermediate structure contains more potential sites for generating the maximum atomic rearrangement and loosely packed regions under an external excitation. The features of atomic rearrangement and structural changes under the rejuvenation process are discussed in detail.     

Benzazoles. 3*. Synthesis and arylsulfonylation of 2-substituted benzimidazoles

2-Alkylbenzimidazoles have been obtained from o-nitroaniline and aliphatic carboxylic acids by reductive cyclization. Interaction of the former with arenesulfonyl chlorides led to the synthesis of 2-alkyl-1-arylsulfonylbenzimidazoles, the yield of which depended on the structure of the substituent in position 2.     

Reactions of Quinazoline Alkaloids and their Derivatives with Electrophilic Reagents

Nitration of deoxypeganine (DOP), deoxyvasicinone (DOV), 2,3-tetramethylene-, 2,3-pentamethylene-, and 3,4-dihydroquinazol-4-ones and their 1,2-dihydro derivatives was studied. It was shown that the reaction pathway changed depending on the presence of a carbonyl on C-4 and an N=C bond in these compounds. Only the H atom on C-6 was subject to nitration if both functional groups were present, for example DOV and its homologs. Substitution of the H atom of either the 6-position (DOP, 1,2-dihydro-DOV, and their homologs) or the 6- and 8-positions simultaneously (DOP and its homologs) was enhanced if one of these functional groups was missing depending on the substrate:nitrating agent ratio. The bromination and nitration reactions of 1,2-dihydro-DOV and its analogs in a 1:2 ratio were accompanied by oxidation of the N¹H-CH bond with formation of 6,8-dibromo- and 6,8-nitro-DOV and their homologs. The difference in the behavior of these compounds was due to the different nucleophilicity of the benzene rings in them. The reaction of 1,2-dihydro-DOV and its homologs with isocyanates and p-nitro- and p-methylbenzoic acid chlorides was studied. 6-Nitro- and 6,8-dinitro-DOP and 6,8-dibromo- and 6,8-dinitro-DOV and their homologs and 6-bromo- and 6-nitro-1,2,3,4-tetrahydro-2,3-polymethylenequinazol-4-ones and their 1-alkyl(aryl)-carbamoyl and p-nitro(methyl)-benzoyl derivatives were synthesized. The molecular structures of 1-ethyl-and 1-(o-chlorophenyl)-carbamoyl-1,2-dihydrodeoxyvasicinones and 6,8-dinitro-2,3pentamethylene-3,4-dihydroquinazol-4-one were established. UDC 547.944/945 547.856.1 Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 387-393, July-August, 2008. Original article submitted May 5, 2008.     

Synthesis of bicyclic analogues of deoxyvasicinone

6-Methyl-2,3-tri-, -tetra-, and -pentamethylene-3,4-dihydropyrimidin-4-ones and 6-phenyl-2,3-tri-3,4-dihydropyrimidin-4-one (bicyclic analogues of deoxyvasicinone) have been synthesized by the condensation of ethyl esters of -aminocrotonic and -aminocinnamic acids with lactams. It has been shown that the occurrence of the reaction and yields of the products of the condensation of ethyl -aminocrotonate with lactams depend both on the number of methylene groups in the lactams and also on the reaction conditions. With an increase in the number of methylene groups of the lactams the yields of condensation products decrease.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. A. Navoi Samarkand State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 394–396, May–June, 1991.