Photochemistry of N-(selenoalkyl)-phthalimides. Formation of N, Se-heterocyclic systems

A variety of N-(selenomethyl)alkyl-phthalimides (alkyl = -(CH2)n-; n = 2-5, 1a, b, d, e) and N-(selenobenzyl)propyl phthalimide (1c) were synthesized and their photochemistry was studied at λ = 300 nm. Steady-state photolysis and laser time-resolved spectroscopy studies confirmed that these reactions proceeded by direct or acetone-sensitized excitation followed by intramolecular electron transfer (ET) between Se atom and the phthalimide moiety. Two main pathways are possible after ET: proton transfer to the ketyl radical anion from the CH3Se+ or the -CH2Se+- moieties, yielding the corresponding biradicals. Collapse of these biradicals yields cyclization products with the respective endo or exo selenium-containing heterocycles. Competition between both proton transfer processes depends on the chain length of the alkyl spacer between the phthalimide and Se groups as well as the size of the cycle being formed.Fil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Heredia, Adrián Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Argüello, Juan Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Peñeñory, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Conformational modulation of sequence recognition in synthetic macromolecules

The different triplet sequences in high molecular weight aromatic copolyimides comprising pyromellitimide units ("I") flanked by either ether-ketone ("K") or ether-sulfone residues ("S") show different binding strengths for pyrene-based tweezer-molecules. Such molecules bind primarily to the diimide unit through complementary π-π-stacking and hydrogen bonding. However, as shown by the magnitudes of 1H NMR complexation shifts and tweezer-polymer binding constants, the triplet "SIS" binds tweezer-molecules more strongly than "KIS" which in turn bind such molecules more strongly than "KIK". Computational models for tweezer-polymer binding, together with single-crystal X-ray analyses of tweezer-complexes with macrocyclic ether-imides, reveal that the variations in binding strength between the different triplet sequences arise from the different conformational preferences of aromatic rings at diarylketone and diarylsulfone linkages. These preferences determine whether or not chain-folding and secondary π−π-stacking occurs between the arms of the tweezermolecule and the 4,4'-biphenylene units which flank the central diimide residue

Ciklički i makrociklički organski spojevi - pregledni rad posvećen Lavoslavu Ružički

Ružička opened the field of cyclic molecules such as cyclic terpenes and cyclic ketones with up to 17 ring atoms. This work until now was extended in many directions such as cyclic paraffins, crown ethers and cryptands and cyclic ester amides. Cyclic molecules are formed upon electron transfer and intramolecular association of polymers with two active ends and they are synthesized by directed cyclization of bifunctional macromolecules. In the course of step growth polymerization and ring opening polymerization, ring chain equilibria may be established; the larger the monomer unit the easier is the separation of pure oligomers such as the heptamer of cyclododecene with 84 carbon atoms in the ring. Still many questions remain open, in particular whether there are macrocyclic catenanes in commercial polycondensates.Ružička je otvorio polje cikličkih organskih molekula kao što su ciklički terpeni i ketoni s do 17 atoma u prstenu. U međuvremenu se proučavanje područja proširilo u brojnim smjerovima kao što su ciklički parafini, krunasti eteri i kriptandi te ciklički esterski amidi. Cikličke molekule nastaju prijenosom elektrona i intramolekulskim asocijacijama polimera s dvije aktivne krajnje skupine, a sintetiziraju se izravnom ciklizacijom difunkcionalnih makromolekula. Tijekom stupnjevitih reakcija polimerizacije i polimerizacija otvaranjem prstena može doći do uspostave ravnoteže prsten - lanac pri čemu, što je veća monomerna jedinica tim je lakše odvajanje oligomera kao što je heptamer ciklododekana s 84 ugljikova atoma u prstenu. Ipak, brojna pitanja ostaju otvorena kao što su postojanje makrocikličkih katenana u komercijalnim polikondenzatima

Ciklički i makrociklički organski spojevi - pregledni rad posvećen Lavoslavu Ružički

Ružička opened the field of cyclic molecules such as cyclic terpenes and cyclic ketones with up to 17 ring atoms. This work until now was extended in many directions such as cyclic paraffins, crown ethers and cryptands and cyclic ester amides. Cyclic molecules are formed upon electron transfer and intramolecular association of polymers with two active ends and they are synthesized by directed cyclization of bifunctional macromolecules. In the course of step growth polymerization and ring opening polymerization, ring chain equilibria may be established; the larger the monomer unit the easier is the separation of pure oligomers such as the heptamer of cyclododecene with 84 carbon atoms in the ring. Still many questions remain open, in particular whether there are macrocyclic catenanes in commercial polycondensates.Ružička je otvorio polje cikličkih organskih molekula kao što su ciklički terpeni i ketoni s do 17 atoma u prstenu. U međuvremenu se proučavanje područja proširilo u brojnim smjerovima kao što su ciklički parafini, krunasti eteri i kriptandi te ciklički esterski amidi. Cikličke molekule nastaju prijenosom elektrona i intramolekulskim asocijacijama polimera s dvije aktivne krajnje skupine, a sintetiziraju se izravnom ciklizacijom difunkcionalnih makromolekula. Tijekom stupnjevitih reakcija polimerizacije i polimerizacija otvaranjem prstena može doći do uspostave ravnoteže prsten - lanac pri čemu, što je veća monomerna jedinica tim je lakše odvajanje oligomera kao što je heptamer ciklododekana s 84 ugljikova atoma u prstenu. Ipak, brojna pitanja ostaju otvorena kao što su postojanje makrocikličkih katenana u komercijalnim polikondenzatima

Model studies on the synthesis of madangamine alkaloids. Assembly of the macrocyclic rings

Using simplified model derivatives, the assembly of the macrocyclic rings of madangamines, including the 13- and 14-membered D rings of madangamines C-E, the all-cis-triunsaturated 15-membered D ring of madangamine A, and the (Z,Z)-unsaturated 11-membered E ring common to madangamines A-E, has been studied

Linear and macrocyclic water soluble polyacylhydrazones and their utilisation in coatings

© 2018 Elsevier B.V. Water soluble polyacylhydrazones have been generated that contain a high proportion of renewable materials. The polyacylhydrazones were found to be present simultaneously as linear and macrocyclic species, the latter being favoured at higher concentrations and in certain combinations of levulinoyl ester/acyldihydrazide. Levulinoyl esters with multiple ketone reactive sites were targeted as building blocks for the backbone. Reaction of these species in aqueous media with commercially available acyldihydrazides afforded a series of high solids-content water soluble polyacylhydrazone solutions. Evaporation of the water from the solutions reproducibly generated films with differing and useful characteristics. One of the polyhydrazones was successfully formulated into two different types of resin bases of commercial coating systems, producing paint products with renewable content