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Showing 1 to 18 of 18 for “"biradical"”.
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Characterizing triplet azo biradical and corannulene- halogen complexes by laser flash photolysis
<p>In this work the laser flash photolysis technique has been used to study two photo-reaction systems: 1) the photolysis of aryl azides in solution and in solid-state 2) the photo-reaction of corannulene in halogenated solvents.</p><p>Singlet aryl nitrene was formed upon irradiation of aryl …
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PHOTOCHEMICAL HYDROXYLATION OF 1-METHYLANTHRAQUINONES: SYNTHESIS OF 9`-HYDROXYALOESAPONARIN II
… carbonyl. The hydrogen transfer results in a 1,x biradical which then undergoes a variety of reactions. One of these, oxidation of an alkyl substituent ortho to one of the carbonyls, was believed to go through formation of an endoperoxide. Photolysis of 1-methyl-9,10-anthraquinones using 419 nm …
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Synthesis of benzocarbazoles, indoloquinolines and indolonaphthridines from thermolysis of benzoenynyl ketenimines and carbodiimides
… undergo cycloaromatization through two competing biradical mechanisms under thermal conditions and therefore could serve as potential DNA cleaving agents. The resultant nitrogen-containing hetereocyclic compounds are also biologically interesting. The research described herein provides a easy …
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Mechanistic and synthetic studies of the intramolecular [4+2] cycloaddition of conjugated enynes
… by a stepwise annulation mechanism involving biradical intermediates. An investigation of the use of protic solvents has shown that alcohols, in particular 2,2,2-trifluoroethanol, can significantly improve the isolated yield of products. The application of strained cyclic acetylenes, …
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PHOTOLYSIS OF1-METHYL-9,10-ANTHRAQUINONE DERIVATIVES AND THEIR POTENTIAL REACTIVITY IN THE PHOTOENOL DIELS-ALDER REACTION
… density and the geometry of the intermediate 1,4-biradical (BR). Hydrogen bonding of the intermediate BR aids the intermolecular Diels-Alder reaction upon the formation of the photo induced diene by preventing conversion back to starting material. A series of hydroxy, methyl, and methoxy …
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Part 1: Progress Toward the Total Synthesis of Platensimycin. Part 2: Aromatic Ions: Carbon-Based Nucleofuges and Chiral Cyclopropenones and Formamides
… to use a thermal rearrangement, through a biradical intermediate, and then radical induced [3+2] cycloaddition between a vinyl cyclopropane and pendant olefin to create the core of platensimycin. A revised strategy was employed using a palladium(0) catalyzed Heck cascade and palladium(II) …
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The thermal degradation of polystyrene.
… results a mechanism is proposed involving biradical cage combination. The presence of weak links in thermally-initiated polystyrenes cannot be accounted for in terms of peroxidic links incorporated into the polymer chains. However such links do reduce the thermal stability of the polymer. …
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Design, synthesis, and characterization of conjugated polymers and functional paramagnetic materials for dynamic nuclear polarization
… and characterization of a series of radicals and biradicals for use as dynamic nuclear polarization (DNP) agents is described. DNP is a method to enhance the S/N-ratio in solid-state nuclear magnetic resonance (SS-NMR) that involves transferring the polarization of electrons, which are more easily …
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Synthesis of derivatives of 4H-cyclopenta[ def]phenanthren-4-one and development of synthetic strategies for the polycyclic aromatic hydrocarbons with carbon frameworks represented on the surface of C60
… benzoenyne-allene 58. Two cycles of a C2--C6 biradical cyclization reaction followed by a radical-radical coupling then afforded the formal [4+2] Diels-Alder cycloaddition adduct 60, which in turn underwent tautomerization to give 61. Reduction with tri-n-butyltin hydride then gave the ketal …
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Interplay of Spin and Photophysics in Luminescent Open-Shell Molecular Semiconductors
… 7, we extend these results to a luminescent biradical structure which supports a quintet (*S*=2) excited state. The light-induced cycling through this state drastically increases the strength of the exchange coupling between the two radical spins, and leads to a long-lived ground-state …
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Methodology investigations for the synthesis of biologically important nitrogen-containing heterocycles
… showcasing an oxidation, de-carboxylation and biradical coupling cascade, forging three C-C bonds in a single step, are also presented. The second half of chapter three expands on the first, further developing the methodology towards an open-air, dual catalytic Manganese-Cobalt/Copper system. …
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Exploring the Electronic Structure of Strongly Correlated Molecular Systems using Tensor Product Selected Configuration Interaction
… and interpretable TPSCI can be on an open-shell biradical transition bimetallic complex, in addition to, hexabenzocoronene that is not straightforward clustering due to the conjugated benzene rings. To alleviate the previous system size limitations, we recently implemented a Restricted Active …
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A STUDY OF THE ELECTRONIC PROPERTIES OF SOME HETEROCYCLIC COMPOUNDS AND THE THERMAL DECOMPOSITION OF METHYLATED THIOBUTYROLACTONES
… were probably formed from the cyclization of biradical precursors. However, the amounts of decomposition products generated from further fragmentation of these cyclic intermediates indicated that these compounds may be produced in small quantities.
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Synthetic Applications Of The Photochemical Cycloaddition Reactions Of N-acylindoles And Conformational Studies Of The Cycloadducts
… 0.32. It is concluded that the proportion of the biradical intermediates proceeding to the adducts for the CEI cycloaddition is circa 2% and that circa 98% go back to the starting materials. In contrast, with NBI 16% of the biradicals proceed to adduct and 84% revert to starting materials.;The …
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Synthesis of o-isotoluenes, o-quinodimethanes, and benzoenynyl carbodiimides and their cyclizations to polycyclic and heterocyclic compounds
… via a thermally-induced biradical-forming reaction. The Pd-catalyzed cross-coupling reaction between methyl 2-iodobenzoate and 1-alkynes furnished methyl 2-(1-alkynyl)benzoates, which were hydrolyzed to afford the corresponding benzoic acids. Treatment of the benzoic acids …
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Investigation of the quinone sites in reaction centers from Rhodobacter sphaeroides by pulsed EPR and spectral simulations
… mutants at chain M residue 265 and the QA-QB- biradical are presented. The concepts developed in the previous chapters are applied here to understand the effect of mutations and the presence of two semiquinones to the quinone site structure.
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Molecular origins of polymorphic phase transitions for dynamic organic electronics
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms
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Predictive chemical kinetics : enabling automatic mechanism generation and evaluation
… ab initio model of the reaction of the Criegee biradical CH 200 with small carbonyls that reproduces recent experimental results. Finally, the ideas and techniques of estimating reaction kinetics are brought together for the development of a detailed kinetics model of the oxidation of …