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Introducing PeptoPlexes: Polylysine-block-Polysarcosine Based Polyplexes for Transfection of HEK 293T Cells
2014
A series of well-defined polypeptide-polypeptoid block copolymers based on the body's own amino acids sarcosine and lysine are prepared by ring opening polymerization of N-carboxyanhydrides. Block lengths were varied between 200-300 for the shielding polysarcosine block and 20-70 for the complexing polylysine block. Dispersity indexes ranged from 1.05 to 1.18. Polylysine is polymerized with benzyloxycarbonyl as well as trifluoroacetyl protecting groups at the ϵ-amine group and optimized deprotection protocols for both groups are reported. The obtained block ionomers are used to complex pDNA resulting in the formation of polyplexes (PeptoPlexes). The PeptoPlexes can be successfully applied i…
Synthesis and characterization of bisalkylated polysarcosine-based lipopolymers
2019
The use of PEGylated lipids for the synthesis of stealth liposomes and lipid formulations for nucleic acid delivery has promoted the development of nanoparticle based drugs for cancer therapy, and chronic diseases. Moreover, several other nanomedicines based on these materials have advanced into clinical trails. This enormous success, however, has recently been compromised by the occurrence of immune responses towards PEG, which render pharmacokinetics and can substantially reduce the therapeutic efficiency of drugs. Therefore, alternatives for PEGylated lipids with comparable or even identical solution properties are required. In this work, we report the synthesis of polysarcosine based li…
Selenoproteins, cholesterol-lowering drugs, and the consequences: revisiting of the mevalonate pathway.
2004
3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and peroxisome proliferator-activated receptor alpha activators (fibrates) are the backbone of pharmacologic hypercholesterolemia and dyslipidemia treatment. Many of their clinical effects, however, are still enigmatic. This article describes how a side road of the mevalonate pathway, characterized in recent years, can rationalize a major fraction of these unexplained observations. This side road is the enzymatic isopentenylation of selenocysteine-tRNA([Ser]Sec) (Sec-tRNA), the singular tRNA to decode the unusual amino acid selenocysteine. The functionally indispensable isopentenylation of Sec-tRNA requires a unique interm…
Thermal Rearrangements of Perchlorohexatrienes-Structures and Experimental and Theoretical Evaluation of Pathways to Isomerization and Cyclization
2009
We have prepared trans- (1) and cis-octachloro-1,3,5-hexatriene (2) by known routes and studied their thermal behavior experimentally and theoretically by ab initio calculations. The three double bonds in 1 and 2 are completely decoupled due to steric hindrance by the eight Cls, as indicated by calculations as well as the single-crystal X-ray structure of 1. The cis isomer 2 can be isomerized to the trans isomer 1 by heating it to 220–250 °C either neat or dissolved in high-boiling solvents, leading to a roughly 2:1 mixture of trans and cis isomers. Calculations at several different levels of theory predict 1 and 2 to be isoenergetic within 2 kJ mol–1. Unimolecular cis/trans isomerization i…
Rare earth metal complexes that contain linked amido-cyclopentadienyl ligands: ansa-metallocene mimics and “constrained geometry” catalysts
2003
A survey of group 3 metal complexes that contain a linked amido-cyclopentadienyl ligand is given. Originally designed as ansa-metallocene analogues for the development of single-component olefin polymerization catalysts, variations in the metals and ligand substituents have allowed the synthetic access to new rare earth metal complexes including olefin polymerization initiators, divalent complexes and heterobimetallic metallocenes. The linked amido-cyclopentadienyl ligands have made half-sandwich complexes of group 3 metals accessible in a more systematic manner and provided a better understanding of the electronic and steric constraints of chelating ligands for the larger rare earth metal …
ChemInform Abstract: Asymmetric Synthesis of Bicyclic Amino Acid Derivatives by Aza-Diels- Alder Reactions in Aqueous Solution.
2010
Derivatives 7–10 and 13–16 of methyl and ethyl 2-azabicyclo[2.2.1]heptane-3-carboxylates are synthesized by Aza-Diels-Alder reactions of chiral iminium ions, formed in situ from glyoxylic acid and chiral amines, with cyclopentadiene. Whereas the heterodienophiles derived from phenylglycinol and esters of sterically more demanding amino acids fail to undergo asymmetric cycloadditions, with alanine methyl ester and (R)-1-phenylethylamine hydrochoride the cycloadducts are formed in yields of 15 and 52%, respectively, reaching de values of up to 90:10 for the exo isomers.
Inhibitoren der Korrosion 10 (1). Nachweis der Sekundärinhibition durch Allyl-triphenyl-phosphonium- bzw. arsoniumbromid und N-Allyl-chinaldiniumbrom…
1971
Triphenyl-allyl-phosphonium- (1) und -arsoniumsalze (2) sowie Allyl-chinaldinium-bromid (4) sind Korrosionsinhibitoren mittlerer Wirksamkeit. Sie werden von Carbonyleisenpulver im sauren Medium zu Triphenylphosphin bzw. Triphenylarsin bzw. Chinaldin reduziert. Triphenylphosphin und Triphenylarsin, die sich als Schicht auf dem Carbonyleisenpulver befinden, konnen nach Extraktion dunnschichtchromatographisch identifiziert werden. Die Allylgruppe wird aus den Verbindungen 1, 2 und 4 durch Eisen als Propen, Propan und wahrscheinlich als Cyclopropan abgelost. Die gaschromatographisch bestimmten Mengen an Kohlenwasserstoffen stehen in guter Ubereinstim-mung mit den gravimetrisch ermittelten Werte…
Mono(cyclopentadienyl) Complexes of the Rare-Earth Metals
2002
I. Introduction 1953II. Overview of Synthesis, Structure, and Properties 1954A. Synthetic Methods 1954B. Ligands and Structures 1955III. Halo Complexes 1956A. General 1956B. Divalent Halo Complexes 1956C. Trivalent Halo Complexes 1957IV. Chalcogenido Complexes 1958A. General 1958B. Divalent Chalcogenido Complexes 1958C. Trivalent Chalcogenido Complexes 1959V. Pnicogenido Complexes 1960A. General 1960B. Divalent Amido and Phosphido Complexes 1960C. Trivalent Pnicogenido Complexes 19611. Bis(amido) Complexes 19612. Mixed Halo and Chalcogenido Complexes 1962VI. Hydrocarbyl and Silyl Complexes 1963A. General 1963B. Divalent Complexes 19631. Metallacarbaboranes 19632. Bimetallic Naphthalene Comp…
A theoretical determination of the electronic spectrum of Methylenecyclopropene
1996
The vertical electronic spectrum of methylenecyclopropene, the prototype of the nonalternant hydrocarbons known as fulvenes, has been studied using multiconfigurational second-order perturbation theory. The calculations comprise three valence states and the 3s, 3p, and 3d members of the Rydberg series converging to the first π ionization limit. Vertical excitation energies to three valence states are found at 4.13, 6.12, and 6.82 eV. The second of them corresponds to an excitation from the highest occupied σ orbital to a π* orbital, while the other two are π → π* excitations. The third transition gives rise to the most intense feature in the electronic spectrum. The results are rationalized…
Synthesis and activity of zirconocene catalysts supported on silica-type sol-gel carrier for ethylene polymerization
2001
Synthesis and activity of bis(cyclopentadienyl)zirconium dichloride catalyst supported on unconventional silica-type material obtained in sol-gel process and activated by organoaluminium co-catalyst were studied. The effect of support modification conditions (thermal dehydration and/or modification by organoaluminium compound) and a type of co-catalyst on an activity of the catalytic system in ethylene polymerization and properties of resulting polymers were investigated and compared with results obtained earlier for vanadium catalysts supported on mentioned sol-gel carrier. The most appropriate method of the sol-gel silica-type support preparation is thermal pre-treating (200°C) followed b…