40052-63-9Relevant articles and documents
The synthetic tuning of clickable pH responsive cationic polypeptides and block copolypeptides
Engler, Amanda C.,Bonner, Daniel K.,Buss, Hilda G.,Cheung, Eva Y.,Hammond, Paula T.
, p. 5627 - 5637 (2011)
A series of pH responsive synthetic polypeptides has been developed based on an N-carboxyanhydride ring opening polymerization combined with a facile and versatile click chemistry. Poly(γ-propargyl l-glutamate) (PPLG) homopolymers and poly(ethylene glycol-b-γ-propargyl l-glutamate) (PEG-b-PPLG) block copolymers were substituted with various amine moieties that range in pKa and hydrophobicity, providing the basis for a library of new synthetic structures that can be tuned for specific interactions and responsive behaviors. These amine-functionalized polypeptides have the ability to change solubility, or reversibly self-assemble into micelles with changes in the degree of ionization; they also adopt an α-helical structure at biologically relevant pHs. Here we characterize the pH responsive behavior of the new polypeptides and the hydrolysis of the ester containing amine side chains. We examine the reversible micellization with block copolymers of the polypeptides and nucleic acid encapsulation that demonstrate the potential use of these materials for systemic drug and gene delivery.
Radical cage effects in the photochemical degradation of polymers: Effect of radical size and mass on the cage recombination efficiency of radical cage pairs generated photochemically from the (CpCH2CH 2N(CH3)C(O)(CH2)nCH 3)2Mo2(CO)6 (n = 3, 8, 18) complexes
Schutte, Erick,Weakley,Tyler, David R.
, p. 10319 - 10326 (2003)
This study explored the effect of radical size, chain length, and mass on the cage recombination efficiency of photochemically generated radical cage pairs. Radical cage pairs containing long-chain radicals of the type [(CpCH 2CH2N(CH3)C(O)(CH2) nCH3)(CO)3Mo?, ?Mo(CO)3(CpCH 2CH2(CH3)NC(O)(CH2) nCH3)] were generated in hexanes/squalane solution by photolysis (λ = 546 nm) of the Mo-Mo bonds in (CpCH2CH 2N-(CH3)C(O)(CH2)nCH 3)2Mo2(CO)6 (n = 3, 8, 18). The cage recombination efficiencies (denoted as FcP, where F cP = kcP/(kcp + kdP), k dP is the diffusion rate constant, and kcP is the radical recombination rate constant) for the radical cage pairs were obtained by extracting them from quantum yield measurements for the photoreactions with CCl4 (a metal-radical trap) as a function of solvent system viscosity. The results show that FcP increases as the length of the chain on a radical center increases. This finding likely provides at least one of the reasons why the quantum yields for photolytic polymer degradation (and long-chain molecules, in general) decrease as the polymer chains get longer. In quantitative terms, plots of kdP/kcP were linearly proportional to mass1/2/radius2, in agreement with the prediction of Noyes' cage effect theory. The "radius" of a long-chain radical, such as those studied herein, is rather vague, and for that reason a less ambiguous structural parameter was sought to replace the r2 term in the Noyes expression. Plots of kdP/kcP vs mass1/2/surface area suggest that surface area can be used in place of the radius2 term in the Noyes expression. The significance of being able to use a particle's surface area in the Noyes expression is that the expression becomes useful for nonspherical particles. The new expression allows the approximate prediction of FcP values for radicals of different sizes and masses.
A new water soluble copper N-heterocyclic carbene complex delivers mild O6G-selective RNA alkylation
Rasale, Dnyaneshwar,Patil, Kiran,Sauter, Basilius,Geigle, Stefanie,Zhanybekova, Saule,Gillingham, Dennis
supporting information, p. 9174 - 9177 (2018/08/23)
We show here that copper carbenes generated from diazo acetamides alkylate single RNAs, mRNAs, or pools of total transcriptome RNA, delivering exclusively alkylation at the O6 position in guanine (O6G). Although the reaction is effective with free copper some RNA fragmentation occurs, a problem we resolve by developing a novel water-stable copper N-heterocyclic carbene complex. Carboxymethyl adducts at O6G are known mutagenic lesions in DNA but their relevance in RNA biochemistry is unknown. As a case-in-point we re-examine an old controversy regarding whether O6G damage in RNA is susceptible to direct RNA repair.
Development of a chiral bis(guanidino)iminophosphorane as an uncharged organosuperbase for the enantioselective amination of ketones
Takeda, Tadahiro,Terada, Masahiro
supporting information, p. 15306 - 15309 (2013/11/06)
Chiral bis(guanidino)iminophosphoranes were designed and synthesized as chiral uncharged organosuperbase catalysts that facilitate activation of less-acidic pro-nucleophiles. The newly developed bis(guanidino) iminophosphoranes, which possess the highest basicity among chiral organocatalysts reported to date, were proven to be a superb class of chiral organosuperbases by reaction of azodicarboxylates with 2-alkyltetralones and their analogues as the less acidic pro-nucleophiles.
