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1.
ABSTRACT Copolymers of 1,5-dioxepan-2-one (DXO) and e-caprolactone (?-CL), δ-valerolactone (δ-VL) or L-lactide (LLA) have been synthesized and characterized. High molecular weight copolymers were obtained using stannous-2-ethyl hexanoate as catalyst in bulk. Reactivity ratios for the copolymerization of DXO and δ-VL were determined at 110°C as rVL=0.5 and rDXO=2.3. At high conversion, depolymerization of δ-VL occurred, resulting in lower molecular weight and variations in the copolymer composition. Physical properties, such as crystallinity and melting temperature of the DXO-copolymers proved to be strongly dependent on the choice of comonomer and on the molar composition of the copolymers. DXO appears to be incorporated into the poly-?-caprolactone (PCL) crystals and to some extent into the poly-δ-valerolactone (PVL) crystals, resulting in a more gradual decrease in crystallinity with increasing amount of DXO. 相似文献
2.
Stevens K Claeys DD Catak S Figaroli S Hocek M Tromp JM Schürch S Van Speybroeck V Madder A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(25):6940-6953
Oligodeoxynucleotides incorporating a reactive functionality can cause irreversible cross-linking to the target sequence and have been widely studied for their potential in inhibition of gene expression or development of diagnostic probes for gene analysis. Reactive oligonucleotides further show potential in a supramolecular context for the construction of nanometer-sized DNA-based objects. Inspired by the cytochrome P450 catalyzed transformation of furan into a reactive enal species, we recently introduced a furan-oxidation-based methodology for cross-linking of nucleic acids. Previous experiments using a simple acyclic building block equipped with a furan moiety for incorporation into oligodeoxynucleotides have shown that cross-linking occurs in a very fast and efficient way and that substantial amounts of stable, site-selectively cross-linked species can be isolated. Given the destabilization of duplexes observed upon introduction of the initially designed furan-modified building block into DNA duplexes, we explore here the potential benefits of two new building blocks featuring an extended aromatic system and a restored cyclic backbone. Thorough experimental analysis of cross-linking reactions in a series of contexts, combined with theoretical calculations, permit structural characterization of the formed species and allow assessment of the origin of the enhanced cross-link selectivity. Our experiments clearly show that the modular nature of the furan-modified building blocks used in the current cross-linking strategy allow for fine tuning of both yield and selectivity of the interstrand cross-linking reaction. 相似文献
3.
Jawalekar AM Op de Beeck M van Delft FL Madder A 《Chemical communications (Cambridge, England)》2011,47(10):2796-2798
2'-O-(3-(Furan-2-yl)propyl)adenosine was synthesized and evaluated for interstrand crosslink (ICL) formation in DNA duplexes. In situ oxidation of the furan moiety with NIS showed rapid crosslink formation to dA and dC, while dT and dG were inactive. 相似文献
4.
The synthesis of nucleosides modified with an extra imidazole, carboxyl and hydroxyl group is described. These nucleosides can be incorporated into an oligonucleotide duplex, thus generating a novel type of serine protease mimic. 相似文献
5.
RD Harris WS Baker Van Stipdonk MJ RM Crooks EA Schweikert 《Rapid communications in mass spectrometry : RCM》1999,13(14):1374-1380
A suite of keV polyatomic or 'cluster' projectiles was used to bombard unoxidized and oxidized self-assembled monolayer surfaces. Negative secondary ion yields, collected at the limit of single ion impacts, were measured and compared for both molecular and fragment ions. In contrast to targets that are orders of magnitude thicker than the penetration range of the primary ions, secondary ion yields from polyatomic projectile impacts on self-assembled monolayers show little to no enhancement when compared with monatomic projectiles at the same velocity. This unusual trend is most likely due to the structural arrangement and bonding characteristics of the monolayer molecules with the Au(111). Copyright 1999 John Wiley & Sons, Ltd. 相似文献
6.
Strain promoted cycloaddition is presented as a tool for RNA conjugation on the solid phase; RNA-cyclooctyne conjugates are prepared by cycloaddition to both azide (strain-promoted azide-alkyne cycloaddition, SPAAC) and nitrile oxide dipoles (strain-promoted nitrile oxide-alkyne cycloaddition, SPNOAC). The conjugation is compatible with 2'-OMe blocks and with 2'-O-TBDMS protection on the ribose moieties of the sugar. Nitrile oxide dipoles are found to be more reactive click partners than azides. The conjugation proceeds within 10 min in aqueous solvents, at room temperature without any metal catalyst and tolerates dipoles of varying steric bulk and electronic demands, including pyrenyl, coumarin and dabcyl derivatives. 相似文献
7.
We herein describe the synthesis of furan containing peptides for further post-synthetic derivatisation in solution through our recently developed furan-oxidation-labeling technology. Previously, it was reported by others that during acidic cleavage of furan-modified peptides, furan moieties can suffer from degradation. We demonstrate here that this degradation is position dependent and can be fully suppressed through introduction of proximate aromatic residues. Versatile introduction of 2-furylalanine at internal, C-terminal as well as the sensitive N-terminal positions has now been proven possible. 相似文献
8.
A Mukherjee M Dasgupta DJ Hinde CR Morton AC Berriman RD Butt JO Newton H Timmers 《Pramana》2001,57(1):195-198
Fusion cross-sections for the 7Li + 12C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy
evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their
contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections
due to the breakup of 7Li may not be significant for 7Li + 12C reaction at energies around the barrier. 相似文献
9.
Ryan D Madder Chu-Young Kim Pooja P Chandra Jeffrey B Doyon Teaster A Baird Carol A Fierke David W Christianson Judith G Voet Ahamindra Jain 《The Journal of organic chemistry》2002,67(2):582-584
QSAR has been used to elucidate the origin of the hydrophobicity and binding affinity of a small library of fluoroaromatic inhibitors of F131V carbonic anhydrase II. Our analysis predicted the presence of a twisted amide conformation for several bound inhibitors, which we confirmed crystallographically. We also determined that the hydrophobicity of the inhibitors as a whole results from the fragment hydrophobicities of their fluorobenzyl rings, corrected for field effects and the presence of an intramolecular F.H contact in solution. The loss of this interaction on binding to the enzyme makes the affinity sensitive to the same terms, but with the opposite dependence on the F.H contact. In the case of the four inhibitors bound as twisted amides, this F.H contact must be retained to some extent in the bound state in order for their affinities to be consistent with our QSAR analysis of the entire set of 17 molecules. 相似文献
10.