Synthesis of Main-Chain-Type Polyrotaxanes by New Click Polymerization Using Homoditopic Nitrile N-Oxides via Rotaxanation−Polymerization Protocol
Main-chain-type polyrotaxanes (9 and 12) and polyrotaxanes (10 and 13) were synthesized by a new click polymerization using unstable and stable homoditopic nitrile N-oxides according to rotaxanation and polymerization protocol. Rotaxane monomers were prepared from ethynyl-functionalized crown ether and sec-ammonium salt via the typical urethane end-capping protocol. The homoditopic nitrile N-oxide 8′ was generated in situ through the reaction of the corresponding hydroxamoyl chloride 8 with molecular sieves 4 Å. The click polymerization of diethynyl-functionalized rotaxane 5 and rotaxane monomer 7 with 8′ efficiently proceeded in the absence of a catalyst to afford well-defined polyrotaxanes 9 and 10 containing a polyisoxazole backbone in high yields. The polymerization of a newly developed kinetically stabilized homoditopic nitrile N-oxide 11 with rotaxane monomers yielded well-defined polyrotaxanes 12 and 13 in high yields under similar conditions. The structures of polyrotaxanes (9 and 1...
We recently generalized the formerly alignment-dependent multivariate image analysis applied to quantitative structure–activity relationships (MIA-QSAR) method through the application of the discrete Fourier transform (DFT), allowing for its application to noncongruent and structurally dive ... more
Poly-ADP-ribosylation (PARylation) is a protein posttranslational modification (PTM) that is critically involved in many biological processes that are linked to cell stress responses. It is catalyzed by a class of enzymes known as poly-ADP-ribose polymerases (PARPs). In particular, PARP1 is ... more
This review focuses on the type A cytochrome c oxidases (CcO), which are found in all mitochondria and also in several aerobic bacteria. CcO catalyzes the respiratory reduction of dioxygen (O2) to water by an intriguing mechanism, the details of which are fairly well understood today as a r ... more
Rohm and Haas Powder Coatings is delighted to announce that its Reading, Pennsylvania, facility is the first site in the world to receive the RCMS® Site Certification awarded by the American Chemical Council (ACC).
When Raj Gupta, Chairman and CEO of Rohm and Haas Company, became Chairman ... more