Controlled radical polymerization of anthracene‐containing methacrylate copolymers for stimuli‐responsive materials

Novel reversible networks utilizing photodimerization of crosslinkable anthracene groups and thermal dissociation were investigated. Reversible addition‐fragmentation chain transfer polymerization yielded well‐defined copolymers with 9‐anthrylmethyl methacrylate (AMMA) and other alkyl methacrylates such as methyl methacrylate (MMA) and 2‐ethylhexyl methacrylate (EHMA) having different AMMA compositions. Well‐controlled block copolymerization of AMMA and alkyl methacrylates was also successfully accomplished using a trithiocarbonate‐terminated poly(alkyl methacrylate) macro‐chain transfer agent. The anthracene‐containing copolymers showed reversibility via crosslinking based on photodimerization with ultraviolet irradiation and subsequent thermal dissociation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2302–2311     

White Light Emissive DyIII Single‐Molecule Magnets Sensitized by Diamagnetic [CoIII(CN)6]3− Linkers

The self‐assembly of Dy^III–3‐hydroxypyridine (3‐OHpy) complexes with hexacyanidocobaltate(III) anions in water produces cyanido‐bridged {[Dy^III(3‐OHpy)₂(H₂O)₄] [Co^III(CN)₆]}?H₂O ( 1 ) chains. They reveal a single‐molecule magnet (SMM) behavior with a large zero direct current (dc) field energy barrier, ΔE=266(12) cm^?1 (≈385 K), originating from the single‐ion property of eight‐coordinated Dy^III of an elongated dodecahedral geometry, which are embedded with diamagnetic [Co^III(CN)₆]^3? ions into zig‐zag coordination chains. The SMM character is enhanced by the external dc magnetic field, which results in the ΔE of 320(23) cm^?1 (≈460 K) at H_dc=1 kOe, and the opening of a butterfly hysteresis loop below 6 K. Complex 1 exhibits white Dy^III‐based emission realized by energy transfer from Co^III and 3‐OHpy to Dy^III. Low temperature emission spectra were correlated with SMM property giving the estimation of the zero field ΔE. 1 is a unique example of bifunctional magneto‐luminescent material combining white emission and slow magnetic relaxation with a large energy barrier, both controlled by rich structural and electronic interplay between Dy^III, 3‐OHpy, and [Co^III(CN)₆]^3?.     

Synthesis of bi-fluorescence-labeled lactoside: A substrate for continual assay of ceramide glycanase

A bi-fluorescence labeled derivative suitable for analysis of ceramide glycanase activity was constructed from 4-pentenyl lactoside. Selective modification of the galactosyl residue was attained by formation of 4′,6′-naphthylmethylidene derivative, which was followed by regioselective reductive ring opening. The aglycon was extended by Michael addition of 2-aminoethanetiol, and dansylated at the terminal amino group. Excitation of the naphthyl group results in emission from the dansyl group, while the emission from the naphthyl group is quenched by the dansyl group. Upon digestion with ceramide glycanase, the energy transfer is severed and a decrease in the dansyl emission concommitant with an increase in the naphthyl emission was observed. This substrate was successfully used to analyze ceramide glycanase activity.     

Fluorescence study of polyelectrolyte complex formation III: Mobility of probes in microdomains

The mobility of fluorescent probe molecules in the microdomains formed by polyelectrolyte complexes (PEC) in aqueous solution was investigated by the fluorescence polarization method. The degree of fluorescence polarization (p) for the anthracene (Anth) chromophores attached to anionic polyelectrolytes increased with complexation, indicating the restricted mobility of probe molecules in the PEC microdomains. These p values depended on the properties of added polycations, which were not in parallel with the fluorescence intensities of the Anth chromophores.     

Nudenoic acid: A novel tricyclic sesquiterpenoid from the Taiwanese liverwort Mylia nuda

Nudenoic acid, a new sesquiterpene possessing a novel tricyclic skeleton, was isolated from a Taiwanese liverwort Mylia nuda. The structure of nudenoic acid was determined by spectroscopic means and X-ray analysis.     

HRTEM study of new superconducting lead cuprate (Pb, Cu) (Eu, Ce)2(Eu, Sr)2Cu2Oz

Crystallographic properties of a new lead cuprate superconducting material (Pb, Cu) (Eu, Ce)₂(Eu, Sr)₂Cu₂O_z are examined by electron probe micro-analysis and transmission electron microscopy. It is confirmed that although the sample examined here is not of single-phase, the composition of the superconducting phase is close to the nominal composition. From TEM observations, it follows that the crystal structure of the new phase is similar to that of Tl-1222 which consists of a fluorite type block, a rock salt type layer and a perovskite block.