Remarkable Change in Fluorescence Emission of Poly(diphenylacetylene) Film via in situ Desilylation Reaction: Correlation with Variations in Microporous Structure,Chain Conformation,and Lamellar Layer Distance

Fluorescence (FL) emission properties, microporous structures, energy‐minimized chain conformations, and lamellar layer structures of the silicon‐containing poly(diphenylacetylene) derivative of p‐PTMSDPA before and after desilylation were investigated. The nitrogen‐adsorption isotherms of p‐PTMSDPA film before and after desilylation were typical of type I, indicating microporous structures. The BET surface area and pore volume of the p‐PTMSDPA film were significantly reduced after the desilylation reaction, simultaneously, its FL emission intensity remarkably decreased. The theoretical calculation on both model compounds of p‐PTMSDPA and its desilylated polymer, PDPA, showed a remarkable difference in chain conformation: The side phenyl rings of p‐PTMSDPA are discontinuously arranged in a zig‐zag pattern, while the PDPA is continuously coiled in a helical manner. The lamellar layer distance (LLD) in the p‐PTMSDPA film significantly decreased after the desilylation reaction.

     

Integrated microfluidic device for the separation and electrochemical detection of catechol estrogen-derived DNA adducts

Catechol estrogen-derived DNA adducts are formed as a result of the reaction of catechol estrogen metabolites (e.g., catechol estrogen quinones) with DNA to form depurinating adducts. Developing a new methodology for the detection of various DNA adducts is essential for medical diagnostics, and to this end, we demonstrate the applicability of on-chip capillary electrophoresis with an integrated electrochemical system for the separation and amperometric detection of various catechol estrogen-derived DNA adducts. A hybrid PDMS/glass microchip with in-channel amperometric detection interfaced with in situ palladium decoupler is utilized and presented. The influence of buffer additives along with the effect of the separation voltage on the resolving power of the microchip is discussed. Calibration plots were constructed in the range 0.4–10 μM with r ² ≥ 0.999, and detection limits in the attomole range are reported. These results suggest that on-chip analysis is applicable for analyzing various DNA adducts as potential biomarkers for future medical diagnostics.     

REDUCTIVE DEIMINATION OF SULFOXIMIDES AND SULFIMIDES WITH P-TOLUENESULFONYL NITRITE AND T-BUTYL THIONITRATE1

Abstract

Reduction of sulfimides and sulfoximides with p-toluenesulfonyl nitrite, a new nitrosating agent, gave nearly quantitatively the corresponding deimination products, sulfides and sulfoxides, respectively. In the reaction of dialkyl and aryl alkyl sulfoximides with t-butyl thionitrate, N-t-butylthiosulfoximides were obtained besides the usual deimination products, although diaryl sulfoximides were readily deiminated to the corresponding sulfoxides in good yields in the same treatment. t-Butyl thionitrate was also found to deiminate diphenyl sulfimide to give diphenyl sulfide in good yield. Sulfoximides reacted sluggishly with t-butyl thionitrite, however, eventually affording a small amount of sulfoxides.     

9,9′‐spirobifluorene‐containing polycarbonates: Transparent polymers with high refractive index and low birefringence

Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl₃, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010     

Luminescent properties of phenylenediamine derivatives depending on the redox states

Phenylenediamines bearing the ethoxycarbonyl groups were synthesized to modulate luminescent properties. Switching of the luminescent properties was achieved by redox change between the phenylenediamine and quinonediimine derivatives.     

Photoinduced electron transfer processes of fullerene rotaxanes containing various electron-donors

The photosensitized electron-transfer processes in the rotaxane hybrids composed with electron-accepting fullerenes and various electron-donors placed in the rotaxanes are revealed with time-resolved fluorescence and absorption spectral methods. Porphyrins are most useful as light-harvesting donors and photosensitizing donors. In addition, aromatic amines and ferrocene act as electron-donor and also hole-shifting reagents in multi-component rotaxanes. In the rotaxanes with spatially placed donor-acceptor molecules, the role of triplet states becomes important compared with the covalently connected donor–acceptor molecular systems, which may be related to the “through-space” and “through-bond” electron transfer, respectively. In the designed multi-component rotaxanes which maintain mechanically or topologically the electron-acceptor, electron-donor, and hole-shifter, the photoinduced electron transfer, hole-shift, electron–hole recombination are established. As a whole, contribution of the triplet excited states is prominent compared with the covalently bonded molecules and supramolecular systems constructed with coordination bonds.     

Palladium(II)‐Catalyzed Dehydroboration via Generation of Boron Enolates

The Pd^II‐catalyzed dehydroboration of boron enolates generated from ketones and 9‐iodo‐9‐borabicyclo[3.3.1]nonane was achieved, providing a synthetically versatile protocol from ketones to α,β‐unsaturated ketones. The Pd^II compound employed in this reaction worked catalytically in the presence of Cu(OAc)₂. The high trans‐selectivity of the olefinic moiety was observed. Aryl halide moieties (‐Br and ‐Cl) remained intact for this reaction in spite of the presence of a Pd species. An ester substrate could also be applied when a stoichiometric amount of Pd^II was used. The crossover reactions using boron and silyl enolates revealed that the oxidation reaction is much faster than the Saegusa‐Ito reaction.     

Efficient Synthesis of Cyclic Block Copolymers by Rotaxane Protocol by Linear/Cyclic Topology Transformation

High‐yielding synthesis of cyclic block copolymer (CBC) using the rotaxane protocol by linear‐cyclic polymer topology transformation was first demonstrated. Initial complexation of OH‐terminated sec‐ammonium salt and a crown ether was followed by the successive living ring‐opening polymerizations of two lactones to a linear block copolymer having a rotaxane structure by the final capping of the propagation end. CBC was obtained in a high yield by an exploitation of the mechanical linkage through the translational movement of the rotaxane component to transform polymer structure from linear to cyclic. Furthermore, the change of the polymer topology was translated into a macroscopic change in crystallinity of the block copolymer.     

Synthesis and characterization of 9,9‐bis(4‐hydroxyphenyl and 4‐aminophenyl)dibenzofluorenes: Novel fluorene‐based monomers

Two novel 9,9‐difunctionalized fluorene‐type monomers, 9,9‐bis(4‐hydroxyphenyl‐ and 4‐aminophenyl)‐2,3:6,7‐dibenzofluorenes, are synthesized by the reaction of dibenzenzofluorenone with phenol and aniline. These monomers are used for the preparation of polyester and polyimide as the typical polymers to evaluate the property change such as thermal stability caused by the benzene rings fused to the fluorene skeleton with keeping good solubility, in comparison with the polymers derived from simple fluorenone. In fact, these two new polymers have the fairly enhanced thermal stability and refractive index value along with satisfactory solubility in organic solvents, enough to emphasize the fusion effect. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2602–2605     

New tridentate cyclometalated platinum(II) and palladium(II) complexes of N,2-diphenyl-8-quinolinamine: syntheses, crystal structures, and photophysical properties

A new tridentate cyclometalated platinum(II) complex derived from N,2-diphenyl-8-quinolinamine, which consists of two crystallographic independent molecules with two intermolecular N-H-Cl-Pt hydrogen bonds forming a dimer, exhibited a low-energy luminescence at ca. 740 nm in a 1 × 10⁻³ M dichloromethane solution and a strong emission centered at 670 nm in a solid state, but the analogous palladium(II) complex was nonemissive at room temperature.