Solid-phase synthesis of 4-biaryl-piperidine-4-carboxamides

A novel solid-phase synthesis of 4-biaryl-piperidine-4-carboxamides has been developed using FDMP resin with a carboxamide as the anchor point. With this approach, three points of diversity were incorporated into a GPCR-directed scaffold. Final products were obtained in good purity and yield.     

CHEMOTHERAPEUTIC POLYMERS Ⅻ. SYNTHESIS AND ANTITUMOR ACTIVITY OF POLYAMIDES CONTAINING 5-FLUOROURACILS AS PENDANT GROUP

Six polyamides with pendant 5-fluorouracil group were synthesized by the polycondensation ofdi-p-nitrophenyl N-(5-fluorouracil-1-acetyl)glutamate with a series of polymethylene diamines.All of the new polyamides obtained are soluble in water. Their chemical structures were confirmedby ~1H NMR, UV and IR spectra as well as elemental analyses. The antitumor activity of some ofthese polyamides were tested against Ehrlich Ascites Carcinoma in mice, III_a showed an inhibitionrate of 43%.     

A polymer-based microfluidic device for immunosensing biochips

This paper describes the design, fabrication, and test of a PDMS/PMMA-laminated microfluidic device for an immunosensing biochip. A poly(dimethyl siloxane)(PDMS) top substrate molded by polymer casting and a poly(methyl methacrylate)(PMMA) bottom substrate fabricated by hot embossing are bonded with pressure and hermetically sealed. Two inlet ports and an air vent are opened through the PDMS top substrate, while gold electrodes for electrochemical biosensing are patterned onto the PMMA bottom substrate. The analyte sample is loaded from the sample inlet port to the detection chamber by capillary force, without any external intervening forces. For this and to control the time duration of sample fluid in each compartment of the device, including the inlet port, diffusion barrier, reaction chamber, flow-delay neck, and detection chamber, the fluid conduit has been designed with various geometries of channel width, depth, and shape. Especially, the fluid path has been designed so that the sample flow naturally stops after filling the detection chamber to allow sufficient time for biochemical reaction and subsequent washing steps. As model immunosensing tests for the microfluidic device, functionalizations of ferritin and biotin to the sensing surfaces on gold electrodes and their biospecific interactions with antiferritin antiserum and streptavidin have been investigated. An electrochemical detection method for immunosensing by biocatalyzed precipitation has been developed and applied for signal registration. With the biochip, the whole immunosensing processes could be completed within 30 min.     

A dimer of α‐ and β‐dihydro­arte­misinin: bis­(3,6,9‐trimethyl‐3,12‐epidioxy‐3,4,5,5a,6,7,8,8a,9,10‐deca­hydro‐12H‐pyrano[4,3‐j][1,2]­benzo­dioxepin‐10‐yl) ether

The title compound, C₃₀H₄₆O₉, prepared from a mixture of α‐ and β‐dihydro­artemisinin, has α‐ and β‐arteether moieties linked via an –O– bridge, so that the mol­ecule is asymmetric about the bridge. The endoperoxide bridges of the parent compounds have been retained in each half of the ether‐bridged dimer. The rings exhibit chair and twist–boat conformations.     

Palladium-catalyzed cascade reactions of benzyl halides with N-allyl-N-(2-butenyl)-p-toluenesulfonamide

Reaction of benzyl halides with N-allyl-N-(2-butenyl)-p-toluenesulfonamide 1 in the presence of a palladium catalyst afforded dihydropyrroles 3 in moderate to excellent yields. It is proposed that the cyclic products were formed via a palladium-catalyzed cascade cyclization-coupling process.     

A hierarchical assembly strategy for near-infrared photothermal conversion: unconventional heterogeneous metalla[2]catenanes

Herein, we report a hierarchical assembly strategy for constructing heterogeneous half-sandwich organometallic D–A (D = π-donor, A = π-acceptor) interlocked structures, and their application in near-infrared (NIR) photothermal conversion. Thienothiophene and diketopyrrolopyrrole groups were selected as the D and A units, leading to two homogeneous metalla[2]catenanes with D–D–D–D and A–A–A–A stacks, respectively. By the ordered secondary assembly of homogeneous metalla[2]catenanes, two unprecedented heterogeneous D–A metalla[2]catenanes comprising an unusual mixed D–A–D–D and unconventional D–A–A–A stacks were realized by the combination of multiple noncovalent interactions, as all demonstrated by a detailed X-ray crystallographic study. Benefiting from the mixed D–A stacking modes, NIR absorption of heterogeneous D–A metalla[2]catenanes is significantly enhanced in contrast to homogeneous metalla[2]catenanes. Thanks to the enhanced NIR absorption and the fluorescence quenching effect from half-sandwich organometallic fragments, heterogeneous D–A metalla[2]catenanes displayed high-performance NIR photothermal conversion properties (η = 27.3%).

Herein, we report a hierarchical assembly strategy for constructing heterogeneous half-sandwich organometallic D–A (D = π-donor, A = π-acceptor) interlocked structures, and their application in near-infrared (NIR) photothermal conversion.     

First principles study of the structure,electronic state,and stability of CmN2 clusters

Geometric and electronic properties of C_mN₂ (m = 1–14) clusters have been investigated by density functional theory using the hybrid B3LYP functional and the 6‐311G(d) basis set. Harmonic frequencies for these clusters are given to aid in the characterization of the ground states. These results show that C_mN₂ (m = 1–14) clusters form linear structures with D_∞h symmetry. Two N atoms favor to bond at ends in linear isomers. The chains with odd m have triplet ground states whereas the ones with even m have singlet ground states. The calculated HOMO–LUMO gaps and ionization potentials all show that the C_mN₂ (m = 1–14) clusters with even m are more stable than those with odd m, which is consistent with the observed even–odd alternation of the time‐of‐flight signal intensities. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Crosslinking polydopamine/cellulose nanofibril composite aerogels by metal coordination bonds for significantly improved thermal stability,flame resistance,and thermal insulation properties

Cellulose nanofibril (CNF) aerogels have attracted great interests in recent years due to the low cost, sustainability and biocompatibility of raw CNF. However, the poor thermal stability and flammable feature of CNF aerogels have limited their wider applications. In this paper, polydopamine/CNF composite aerogels with good comprehensive properties are fabricated by modification of CNF with polydopamine and metal coordination bonds crosslinking. The microstructure and properties of composite aerogels are thoroughly characterized by a variety of tests. It is found that the microstructure of aerogels are more regular and the compressive strength of aerogels are enhanced by the incorporation of polydopamine and Fe³⁺ crosslinking. Importantly, the thermal stability and flame resistance of aerogels are significantly improved, which permit the application of composite aerogels in high-temperature thermal insulation. In addition, the reversible characteristic of metal coordination bonds allows the water induced healing of fractured composite aerogels. This study is expected to provide information for future development of green and high-performance aerogels.

Graphic abstract

     

Synthesis and properties of polyketones containing thiophene links

A series of polyketones containing thiophene links was synthesized by the Friedel-Crafts polymerization of these dithienylalkanes with aromatic diacid chlorides or dicarbonyl chlorides comprising thiophene links with diphenyl compounds. The resulting polymers had inherent viscosities in the range of 0.11–0.27 dL/g and showed poor solubilities to common organic solvents except strong acids. These thiophene-based polyketones exhibited fairly good thermal stabilities. The TGA data revealed 5% weight losses at 375–450°C and residual weights at 500°C were 43–79% under nitorgen. It was found that the thermal stabilities of these polymers were superior to those of polymides or polysulfonamides containing thiophene links and almost comparable to common aromatic polyketones     

Chromatographic evaluation of poly (trans-1,2-cyclohexanediyl-bis acrylamide) as a chiral stationary phase for HPLC

Chiral stationary phases (CSPs) based on polymeric (R,R)- or (S,S)-1,2-diaminocyclohexane (DACH) derivatives are synthesized. When bonded to 5 microm porous spherical silica gel, the poly (trans-1,2-cyclohexanediyl-bis acrylamide) based poly-cyclic amine polymer (P-CAP) stationary phases is proved to be effective chiral stationary phases that could be used in the normal-phase mode, polar organic mode and with halogenated solvents mobile phases, if desired. Since these are entirely synthetic CSPs, the elution order of all enantiomers can be reversed between the (R,R) P-CAP and (S,S) P-CAP columns. Because of the high loading of chiral selectors, the columns exhibit very high sample capacities. Thus, P-CAP columns are useful for preparative and semi-preparative enantiomeric separations. The application of these CSPs and optimization of their separations are discussed.