Ultrasound assisted copolymerization of acrylonitrile with N-amino phenyl maleimides and N-amino phenyl 2,3 dimethyl maleimides

The N-amino phenyl maleimide (N-APhM) and N-amino phenyl 2,3 dimethyl maleimide (N-APhDiMeM) derivatives were prepared by the condensation of phenyl hydrazine with maleic anhydride and 2,3 dimethyl maleic anhydride respectively. (13)C NMR spectroscopy proved the formation of the symmetric amino maleimide structure and not the pyridazinone or aminoisomaleimides. The copolymerization of acrylonitrile with the (N-APhM) and (N-APhDiMeM) were prepared using ultrasound. The thermal behavior of the prepared copolymers, under nitrogen atmosphere, was investigated using thermogravimetry (TG) techniques. The dyeing of the copolymers formed has been studied using both conventional and ultrasonic techniques. The effect of dye bath pH, ultrasonic power, dyeing time and temperature were studied. Color strength values obtained were found to be higher using ultrasound than with conventional heating. The results of fastness properties of the dyed copolymers were also studied.     

Fourier 13C NMR and PMR including 13C satellites of oriented cyanopropyne

Fourier ¹³C and proton NMR spectra of cyanopropyne partially oriented by a nematic phase have been recorded and interpreted. It is shown that more accurate measurements are obtained much more rapidly by observing ¹³C satellites by Fourier PMR than by direct observation of the ¹³C spectrum. The geometry has been extracted from direct couplings; a small but systematic discrepancy with microwave spectroscopy is observed for the carboncarbon bond lengths.     

Selective functionalization of crown ethers via arene chromium tricarbonyl complexes

The crown ethers dibenzo-16-crown-4 and dibenzo-18-crown-5 and a diaryl polyether were complexed by the chromium tricarbonyl group for the purpose of selective functionalization. This complexation did indeed permit exclusive functionalization of the complexed ring. CHO and CH₂OH functionalities were introduced ortho to the ether group. It was noted that the nature of the two ether chains had a strong influence on the regioselectivity of the functionalization, which occurred preferentially on the side with the polyether chain. Photochemical decomplexation produced functionalized organic crown ethers.     

Enhanced alkaline protease production in addition to α-amylase via constructing a Bacillus subtilis strain

Bacillus subtilis Bios 11 strain was previously isolated and identified. This strain naturally produces a high level of α-amylase. The multicopy (pS1) plasmid that carries the complete alkaline protease aprA gene was introduced to this host strain by transformation. The newly constructed strain was found to express the aprA gene and produces a high level of alkaline protease. The level of α-amylase production was not affected compared with the parent strain. The pS1 plasmid in the new host was proved to be segregationally and structurally stable, and the multicopy aprA gene was expressed at the stationary phase. This expression did not affect growth rate and sporulation frequency. Moreover, the level of α-amylase was maintained. Both alkaline protease and α-amylase enzymes were purified using a single-step affinity chromatography column. The use of the newly constructed strain would be valuable to the enzyme industry and would promote recycling of some food-processing wastes.     

Ultrahigh resolution crystal structures of human carbonic anhydrases I and II complexed with "two-prong" inhibitors reveal the molecular basis of high affinity

The atomic-resolution crystal structures of human carbonic anhydrases I and II complexed with "two-prong" inhibitors are reported. Each inhibitor contains a benzenesulfonamide prong and a cupric iminodiacetate (IDA-Cu(2+)) prong separated by linkers of different lengths and compositions. The ionized NH(-) group of each benzenesulfonamide coordinates to the active site Zn(2+) ion; the IDA-Cu(2+) prong of the tightest-binding inhibitor, BR30, binds to H64 of CAII and H200 of CAI. This work provides the first evidence verifying the structural basis of nanomolar affinity measured for two-prong inhibitors targeting the carbonic anhydrases.     

Inhibition of matrix metalloproteinase-9 by "multi-prong" surface binding groups

A novel strategy of blocking the active site accessibility of MMP-9 by "multi-prong" surface binding groups is described.     

Thermal dimensional stability of isotropic polyoxymethylene

A parametric mapping analysis of the effect of various structural and morphological parameters on the thermal dimensional stability of polyoxymethylene is highlighted. The molecular composites model is found to describe adequately the expansional behavior of isotropic polyoxymethylene. The thermal expansivity is highly sensitive to the level of crystallinity followed by the transverse dimension of the crystallites. The longitudinal dimension of the crystallites, however, is not effective in altering the expansion behavior of isotropic polyoxymethylene. When comparing the model calculations with experimentally published data, an agreement of better than 15% is observed.     

Etude par RMN des 2,2′-Dihalogeno-Diethylethers—I: Effet de Température

NMR spectra of disubstituted ethers with the formula (X? CH₂? CH₂)₂O, X = Cl, Br, I, have been studied. Spectra of neat liquids at ambient temperature and spectra of these compounds in CS₂ at different temperatures have been analysed. It has been possible to assign the chemical shifts. In each case, the more populated rotamers have been determined. Additionally, for these three compounds dissolved in CS₂, it is shown that the gauche form becomes more stable with cooling. The authors propose a procedure, using spectral decomposition, which allows the analysis of AA′BB′spectra almost degenerated in A₂B₂ cases.     

Double Rotors with Fluxional Axles: Domino Rotation and Azide–Alkyne Huisgen Cycloaddition Catalysis

The simple preparation of the multicomponent devices [Cu₄( A )₂]⁴⁺ and [Cu₂( A )( B )]²⁺, both rotors with fluxional axles undergoing domino rotation, highlights the potential of self‐sorting. The concept of domino rotation requires the interconversion of axle and rotator, allowing the spatiotemporal decoupling of two degenerate exchange processes in [Cu₄( A )₂]⁴⁺ occurring at 142 kHz. Addition of two equiv of B to rotor [Cu₄( A )₂]⁴⁺ afforded the heteromeric two‐axle rotor [Cu₂( A )( B )]²⁺ with two distinct exchange processes (64.0 kHz and 0.55 Hz). The motion requiring a pyridine→zinc porphyrin bond cleavage is 1.2×10⁵ times faster than that operating via a terpyridine→[Cu(phenAr₂)]⁺ rupture. Finally, both rotors are catalysts due to their copper(I) content. The fast domino rotor (142 kHz) was shown to suppress product inhibition in the catalysis of the azide–alkyne Huisgen cycloaddition.