Thiol‐ene clickable hyperscaffolds bearing peripheral allyl groups

Radical catalyzed thiol‐ene reaction has become a useful alternative to the Huisgen‐type click reaction as it helps to expand the variability in reaction conditions as well as the range of clickable entities. Thus, direct generation of hyperbranched polymers bearing peripheral allyl groups that could be clicked using a variety of functional thiols would be of immense value. A specifically designed AB₂ type monomer, that carries two allyl benzyl ethers groups and one alcohol functionality, was shown to undergo self‐condensation under acid‐catalyzed melt‐transetherification to yield a hyperbranched polyether that carries numerous allyl end‐groups. Importantly, it was shown that the kinetics of polymerization is not dramatically affected by the change of the ether unit from previously studied methyl benzyl ether to an allyl benzyl ether. The peripheral allyl groups were readily clicked quantitatively, using a variety of thiols, to generate an hydrocarbon‐soluble octadecyl‐derivative, amphiphilic systems using 2‐mercaptoethanol and chiral amino acid (N‐benzoyl cystine) derivatized hyperbranched structures; thus demonstrating the versatility of this novel class of clickable hyperscaffolds. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Patterned immobilization of biomolecules by using ion irradiation‐induced graft polymerization

A new method for biomolecular patterning based on ion irradiation‐induced graft polymerization was demonstrated in this study. Ion irradiation on a polymer surface resulted in the formation of active species, which was further used for surface‐initiated graft polymerization of acrylic acid. The results of the grafting study revealed that the surface graft polymerization using 20 vol % of acrylic acid on the poly(tetrafluoroethylene) (PTFE) film irradiated at the fluence of 1 × 10¹⁵ ions/cm² for 12 h was the optimum graft polymerization condition to achieve the maximum grafting degree. The results of the fluorescence microscopy also revealed that the optimum fluence to achieve the maximum fluorescence intensity was 1 × 10¹⁵ ions/cm². The grafting of acrylic acid on the PTFE surfaces was confirmed by a fluorescence labeling method. The grafted PTFE films were used for the immobilization of amine‐functionalized p‐DNA, followed by hybridization with fluorescently tagged c‐DNA. Biotin‐amine was also immobilized on the acrylic acid grafted PTFE surfaces. Successful biotin‐specific binding of streptavidin further confirmed the potential of this strategy for patterning of various biomolecules. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6124–6134, 2009     

Crystal structure of 4-(4'-diethylaminophenyl)-6-(4-methoxyphenyl)-(2-pyrrolidin-1-yl)-pyridine-3-carbonitrile.

4-(4'-Diethylaminophenyl)-6-(4-methoxyphenyl)-(2-pyrrolidin-1-yl)-pyridine-3-carbonitrile (DMPPC) was studied by X-ray diffraction methods due to its non-linear optical properties. The pyrrolidine and pyridine rings adopt half-chair and planar conformations, respectively. The molecules in the crystal are stabilized by C-H...O and C-H...N types of intermolecular interactions in addition to van der Waals forces.     

Refinement of the function for the evaluation of the N-H…O hydrogen bond potential energy

The parameters of the hydrogen bond potential energy function proposed earlier have been refined using the increased data available on N-H…O hydrogen bonds. The full-matrix least-square refinement procedure has been used and the discrepancy index has dropped down to a final value of 0 · 176. A linear interpolation has been proposed for the border regions where the hydrogen bonds are weak and the results are discussed.     

Generation of desired signals from acoustic drivers

A general but systematic procedure has been developed to control transient signal generation for the study of internal noise propagation from aircraft engines. Transform techniques are used in a simple algorithm to produce signals—pulses in this study—of any desired waveform from acoustic drivers. By a judicious input, the accurate driver response function is calculated. From the driver response function the limiting frequency characteristics are determined. The undesirable frequencies where the driver response is poor are eliminated from the analysis. The inverse of the response function is then convolved with the desired signal to produce a synthesized signal. The shape of the synthesized signal is in general quite awkward, in both the time and the frequency domain. Nevertheless, when the distorted signal is fed into the driver, the driver generates the desired signal. The driver is operated in two environments—in a free field and in a duct—and results are presented to show the impedance matching effect of the driver. A set of results with a high frequency cut-off value as a parameter is given to demonstrate the extent of the applicability of the synthesis procedure. The error in the numerical inversion is highlighted. The results show that, within the imposed guidelines, it is possible to generate desired signals through the signal synthesis procedure.     

Synthesis of 3 : 4 dihydro 2H-pyrano (2, 3-b) quinolines

The synthesis of 3 : 4 dihydro 2H-pyrano(2, 3-b) quinolines is described.     

Photochemical synthesis of 2-substituted benzothiazoles

The photochemical reaction of 1 -indolethiocarbanilides 1 , di- and tri-substituted thioureas 3–5 and 4,4 -di-methyl-2,6-dioxothiocyclohexanecarboxanilides 9 affording the respective benzothiazoles are described.     

Pressure dependence of the Grüneisen parameter of sodium and potassium

Temperature changes associated with adiabatic pressure changes (?T/?P)_s have been measured for sodium and potassium at room temperature (297 K) under hydrostatic pressures up to 32 kbar. For both metals a large decrease in the value of (?T/?P)_s is observed as the pressure increases. The Grüneisen parameter γ is related to (?T/?P)_s by γ = B_s(?T/?T)_s/T where B_s is the adiabatic bulk modulus. Available data for the pressure dependence of B_s and the isothermal bulk modulus B_T are used to predict the pressure and volume dependence of γ.