Dissipative Synthetic DNA‐Based Receptors for the Transient Loading and Release of Molecular Cargo

Supramolecular chemistry is moving into a direction in which the composition of a chemical equilibrium is no longer determined by thermodynamics but by the efficiency with which kinetic states can be populated by energy consuming processes. Herein, we show that DNA is ideally suited for programming chemically fueled dissipative self‐assembly processes. Advantages of the DNA‐based systems presented in this study include a perfect control over the activation site for the chemical fuel in terms of selectivity and affinity, highly selective fuel consumption that occurs exclusively in the activated complex, and a high tolerance for the presence of waste products. Finally, it is shown that chemical fuels can be used to selectively activate different functions in a system of higher complexity embedded with multiple response pathways.     

Solvents Effects on Film Morphologies and Memory Behavior of a Perylenediimide‐Containing Pendent Polymer

The large polydispersity index of functional pendant polymers has hindered their application in semiconductors. Herein, a novel pendant polymer with perylenediimide (PDI) in the side chains was successfully synthesized through ring‐opening metathesis polymerization (ROMP) with a very low polydispersity index. The synthesized polymers were spin‐coated on indium tin oxide (ITO) substrate by using a mixture of 1,2‐dichlorobenzene (o‐DCB) and methanol (MeOH) solvents. The surface morphologies and intermolecular π–π stacking of the fabricated film could be adjusted through tuning of the ratio of o‐DCB and MeOH, and thus, the sandwich‐structured device of ITO/polymer/aluminum exhibited different electrical behavior. The threshold voltages of the devices decreased as the MeOH content was increased from 0 to 30 % (v/v); however, the device changed from being unrewritable to rewritable if the MeOH content was increased to 40 %; a probable mechanism for this process is discussed. It is hoped that this new idea of synthesizing narrow polydispersity index pendant polymers, and the fabrication of high‐quality films through the use of a mixture of solvents could allow high‐performance memory devices to be prepared in the future.     

On a “structure intermediate between quasiperiodic and random”

This paper proves rigorously that the structure factor of the structure intermediate between quasiperiodic and random introduced by Aubry. Godréche, and Luck is purely singluar continuous apart from a delta function at zero for most choices of the parameters. The result is based on a proof that a flow under a steep function over an irrational circle rotation is weakly mixing for most parameters, and on the wonderland Theorem.     

Resonant frequencies and quality factors in lossy NRD cylindrical resonators

In this paper the fundamental effects of losses on resonant parameters (frequencies and quality factors) are analyzed for circular-cylindrical dielectric resonators inserted between metal plates, in the configuration also called NRD (Non-Radiative Dielectric).Power dissipations are considered both in the dielectric and in the conductors. Complex resonant frequencies and closed-form expressions for the relevant quality factors are derived rigorously for arbitrary resonant modes, even without circular symmetry. Numerical results are presented and discussed, making also use of experimental data obtained by means of a suitable NRD set-up.The present analysis accurately provides the basic information for a more realistic design of up-to-date millimeter-wave frequency-selective devices in NRD circuitry.     

Speeds of sound and isothermal compressibilities in the water-rich region of aqueous 2-butoxyethanol and 2-butanone at 25°C

Speeds of sound were measured at 25°C in the water-rich region of aqueous 2-butoxyethanol (BE) and 2-butanone (BUT). Density, heat capacity, and thermal expansivity data available in literature were used to calculate isothermal compressibilities, _T . The composition derivative, N ( _T/n_B), a third derivative of Gibbs free energy, showed a peak anomaly atx _BE=0.0175 for BE-H₂O, and a bend atx _BUT=0.033 for BUT-H₂O. n_B (n_BE or n_BUT) is the amount of the solute andx _BE andx _BUT are the respective mole fractions. The location of these anomalies were the same as those of other third derivatives found earlier for the same aqueous solutions. These anomalies were shown earlier to mark the transition point across which the mixing scheme changes in a qualitative fashion.     

Direct observation of hydrophobic interactions in aqueous solutions of organic compounds by supercooling and enthalpies of mixing

Supercooling temperatures and enthalpies of mixing with some solvents have been examined for two kinds of solutions subjected to different thermal treatments (solutions I and II) of tetrahydrofuran (THF), isopropyl alcohol (2-PrOH), and ethyleneglycol butylether (BE), and ethyleneglycol isobutylether (i-BE) in order to observe more directly the structural organization of water molecules around a nonpolar molecule in an aqueous solution. For THF and 2-PrOH solutions, supercooling temperatures of solution I were found to be 2–3 degrees higher than those of solution II, and differences H_I-H_II were found to be about 3 kJ mol^–1. It has been concluded that these results directly reflect the difference in the stability of hydrogen-bonded water networks in an aqueous solution.     

Third-Order Optical Nonlinearity Studies of p-Heptaphenyl Derivatives-Doped Sol-Gel Processed Composite Glass and THF Solution by Degenerate Four-Wave Mixing and Optical Kerr Gate Measurements

We have investigated the nonlinear optical performance of new UV photostable dyes, didecyl and didecyloxy substitutedpara-polyphenyl heptamers (DDPPH and DDOPPH hereafter, respectively) using the techniques of degenerate four-wave mixing (DFWM) and optical Kerr gate (OKG). The studies were performed on the dyes dissolved in THF solution and doped in sol-gel processed composite-glass. The magnitudes and the signs of the real and the imaginary components of the complex third-order optical susceptibilities were determined by the heterodyned OKG method and compared to the values obtained from concentration dependent homodyne Kerr gate and DFWM measurements. The observed effective second hyperpolarizability γ values are dependent on the optical intensity and the pulse width of the pumping source beam. Doping of the dyes in composite-glass allows to increase the interaction length providing the prospect of using them as building blocks for photonic devices.     

苯并[b]萘并[2′,3′∶5,6][1,4]二噻英并[2,3-i]噻蒽-5,7,9,14,16,18-六酮的合成及其三阶非线性光学性能

以1,4-萘醌为原料,合成了含硫的醌构稠杂环化合物苯并[b]萘并[2′,3′∶5,6][1,4]二噻英并[2,3-i]噻蒽-5,7,9,14,16,18-六酮(4),其结构经1HNMR和IR确证。采用波长为800nm,脉宽为80fs的Ti∶Sapphire飞秒激光,运用双光束简并四波混频法测定了4的三阶非线性光学性能,结果表明,4的三阶非线性光学极化率χ(3),非线性折射率n2,分子二阶超极化率γ和响应时间分别为2.89×10-13esu,5.31×10-12esu,3.14×10-31esu和101fs。并分析了4的分子结构对其三阶非线性光学性能的影响。     

Alkyl-chain branched effect on the aggregation and photophysical behavior of polydiarylfluorenes toward stable deep-blue electroluminescence and efficient amplified spontaneous emission

Robust branched polydiarylfluorenes are constructed forstable deep-blue electroluminescence and efficient amplified spontaneous emission.     

A new formula for the entropy of mixing in polymer systems and free volume

The famous equations of Flory-Huggins for the entropy of mixing with one highmolecular component are of great importance for polymer physics. But Gujrati stated in 1980 [12] that these equations cannot be exact. This is why we derived a new formula for the dependence of the entropy from the fraction of vacant sites in a quasi-lattice. It differs significantly from that of Huggins and still more from that of Flory in the case of low free volume. The equations of Flory-Huggins are correct with reference to low polymer content only.If our formula for entropy is used instead of that of Huggins an important result of the theory of Gibbs-DiMarzio is called in question. The increase of thermal expansion at the glass transition cannot be explained by an increase of vacant sites. A growth of the number of unoccupied sites according to the thermodynamic equilibrium condition would bring about a far too great thermal expansion coefficient. From estimations of the energy of interaction between polymer molecules, which can be found in literature, it follows that the increase of entropy is far too small to enable the formation of vacant sites above the glass transition. It is unambiguously shown that the free volume, commonly regarded to be the decisive quantity with respect to glass transition, cannot consist of holes as considered in the quasi-lattice model and in many theoretical treatments.