Palladium-catalyzed beta-allylation of 2,3-disubstituted indoles

Given the prevalence of the indole nucleus in biologically active compounds, the direct C3-functionalization of 2,3-disubstituted indoles represents an important problem. Described is a general, high-yielding method for the palladium-catalyzed beta-allylation of carba- and heterocycle fused indoles, including complex natural product substrates.     

A new approach toward light-harvesting reverse micelles from donor-acceptor miscible blends

In the present paper, we report a new approach toward light-harvesting reverse micellar systems from molecular blends of anthracene and perylene building blocks. The self-assembly initiated by protonation of the molecular blends gave rise to the mixed reverse micelles, in which intermolecular energy transfer from the anthracene to the perylene chromophores was observed. The atomic force microscope (AFM) studies on the reverse micelles prepared from the donor and acceptor blends at a range of the feed ratios showed a number of nanoscale-sized spherical objects homogeneously dispersed on the highly oriented pyrolytic graphite (HOPG) substrate. The critical micelle concentration (cmc) values of the reversed micelles at the donor:acceptor ratios of 100:0, 50:50, and 0:100 were estimated to be 7, 3, and 10 μM by fluorescence batch titrations, respectively, indicating that the cmc values should be almost equivalent regardless of the constitution of each chromophoric component. Attempt to generate the mixed reverse micelles through pairwise mixing of the donor- and acceptor-based reverse micelles resulted in spectral behaviors identical with those obtained by the self-assembly employing the donor-acceptor blends. This suggests that these two reverse micelles undergo thermodynamic exchange of the surfactant molecules to afford the mixed reverse micelles when mixing the two discrete reverse micellar systems.     

Iridium-catalyzed enantioselective cycloisomerization of nitrogen-bridged 1,6-enynes to 3-azabicylo[4.1.0]heptenes

A cationic iridium complex catalyzes a cycloisomerization of nitrogen-bridged 1,6-enynes to give 3-azabicyclo[4.1.0]heptenes in good to high yield. When an iridium-chiral diphosphine complex is used, the reaction proceeds enantiomerically to give chiral cyclopropanes fused by a six-membered ring system.     

Polyferrocenes: metallopolymers with tunable and high refractive indices

The refractive index, molar refraction and Abbe number of polyferrocene derivatives are reported and the values indicate that these materials are very promising for a range of photonics applications.     

Optical control over photoconductivity in polyferrocenylsilane films

We report the study and elucidate the origin of the photoconductivity of polyferrocenylsilanes achieved through photooxidation performed by ultraviolet irradiation in the presence of chloroform. The persistence over months of the changes in the optoelectronic properties allowed more detailed studies of the charge photogeneration process. The photocurrent spectrum mimics that of the absorption indicating that the photooxidized material is not a mechanical mixture of oxidized and unoxidized polymer units. Photomodulation spectroscopy revealed the existence of long-lived photoexcited states with a lifetime in the millisecond range. They have been interpreted as trapped excitons at the oxidized sites where the polymer is deformed due to the presence of the chloroform derived counter ions. Because of the relatively long lifetime of the trapped excitons they can dissociate and the formed charge carriers can be separated in an externally applied electric field. The effect of the polymer chain deformation around the oxidized unit extends over the neighboring polymer units. In light of the potential applications of this class of polymers in various electronic and photonic devices, the clarification of such a basic process as the photocurrent generation will be a key factor for further technological development.     

An analysis of the viability of polymer flooding as an enhanced oil recovery technology

The concept of improving oil recovery through polymer flooding is analysed. It is shown that while the injection of a polymer solution improves reservoir conformance, this beneficial effect ceases as soon as one attempts to push the polymer solution with water. Once water injection begins, the water quickly passes through the polymer creating a path along which all future injected water flows. Thus, the volume of the polymer slug is important to the process and an efficient recovery would require that the vast majority of the reservoir be flooded by polymer. It is also shown that the concept of grading a polymer slug to match the mobilities of the fluids at the leading and trailing edges of a polymer slug does not work in a petroleum reservoir. While this process can supply some additional stability to the slug, it is shown that for the purposes of enhanced oil recovery this additional stability is not great enough to be of any practical use. It is found that in this case the instability has simply been hidden in the interior of the slug and causes the same sort of instability to occur as was the case for the uniform slug.     

Stationary Determinantal Processes on $${\mathbb {Z}}^d$$ Z d with N Labeled Objects per Site,Part I: Basic Properties and Full Domination

Journal of Theoretical Probability - We study a class of stationary determinantal processes on configurations of N labeled objects that may be present or absent at each site of $${\mathbb {Z}}^d$$...