Multiply reconfigurable ‘plug and play’ molecular logic via self-assembly

A substantial set of ion-driven molecular logic gates are implemented in turn by arranging the association between easily available lumophores and receptors in detergent micelles.

Palladium catalysed formal 6-endo-trig approaches to pumiliotoxin alkaloids: interception of the elusive cyclopropyl intermediate

Intramolecular Heck cyclisation of (E)-vinyl bromides leads to indolizidines, related to pumiliotoxin alkaloids, in which the stereochemistry of the trisubstituted double bond undergoes inversion. A cyclopropyl intermediate, which is believed to be responsible for the double bond inversion, has been intercepted by forcing an 'early' beta-hydride elimination on this species. The relative stereochemistry of this cyclopropyl intermediate determines the regioselectivity of the final beta-hydride elimination. In this case all three beta-hydride eliminations were stereochemically permitted, giving rise to a mixture of three isomeric products, differing in the position of a double bond. (Z)-Vinyl bromides were found to be less reactive than (E)-vinyl bromides, but on cyclisation gave the required conjugated diene, with inversion of the vinyl bromide stereochemistry, as the sole reaction product. This methodology will allow rapid stereoselective access to the diene-based pumiliotoxin alkaloids.

From PASS 1 to YES to AND logic: building parallel processing into molecular logic gates by sequential addition of receptors

The synthesis and photophysical characterization of a novel molecular logic gate 4, operating in water, is demonstrated based on the competition between. fluorescence and photoinduced electron transfer (PET). It is constructed according to a 'fluorophore-spacer-receptor(1)-spacer-receptor(2)' format where anthracene is the. fluorophore, receptor(1) is a tertiary amine and receptor(2) is a phenyliminodiacetate ligand. Using only protons and zinc cations as the chemical inputs and. fluorescence as the output, 4 is demonstrated to be both a two-input AND and INH logic gate. When 4 is examined in context to the YES logic gates 1 and 2, and the two-input AND logic gate 3 and three-input AND logic gate 5, each with one or more of the following receptors including a tertiary amine, phenyliminodiacetate or benzo-15-crown-5 ether, logic gate 4 is the missing link in the homologous series. Collectively, the molecular logic gates 1-5 corroborate the PET 'fluorophore-spacer-receptor' model using chemical inputs and a light-signal output and provide insight into controlling the. fluorescence quantum yield of future PET-based molecular logic gates.

Measuring conflict and agreement between two prioritized knowledge bases in possibilistic logic.

In this paper we investigate the relationship between two prioritized knowledge bases by measuring both the conflict and the agreement between them.First of all, a quantity of conflict and two quantities of agreement are defined. The former is shown to be a generalization of the well-known Dalal distance which is the hamming distance between two interpretations. The latter are, respectively, a quantity of strong agreement which measures the amount ofinformation on which two belief bases “totally” agree, and a quantity of weak agreement which measures the amount of information that is believed by onesource but is unknown to the other. All three quantity measures are based on the weighted prime implicant, which represents beliefs in a prioritized belief base. We then define a degree of conflict and two degrees of agreement based on our quantity of conflict and quantities of agreement. We also consider the impact of these measures on belief merging and information source ordering.