Motor proteins and other biological machines are highly efficient at converting energy into directed motion and driving chemical systems away from thermodynamic equilibrium. But even though these biological structures have inspired the design of many molecules that mimic aspects of their behaviour, artificial nanomachine systems operate almost exclusively by moving towards thermodynamic equilibrium, not away from it. Here we show that information about the location of a macrocycle in a rotaxane-a molecular ring threaded onto a molecular axle-can be used, on the input of light energy, to alter the kinetics of the shuttling of the macrocycle between two compartments on the axle. For an ensemble of such molecular machines, the macrocycle distribution is directionally driven away from its equilibrium value without ever changing the relative binding affinities of the ring for the different parts of the axle. The selective transport of particles between two compartments by brownian motion in this way bears similarities to the hypothetical task performed without an energy input by a 'demon' in Maxwell's famous thought experiment. Our observations demonstrate that synthetic molecular machines can operate by an information ratchet mechanism, in which knowledge of a particle's position is used to control its transport away from equilibrium.

Sulfur-containing molecules such as thioethers are commonly found in chemical biology, organic synthesis, and materials chemistry. While many reliable methods have been developed for preparing these compounds, harsh reaction conditions are usually required in the traditional methods. The transition metals have been applied in this field, and the palladium-catalyzed coupling of thiols with aryl halides and pseudo halides is one of the most important methods in the synthesis of thioethers. Other metals have also been used for the same purpose. Here, we summarize recent efforts in metal-catalyzed C-S bond cross-coupling reactions, focusing especially on the coupling of thiols with aryl- and vinyl halides based on different metals.

Oligoaryl is an important class of compounds which exhibit a variety of fascinating properties for optoelectronic interests. 1 Incorporation of five-membered heteroaromatic moieties into these conjugated molecules will occasionally increase fluorescence quantum yields and the optoelectronic properties of the oligomers can be tuned. 1 Most syntheses of these heteroaromatic containing oligomers involve the transition-metal catalyzed cross coupling reactions of the corresponding aryl components. 2 In general, the presence of a long chain aliphatic substituent in these heteroaromatic rings will increase the solubility in organic solvent and hence enhance the processibility of these materials. 1 However, introduction of such alkyl substituent at C 3 and/or C 4 positions in these heteroaromatic rings for further cross coupling reactions is not trivial. 3 Cyclization of the 1,4-dicarbonyl moiety with heteroatom-containing reagents provides an alternative procedure for the construction of these five-membered heterocycles. [3][4][5] It is known that annulation of allenylmethanols can afford the corresponding five-membered oxygen heterocycles. 6 In addition, annulation of allenyl carbonyl compounds, 7 propargylic acetals, 8 or oxiranes 9,10 furnishes a powerful arsenal for the synthesis of substituted furans. The applications of propargylic metallic species have paved a useful path for the construction of furan skeletons. 11 We recently reported that propargylic dithioacetal 1 can serve as an allene 1,3-zwitterion synthon (eq 1). 12 The interesting feature for this reaction involves an umpolung of one of the two carbonsulfur bonds in the dithioacetal functionality. The organocopper intermediate 2 can react with a number of electrophiles leading to either allenyl or alkynyl product 3 or 4. The chemoselectivity of this reaction depends on the nature of the electrophile. It is envisaged that the reaction of 2 with an aldehyde 6 or an aldimine 8 may yield the intermediate alcohol 5a, or amine 5b, respectively.

HighlightPhytoplasma effector SAP11 modulates plant volatile organic compound emissions by suppressing the expression of NbOMT1, which encodes an O-methyltransferase required for the biosynthesis of 3-isobutyl-2-methoxypyrazine.

FeCl(3) in combination with bisphosphine ligands represents an efficient catalyst system for the cross-coupling of aryl- and alkyl thiols with aryl iodides, a broad spectrum of functional groups can be tolerated during the catalysis.