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A family of barbituric and thiobarbituric acid end capped small molecule semiconductors were synthesized, characterized and shown to exhibit n-channel organic thin film transistor properties. By changing the N-alkyl substituent from methyl to ethyl, a dramatic increase in electron mobilities was observed with values nearing 0.3 cm2 V−1 s−1.

Charge extraction properties of various binary and ternary blends of organic photovoltaic devices covering both polymers and small molecules are studied. Due to their bipolar nature, both slow and fast carrier mobilities are identified from the extraction current transient. The equilibrium carrier concentration is also estimated for each of the blend films. The product of the slow carrier mobility and equilibrium concentration spreading two orders of magnitude can be used to estimate the short circuit current density. A good agreement between the estimated and measured short circuit current density is obtained with the accuracy reliant on the estimation of the slowest carrier mobility. This simplistic approach will be very useful to predict the short circuit current density for devices based on new materials.

The synthesis of a series of novel, unsymmetrically substituted benzothiadiazole-containing vinyl monomers and their free radical polymerization with and without the control of a reversible addition−fragmentation chain transfer (RAFT) agent is reported. The resulting polymers with electroactive pendants show tunable absorption and emission spectra depending on their molecular architecture. Using RAFT allows the synthesis of block copolymers using a hole-transporting vinyl-triarylamine as a second monomer. Efficient energy transfer between the two pendants has been detected. Cyclic voltammetry and photoelectron spectroscopy in air measurements have been employed to reveal the location of the HOMO and LUMO of the block copolymers. The block copolymers also influence the morphology of spin-casted films and show rectifying behavior in organic photovoltaic devices.

Rice Blast Disease, caused by the fungus Pyricularia oryzae, is one of the most important diseases of rice. Several enzymes in the melanin biosynthetic pathway have proven to be valuable targets for development of rice blast fungicides. In particular, inhibitors of trihydroxynaphthalene reductase (3HNR), which catalyzes the conversion of trihydroxynaphthalene to vermelone, have yielded commercially useful rice fungicides. The X-ray structure of 3HNR has been published recently, presenting an opportunity to use this information in the de novo design of novel 3HNR inhibitors that may exhibit useful rice blast activity. We used the LeapFrog program to develop a docking model for interaction of ligands with the active site of THNR. The final model gave a good correlation between calculated binding energy and log Ki and was used to design novel ligands and score compounds for synthesis. Using this as a tool, we synthesized inhibitors in the nanomolar range and also developed several inhibitors that did not conform to the properties of the THNR active site. Leapfrog was able to locate a previously unrecognized binding pocket that could accommodate these otherwise anomalous regions of structure.

A structure-device performance correlation in bulk heterojunction solar cells for new indandione-derived small molecule electron acceptors, FEHIDT and F8IDT, is presented. Devices based on the former exhibit higher power conversion efficiency (2.4%) and higher open circuit voltage, a finding consistent with reduced intermolecular interactions.

Reaction of pyridine-3-carbaldehyde methylhydrazone with 1,1'-carbonylbis-1H-imidazole afforded (E)-1'-methyl-2'-(3"-pyridyl) methylidene ]-1H-imidazole-1-carbohydrazide (2). Reaction of (2) with ethylamine, ethanol, ethanethiol, hydrazine monohydrate and methoxyamine afforded the corresponding semicarbazide, carbazate, thiocarbazate, carbonohydrazide and 4-methoxysemicarbazide derivatives (3a-d,g). Reaction of (2) with methylhydrazine gave the carbonohydrazide derivative (3f) together with 2,4-dimethyl-6-(3'-pyridyl)-1,4,5,6-tetrahydro-1,2,4,5-tetrazin-3(2H)-one (4a). The preparation of (E)-3-[(3'-pyridyl) methylideneamino ]oxazolidin-2-one (5a) and (E)-3-[(3'-pyridyl) methylideneamino ]tetrahydro-2H-1,3-oxazin-2-one (5b) is described.

Reaction of pyridine-3-carbaldehyde methylhydrazone with 1,1'-carbonylbis-1H-imidazole afforded (E)-1'-methyl-2'-(3"-pyridyl) methylidene ]-1H-imidazole-1-carbohydrazide (2). Reaction of (2) with ethylamine, ethanol, ethanethiol, hydrazine monohydrate and methoxyamine afforded the corresponding semicarbazide, carbazate, thiocarbazate, carbonohydrazide and 4-methoxysemicarbazide derivatives (3a-d,g). Reaction of (2) with methylhydrazine gave the carbonohydrazide derivative (3f) together with 2,4-dimethyl-6-(3'-pyridyl)-1,4,5,6-tetrahydro-1,2,4,5-tetrazin-3(2H)-one (4a). The preparation of (E)-3-[(3'-pyridyl) methylideneamino ]oxazolidin-2-one (5a) and (E)-3-[(3'-pyridyl) methylideneamino ]tetrahydro-2H-1,3-oxazin-2-one (5b) is described.

Reductive alkylation of 3,5-dimethoxybenzoic acid with haloalkanes afforded the 1-alkyl- 3,5-dimethoxycyclohexa-2,5-diene-1-carboxylic acid derivatives (3a-e) which, upon esterification and hydrolysis, furnished methyl 1-alkyl-3-hydroxy-5-oxocyclohex-3-ene-l-carboxylate derivatives (4f-j). Reaction of (4f-j) with butyric anhydride gave methyl 1-alkyl-4-butyryl- 3-hydroxy-5-oxocyclohex-3-ene-1-carboxylate derivatives (6a-e) which were converted into methyl 1-alkyl-4-[1-( ethoxyimino )butyl]-3-hydroxy-5-oxocyclohex-3-ene-1-carbo xyate derivatives (2a-e). Similarly, the oxime O-ether derivative (2f) was prepared from the amide (41), obtained from reaction of (3b) with N,N′- carbonyldiimidazole and dimethylamine followed by hydrolysis.