Split-gate organic field-effect transistors for high-speed operation.

Split-gate organic field-effect transistors have been developed for high-speed operation. Owing to the combination of reduced contact resistance and minimized parasitic capacitance, the devices have fast switching characteristics. The cutoff frequencies for the vacuum-evaporated devices and the solution-processed devices are 20 and 10 MHz, respectively. A speed of 10 MHz is the fastest device reported so far among solution-processed organic transistors.

Anomalous pressure effect in heteroacene organic field-effect transistors.

Anomalous pressure dependent conductivity is revealed for heteroacene organic field-effect transistors of dinaphtho[2, 3-b:2', 3'-f]thieno[3, 2-b]thiophene single crystals in the direction of a and b crystallographic axes. In contrast to the normal characteristics of a monotonic increase in mobility µ with the application of external hydrostatic pressure P in conductors, we found that the present organic semiconductor devices exhibit nonmonotonic and gigantic pressure dependence including an even negative pressure coefficient dµ/dP. In combination with a structural analysis based on x-ray diffraction experiments under pressure, it is suggested that on-site molecular orientation and displacement peculiar in heteroacene molecules are responsible for the anomalous pressure effect.

Pyrrolo-annelated tetrathiafulvalenes: the parent systems

The synthesis of a number pyrrolo-annelated tetrathiafulvalenes, including the parent bis(pyrrolo[3,4-d])tetrathiafulvalene (7) is decribed. Starting from readily available 4,5-bis(bromomethyl)-1, 3-dithiole-2-thione (14) and sodium tosylamide, the parent 7 and the asymmetric monopyrrolo tetrathiafulvalenes 23a,b were prepared in good yields via a nonclassical and simple pyrrole synthesis. Furthermore, a series of asymmetrical N-alkylated monopyrrolo/monodihydropyrrolotetrathiafulvalenes was prepared starting from primary amines and 14. A detailed study of the fundamental redox behavior of this class of heterocycles is reported. NMR spectroscopy, cyclic voltammetry, and PM3 MO calculations revealed that the pyrrolo-annelated tetrathiafulvalenes have highly extended pi-surfaces. The X-ray crystallographic analyses of the monopyrrolo tetrathiafulvalenes 22b and 24b, together with preliminary formation of a charge-transfer complex between the parent donor 7 and TCNQ, are also reported.

The first electrochemically active cuppedophanes: bis(tetrathiafulvalene)cuppedophanes

The synthesis of the first tetrathiafulvalene-containing cuppedophanes is reported, together with conformational study of the structures by (1)H NMR spectroscopy. The bis(TTF)cuppedophane 6 represents a novel type of cuppedophane.

A flexible cyclophane: design, synthesis, and structure of a multibridged tris-tetrathiafulvalene (TTF) macrocycle

The tris-tetrathiafulvalene (TTF) macrocycles 3 with a large end-cavity were effectively synthesized from the readily available tetrakis(cyanoethylthio)TTF by means of a selective deprotection/realkylation sequence followed by an intramolecular coupling reaction. Crystar structure analyses revealed that the neutral molecules include two (3a) or one chloroform molecule (3b) as solvent of crystallization inside the cavity, whereas the I3- salt of 3b, obtained by electrocrystallization, has a molecular structure which is different from that of the neutral molecule in that the cavity has completely collapsed.

Synthesis and spectroscopic properties of

The title compound has been synthesized as the first oligothiophenophane that has the typical stacking structure of a layered cyclophane and can behave as an ideal pi-dimer model.