Solution processable organic field-effect transistors utilizing an alpha,alpha'-dihexylpentathiophene-based swivel cruciform

A pentathiophene-based swivel cruciform, which allows rotation between the cruciform arms, was synthesized. Homogeneous microcrystalline films were processed from solution, and field-effect transistors utilizing this dimer gave hole mobilities up to 0.012 cm2/V.s.     

The structure of a new crystalline cevane alkaloid: its identity with persicanidine B and harepermine

The structure of a new crystalline base (melting point (mp) 167-169 degrees C) obtained from Fritillaria imperialis was elucidated as (20R, 25R)-5alpha,17beta-cevanine-3beta,6beta-diol, X-ray diffraction analysis of the mono-hydrate. The base was found to be identical with persicanidine B and also with harepermine.     

Phosphorus-nitrogen compounds. Part 13. Syntheses, crystal structures, spectroscopic, stereogenic, and anisochronic properties of novel spiro-ansa-spiro-, spiro-bino-spiro-, and spiro-crypta phosphazene derivatives

The condensation reactions of N2Ox (x = 2, 3) donor-type aminopodand (4) and dibenzo-diaza-crown ethers (5, 6, and 9) with hexachlorocyclotriphosphazatriene, N3P3Cl6, produce two kinds of partially substituted novel phosphazene derivatives, namely, spiro-bino-spiro- (19) and spiro-crypta (21, 22, and 25) phosphazenes. The partially substituted spiro-ansa-spiro-phosphazene (11) reacted with pyrrolidine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) give the corresponding new fully substituted phosphazenes (14 and 16). Unexpectedly, the reactions of 23 and 24 with pyrrolidine result in only geminal crypta phosphazenes (26 and 27). The solid-state structures of 16 and 22 have been determined by X-ray diffraction techniques. The relative inner hole-size of the macrocycle in the radii of 22 is 1.27 A. The relationship between the exocyclic NPN (alpha') and endocyclic (alpha) bond angles for spiro-crypta phosphazenes and exocyclic OPN (alpha') bond angles for spiro-ansa-spiro- and spiro-bino-spiro-phosphazenes with 31P NMR chemical shifts of NPN and OPN phosphorus atoms, respectively, have been investigated. The structures of 10, 14, 16, 19, 21, 22, and 25-27 have also been examined by FTIR, 1H, 13C, and 31P NMR, HETCOR, MS, and elemental analyses. The 31P NMR spectra of 10, 21, 22, and 25 indicate that the compounds have anisochrony. In compounds 16 and 22, the spirocyclic nitrogen atoms have pyramidal geometries resulting in stereogenic properties.     

Spectral and photophysical studies on cruciform oligothiophenes in solution and the solid state

The photophysical and spectroscopic properties of a new class of oligothiophene derivatives, designated as cruciform oligomers, have been investigated in solution (room and low temperature) and in the solid state (as thin films in Zeonex matrixes). The study comprises absorption, emission, and triplet-triplet absorption spectra, together with quantitative measurements of quantum yields (fluorescence, intersystem crossing, internal conversion, and singlet oxygen formation) and lifetimes. The overall data allow the determination of the rate constants for all decay processes. From these, several conclusions are drawn. First, in solution, the main deactivation channels for the compounds are the radiationless processes: S(1) --> S(0) internal conversion and S(1) --> T(1) intersystem crossing. Second, in general, in the solid state, the fluorescence quantum yields decrease relative to solution. A comparison is made with the analogous linear alpha-oligothiophenes, revealing a lower fluorescence quantum efficiency and, in contrast to the normal oligothiophenes, that internal conversion is an important channel for the deactivation of the singlet excited state. Replacement of thiophene by 1,4-phenylene units in the longer-sized cruciform oligomer increases the fluorescence efficiency. The highly efficient generation of singlet oxygen through energy transfer from the triplet state (S(Delta) approximately 1) provides support for the measured intersystem crossing quantum yields and suggests that reaction with this may be an important pathway to consider for degradation of devices produced with these compounds.     

Estimation of cholinesterase inhibitory and antioxidant effects of the leaf extracts of Anatolian Ficus carica var. domestica and their total phenol and flavonoid contents

Ficus carica var. domestica Tsch. & Rav. (common fig) is widely grown in Turkey and exported for its edible fruits. In this study, the n-hexane, chloroform, acetone, methanol, n-butanol, and water extracts of the leaves of F. carica var. domestica were screened for their cholinesterase inhibitory and antioxidant activities. Cholinesterase inhibition against acetyl- (AChE) and butyrylcholinesterase (BChE) was measured by the spectrophotometric method of Ellman at concentrations of 25, 50, and 100 microg/mL., while antioxidant activity was tested using three in vitro methods; 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, metal-chelation capacity, and ferric-reducing antioxidant power (FRAP). Total phenol and flavonoid contents of the extracts were determined spectrophotometrically. Our results revealed that the n-hexane and acetone extracts exerted a notable inhibition against both AChE (62.9 +/- 0.9% and 50.8 +/- 2.1%, respectively) and BChE (76.9 +/- 2.2% and 45.6 +/- 1.3%, respectively). However, they had low activity in the antioxidant tests. The chloroform extract was found to be the richest in total flavonoid content (252.5 +/- 1.1 mg/g quercetin equivalent), while the n-butanol extract had the highest total phenol amount (85.9 +/- 3.2 mg/g extract gallic acid equivalent).     

A Dft Investigation of the Interaction of B- And Al-Doped C<Subscript>60</Subscript> Fullerenes with Cyclopropylpipezarine

Interactions and natural bond orbital analysis of cyclopropylpiperazine(cppp) and B- or Al-doped C₆₀ fullerenes are investigated by quantum mechanical calculations. The structural and electronic properties, such as NH stretching vibrations, nuclear magnetic shielding tensors of ²⁷Al and ¹¹B nuclei or the energy gap are also investigated. All calculations are carried out in the gas phase and water media. Results of the bond order and the binding energy suggest that chemisorption occurs between the cppp nitrogen atom and boron or aluminum atoms of fullerenes. The Alcomplex in water is foundto have the highest binding energy. Further, AlC₅₉…cppp complexes have a slightly higher kinetic stability and a low chemical reactivity. However, BC₅₉…cppp works as a function-type sensor for cppp.     

Seed-directed synthesis of zeolites with enhanced performance in the absence of organic templates

We demonstrate here a seed-directed synthesis (SDS) of Beta, Levyne, and Heulandite zeolites in the absence of organotemplates, where the seeds drive crystallization of the zeolites. Compared with conventional Beta synthesized in the presence of organic templates, Beta-SDS exhibits large textural parameters, stable Al species, and unprecedentedly high density of active sites, resulting in superior catalytic activity and selectivity for valuable products in catalysis.