Charge‐transfer complexes of N‐methyl‐, N‐iso­propyl‐, N‐butyl‐ and N‐iso­butyl­carbazole with 3,5‐di­nitro­benzoic acid

In the title four compounds, C₁₃H₁₁N·C₇H₄N₂O₆, (I), C₁₅H₁₅N·C₇H₄N₂O₆, (II), C₁₆H₁₇N·C₇H₄N₂O₆, (III), and C₁₆H₁₇N·C₇H₄N₂O₆, (IV), the donor and acceptor mol­ecules are stacked alternately to form one‐dimensional columns. In (I), the N‐methyl group of the donor is nearly eclipsed with respect to one of the nitro groups of the neighboring acceptor in a column, whereas the N‐iso­propyl, N‐butyl and N‐iso­butyl groups are in anti positions with respect to one of the nitro groups of the neighboring acceptor in compounds (II)–(IV).     

1,3‐Propane­di­ammonium bis(3′‐nitro‐trans‐cinnamate) and trans‐1,2‐cyclo­hexane­di­ammonium bis(3′‐nitro‐trans‐cinnamate)

In the title two adducts, C₃H₁₂N₂²⁺·2C₉H₆NO₄^?, (I), and C₆H₁₆N₂²⁺·2C₉H₆NO₄^?, (II), hydrogen bonds between the di­ammonium and carboxyl­ate ions form a two‐dimensional network parallel to the ab plane in (I) and one‐dimensional chains along the c axis in (II). The cyclo­hexane­di­ammonium ion in (II) has a crystallographic twofold axis.     

Tetra‐μ‐acetato‐O:O′‐bis­[(7‐aza­indole‐N)­copper(II)]

The title complex, [Cu₂(C₂H₃O₂)₄(C₇H₆N₂)₂], shows a binuclear cage structure having an inversion centre. There are intramolecular N—H?O hydrogen bonds between the 7‐aza­indole ligands and the bridging acetate O atoms.     

Syntheses of thiopyrone and pyrone derivatives by photocyclization reaction of 3‐aryl‐2‐( Benzothien‐3‐yl)propenoic acids

Naphtho[1,2‐b][1]benzothiophene‐6‐carboxylic acids, 6H‐benzo[b]naphtho[2,3‐d]thiopyran‐6‐ones and 6H‐benzo[b]naphtho[2,3‐d]pyran‐6‐ones were synthesized in one step by the photocyclization reaction of 3‐aryl‐2‐([1]benzothien‐3‐yl)propenoic acids. The photocyclization reaction did not occur when the 3‐aryl group contained the electron‐withdrawing nitro group. The assignment of the ¹H and ¹³C nmr spectra of 6H‐benzo[b]naphtho[2,3‐d]thiopyran‐6‐one and 6H‐benzo[b]naphtho[2,3‐d]pyran‐6‐one by two‐dimensional nmr methods is described. The difference between the chemical shift values of H12 for these two compounds is attributed to different molecular geometries.     

Aqua­nitro(α,β,γ,δ‐tetra­phenyl­porphy­rinato)­cobalt(III) N,N‐di­methyl­form­amide disolvate

In the title compound, [Co(tpp)(NO₂)(H₂O)]·2dmf or [Co(C₄₄H₂₈N₄)(NO₂)(H₂O)]·2C₃H₇NO, a distorted octahedral Co^III complex shows an orientational disorder such that the positions of the nitro and aqua ligands are exchanged. As a result, the averaged structure has an inversion centre at the Co atom. The di­methyl­form­amide mol­ecule also has a positional disorder.     

Redetermination of bis{[(2‐hydroxy­phenyl­methyl)­bis(2‐pyridyl­methyl)­aminato]copper(II)} diperchlorate

The structure of the title compound, [Cu₂(C₁₉H₁₈N₃O)₂](ClO₄)₂, was reported with insufficient accuracy because of a twinning problem by Adams, Bailey, Campbell, Fenton & He [J. Chem. Soc. DaltonTrans. (1996), pp. 2233–2237]. The dinuclear phenolate‐bridged Cu^II complex has an inversion centre.     

Chloro­[N′,N′‐diethyl‐N,N‐bis(2‐pyri­dyl­methyl)­ethyl­enedi­amine‐κ4N]copper(II) perchlorate

The title mononuclear copper(II) complex, [CuCl(C₁₈H₂₆N₄)]ClO₄, shows a square‐pyramidal coordination with the diethyl­amino N atom at the apical position. Large anisotropies in the displacement parameters of the non‐H atoms of the ligand seem to be due to rotational disorder of the ClO₄^? anion.     

Quantum-Statistics Behavior of the Exciton-Biexciton System In GaAs/AlAs Type-II Superlattices

We have investigated the quantum-statistics behavior of the exciton-biexciton system from the photoluminescence properties in (GaAs) m /(AlAs) m type-II superlattices with m = 12 and 13 monolayers, where the lowest-energy type-II exciton consists of the n = 1 X electron of AlAs and n = 1 o heavy hole of GaAs. The long exciton lifetime of the order of w s due to the indirect transition nature enables us to obtain precisely the density relation between the exciton and biexciton from the line-shape analysis of time-resolved photoluminescence spectra. In a relatively low exciton-density region, the biexciton density obeys a well-known square law. At an exciton density around 1 2 10 10 cm m 2 , the biexciton density suddenly increases with a threshold-like nature. This behavior, which is realized at a bath temperature up to 8 K under an excitation power of the order of 100 mW/cm 2 , results from the characteristics of Bose-Einstein statistics of the exciton-biexciton system.     

Isotope-selective laser photodetachment for 129I accelerator mass spectrometry

2D coordination polymer iron(II) spin crossover complexes containing 3,5-lutidine with host framework Fe(3,5-lutidine)₂Ni(CN)₄were synthesized. Their spin crossover properties were studied by temperature dependent ⁵⁷Fe Mössbauer spectroscopy. Materials show gradual incomplete spin crossover with distinct thermochromism, while only 25 % of iron(II) ions are switched to the low spin state at 80 K, as determined by a detailed ⁵⁷Fe Mössbauer study.     

Recent developments of optical fiber sensors for automotive use

Optical fiber sensing technologies are expected to apply for many future electronic control systems in automobiles, because of their inherent outstanding features, such as high noise immunity, high heat resistance, and flexible light propagation paths which can be applied to measure the movements and directions of the mobiles. In this paper, two typical applications of fiber sensing technologies in automobiles are described in detail. The combustion flame detector is one of the typical applications of a fiber spectroscopic technology which utilizes the feature of high noise and heat resistibility and remote sensibility. Measurement of engine combustion conditions, such as the detonation, the combustion initiation, and the air-fuel ratio, have been demonstrated in an experimental fiber sensing method. Fiber interferometers, such as a fiber gyroscope, have great possibilities in future mobile applications because they are applicable to many kinds of measurements for movements and physical variables. An optical fiber gyroscope utilizing the single polarized optical fiber and other optical devices has been developed. Quite an accurate measurement of vehicle position was displayed on a prototype navigation system which installed the fiber gyroscope as a rotational speed sensor.