Photoinduced intramolecular electron-transfer reactions in carbazole-fullerene and phenothiazine-fullerene linked compounds in benzene and benzonitrile as studied by fluorescence, transient absorption, time-resolved EPR, and magnetic field effects

Photoinduced intramolecular electron-transfer reactions in carbazole (Cz)-fullerene (C₆₀) (Cz(8)C₆₀) and phenothiazine (Ph)-C₆₀ (Ph(n)C₆₀ (n=8, 10, 12)) linked compounds have been investigated in benzene and benzonitrile by fluorescence, transient absorption, and time-resolved electron paramagnetic resonance measurements, and by magnetic field effects on the decay rate constants of the photogenerated biradicals. In benzonitrile, photoinduced intramolecular electron transfer from Cz to the singlet excited state of C₆₀ (¹C₆₀ ^*) occurred in Cz(8)C₆₀, but not to the triplet excited state (³C₆₀ ^*), while the intramolecular electron-transfer to both¹C₆₀ ^* and³C₆₀ ^* occurred in Ph(n)C₆₀ (n=8, 10, 12). In benzene, on the other hand, no electron transfer to both¹C₆₀ ^* and³C₆₀ ^* took place in all linked compounds. These results were interpreted in terms of the different Gibbs free energy changes in the two solvents.     

Structural and spectroscopic characterization of (mu-hydroxo or mu-oxo)(mu-peroxo)diiron(III) complexes: models for peroxo intermediates of non-heme diiron proteins

(mu-Hydroxo or oxo)(mu-1,2-peroxo)diiron(III) complexes having a tetradentate tripodal ligand (L) containing a carboxylate sidearm [Fe2(mu-OH or mu-O)(mu-O2)(L)2]n+ were synthesized as models for peroxo-intermediates of non-heme diiron proteins and characterized by various physicochemical measurements including X-ray analysis, which provide fundamental structural and spectroscopic insights into the peroxodiiron(III) complexes.     

Synthesis of 9-arylamino- and (Z)-9-arylimino-9H-pyrrolo[1,2-a]indoles by reactions of 2-(pyrrol-1-yl)benzaldehydes with aryl amines

Heating mixtures of 2-(pyrrol-1-yl)benzaldehydes and aryl amines under argon afforded 9-arylamino-9H-pyrrolo[1,2-a]indoles, via cyclization of the resulting 2-(pyrrol-1-yl)benzaldimine intermediates. Heating in the presence of oxygen afforded (Z)-9-arylimino-9H-pyrrolo[1,2-a]indoles, which were successfully hydrolyzed with hydrochloric acid to give pyrrolo[1,2-a]indol-9-ones.     

Structure and dioxygen-reactivity of copper(I) complexes supported by bis(6-methylpyridin-2-ylmethyl)amine tridentate ligands

The structure and dioxygen-reactivity of copper(I) complexes R supported by N,N-bis(6-methylpyridin-2-ylmethyl)amine tridentate ligands L2R[R (N-alkyl substituent)=-CH2Ph (Bn), -CH2CH2Ph (Phe) and -CH2CHPh2(PhePh)] have been examined and compared with those of copper(I) complex (Phe) of N,N-bis[2-(pyridin-2-yl)ethyl]amine tridentate ligand L1(Phe) and copper(I) complex (Phe) of N,N-bis(pyridin-2-ylmethyl)amine tridentate ligand L3(Phe). Copper(I) complexes (Phe) and (PhePh) exhibited a distorted trigonal pyramidal structure involving a d-pi interaction with an eta1-binding mode between the metal ion and one of the ortho-carbon atoms of the phenyl group of the N-alkyl substituent [-CH2CH2Ph (Phe) and -CH2CHPh2(PhePh)]. The strength of the d-pi interaction in (Phe) and (PhePh) was weaker than that of the d-pi interaction with an eta2-binding mode in (Phe) but stronger than that of the eta1 d-pi interaction in (Phe). Existence of a weak d-pi interaction in (Bn) in solution was also explored, but its binding mode was not clear. Redox potentials of the copper(I) complexes (E1/2) were also affected by the supporting ligand; the order of E1/2 was Phe>R>Phe. Thus, the order of electron-donor ability of the ligand is L1Phe相似文献   

Grinding-induced equimolar complex formation between thiourea and ethenzamide

We prepared and characterized a grinding-induced equimolar complex of thiourea with ethenzamide. When thiourea and ethenzamide were co-ground at a molar ratio of 3 : 1, new powder X-ray diffraction (PXRD) peaks were observed in addition to PXRD peaks of thiourea crystals. The optimum stoichiometry of the new structure was confirmed as 1 : 1 mol/mol. Effect of grinding time on the thiourea-ethenzamide equimolar complex formation was investigated by using PXRD, differential scanning calorimetry and Fourier transform infrared spectroscopy. The equimolar crystal structure was confirmed by X-ray diffraction measurements of the single crystal which was recrystallized from ethanol. It was found that the intermolecular hydrogen bond formations between thiourea and ethenzamide molecules contributed to the equimolar complex formation. The complex formation was not observed in the cases where benzamide, salicylamide or 3-ethoxybenzamide was co-ground with thiourea. 2-Alcoxyl benzamide structures should be required for the grinding-induced equimolar complex formation with thiourea.     

Development of a regenerable cell culture system that senses and releases dead cells

We developed a rapidly regenerable cell culture system in which the cell culture substrate detects cell death and selectively releases the dead cells. This culture material was achieved by combining a detector that responds to the signal from the dead cells and an actuator to release the dead cells. Benzo-18-crown-6-acrylamide (BCAm) with a pendant crown ether receptor was used as the sensor to recognize cellular signals and N-isopropylacrylamide (NIPAM) was used as the actuator. This copolymer of NIPAM and BCAm can respond to potassium ions and change its nature from hydrophobic to hydrophilic at the culture temperature of 37 degrees C. Living cells concentrate potassium ion internally; when cells die, potassium ions are released. The polymer surface recognizes the potassium ions released from the dead cells, the NIPAM hydrates, and the dead cells are selectively detached. This in vitro culture system is a novel one in which artificial culture materials work cooperatively with cellular metabolism by responding to this signal from the cells, thereby realizing in vitro tissue regeneration partly mimicking the mechanisms of in vivo homeostasis.     

Chemical bonding effect in electron scattering by gaseous molecules

The experimental intensity of 30 keV electron small angle scattering by a gaseous molecule is much different from the calculation using usual independent atom model. This is due to the rearrangement of electron distribution in a molecule by the formation of chemical bonds, and is called chemical bonding effect (CBE). The molecules studied are mainly hydrocarbons such as methane, acetylene, ethane, etc. and some non-hydrocarbons. The measurement was carried out on both elastic and total scattering and the effect was found for not only elastic but also inelastic scattering. The effect is relatively large for hydrogen rich molecules as H₂O, NH₃ and hydrocarbons, but is essentially related to the number of atoms contained in molecules. The origin of CBE will attribute mainly to the concentration of inner atomic electrons resulting from chemical bonding.     

Fast oxygen ion migration in Cu–In–oxide bulk and its utilization for effective CO2 conversion at lower temperature

Efficient activation of CO₂ at low temperature was achieved by reverse water–gas shift via chemical looping (RWGS-CL) by virtue of fast oxygen ion migration in a Cu–In structured oxide, even at lower temperatures. Results show that a novel Cu–In₂O₃ structured oxide can show a remarkably higher CO₂ splitting rate than ever reported. Various analyses revealed that RWGS-CL on Cu–In₂O₃ is derived from redox between Cu–In₂O₃ and Cu–In alloy. Key factors for high CO₂ splitting rate were fast migration of oxide ions in the alloy and the preferential oxidation of the interface of alloy–In₂O₃ in the bulk of the particles. The findings reported herein can open up new avenues to achieve effective CO₂ conversion at lower temperatures.

Efficient activation of CO₂ at low temperature was achieved by reverse water–gas shift via chemical looping (RWGS-CL) by virtue of fast oxygen ion migration in a Cu–In structured oxide, even at lower temperatures.     

Quadruply BN-Fused Tetrathia[8]circulenes with Flexible Frameworks: Synthesis,Structures and Properties

Quadruply BN-fused tetrathia[8]circulenes were synthesized through four-fold electrophilic borylation. The single-crystal X-ray diffraction analysis revealed that the BN-fused tetrathia[8]circulene with peripheral phenyl groups exhibits crystal polymorphism, in which the circulene core adopts both planar and saddle conformations in the solid state. The experimental and theoretical studies revealed that the weaker aromaticity of azaborine compared with benzene renders the flexibility of the BN-fused tetrathia[8]circulenes.