Bonding modes of nitrite and nitrate in palladium(II) and platinum(II) complexes

The crystal structures of the well-known complexes, [(Me₄en)M(II)X₂] (Me₄en?=?N,N,N??,N??-tetramethylethylenediamine; M(II)?=?Pd(II) or Pt(II); X ^??=?NO₂ ^? or NO₃ ^?) have been determined. For [(Me₄en)Pd(NO₂)₂] and [(Me₄en)Pt(NO₂)₂], the nitrite anion acts as a monodentate N-donor ligand in the solid state. In contrast, for [(Me₄en)Pd(ONO₂)(O₂NO)], the two nitrate anions act as a monodentate O-donor (ONO₂) and a bidentate O,O??-donor (O₂NO). Recrystallization of [(Me₄en)Pt(NO₃)₂] from Me₂SO yields the Me₂SO adduct with a monodentate O-donor nitrate and a counteranionic nitrate, [(Me₄en)Pt(ONO₂)(S-Me₂SO)](NO₃). The solution behavior of these complexes, including the equilibrium between coordinated and free Me₂SO, has been investigated.     

Self-rotation of elliptically polarized light in Doppler-broadened rubidium atoms

We present a theoretical and experimental study of self-rotation of incident elliptically polarized light on a rubidium atomic vapor. We construct density matrix equations, which are then solved numerically, and further averaged over atomic transit times and a Maxwell-Boltzmann velocity distribution. We calculate the rotation angle as a function of detuning for various laser intensities and polarizations. We compare the calculated results with experimental results and find good agreement between them.     

Adsorption and thermal decomposition of 2-octylthieno[3,4-b]thiophene on Au(111)

The adsorption and thermal stability of 2-octylthieno[3,4-b]thiophene (OTTP) on the Au(111) surfaces have been studied using scanning tunneling microscopy (STM), temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). UHV-STM studies revealed that the vapor-deposited OTTP on Au(111) generated disordered adlayers with monolayer thickness even at saturation coverage. XPS and TPD studies indicated that OTTP molecules on Au(111) are stable up to 450K and further heating of the sample resulted in thermal decomposition to produce H(2) and H(2)S via C-S bond scission in the thieno-thiophene rings. Dehydrogenation continues to occur above 600K and the molecules were ultimately transformed to carbon clusters at 900K. Highly resolved air-STM images showed that OTTP adlayers on Au(111) prepared from solution are composed of a well-ordered and low-coverage phase where the molecules lie flat on the surface, which can be assigned as a (9×2√33)R5° structure. Finally, based on analysis of STM, TPD, and XPS results, we propose a thermal decomposition mechanism of OTTP on Au(111) as a function of annealing temperature.     

Salicylimine-based fluorescent chemosensor for aluminum ions and application to bioimaging

In this study, an assay to quantify the presence of aluminum ions using a salicylimine-based receptor was developed utilizing turn-on fluorescence enhancement. Upon treatment with aluminum ions, the fluorescence of the sensor was enhanced at 510 nm due to formation of a 1:1 complex between the chemosensor and the aluminum ions at room temperature. As the concentration of Al(3+) was increased, the fluorescence gradually increased. Other metal ions, such as Na(+), Ag(+), K(+), Ca(2+), Mg(2+), Hg(2+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), Cr(3+), Fe(3+), and In(3+), had no such significant effect on the fluorescence. In addition, we show that the probe could be used to map intracellular Al(3+) distribution in live cells by confocal microscopy.     

Ethylene/Norbornene Copolymerization with iPr(Cp)(Flu)ZrCl2 Catalyst: Effect of MAO Cocatalyst and 3rd Monomer

The copolymerization of ethylene and norbornene (N) was carried out with iPr(Cp)(Flu)ZrCl₂ catalyst and modified methylaluminoxane (MMAO) cocatalyst. The catalytic activity was dependent on the structure of MMAO, i.e., MMAO-4 exhibited higher catalyst activity than MMAO-3A containing more i-butyl groups. The glass transition temperature (T_g) and the composition of the produced copolymer were not affected by MMAO type. With styrene derivatives as 3^rd monomer, T_g of copolymer increased while the catalytic activity decreased. With the addition of 3^rd monomer, not only the content of 3^rd monomer but also the content of N increased.     

Isolation of Industrial Important Bioactive Compounds from Microalgae

Microalgae are known as a rich source of bioactive compounds which exhibit different biological activities. Increased demand for sustainable biomass for production of important bioactive components with various potential especially therapeutic applications has resulted in noticeable interest in algae. Utilisation of microalgae in multiple scopes has been growing in various industries ranging from harnessing renewable energy to exploitation of high-value products. The focuses of this review are on production and the use of value-added components obtained from microalgae with current and potential application in the pharmaceutical, nutraceutical, cosmeceutical, energy and agri-food industries, as well as for bioremediation. Moreover, this work discusses the advantage, potential new beneficial strains, applications, limitations, research gaps and future prospect of microalgae in industry.     

Dependence of the heavy-hole exciton reduced mass on quantum-well size in InGaAs/GaAs heterostructures

We present low temperature photoluminescence investigations of the exciton ground state of In_0.14Ga_0.86As/GaAs quantum wells (QW) in the presence of pulsed magnetic fields up to 50 T. The exciton in-plane reduced mass and the heavy-hole in-plane mass are determined from the best fit of theoretical calculations to the magnetic field dependence of PL peaks. When the QW thickness decreases, their masses increases due to valence-band mixing effect.     

Migration-enhanced epitaxy (MEE) growth of five-layer asymmetric coupled quantum well (FACQW) and its cross-sectional STM observation

The five-layer asymmetric coupled quantum well (FACQW) is a new potential-tailored quantum well that is promising for ultra-fast and ultra-low-voltage optical modulators and switches. FACQW samples were grown by the migration-enhanced epitaxy (MEE) and the conventional molecular beam epitaxy methods with steep and flat heterointerfaces in the monolayer accuracy. They were characterized with the cross-sectional scanning tunneling microscopy (STM). In the cross-sectional STM image, double-stripe structures with different contrast were observed. The stripe area corresponds to the FACQW (about 10 nm wide), sandwiched with the AlGaAs barrier layers (15 nm wide). A dark line observed at the middle of the FACQW stripe area corresponds to the 3-monolayer-thick AlAs layer. The cross-sectional STM images of the high-quality heterointerface FACQW structures were successfully observed for the samples grown by the MEE method. More detailed studies of this kind of cross-sectional STM observations will be very effective to obtain the optimized growth conditions for fine and complicated ultra-thin structures.     

Reinvestigation in the photoreaction of 1-naphthalenecarbonitrile and furan

Photocycloaddition of furan to 1-naphthalenecarbonitrile (1) was reinvestigated. Irradiation of the mixture through Pyrex filter yielded endo-[4+4] adduct (2) and syn-[2+2] adduct (4). Considering the secondary orbital interaction in the singlet-state [4+4] photocycloaddition, the favorable formation of exo-[4+4] cyclodimer (3) over 2 followed by a facile Cope rearrangement was proposed for the formation of 4, and confirmed by a low temperature irradiation experiment.