β-Cyclodextrin Inclusion Complexes of Aromatic Amines and Nitrocompounds and their Photoinduced Electron Transfer Reaction with the Tris(2,2'-bipyridine)ruthenium(II) Complex

The formation of -cyclodextrin (-CD) inclusioncomplexes of aromatic amines and nitrocompounds have been studied by absorptionand emission spectral methods. Among the different compounds studied, p-nitrobenzoic acid showed the smallest K_f value. 3,5-dinitrobenzoic acid showed the highest K_f value due to the formation of a hydrogenbond between the nitro group and the hydrogen in the hydroxyl groupof CD, and this is not possible with p-nitrobenzoic acid. The lower K_f values in the range 60–70 observed for ortho substituted compounds indicate the steric effect imposed by the ortho substitution of the compound. The para substituted compounds showed higher K_f values in the range 110–130 due to the hydrophobic effect and also due tothe absence of a steric effect. The lifetime of the Ru(II) complex is not affected by the presence of -CD. When the aromatic amines and nitrocompounds are used as quenchers for the excited state [Ru(bpy)₃]²⁺, the quenching rate constant (k_q) values are not significantly affected by the presence of -CD. This indicates that the electron donor or electronacceptor groups are not included into the cavity of -CD.     

Stiff magnetofluid cosmological model

We intestigate the behavior of the magnetic field in a cosmological model filled with a stiff perfect fluid in general relativity. The magnetic field is due to an electric current along thex axis. The behavior of the model when a magnetic field is absent is also discussed.     

On the formation of “symmetrical” phenoxazinone derivative related to the actinomycin D chromophore

In studies related to the synthesis of 2-deamino chromophores of actinomycin by reaction of nitrous acid in fluoroboric acid via diazotization of the 2-amino group in the chromophore, the unknown fluorescent product is identified as the symmetrical phenoxazinone by cmr and pmr.     

Transverse surface and slab modes in semiconductor superlattices

It is shown from the exact equations for transverse electromagnetic waves propagating in a superlattice that in the long-wavelength limit the superlattice has the optical properties of a conventional uniaxial medium. This result is used to derive the dispersion equations for polaritons at single and double interfaces between superlattices and ordinary media.     

An Optical Method for Profilometry

Experimental Techniques -     

The reaction between an azomethine and malonyl dichloride

The reaction of o-hydroxybenzylideneamine and malonyl dichloride produces coumarin-3-carboxanilide.     

Doppler-free heterodyne spectroscopy of Hα. measurement of the 2s12 collisional quenching in gas cell

By applying Doppler-free heterodyne spectroscopy techniques to the hydrogen Balmer-α line (λ = 656 nm), one observes a dramatic improvement in S/N ratios for large detection frequencies, δ. Short-noise limited signals are obtained for δ > 2 MHz. Signal phase shifts yield the first “in situ” measurement of the collisional quenching of the 2s_{$\text{1}\text{2}$} metastable state in gas discharges.     

Diastereo- and regioselective Diels-Alder reactions of 2-phosphaindolizines

1,3-Bis(alkoxycarbonyl)-2-phosphaindolizines undergo Diels-Alder reactions at the CP- functionality with 2,3-dimethylbutadiene and with isoprene in the presence of sulfur with complete diastereoselectivity. The reaction with isoprene occurs with 100% regioselectivity as well. 3-Ethoxycarbonyl-1-methyl-2-phosphaindolizine, however, fails to undergo Diels-Alder reaction under these conditions. Difference in the dienophilic reactivities of mono- and bis(alkoxycarbonyl) substituted 2-phosphaindolizines and the observed regioselectivity in the Diels-Alder reaction has been rationalized on the basis of DFT calculations. The relative stabilities of the transition structures have been explained on the basis of the NBO analysis.