Synthesis of 1-trifluoroacetyl-3-dialkylamino-methyl-5-monosubstituted benzimidazoline-2-thiones using trifluoroacetic acid as an acylating agent

1-Trifluoroacetyl-3-dialkylaminomethyl-5-monosubstituted benzimidazoline-2-thiones have been synthesized from p-substituted anilines which were acetylated with trifluoroacetic acid. The trifluoroacetanilides were nitrated, reduced and cyclised with carbon disulphide in the presence of alcoholic potassium hydroxide and finally treated with formaldehyde and suitable secondary amines to afford the Mannich bases. The compounds were characterised by their analytical and spectral (ir, pmr, ¹⁹F and mass) data. The synthesized compounds have been screened for anti-inflammatory and analgesic activity and found to be active.     

Solvent effects on the absorption and fluorescence spectra of coumarins 6 and 7 molecules: determination of ground and excited state dipole moment

Absorption and fluorescence emission spectra of coumarins 6 and 7 were recorded in solvents with different solvent parameters, viz., dielectric constant epsilon and refractive index n. The fluorescence lifetime of these dyes were measured in butanol at higher values of viscosity over temperature. Experimental ground and excited state dipole moments are determined by means of solvatochromic shift method and also the excited state dipole moments are determined in combination with ground state dipole moments. It was determined that dipole moments of the excited state were higher than those of the ground state in both the molecules.     

Electrohydrocyclization of alkoxy tether substituted mixed enone/enoate and bisenone systems: retention versus elimination

The electrohydrocyclization of tethered enone/enoate or bisenone systems which contain an alkoxyl substituent in the tether was studied. Rather surprisingly, the cyclization of these compounds afforded very different products depending upon the alkoxy substituent. This behavior and its potential applications will be discussed.     

Leucoxol,a new diterpenoid from acacia leucophloea. X-ray structure determination

From $\text{Acacia leucophloea}$ (Roxb.) Willd. (Mimosaceae) the new diterpenoid 11α, 16-epoxy-1β, 15$\text{R}$-dihydroxy-isopimar-8(14)-ene (leucoxol) has been isolated. Its structure was determined by X-ray diffraction analysis.     

Characterization of new fluorescent peroxidase substrates

The reagents Lumigen PS-1 and Lumigen PS-3 were originally developed as chemiluminescent substrates for ultrasensitive detection of horseradish peroxidase (HRP) in homogeneous solution and membrane blotting assays. However, an additional unique feature of these acridan-based reagents is the generation of a fluorescent species on reaction with peroxidase, a property which has been termed as chemifluorescence. These reagents, therefore, represent the first dual-use substrates enabling both chemiluminescent and fluorescent detection. We have developed several additional acridan-based substrates for fluorescent detection of HRP which are capable of subattomole detection sensitivity. By varying several structural parameters within the class of compounds we have produced substrates which either produce fluorescence alone or both chemiluminescence and fluorescence.     

13C NMR relaxation study of molecular motions in tetraphenyltin and tetra(p-tolyl)tin in solution

The Woessner approach is applied to the 13C relaxation data for tetraphenyltin (1) and tetra(p-tolyl)tin (2) in CDCl3 solution over the temperature range 5-42 degrees C to obtain correlation times for rotational motions and hence the activation barriers. Quantum mechanical computations were carried out to obtain the rotational energy barriers for comparison. For 2 the relaxation data indicate (1) slower ring rotation than in 1, (2) highly hindered internal rotation of the methyl group. IR and chemical shift data support the hypothesis of hyperconjugation of the methyl correlated with interaction between the pi-electrons and the 5d orbitals of tin in the (p-tolyl)Sn moiety to account for the hindrances to the rotations of the ring and the methyl. The activation barrier for the tolyl group rotation is found to be much higher than that for the phenyl rotation. However, the Woessner approach yields an anomalously high barrier for the methyl rotation. An explanation based on correlated rotations of the tolyl ring and the methyl is offered.     

A decomposition of continuity via ideals

A new class of sets in ideal topological spaces is introduced and using these sets, a decomposition of continuity is given.      

Heat transfer in channel flow of a micropolar fluid

The study of heat transfer in channel flow has been done by previous authors for Newtonian and elastico-viscous fluids. It is the aim of the present paper to study the temperature profile for flow of a micropolar fluid in a channel induced by a constant axial pressure gradient, when the walls are maintained at constant temperatures. We have examined the effects of microrotation on the temperature profile and on the kinetic energy of the fluid. Three cases have been chosen by us for detailed study: (i) both the walls are maintained at different constant temperatures, (ii) both the walls are maintained at the same constant temperature, (iii) one wall is kept at a constant temperature and there is no heat flux at the other wall.     

Solvent Dependence on Structure and Electronic Properties of 7-(Diethylamino) - 2H -1- Benzopyran-2- one (C-466) Laser Dye

In this work, we studied influences on the absorption and fluorescence emission spectra of coumarin-4066 (C-466) with different solvent polarity scale. The spectral shifts reflect the effect of the equilibrium solvents association across the energized solute particle, which adjusts inertially as a result of quick charge realignment upon radiative deactivation to the lowest electronic state. The dipole moments of C-466 are determined by employing the Bakhshiev, Kawski-Chamma-Viallet, Lippert-Mataga and McRae relations. The results from all these methods are, excited state dipole moment of C-466 is higher than the ground state dipole moments and which indicates molecule is less polar in the ground state. Theoretical analysis was also carried out by Density Functional theory (DFT and TD –DFT) employing the BECKE-1998 (exchange)/STO-6G basic set in ethanol solvent and in vacuum medium. The HOMO-LUMO, Solvent Accessible Surfaces (SAS) and Molecular Electrostatic Potential (MEP) were analysed to acquire additional knowledge of the molecular arrangement and electronic properties of C-466. These photophysical properties suggest delineation can be mauled for laying out new luminescent tests for various solvents microenvironment.