Chaos and order in librating quantum planar elastic pendulum

Nonlinear Dynamics - We investigate, numerically and analytically, the quantum mechanics of planar elastic pendulum in libration. The classical phase space of the system consists of both regular...     

Cyanuric chloride–dimethylformamide mediated cleavage of cyclopropylcarbinols-synthesis of phenolic antioxidant and construction of a new vinylcyclopropane skeleton

Differently substituted cyclopropylcarbinols underwent ring cleavage with easily accessible cyanuric chloride–N,N-dimethylformamide adduct to produce homoallylic chlorides or dienes depending on the nature and location of the substituents. A mechanistic explanation of the aforesaid observations has been provided. A promising antioxidant compound was prepared following this protocol and studied against Fenton’s reagent. This methodology was utilized to construct hitherto unreported vinylcyclopropane frameworks bearing homoallylic chloride and diene moieties.     

Triphenylpyridine-based star-shaped π-conjugated oligomers with triphenylamine core: synthesis and photophysical properties

Two novel star-shaped π-conjugated oligomers bearing a triphenylpyridine moiety as peripheral units and triphenylamine as a core have been synthesized via the threefold Heck/Sonogoshira coupling reaction protocol and their absorption and fluorescence properties have been examined. These oligomers showed excellent solubility in common organic solvents, emit light in blue and violet regions, and have high thermal stability.     

Pyridine-cored V-shaped π-conjugated oligomers: synthesis and optical properties

A new series of V-shaped pyridine-cored π-conjugated oligomers are synthesized utilizing two-fold Heck/Suzuki coupling reactions. Optical properties of these compounds (λ_max=390–449 nm, Φ_fl=79–5%, in solutions) are discussed. They are shown to be thermally stable and soluble in common organic solvents. Stilbenoid oligomers exhibited much higher fluorescence quantum yields than tri- and tetra-phenylethylene substituted oligomers in solutions.     

Phase retrieval in optical fiber modal interference for structural health monitoring

A method based on data dependent system (DDS) for extraction of phase in fiber modal interference is presented. The interference patterns of LP₀₁ & LP₁₁, LP₀₁ & LP₀₂ and LP₀₆ &LP₀₇ within the fiber have been recorded under different launching conditions. The patterns were characterized by means of autoregressive model and the self coherence functions of the corresponding interferogram were determined. It would provide the phase distribution of the pattern and the modulation of group delay due to the measurand. An application has been made for measuring strain in a simply supported beam under different loading conditions. Results are presented for the applied strain in the range of 270-1500 μ strain.     

Reaction of a Metallamacrocycle Leading to a Mercury(II)⋅⋅⋅Palladium(II)⋅⋅⋅Mercury(II) Interaction

All wrapped up : The reaction of a 22‐membered macrocycle derived from bis(o‐formylphenyl)mercury and 1,2‐phenylenediamine with palladium(II) results in cleavage of the macrocycle and concomitant formation of a trimetallic complex (see picture; phenyl rings truncated for clarity). The nature of the Hg^II???Pd^II???Hg^II interaction was investigated by theoretical studies.

     

Versatile, fragrant, convertible isonitriles

The metalation of oxazoles leads to ring opening to the isocyanoenolate that can be O-acylated to give the unsaturated isonitriles. These substances undergo conventional multicomponent reactions. The products of their reactions are readily converted to acyl substitution products by treatment with acid and a nucleophile. These unsaturated isonitriles are notable by their simple preparations and, unusually, their nonoffensive odors.     

Existence of a size-dependent diffusivity maximum for uncharged solutes in water and its implications

Recent studies suggest that there exists a size-dependent diffusivity maximum in binary mixtures interacting via Lennard-Jones potential when the size of one of the two components is varied (Ghorai, P. K.; Yashonath, S. J. Phys. Chem., 2005, 109, 5824). We discuss in the present paper the importance of the existence of a size-dependent maximum for an uncharged solute in liquid or amorphous solid water and its relation to the ionic conductivity maximum in water. We report molecular dynamics investigations into the size dependence of the self-diffusivity, D, of the uncharged solutes in water at low temperatures (30 K) with immobile as well as mobile water. We find that a maximum in self-diffusivity exists as a function of the size of solute diffusing within water at low temperatures but not at high temperatures. This is due to the relatively weak interactions between the solute and the water compared to the kinetic energy at room temperature. Previously, we have shown that a similar maximum exists for guests sorbed in zeolites and is known as the levitation effect (LE). Thus, it appears that the existence of a size-dependent maximum is universal and extends from zeolites to simple liquids to solvents of polyatomic species. We examine the implications of this for the size-dependent maximum in ionic conductivity in polar solvents known for over a hundred years. These results support the view that the size-dependent maximum seen for ions in water has its origin in the LE (see Ghorai, P. Kr.; Yashonath, S.; Lynden-Bell, R. M. J. Phys. Chem. 2005, 109, 8120).