CuCl catalyzed green and efficient one-pot synthesis of aminoindolizine frameworks via three-component reactions of aldehydes, secondary amines, and terminal alkynes in PEG

CuCl catalyzes efficient synthesis of aminoindolizine scaffolds by one-pot reactions in PEG of pyridine- or quinoline-2-carboxaldehydes with secondary amines and terminal alkynes via tandem C-H activation, coupling, and cyclization reactions. The reactions are easy to perform, atom-economic, environment friendly, broad in scope, and allow the generation of a number of biologically potent aminoindolizine frameworks from readily accessible starting materials.     

Light-Induced Formation of Thymine-Containing Mercury(II)-Mediated Base Pairs

By applying caged thymidine residues, DNA duplexes were created in which Hg^II-mediated base pair formation can be triggered by irradiation with light. When a bidentate ligand was used as the complementary nucleobase, an unprecedented stepwise formation of different metal-mediated base pairs was achieved.     

Sequential detection of Cu2+ and cysteine using an imidazole‐based chemosensor in aqueous solution

A highly substituted imidazole‐based colorimetric and fluorogenic chemosensor, 2‐methoxy‐4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)phenol (L), for the detection of Cu²⁺ ion and subsequent colorimetric detection of an amino acid, cysteine, was investigated. L exhibited a distinct color change from colorless to red in the presence of Cu²⁺ in an aqueous medium. The L‐Cu²⁺ complex can also be used to detect cysteine by the naked eye over a series of amino acids. The receptor L behaves as a highly selective colorimetric and fluorescent sensor for Cu²⁺ ions at concentrations as low as 4.33 and 2.25 μM, respectively. These values are much less compared to the WHO recommended limit of 30 μM for Cu²⁺ in drinking water. From Job's plot and the ESI‐MS spectrum, a 1:1 stoichiometric complex between L and Cu²⁺ ions can readily be reckoned. This binding was also substantiated by the EPR spectrum and magnetic susceptibility measurements. Additionally, the binding of L with Cu²⁺ ions was also manifested in the detection of B16F10 cells. This was substantiated through fluorescence microscopy. The spectrum of the L‐Cu²⁺ entity was also attempted to reproduce theoretically. The probable structure of this was also propounded through Density Functional Theory.     

Controlling the isomerization dynamics of iodide acetonitrile dimer complex by optimally designed electromagnetic field: A wave packet based approach

Both symmetric and asymmetric forms of the iodide acetonitrile dimer complex are known to exist with a higher stability shown by the symmetric isomer. Dynamics of this isomerization has been investigated on reduced dimensional surface in absence/presence of external electromagnetic field using Gaussian wave packet as the starting wave function. When the symmetric isomer has been taken as the initial structure, isomerization does not takes place without the external field due to high energy barrier, whereas with the asymmetric isomer as the starting one, isomerization takes place spontaneously with an equal population of both isomers. Our target in this study has been to get a dominant population of asymmetric isomer which is not possible without the application of electromagnetic field. However, it has also been seen that a simple monochromatic field cannot achieve this goal. Only by application of optimally designed polychromatic field the dominating population of asymmetric isomer can be obtained.     

Alpha radioactivity in human blood and its possible correlation to ailment pattern

Journal of Radioanalytical and Nuclear Chemistry - Human blood, beside its multi-functional activities, may carry different ionizing radiation emitters to the whole body, spatially alpha emitters,...     

An audio encryption based on distinct key blocks along with PWLCM and ECA

This paper presents a robust audio encryption scheme based on three consecutive phases, accomplished as cyclic shift followed by ciphering and wound up by shuffling, to break the high correlation amongst the neighbouring region of a plain audio. To encrypt a plain audio, the entire audio is split into different blocks of 64 bytes each and distinct key blocks are used for those audio blocks in the foregoing three phases. At first, the correlation of each audio block is reduced by the cyclic shift; thereafter, these shifted blocks are ciphered with piecewise linear chaotic map (PWLCM) along with elementary cellular automata (ECA) and finally, turns up with shuffling of ciphered bytes for better diffusion. The significant feature of this scheme is to generate distinct key blocks, which are highly sensitive to the secret key, a combination of the 64-byte external key along with the plain audio-dependent value. Moreover, these key blocks are derived using PWLCM from the secret key along with the preceding key block and previous encrypted block to achieve resistance against the known plain-text attack. It uses key space as large as \(2^{576}\) to resist brute-force attacks. The robustness as well as competence of this scheme is established with statistical analyses, cryptanalysis, randomness analysis and comparisons with existing schemes.

     

An efficient block-level image encryption scheme based on multi-chaotic maps with DNA encoding

Nonlinear Dynamics - This paper presents an efficient image encryption scheme based on permutation followed by diffusion, where both of these phases use 2-d Sine logistic modulation map (SLMM) with...     

A Remarkable Fluorescence Quenching Based Amplification in ATP Detection through Signal Transduction in Self-Assembled Multivalent Aggregates

Signal transduction is essential for the survival of living organisms, because it allows them to respond to the changes in external environments. In artificial systems, signal transduction has been exploited for the highly sensitive detection of analytes. Herein, a remarkable signal transduction, upon ATP binding, in the multivalent fibrillar nanoaggregates of anthracene conjugated imidazolium receptors is reported. The aggregates of one particular amphiphilic receptor sensed ATP in high pm concentrations with one ATP molecule essentially quenching the emission of thousands of receptors. A cooperative merging of the multivalent binding and signal transduction led to this superquenching and translated to an outstanding enhancement of more than a millionfold in the sensitivity of ATP detection by the nanoaggregates; in comparison to the “molecular” imidazolium receptors. Furthermore, an exceptional selectivity to ATP over other nucleotides was demonstrated.