Sodium borohydride-iodine mediated reduction of γ-lactam carboxylic acids followed by DDQ mediated oxidative aromatisation: a facile entry to N-aryl-formylpyrroles

A simple methodology for the conversion of substituted N-aryl-γ-lactam 2/3-carboxylic acids to substituted N-aryl-2/3-formyl-pyrroles has been developed. Several N-aryl-γ-lactam 2/3-carboxylic acids were reduced to substituted (N-aryl-pyrrolidine-2/3-yl)-methanols in good yields at room temperature using sodium borohydride-iodine. Controlled oxidation and aromatisation of these alcohols using DDQ produced N-aryl-2/3-formyl-pyrroles.     

The Nonclassicality and Decoherence of a Superposition State Generated in a Resonant Cavity

We discuss nonclassicality of a superposition of coherent states in terms of sub-Poissonian photon statistics as well as the negativity of the Wigner function. We derive an analytic expression for the Wigner function from which we find that the function has some negative region in phase space. We obtain a compact form of the Wigner function when decoherence occurs and study the effect of decoherence on the state. We demonstrate the behaviour of the nonclassicality indicator.     

Morphological consequences of metal ion-peptide vesicle interaction

The triskelion peptide conjugate 1, having a Trp-Trp dipeptide unit on the three arms, was synthesized and studied for the interaction of peptide-based soft structures with metal ions, by fluorescence and microscopic analyses. We observed that fluorescence was significantly quenched upon addition of Cu(II) metal ions, whereas the addition of other metal ions also caused moderate to insignificant changes in the fluorescence emission, suggesting specificity of this triskelion peptide 1 for Cu(II) ions. The addition of Cu(II) and other metal ions also altered the morphology of preformed vesicles obtained from triskelion peptide 1 in a concentration-dependent fashion, as observed from microscopic analysis. Such metal-responsive soft structures may find potential use as novel materials for delivery and sensing applications.     

Chemical Approach Towards Broadband Spintronics on Nanoscale Pyrene Films

The injection of pure spin current into the non-magnetic layer plays a crucial role in transmitting, processing, and storing data information in the realm of spintronics. To understand broadband molecular spintronics, pyrene oligomer film (≈20 nm thickness) was prepared using an electrochemical method forming indium tin oxide (ITO) electrode/pyrene covalent interfaces. Permalloy (Ni₈₀Fe₂₀) films with different nanoscale thicknesses were used as top contact over ITO/pyrene layers to estimate the spin pumping efficiency across the interfaces using broadband ferromagnetic resonance spectra. The spintronic devices are composed of permalloy/pyrene/ITO orthogonal configuration, showing remarkable spin pumping from permalloy to pyrene film. The large spin pumping is evident from the linewidth broadening of 5.4 mT at 9 GHz, which is direct proof of spin angular momentum transfer across the interface. A striking observation is made with the high spin-mixing conductance of ≈1.02×10¹⁸ m⁻², a value comparable to the conventional heavy metals. Large spin angular moment transfer was observed at the permalloy-pyrene interfaces, especially at the lower thickness of permalloy, indicating a strong spinterface effect. Pure spin current injection from ferromagnetic into electrochemically grown pyrene films ensures efficient broadband spin transport, which opens a new area in molecular broadband spintronics.     

RETRACTED ARTICLE: Effect of electromagnetic field on the stability of viscoelastic fluid film flowing down an inclined plane

The stability of thin electrically conducting viscoelastic fluid film flowing down on a non-conducting inclined plane in the presence of electromagnetic field is investigated under induction-free approximation. Surface evolution equation is derived by long-wave expansion method. The stabilizing role of Hartman number M (magnetic field) and the destabilizing role of the viscoelastic property \({\varGamma}\) and the electric parameter E on such fluid film are established through the linear stability analysis of the surface evolution equation. Investigation shows that at small values of Hartman number (M), the influence of electric parameter (E) on the viscoelastic parameter \({(\varGamma)}\) is insignificant, while for large values of M, E introduces more destabilizing effect at low values of \({\varGamma}\) than that at high values of \({\varGamma }\). An interesting result also perceived from our analysis is that the stabilizing effect of Hartman number (M) is decreasing with the increase of the values of \({\varGamma}\) and E, even it gives destabilizing effect after a certain high value of the electric field depending on the high value of \({\varGamma}\). The weakly nonlinear study reveals that the increase of \({\varGamma}\) decreases the explosive and subcritical unstable zones but increases the supercritical stable zone keeping the unconditional zone almost constant.     

Double versus single helical structures of oligopyridine-dicarboxamide strands. Part 2: The role of side chains

A series of heptameric oligoamides comprising 4-alkoxy-substituted 2,6-diaminopyridine and 2,6-pyridine-dicarbonyl units have been synthesized using convergent methods. The hybridization of these compounds into double helical dimers was studied in solution by ¹H NMR spectroscopy in CDCl₃ or DMSO-d₆ at various concentrations, and in the solid state using X-ray crystallographic analysis. Both solid state and solution data suggest that these compounds follow identical hybridization schemes. In CDCl₃, the oligomers possess dimerization constants considerably (up to 2000-fold) higher than related compounds having no alkoxy substituents on their 2,6-diaminopyridine units. The origin of this effect can be in part interpreted as a result of interactions between the 4-alkoxy side chains when they are present on all pyridine rings. For example, 4-benzyloxy-substituted oligomer 2 has a higher dimerization constant than 4-decyloxy and 4-methoxy-substituted analogues 1 and 3. The crystal structure of 2 reveals multiple aromatic-aromatic interactions between the benzyl side chains, both face-to-face and edge-to-face at various angles surrounding the duplex. In the solid state, these double helices are stacked on top of each other to form long channels filled with water molecules. The 4-methoxy and 4-decyloxy-substituted analogues 1 and 3 have similar dimerization constants, showing that interactions between side chains are not significant between purely aliphatic residues. Consequently, the high stability of the double helices formed by 1 and 3 compared to related compounds having alkoxy substituents on their 2,6-pyridine-dicarbonyl units only does not find its origin in interactions between side chains but in the direct effect of the alkoxy substituents upon main chain aryl-aryl interactions.     

On the microscopic basis of Newton's law of cooling and beyond

The microscopic basis of Newton's law of cooling and its modification when the difference in temperature between the system and the surroundings is very large is discussed. When the system of interest is interacting with a small bath, the effect of the dynamical evolution of the bath variables is important to find out its dynamical feedback on the system. As in the usual system-bath approach, however, the bath is finally considered to be in thermal equilibrium and thereby provides an effective generalization of the Born-Markov master equation. It is shown that the cooling at early time is faster than that predicted by Newton's law due to the dynamical feedback of the bath.     

A strategy for designing "multi-prong" enzyme inhibitors by incorporating selective ligands to the liposomal surface

We offer a novel strategy for designing "multi-prong" inhibitors of enzymes by incorporating selective ligands on the liposomal surface.     

Phosphorus‐Doped Graphene Oxide Layer as a Highly Efficient Flame Retardant

A simple and easy process has been developed to efficiently dope phosphorus into a graphene oxide surface. Phosphorus‐doped graphene oxide (PGO) is prepared by the treatment of polyphosphoric acid with phosphoric acid followed by addition of a graphene oxide solution while maintaining a pH of around 5 by addition of NaOH solution. The resulting materials are characterized by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The as‐made PGO solution‐coated cloth exhibits excellent flame retardation properties. The PGO‐coated cloth emits some smoke at the beginning without catching fire for more than 120 s and maintains its initial shape with little shrinkage. In contrast, the pristine cloth catches fire within 5 s and is completely burned within 25 s, leaving trace amounts of black residue. The simple technique of direct introduction of phosphorus into the graphene oxide surface to produce phosphorus‐doped oxidized carbon nanoplatelets may be a general approach towards the low‐cost mass production of PGO for many practical applications, including flame retardation.