Analytical model for ultrashort pulse laser heating in a titanium nanofilm by implementing dual-phase-lag theory in mathematical analysis

Journal of Thermal Analysis and Calorimetry - Surface modification processes of any metallic structure with the help of laser irradiation are a universal practice. The profoundly focused laser beam...     

Interactions of Solvated Electrons with Nucleobases: The Effect of Base Pairing

We have investigated the effect of base pairing on the electron attachment to nucleobases in bulk water, taking the guanine−cytosine (GC) base pair as a test case. The presence of the complementary base reinforces the stabilization effect provided by water and preferentially stabilizes the anion by hydrogen bonding. The electron attachment in bulk-solvated GC happens through a doorway mechanism, where the initial electron attached state is water bound, and it subsequently gets converted to a GC bound state. The additional electron in the final GC bound state is localized on the cytosine, similar to that in the gas phase. The transfer of the electron from the initial water-bound state to the final GC bound state happens due to the mixing of electronic and nuclear degrees of freedom and takes place at a picosecond time scale.     

Keteniminium-Driven Umpolung Difunctionalization of Ynamides

A three-component Pd-catalyzed coupling of ynamides, aryl diazonium salts, and aryl boronic acids for the synthesis of novel triaryl-substituted enamides is described. This transformation represents the first example of an umpolung regioselective unsymmetrical syn-1,2-diarylation/aryl-olefination of ynamides. The aryl moieties of the diazonium salt (electrophile) and boronic acid (nucleophile) are explicitly incorporated in the electrophilic α- and nucleophilic β-position, respectively, of the ynamide, resulting in a single isomer of the N-bearing tetrasubstituted olefin. The scope is broad (68 examples), showing excellent functional-group tolerance. DFT calculations substantiate the rationale of the mechanistic cycle and the regioselectivity. The chemoselectivity and synthetic potential of the enamide products were also studied.     

Interplay of Anion-π+ and π+-π+ Interactions in Novel Pyrido[2,1-a]isoquinolinium-Based AIEgens - Substituent- and Counterion-Dependent Fluorescence Modulation and Applications in Live Cell Mitochondrial Imaging**

Recently, the concept of anion-π⁺ interactions has witnessed unique applications in the field of AIEgen development. In this contribution, we disclose a consolidated study of a library of N-doped ionic AIEgens accessed through silver-mediated cyclization of pyridino-alkynes. A thorough photophysical, computational and crystallographic study has been conducted to rationalize the observed substituent- and counterion-dependent fluorescence properties of these luminogens. We further elucidate the prominent role of anion-π⁺ interactions, π⁺-π⁺ interactions and other non-covalent interactions, in inhibiting the undesired ACQ effect. Finally, we have also demonstrated the application of selected AIEgens for imaging of mitochondria in live cells.     

A Diruthenium Complex of an N-Pyridyl-o-aminophenol Derivative: A Route to Mixed Valency

An N-pyridyl-o-aminophenol derivative that stabilises mixed-valence states of ruthenium ions is disclosed. A diruthenium complex, [(L_IQ⁰)Ru₂Cl₅] ⋅ MeOH ( 1⋅ MeOH) is successfully isolated, in which L_IQ⁰ is the o-iminobenzoquinone form of 2-[(3-nitropyridin-2-yl)amino]phenol (L_APH₂). In 1 , L_IQ⁰ oriented towards one ruthenium centre is a non-innocent NO-donor redox ligand, whereas another oriented towards another ruthenium centre is an innocent pyridine-donor redox ligand. Complex 1 is a diruthenium(II,III) mixed-valence complex, [Ru^II(L_IQ⁰)(μ-Cl)₂Ru^III], with a minor contribution from the diruthenium(III,III) state. [Ru^III(L_ISQ^.−)(μ-Cl)₂Ru^III] contains L_ISQ^.−, which is the o-iminobenzosemiquinonate anion radical form of the ligand. Complexes 1 ⁻ and 1 ⁺ are diruthenium(II,II), [Ru^II(L_IQ⁰)(μ-Cl)₂Ru^II], and diruthenium(III,III), [Ru^III(L_IQ⁰)(μ-Cl)₂Ru^III], complexes, respectively, of L_IQ⁰. Complex 1 ²⁻ is a diruthenium(II,II) complex of the o-iminobenzosemiquinonate anion radical (L_ISQ^.−), [Ru^II(L_ISQ^.−)(μ-Cl)₂Ru^II], with a minor contribution from the diruthenium(III,II) form, [Ru^III(L_AP²⁻)(μ-Cl)₂Ru^II]. Complex 1 ²⁺ is a diruthenium(III,IV) mixed-valence complex of L_IQ⁰, [Ru^III(L_IQ⁰)(μ-Cl)₂Ru^IV]. Complexes 1 and 1 ²⁺ exhibit inter-valence charge-transfer transitions at λ=1300 and 1370 nm, respectively.     

Synthesis,characterization and arsenate binding events of new mononuclear copper(II) complexes

Two new mononuclear copper (II) complexes [Cu(L)(H₂O)Cl] (1) and [Cu(L)(H₂O)(SCN)] (2) (HL = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol) have been synthesized and characterized in order to investigate their binding interaction with arsenate ions. Complexes 1 and 2 were synthesized by performing reaction of CuCl₂·2H₂O or CuCl₂·2H₂O/NH₄SCN, respectively, with HL using Et₃N as mild base in MeOH solution at room temperature, and characterized by employing a number of analytical techniques, for example, elemental analysis, molar electrical conductivity, FTIR, UV–Vis and mass spectrometry. Their structures, optimized at DFT/B3LYP/6-311G level, show that the copper atom in 1 and 2 exhibits a distorted square pyramidal geometry. In H₂O/MeOH (3:1; v/v) solution, complexes 1 and 2 were examined for their binding affinity towards arsenate ions. The UV–Vis spectroscopic results specify that the arsenate group binds with 1 and 2 in 1:1 M ratio. The UV–Vis titration data were successfully utilized to calculate the binding constants of arsenate-bound Cu(II) complexes, and the values are found to be 1.723 × 10⁴ M^?1 and 2.161 × 10⁴ M^?1, corresponding to 1/AsO₄^3? and 2/AsO₄^3? assemblies, respectively.     

Parameter estimation for 1D PWL chaotic maps using noisy dynamics

Nonlinear Dynamics - Many physical situations involve chaotic systems implemented in hardware. Among them one-dimensional piecewise linear maps are popular candidates for such applications because...     

Critical stability and quantum phase transition of screened two-electron system

The ground state energy and structural properties of a model two-electron system (Zee), bound via screened Coulomb interaction with nuclear charge Z, have been studied under the variational framework. Hylleraas type basis has been adopted for explicit incorporation of the electron–electron correlation. Critical nuclear charges (Z_c) of Zee system have been reported for different screening parameters (μ). Expectation values of different structural properties have been estimated to predict the internal structure of the Zee system. The variation of the structural properties with respect to Z for different μ reveals the signature of quantum phase transition (QPT) in the vicinity of Z_c. Moreover, the nature of variation of these properties with respect to Z in case of bare Coulomb or free system (μ = 0) is completely opposite to those of screened system (μ ≠ 0). Radial two-particle density (TPD) confirms the symmetry breaking of the electronic structure and therefore QPT in the vicinity of Z_c.     

Fixation of cesium on crystalline titania with high leach-resistivity

A study of fixation of caesium on crystalline titania by co-precipitation was carried out. A maximum loading of ∼46wt% of caesium was found to be incorporated in the titania matrix. High leach-resistivity of Cs cations was observed to be in the order of 10⁻⁶–10⁻⁸ g^.m^−2.d⁻¹ by Soxhlet flow refluxing at 97 °C of the composite material calcined at 800, 1000 °C for 48 hours. The analysis of X-ray powder diffractions of the composite materials revealed that cesium was fixed in the crystal lattice of host titania with the formation of new mineral phases of CsTi₄O₉ and Cs₂Ti₅O₁₁. The results, taken together, implicate that a better fixation of caesium on titania can be achieved by calcination at 1000 °C for 48 hours.