CuI catalyzed sulfamidation of arylboronic acid using TsNBr2 at room temperature

An expeditious protocol for amidation arylboronic acid has been developed using TsNBr₂ as the nitrogen source in presence of a CuI as catalyst. Various arylboronic acids could be transformed into corresponding N-arylsulfonamide derivatives within a very short time using CuI as catalyst in presence of DBU at room temperature.     

Heterobimetallic dioxomolybdenum(VI) complexes derived from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone: Synthesis and characterization

The heterobimetallic complexes [MMoO₂(L)(H₂O)₂] (where M = Zn²⁺ (1), Cu²⁺ (2), and Co²⁺ (4)) and [{MMoO₃(H₂L)(H₂O)₂}₂] (where M = Ni²⁺ (3) and Mn²⁺ (5)) are synthesized from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (H₄L) using the monometallic precursor complex [MoO₂(H₂L)]·H₂O in ethanol. The composition of the complexes is established based on the data obtained from the elemental analysis and molecular weight determinations. The structure of the complexes is discussed in the light of data obtained from molar conductance, magnetic moment, electronic, EPR and IR spectroscopic studies.     

Synthesis of bioactive heterocycles using reusable heterogeneous catalyst HClO4–SiO2 under solvent-free conditions

We are reporting a simple, efficient and green protocol for the synthesis of chromenes and dihydropyrimidines (products of Knoevenagel and Biginelli reaction, respectively) by the use of silica-supported perchloric acid (HClO₄–SiO₂) as an effective heterogeneous catalyst. Short reaction times, high product yields, simple procedure and reusability of the catalyst are the superior characteristics of this protocol.     

Subnatural linewidth in a strongly-driven degenerate two-level system

We observe linewidths below the natural linewidth for a probe laser on a degenerate two-level F → F′ transition, when the same transition is driven by a strong control laser. We take advantage of the fact that each level of the transition is made of multiple magnetic sublevels, and use the phenomenon of electromagnetically induced transparency (EIT) or absorption (EIA) in multilevel systems. Optical pumping by the control laser redistributes the population so that only a few sublevels contribute to the probe absorption, an explanation which is verified by a density-matrix analysis of the relevant sublevels. We observe more than a factor of 3 reduction in linewidth in the D₂ line of Rb in room-temperature vapor. Such subnatural features vastly increase the scope of applications of EIT, such as high-resolution spectroscopy and tighter locking of lasers to atomic transitions, since it is not always possible to find a suitable third level.     

Cosmological Models with Time Dependent G and Λ Coupling Scalars

A cosmological model in which the universe has its critical density and gravitational constants generalized as coupling scalars in Einstein's theory is considered. A general method of solving the field equations is given. An exact solution for matter distribution in cosmological models satisfying G=G₀(R/R₀)ⁿ is presented. Corresponding physical interpretations of the cosmological solutions are also discussed.     

Cosmological Models with Time Dependent G and A Coupling Scalars

A cosmologicM model in which the universe has its critical density and gravitational constants generalized as coupling scalars in Einstein＇s theory is considered. A general method of solving the field equations is given. An exact solution for matter distribution in cosmological models satisfying G = G0（ R/ R0）^n is presented. Corresponding physical interpretations of the cosmological solutions are also discussed.     

Characterization of heterobimetallic and mixed-valence complexes of molybdenum(V) derived from bis(2-hydroxy-1-naphthaldehyde) malonoyldihydrazone

Heterobimetallic complexes [UO₂Mo^V(CH₂L)(hzd)(H₂O)₂] _n , [ZnMo^V(CH₂L)(hzd)(H₂O)₂] _n and mixedvalence complexes [Mo^VIO₂Mo^V(CH₂L)(hzd)(H₂O)₂] _n (where hzdH₃ = inhH₃, n = 1; slhH₃, n = 2) are synthesized from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (CH₂LH₄) and monometallic precursor complexes [Mo(CH₂LH₂)(hzd)]·nH₂O (n = 0, 1) in ethanol. The composition of the complexes is established based on the data obtained from the elemental analysis. The structure of the complexes is discussed in the light of data obtained from molar conductance, magnetic moment, electronic, EPR, and IR spectroscopic studies. All complexes have ??B values in the range 1.59?C1.64 B.M., slightly lower than that required for one unpaired electron. The heterobimetallic complexes show two bands, while mixed-valence complexes show only one band in the visible region assigned to the d-d transition. The g-values decrease in going from uranyl-to-molybdenyl-to-zinc complexes containing the isonicotinoyldiazenido (inh) group, however, no such regular trend is observed in the case of complexes containing the salicyloyldiazenido (slh) group in the coordination sphere. In all complexes, the principal dihydrazone ligand is present in the enol form as a bridging hexadentate ligand in the anti-cis configuration where hydrazide ligands are coordinated to the metal centre as a trinegative bidentate ligand in the diazenido form.     

Three and four-body systems in one dimension: Integrability,superintegrability and discrete symmetries

Families of three-body Hamiltonian systems in one dimension have been recently proved to be maximally superintegrable by interpreting them as one-body systems in the three-dimensional Euclidean space, examples are the Calogero, Wolfes and Tramblay Turbiner Winternitz systems. For some of these systems, we show in a new way how the superintegrability is associated with their dihedral symmetry in the three-dimensional space, the order of the dihedral symmetries being associated with the degree of the polynomial in the momenta first integrals. As a generalization, we introduce the analysis of integrability and superintegrability of four-body systems in one dimension by interpreting them as one-body systems with the symmetries of the Platonic polyhedra in the four-dimensional Euclidean space. The paper is intended as a short review of recent results in the sector, emphasizing the relevance of discrete symmetries for the superintegrability of the systems considered.