Metalloantitubercular compounds Part 3: Synthesis,crystal structure,spectroscopy, electrochemistry and antimycobacterial activity of the copper(II) ciproploxacin (cfH) complex and its phenanthroline adduct

The X-ray crystal structures of two ciprofloxacin compounds, viz. [Cu(cfH)₂(Cl)₂] · ₂MeOH · 6H₂O (2) and [Cu(cfH)(phen)Cl]BF₄ · 4H₂O (3) are reported. Complex (2) has a distorted octahedral geometry, whereas for the nitrogen adduct (3) a distorted square–pyramidal geometry is seen. Significant enhancement in the antimycobacterial activity of the copper conjugates correlates with their copper redox couples (Cu²⁺ /Cu⁺) probably due to its relevance to intracellular accumulations and subsequent role in generating oxidative stress.     

Certain monomial curves are set-theoretic complete intersections

LetK be a field and letm ₀,...,m _e −1 be a sequence of positive integers. LetC be the monomial curve in the affinee-space defined parametrically by . If somee−1 terms ofm ₀,...,m _e −1 form an arithmetic sequence thenC is a set-theoretic complete intersection.     

The 5-endo-trig cyclization of D-glucose derived gamma-alkenylamines with mercury (II) salts: synthesis of 1-deoxycastanospermine and its 8a-epi-analogue

The intramolecular aminomercuration of gamma-alkenylamines 1a, 1b and 4 was shown to afford the 5-endo-trig cyclized product exclusively in good yield. The utility of pyrrolidine derivatives thus obtained from D-glucose derived gamma-alkenylamines 1a and 1b was demonstrated in the synthesis of 1-deoxycastanospermine (3a) and 1-deoxy-8a-epi- castanospermine (3b).     

Kinetics and mechanism of oxidation of thiosulphate by the complex ion [MnIV3(μ-O)4(phen)4(H2O)2]4+ (phen = 1,10-phenanthroline) in weakly acidic aqueous media

The trinuclear complex ion [Mn^IV ₃(-O)₄(phen)₄(H₂O)₂]⁴⁺ (1) is quantitatively reduced by an excess of S₂O₃ ^2– to Mn^II, but the binuclear complex [Mn^IIIMn^IV(-O)₂(phen)₄]³⁺, (2) is the only manganese product when [S₂O₃ ^2–] = 1.5 [(1)]. With an excess of S₂O₃ ^2– biphasic kinetics, (1) k ₁ ⁰ (2) k ₂ ⁰ Mn^II is observed, while the reaction with S₂O₃ ^2– = 1.5 [(1)], follows one-step second order kinetics with the second order rate constant k = k ⁰ ₁/[S₂O₃ ^2–]. The rate constant k ⁰ ₁ is independent of c _phen ( = [phen] + [Hphen⁺]) but directly proportional to [H⁺] and [S₂O^2– ₃]. Rapid formation of an adduct between (1) and S₂O^2– ₃, followed by rate-determining one-electron, one-proton reduction of the adduct, appears logical. A comproportionation reaction in one of the subsequent rapid steps leads to (2) without any Mn^II co-product. Kinetic dependences for the second step are same to those for an authentic complex of (2), and further support the assigned reaction sequence.     

Real connective K-theory and the quaternion group

Let be the real connective K-theory spectrum. We compute and for groups whose Sylow 2-subgroup is quaternion of order 8. Using this we compute the coefficients of the fixed points of the Tate spectrum for and . The results provide a counterexample to the optimistic conjecture of Greenlees and May [9, Conj. 13.4], by showing, in particular, that is not a wedge of Eilenberg-Mac Lane spectra, as occurs for groups of prime order.

     

Synthesis of gamma-hydroxyalkyl substituted piperidine iminosugars from D-glucose

D-Glucose was converted to synthetic equivalent of meso-pentodialdose, namely 3-C-(1'-aminoethyl)-alpha-d-ribo-pentodialdo-1,4-furanose 10 that gives an easy access to manipulate the aldehyde functionalities on either sides to get enantiomeric pair of 3. Thus, reduction of C5-aldehyde followed by hydrolysis of 1,2-acetonide functionality and reductive aminocyclization with C1-aldehyde afforded gamma-1,2-dihydroxyethyl piperidine iminosugar 3. On the other hand, first reductive aminocyclization with C5-aldehyde gave piperidine ring skeleton 12 that on removal of 1,2-acetonide and reduction of C1-aldehyde gave ent-3 while chopping of C1-aldehyde in 12 and reduction afforded gamma-hydroxymethyl piperidine iminosugar 4.     

Volumetric,Viscosity and Self-Diffusion Coefficient Studies of [18-Crown-6:M]A Complexed Species in Water at 298.15 K

Density and viscosity measurements were made for aqueous solutions of electrolytes containing 18-crown-6 (18C6) at 298.15 K. A method is proposed to extract the volumetric and viscosity data of the [18C6:M]A complexed species in aqueous solutions from ternary mixtures using the thermodynamic equilibrium constant values at 298.15 K. The apparent molar volume of the [18C6:M]A complexed species have been estimated for these binary solutions. Further, the viscosity data thus obtained were subjected to analysis using the Jones-Dole equation to get viscosity A- and B-coefficients of complexed ions in water. The hydration number and molecular radius of the hydrated complexes in water have been estimated. It was observed that hydration of the complexed ion is strongly influenced by the charge density of the metal ions in the complexed state. The self-diffusion coefficient and correlation time values for the complexes in water were calculated using viscosity data, which indicated that diffusion of complexed species was faster than that of the host ligand 18C6 (D_3d structural entity) in water at 298.15 K. It was suggested that the ionic radii estimated in this work for large hydrophobic cations can be of use in studying electrostatic and hydrophobic interactions especially in aqueous solutions.     

Oxidation of cinnamic acid derivatives: A pulse radiolysis and theoretical study

We introduce an algorithm to solve the secular equation that arises in the time independent multimode expansion of the quadratic vibronic coupling problem in parallel. The implementation can handle expansions of arbitrary length, with the open-ended character of the algorithm achieved through the use of fine grained parallelism to partition the trial vectors. The characteristics of the algorithm are discussed and its utility is illustrated by determining a model photoelectron spectrum of the ethoxy radical (C₂H₅O) using a vibronic expansion involving more than 1 billion vibronic basis states. This calculation also represents the first determination of a photoelectron spectrum obtained using a diabatic Hamiltonian obtained with a recently introduced ab initio surface reshaping procedure.     

A Photoswitchable Solvatochromic Dye for Probing Membrane Ordering by RESOLFT Super-resolution Microscopy**

A switchable solvatochromic fluorescent dyad can be used to map ordering of lipids in vesicle membranes at a resolution better than the diffraction limit. Combining a Nile Red fluorophore with a photochromic spironaphthoxazine quencher allows the fluorescence to be controlled using visible light, via photoswitching and FRET quenching. Synthetic lipid vesicles of varying composition were imaged with an average 2.5-fold resolution enhancement, compared to the confocal images. Ratiometric detection was used to probe the membrane polarity, and domains of different lipid ordering were distinguished within the same membrane.