Thermal decomposition of a generation 4.5 PAMAM dendrimer platinum drug conjugate

A nanoscale multivalent platinum drug based on a poly(amidoamine) [PAMAM] dendrimer (generation 4.5, carboxylate surface) has been synthesized and fully characterized using a variety of spectroscopic, chromatographic and thermal methods. Treatment of the dendrimer with an aqueous solution containing an excess diaquo(cis-1,2-diaminocyclohexane)platinum(II) produces a conjugate containing approximately forty (diaminocyclohexane)platinum(II) moieties at the surface of the dendrimer. This material undergoes smooth two-stage thermal decomposition to provide residual platinum oxide reflecting the platinum loading in the drug.     

Use of cyclotron-produced isotopes for analytical investigation: Determination of vanadium in gallium

The extraction of the V(V)-BPHA complex into chloroform and benzene was investigated using⁴⁸V tracer produced from the⁴⁵V reaction using the Variable Energy Cyclotron, Calcutta. A neutron activation analysis procedure for the estimation of vanadium in gallium metal samples based on the extraction of V(V)-BPHA complex into benzene is given.     

Crosslinking‐induced morphology change of latex nanoparticles: A study of RAFT‐mediated polymerization in aqueous dispersed media using amphiphilic double‐brush copolymers as reactive surfactants

Amphiphilic double‐brush copolymers (DBCs) with each graft site quantitatively carrying both a hydrophilic poly(ethylene oxide) (PEO) graft and a hydrophobic polystyrene (PSt) graft are synthesized by sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization and ring‐opening metathesis polymerization (ROMP). These DBCs are used as both surfactants and polyfunctional RAFT agents in the radical polymerization of St in aqueous dispersed media. Miniemulsions with narrowly dispersed St‐based nanodroplets are readily obtained after ultrasonication of the reaction mixtures. Without the presence of crosslinker, chain‐extension polymerization of St from the DBCs yields well‐defined polymeric latexes with narrow size distributions. However, with the presence of divinylbenzene (DVB) as the crosslinker, vesicular polymeric nanoparticles are formed as the major product. Such crosslinking‐induced change in morphology of the resulting latex nanomaterials may be ascribed to the increase of interfacial curvature in the heterophase systems during crosslinking polymerization. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3250–3259     

Anomalous thermal expansion of osmium dioxide

The precision lattice parameters of osmium dioxide have been determined at different temperatures, in the temperature range 30–444 °C, using a Unicam high temperature powder camera 19 cm in diameter and CuKα radiation. The data have been used to evaluate the coefficients of thermal expansion at various temperatures by a graphical method. The ‘a’ parameter increases non-linearly with increasing temperature while the ‘c’ parameter remains constant throughout the range of temperature studied indicating a zero coefficient of expansion along the c-direction. The abnormal thermal behaviour of this compound is explained in terms of the electronic configuration of the d-shell of the cation.     

Asymptotically self invariant sets and perturbed systems

Summary Necessary conditions are obtained for the asymptotically self-invariant sets to be uniformly stable in variation and uniformly asymptotically stable in variation and hese results are employed to study the effect of certain perturbations on asymptotically self-invariant sets. Entrata in Redazione il 19 aprile 1971.     

New reagent for the introduction of Boc protecting group to amines: Boc-OASUD

A new reagent, tert-butyl (2,4-dioxo-3-azaspiro [5,5] undecan-3-yl) carbonate (Boc-OASUD) for the preparation of N-Boc-amino acids is described. The Boc-OASUD reacts with amino acids and their esters at room temperature in the presence of a base and gives N-Boc-amino acids and their esters in good yields and purity. Introduction of the Boc group takes place without racemization. The Boc-OASUD, being a solid and more stable, is a better alternative to di-tert-butyl dicarbonate which is low melting and has to be dispensed in plastic containers than glass because of its poor stability.     

Palladium-catalyzed regioselective synthesis of benzosultams from functionalized ynamides and benzotriazoles/tetrazoles

Palladium-catalyzed highly regioselective synthesis of benzotriazole appended benzosultams by the tandem-cyclization of functionalized ynamides with benzotriazoles has been accomplished. This transformation involves the formation of both CN and CC bonds in a single step. Donor solvents appear to enhance the yields of the products. The methodology is also applicable for the generation of triazole/tetrazole appended benzosultams.     

The chemistry of tri- and high-nuclearity palladium(II) and platinum(II) complexes

This review gives an overview of the progress on tri- and high-nuclearity palladium(II) platinum(II) complexes and discusses recent developments in the chemistry of these complexes. Three or more square-planar metal atoms can be assembled in several ways resulting into myriad geometric forms of the resulting complexes. These square planes may be sharing a corner, an edge and two edges or even separated by ligands having their donor atoms incapable of forming chelates yielding dendrimers and self-assembled molecules. A variety of ligands have been used to stabilize these complexes. The chemistry of these complexes has been dealt based on nuclearity of the complexes. Synthetic, spectroscopic, structural aspects and applications of these complexes are described in this review.