Optimized analysis of the critical behavior in polymer mixtures from Monte Carlo simulations

A complete outline is given for how to determine the critical properties of polymer mixtures with extrapolation methods similar to the Ferrenberg-Swendsen techniques recently devised for spin systems. By measuring not only averages but the whole distribution of the quantities of interest, it is possible to extrapolate the data obtained in only a few simulations nearT _c over the entire critical region, thereby saving at least 90% of the computer time normally needed to locate susceptibility peaks or cumulant intersections and still getting more precise results. A complete picture of the critical properties of polymer mixtures in the thermodynamic limit is then obtained with finite-size scaling functions. Since the amount of information extracted from a simulation in this way is drastically increased as compared to conventional methods, the investigation of mixtures with long chains or built-in asymmetries is now possible. As an example, the critical points, exponents, and amplitudes of dense, symmetric polymer mixtures with chain lengths ranging fromN=16 up toN=256 are determined within the framework of the 3D bond fluctuation model using grand canonical simulation techniques. As an example for an asymmetry, the generalization of the method to asymmetric monomer potentials is briefly discussed.     

Metal–Nitrosyl complexes as a source of new vasodilators: Strategies derived from systematic chemistry and nitrosyl ligand reactivity

A series of nitrosyl complexes of empirical formula K_n[M(CN)₅NO], where M = V, Cr, Mn and Co and n = 3, or M = Mo and n = 4, have been prepared which are notional analogues of the widely used vasodilator sodium nitroprusside. Their reactivity towards common nucleophiles (OH^?, NH₂R, NHR₂, HS^? and RS^?), acid and photolysis has been investigated to elucidate the desired properties required of new metal nitrosyls which may have some potential as new non-cyanide-based vasodilators.     

Complexes of 2,2′,2″-Nirtilotriphenol. Part IV. Cage Compounds with Phosphorus(III) and Phosphorus(V)

The ligand 2,2′,2″-nitrilotriphenol reacts with P(III) and P(V) compounds to form corresponding phosphorus complexes. Syntheses and NMR data of 2,2′,2″-nitrilotriphenyl phosphite ( II ), 2,2′,2″-nitrilotriphenyl phosphate ( III ) and of a hydrolysis product of II , 2,2′-[N-(2-hydroxyphenyl)imino]diphenly phosphonate ( IV ), are reported, as well as crystal structures of II and IV . Phosphite II shows a bicycloundecane framework; no N?Pinteraction is present. The phosphonate IV shows two coordinated and one dangling phenol group; the N-atom does not interact with the P-atom. Strong acids protonate II as well as III to form cations: in these, NMR evidence indicates coordination of the N-atom to the P-atom.