New Molecular Receptors with Cyclophosphazene Subunits: Synthesis, Reactivity, and Structure-Property Relationships

A series of hydrophopic ( 2 and 3) and new hydrophilic ( 4– 7) molecular receptors of the PNP-lariat ether with tetra-substituted cyclotriphosphazene subunits have been prepared by the complete nucleophilic substitution of chlorine atoms in the reactive PNP-crown precursor 1 with the respective sodium cation-paired oxyanions (phenoxy 2, -naphthoxy 3, and methoxytrioxyethylenoxy 4) and aliphatic amines (n-propylamine 5 aziridine 6, and pyrrolidine 7). Their structures were established by MS and ³¹P NMR spectroscopy and their metal ion complexing properties tested by a TLC method. Comparison of the complexation behaviour for ligands 1– 7 shows that the affinity for particular cations is strongly substituent-dependent and, in general, is significantly enhanced by cooperation of the side arm donor atoms (O or N) with the parent PNP-crown structure in the binding process. The remarkable affinity of some ligands for selected cations, in particular lithium, cesium, and silver ions, is interpreted in terms of structure-property relationships.     

Preparation of Nanocrystalline Indium Antimonide Through β-Hydride Elimination from New Indium-Antimony Single-Source Precursors

The 1:1 mole ratio reaction of t-Bu₃In with Sb(SiMe₃)₃ results in the formation of the Lewis acid-base adduct t-Bu₃In Sb(SiMe₃)₃ (1), while the dimeric compound [t-Bu₂InSb(SiMe₃)₂]₂ (2) is isolated from the 1:1 reaction of t-Bu₂InCl with Sb(SiMe₃)₃. Both the 2:1 reactions of t-Bu₂InCl with Sb(SiMe₃)₃ and t-Bu₂InCl with 2 result in the formation of the mixed-bridge compound (3), however, ¹H NMR studies suggest that this compound is unstable in solution. Thermolysis of 1, 2, and t-Bu₃Ga Sb(SiMe₃)₃ (4) results in the formation of nanocrystalline InSb or GaSb through a -hydride elimination pathway.     

Trees in Renorming Theory

A systematic study is made of the isomorphic properties of theBanach space C₀(     

Signed Hypergraph Designs and Diagonal Forms for Some Incidence Matrices

Given a t-uniform hypergraph H on k vertices and an assignment of integers f(T) to the t -subsets T of a v-set X, v k + t, we give necessary and sufficient conditions for the existence of an assignment of integer multiplicities h(G) to those subhypergraphs G of the complete t-uniform hypergraph on v vertices that are isomorphic to H so that the sum of the integers h(G) over those G that contain T is f(T). Our main theorem is stated in terms of integral matrices. As a consequence of our main theorem, e also determine a diagonal form, and hence the p-rank for all primes p, for the incidence matrix of t-subsets versus subhypergraphs isomorphic to H.     

Z,Z-dienes via acetylene carbocupration: synthesis of navel orangeworm pheromone

A range of conjugated $\text{Z}$,$\text{Z}$-dienes have been prepared in a stereo-specific manner $\text{via}$ acetylene carbocupration: the value of this procedure has been illustrated by an extremely short synthesis of hexadeca-11$\text{Z}$, 13$\text{Z}$-dienal a principle component of Navel Orangeworm Pheromone.