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.     

The TEM characterization of the lamellar structure of osteoporotic human trabecular bone

The lamellar structure of osteoporotic human trabecular bone was characterized experimentally by means of transmission electron microscopy (TEM). More specifically, the TEM was used to determine if trabecular bone exhibits similar lamellar structural motifs as cortical bone by analyzing unmineralized, mineralized and demineralized bone, and to study the influence of the osteocyte network on the lamellar structure of osteoporotic trabecular bone. Comparison with normal trabecular bone is included. This paper summarizes partial results of a larger study, which addressed the characterization of the hierarchical structure of normal versus osteoporotic human trabecular bone [Rubin, M.A., 2001. Multiscale characterization of the ultrastructure of trabecular bone in osteoporotic and normal humans and in two inbred strains of mice. MS Thesis, Georgia Institute of Technology.] at several structural scales.     

The molecular structure of the 4-nitrophenyl[bis(ethylsulfonyl)]methane and its response in the formation of the complexes with the strong organic bases

Intermolecular interactions in a synthesized C-acid, 4-nitrophenyl[bis(ethylsulfonyl)]methane have been analysed and its structure determined by X-ray diffraction. The molecular packing in the crystal is governed by CH…O. The dimensions of the hydrogen bonds and the shortest non-bonded distances are also determined. The possible implications in the formation of the hydrogen bonded complexes with the strong organic bases are also discussed.     

Synthesis and characterization of hyperbranched polyesters from glycerol‐based AB2 monomer

This article describes the synthesis of a new glycerol‐based AB₂ type monomer—ethyl{3‐[2‐hydroxy‐1‐(hydroxymethyl)ethoxy]propyl}thioacetate ( 4 ) and its application for the preparation of hyperbranched polyesters. The polycondensation of 4 has been performed over a wide range of catalysts and reaction conditions leading to polymers containing solely primary hydroxyl groups. The polycondensation progress has been monitored by means of ¹H NMR. The degree of branching of the polymers showed to be in the range of 0.5 ± 0.03. The obtained polyesters easily undergo hydrolysis or alcoholysis and may be of interest as recycled materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3860–3868, 2009