3 research outputs found
Boron Difluoride Adducts of a Flexidentate Pyridine-Substituted Formazanate Ligand: Property Modulation via Protonation and Coordination Chemistry
The synthesis and characterization of a flexidentate pyridine-substituted formazanate ligand and its boron difluoride adducts, formed via two different coordination modes of the title ligand, are described. The first adduct adopted a structure that was typical of other boron difluoride adducts of triarylformazanate ligands and contained a free pyridine subsituent, while the second was formed via chelation of nitrogen atoms from the formazanate backbone and the pyridine substituent. Stepwise protonation of the pydridine-functionalized adduct, which is essentially non-emissive, resulted in a significant increase in the fluorescence quantum yield up to a maximum of 18%, prompting study of this adduct as a pH sensor. The coordination chemistry of each adduct was explored through reactions with nickel(II) bromide [NiBr2(CH3CN)2], triflate [Ni(OTf)2] and 1,1,1,4,4,4-hexafluoroacetylacetonate [Ni(hfac)2(H2O)2] salts. Coordination to nickel(II) ions altered the physical properties of the boron difluoride formazanate adducts, including red-shifted absorption maxima and less negative reduction potentials. Together, these studies have demonstrated that the physical and electronic properties of boron difluoride adducts of formazanate ligands can be readily modulated through protonation and coordination chemistry
Effect of counter ions on the self-assembly of polystyrene-polyphosphonium block copolymers
The ability to manipulate block copolymers on the nanoscale has led to many scientific and technological advances. These include nano-scale ordered bulk and thin films and also solution phase components, these are promising materials for making smaller ordered electronics, selective membranes, and also biomedical applications. The ability to manipulate block copolymer material architectures on such small scales has risen from thorough investigations into the properties that affect the architectures. Polyelectrolytes are an important class of polymers that are used to make amphiphilic block copolymers. In this context the authors synthesized polystyrene-b-polyphosphonium block copolymers with different anions coordinated to the polyphosphonium block in order to study the effect of the anion on the aqueous self-assembly of the polymers. The anions play an important role in the solubility of the monomeric materials which results in differences in the self-assembly observed through dynamic light scattering and transmission electron microscopy
Effect of Counterions on the Self-Assembly of Polystyrene–Polyphosphonium Block Copolymers
The
ability to manipulate block copolymers on the nanoscale has
led to many scientific and technological advances. These include nanoscale
ordered bulk and thin films and also solution phase components; these
are promising materials for making smaller ordered electronics, selective
membranes, and also biomedical applications. The ability to manipulate
block copolymer material architectures on such small scales has risen
from thorough investigations into the properties that affect the architectures.
Polyelectrolytes are an important class of polymers that are used
to make amphiphilic block copolymers. In this context the authors
synthesized polystyrene-<i>b</i>-polyphosphonium block copolymers
with different anions coordinated to the polyphosphonium block in
order to study the effect of the anion on the aqueous self-assembly
of the polymers. The anions play an important role in the solubility
of the monomeric materials which results in differences in the self-assembly
observed through dynamic light scattering and transmission electron
microscopy