Crown ethers: sensors for ions and molecular scaffolds for materials and biological models.

Poly(organophosphazene)s and related compounds: Synthesis, properties and applications

Chlorocyclophosphazenes containing a reactive periphery and a robust framework offer an ideal platform for the construction of a large variety of multi-site coordination ligands. Various types of neutral or (multi)anionic multi-site coordinating ligands can be assembled containing different numbers, type and stereochemical orientations of coordination sites reflecting the ease of modulation of these ligand types. Also it is possible to construct new types of macrocyclic ligands using cyclophosphazenes as scaffolds. The interaction of these ligands with transition and main group metals leads to a number of different complex types showing the rich diversity that is present in this family of compounds. A study of these ligands in principle also allows the assembly of the corresponding polymeric ligands.

Phosphazenes as scaffolds for the construction of multi-site coordination ligands

The direct reaction of [NPCl2]n with the difunctional reagent 2,2‘-dihydroxybiphenyl (HOC6H4C6H4OH) and K2CO3 in tetrahydrofuran gave soluble linear phosphazene high polymers instead of the expected cross-linked products. The reaction of [N3P3Cl6] with 1, 2, or 3 equiv of HOC6H4C6H4OH and K2CO3 in acetone gave the known spiro derivatives [N3P3Cl4(O2C12H8)], [N3P3Cl2(O2C12H8)2], and [N3P3(O2C12H8)3] without formation of bridging products, and the dichloro derivative reacted directly with para-substituted phenols HOC6H4R and K2CO3 in acetone to give the new compounds [N3P3(OC6H4R)2(O2C12H8)2] (R = Br, COC6H5, or OCH3), without signs of replacement of the bis(aryloxy) substituents. In an analogous manner, poly(dichlorophosphazene) [NPCl2]n reacted with HOC6H4C6H4OH and K2CO3 in THF without significant cross-linking to give, depending on the mole ratio, the soluble polymer [NP(O2C12H8)]n (Mw = 450 000, Tg = 160 °C) or the partially substituted polymers {[NP(O2C12H8)]0.35[NPCl2]0.65}n. The latter were subseque...

Preparation of a New Type of Phosphazene High Polymers Containing 2,2‘-Dioxybiphenyl Groups

Surface second harmonic generation (SHG) is shown to display optical rotatory effects dependent on the handedness of chiral molecules (2,2’‐dihydroxy‐1,1’binaphthyl) at various interfaces. The polarization of the surface SHG radiation is rotated with respect to that of the input fundamental radiation in a direction indicative of the chirality of the surface molecules. The origin of SHG‐ORD lies in the electric dipole‐allowed χ(2) tensor elements, one of which is associated with the handedness of surface species. The SHG‐ORD rotation is independent of the density of surface species for an optically pure system, but is dependent on the chiral excess for mixtures of enantiomers. It is wavelength dependent but resonance is not required to observe the rotation. The experiments show that while SHG‐ORD has origins quite distinct from ordinary ORD, it can be utilized to measure chiral structures of surfaces.

A second harmonic generation analog of optical rotatory dispersion for the study of chiral monolayers

AIDS-related lymphoma screen results and molecular structure determination of a new crown ether bearing aziridinylcyclophosphazene, potentially capable of ion-regulated DNA cleavage action

New dioxytetraethyleneoxy macrocyclic cyclophosphazene derivatives

A regioselective route to new polytopic receptors by diaminolysis of chlorocyclotriphosphazatriene-containing crown ethers

New Lariat Ether-Type Macrocycles with Cyclophosphazene Subunits

Comparative studies of the naphtholysis of crown-bearing tetrachlorocyclotriphosphazene 2 and its acyclic analogue, nongem-diethoxytetrachlorocyclotriphosphazene 5 (which was synthesized and isolat...

Supramolecular assistance to regioselectivity in the reactions of chlorocyclophosphazenes with sodium oxyanions: macrocyclic effect and anion dependence.

Krystyna Brandt

Papers

AIDS-related lymphoma screen results and molecular structure determination of a new crown ether bearing aziridinylcyclophosphazene, potentially capable of ion-regulated DNA cleavage action

New dioxytetraethyleneoxy macrocyclic cyclophosphazene derivatives

A regioselective route to new polytopic receptors by diaminolysis of chlorocyclotriphosphazatriene-containing crown ethers

New Lariat Ether-Type Macrocycles with Cyclophosphazene Subunits

Supramolecular assistance to regioselectivity in the reactions of chlorocyclophosphazenes with sodium oxyanions: macrocyclic effect and anion dependence.