Recent advances in the supramolecular assembly of cyclophosphazene derivatives.

Cyclophosphazenes are a fascinating group of inorganic heterocyclic compounds whose rings are constituted by the repetition of phosphorus and nitrogen atoms. They have received particular attention due to their easy functionalization and thermal stability and as an excellent core for the preparation of advanced materials. Rigid trispirocyclic derivatives of cyclophosphazenes afford numerous supramolecular structures that are suitable for the formation of host-guest complexes with a variety of guest molecules such as gas molecules and molecular rotor compounds.

New Synthetic Approach to Molecular Rods Using Cyclophosphazene-Based Oligospiranes.

A synthetic approach was developed to prepare a new type of highly functionalized inorganic-organic heterocyclic molecular rod (3a and 3b) consisting of cyclophosphazene and carbocyclic units. Single-crystal X-ray diffraction analysis of 3a revealed that the molecular length was ca. 2.

Imidazole/benzimidazole-modified cyclotriphosphazenes as highly selective fluorescent probes for Cu: synthesis, configurational isomers, and crystal structures.

Configurational isomers (cis and trans) of imidazole- or benzimidazole-modified cyclotriphosphazenes (3a, 4a or 3b, 4b) were designed, synthesized and investigated as fluorescent probes for metal ions. The newly synthesized compounds were characterized by H and P NMR, and MALDI MS spectrometry. The configurations of geometric isomers were analyzed by X-ray crystallography and P NMR spectroscopy on addition of CSA.

The investigation of structural and thermosensitive properties of new phosphazene derivatives bearing glycol and amino acid.

In this study, hexachlorocyclotriphosphazene, N(3)P(3)Cl(6) (cylotriphosphazene), was reacted with hydrophilic and hydrophobic groups to synthesize amphiphilic phosphazene derivatives (4-12). Cylotriphosphazene was reacted triethylene glycol monomethyl ether (TEGME), dipropylene glycol monomethyl ether (DPGME), diethylene glycol monobutyl ether (DEGBE), (1 : 3 mole proportion) in the presence of sodium hydride and using tetrahydrofuran (THF) as solvent at -60 °C. Three isomers (nongeminal cis-2,4,6 (1a-3a); nongeminal trans-2,4,6 (1b-3b); geminal 2,2,4 (1c-3c)) were isolated from the reaction of hexachlorocyclotriphosphazatriene (trimer) (1) with TEGME, DPGME and DEGBE.

Characterisation of temperature-dependent phase transitions in 2,2-trimethylenedioxy-4,4,6,6-tetrachlorocyclotriphosphazene, N3P3Cl4[O(CH2)3O].

Background: The crystal structure of 2,2-trimethylenedioxy-4,4,6,6-tetrachlorocyclo triphosphazene has been determined at 120, 274 and 293 K. The result at 293 K confirms the room temperature Cmc2(1) structure, but at the lower temperatures the space group is Pna2(1). Nevertheless the basic structure remains the same, with only small displacements of the atoms, amounting to an average of 25 pm between 120 and 293 K.

Stereogenic properties of spiranes combined with four equivalent conventional centres of chirality.

Derivatives of the tri-spirane pentaerythritoxy-cyclophosphazene compound, 1, have been used to investigate the stereogenic properties of spiranes combined with four equivalent conventional centres of chirality. In compound 1 the two inner rings are carbocyclic and symmetrical and the two outer rings are cyclotriphosphazenes substituted in different positions to provide the conventional centres of chirality. The case of combining spiranes with four equivalent centres of chirality has been investigated by the reaction of 1 with dimethylamine in a 1 : 8 molar ratio to give four diastereoisomeric products, in which the two cyclophosphazene rings are non-geminally di-substituted in either cis or trans configurations; viz.

Comparison of high-performance liquid chromatography of cyclotriphosphazene derivatives with one or two equivalent stereogenic centres.

High-performance liquid chromatographic (HPLC) methods have been developed for investigating the stereogenic properties of two analogous series of dibenzylamino derivatives of cyclotriphosphazene containing either one or two equivalent stereogenic centres. Separation of the enantiomers of all the racemic compounds has been investigated by chiral HPLC using Whelk-01 and Chiralcel OD columns. In all cases, conditions for separation of enantiomers have been found using a Whelk-01 column with different ratios of tetrahydrofuran in n-hexane as the mobile phase.

The structural and stereogenic properties of pentaerythritoxy-bridged cyclotriphosphazene derivatives: spiro-spiro, spiro-ansa and ansa-ansa isomers.

Reactions of pentaerythritol with hexachlorocyclotriphosphazene, N3P3Cl6, and gem-disubstituted cyclotriphosphazene derivatives, N3P3Cl4R2 [R = Ph, NHBu(t) or (OCH2CF2CF2CH2O)0.5] gave a series of pentaerythritol-bridged derivatives linked spiro-spiro, spiro-ansa and ansa-ansa. The structures and stereogenic properties of the products were characterised by X-ray crystallography and 31P NMR spectroscopy on addition of the chiral solvating agent, (S)-(+)-2,2,2-trifluoro-1-(9-anthryl)ethanol.

Structural investigations of phosphorus-nitrogen compounds. 4. Steric and electronic effects in dibenzylamino derivatives of hexachlorocyclotriphosphazatriene and 4,4,6,6-tetrachloro-2,2-diphenylcyclotriphosphazatriene.

A systematic study is presented on the products of aminolysis of N(3)P(3)Cl(6) (1) and N(3)P(3)Ph(2)Cl(4) (4) with dibenzylamine. Two series of mono- and disubstituted derivatives of compounds (1) and (4), namely N(3)P(3)Cl(5)[N(CH(2)Ph)(2)] (2) and N(3)P(3)Cl(4)[N(CH(2)Ph)(2)](2) (3) and N(3)P(3)Ph(2)Cl(3)[N(CH(2)Ph)(2)] (5) and N(3)P(3)Ph(2)Cl(2)[N(CH(2)Ph)(2)](2) (6) [where (2), (3), (5) and (6) are new structures], are investigated in order to determine whether steric or electronic effects prevail in the formation of dibenzylamino-substituted cyclophosphazenes. The influence of an electron-releasing group (i.