Structural and stereogenic properties of spiro- and ansa-substituted 1,3-propanedioxy derivatives of a spermine-bridged cyclotriphosphazene

Reaction of 1,3-propanediol with the achiral spermine-bridged cyclophosphazene 1 at various molar ratios in THF gives a number of spiro-and ansa-derivatives that exhibit different stereogenic properties, viz. racemic, meso or achiral forms. As expected, spiro forms are preferred (giving mono-, di-, tri- and tetra-substitution), although significant amounts of mono- and di-substituted ansa derivatives also occur. A number of new structures have been characterized by NMR spectroscopy and X-ray crystallography in this work; mono-spiro 2, di-mono-ansa 6 and di-spiro/mono-ansa 8. The mono-ansa compound 3 was observed in solution by NMR spectroscopy but no evidence was found for the monospiro/monoansa 5, a necessary precursor of compound 8. The tri-spiro derivative 7 has been isolated and characterized by 31P NMR spectroscopy, whereas the structures of the di-monospiro 4 (meso) and tetra-spiro 9 have been characterized previously. The stereogenic properties of many of the products have been confirmed by X-ray crystallography and/or by 31P NMR spectroscopy on addition of the chiral solvating agent, (S)-(+)-2,2,2-trifluoro-1-(9-anthryl)ethanol. Although the starting compound 1 is achiral, it is found that unsymmetrically-substituted derivatives with 1,3-propanediol give racemic mixtures for the mono-spiro 2 and tri-spiro 7 derivatives, whereas symmetrically-substituted derivatives such as di-mono-ansa 6 and di-spiro/mono-ansa 8 are meso. It is found that care must taken in interpreting the 'splitting' of 31P NMR signals on addition of CSA in terms of 'chirality' of molecules, because some meso compounds give false positive results due to changes from A2X-like to A2B or ABX spin systems

Novel BODIPY-subphthalocyanine dyads with reasonable photodynamic therapy behaviours

In this study, a set of bio-compatible and NIR emissive BODIPY-subphthalocyanine dyads (SP-DBD1-3) that contain amphiphilic triethyleneglycol units supporting partial water solubility and red absorbing BODIPY monomers (DBD1-3) were prepared. The photophysical and photochemical activities of these monomers, including fluorescence behaviors, singlet oxygen production, absorption, and emission profiles were investigated. The effect of the presence of halogen atoms and the BODIPY unit in dyads on the ability of generating singlet oxygen was evaluated. BODIPY-subphthalocyanine dyads showed two absorption bands at about 550 nm and 650 nm and high singlet oxygen quantum yields (up to 91%) at room temperature. The weaker fluorescence emissions, shorter fluorescence lifetimes but better singlet oxygen production capacities of dyads compared to those of BODIPY monomers have been explainedviathe energy transfer process from the donor subphthalocyanine unit to the acceptor BODIPY part, supporting ISC. Also,in vitrostudies underlined that the novel compounds (DBD1,DBD2,SP-DBD-2, andSP-DBD3) were successful in terms of the induction of cell death under red light; however, they did not affect the cells in dark, indicating these compounds as agents that can be used in photodynamic therapyin vivoin further studies

A cis-directing effect towards diols by an exocyclic P-NHR moiety in cyclotriphosphazenes

Cyclophosphazenes containing the P-NHR moiety in an exocyclic spiro ring, N(3)P(3)Cl(4)[NH(CH(2))(3)O], (1), and N(3)P(3)Cl(4)[NH(CH(2))(3)NMe], (2). were used to investigate a possible directing effect of the P-NHR moiety oil the formation of products in the nucleophilic substitution reactions with diols Such as tetraethyleneglycol, 1,3-propanediol and 2,2-dimetliyl-1,3-propanediol. The (31)P NMR spectra of the reaction Mixtures showed that only one kind of ansa product is formed in each of these reactions. X-ray crystallographic studies of the ansa products [(4a), (5a), (6a) and (7a)] have provided definitive proof of the cis-directing effect of the P-NHR moiety in cyclotriphosphazenes. It is likely that hydrogen-bond interaction between the incoming nucleophile and the P-NHR moiety of the reactant accounts for the preference for products with the substituents cis to the NH group