23739-64-2Relevant articles and documents
Understanding the structural properties of a homologous series of bis-diphenylphosphine oxides
Calcagno, Patrizia,Kariuki, Benson M.,Kitchin, Simon J.,Robinson, James M. A.,Philp, Douglas,Harris, Kenneth D. M.
, p. 2338 - 2349 (2000)
A homologous series of bis-diphenylphosphine oxides (C6H5)2PO-(CH2)nPO(C 6H5)2 (with n = 2-8; denoted 2-8] have been investigated to explore the effects of a range of competing and cooperative intermolecular and intramolecular interactions on the structural properties in the solid state. The important factors influencing the structural properties include intramolecular aspects such as the conformation of the aliphatic chain and the intramolecular interaction between the two P=O dipoles in the molecule, and intermolecular aspects such as long-range electrostatic interactions (dominated by the arrangement of the P=O dipoles), C-H ... O interactions, C-H ... π interactions and π ... π interactions. Compounds 3 and 5 could be crystallized only as solvate co-crystals (3 · water and 5 · (toluene)2], whereas the crystal structures of all the other compounds contain only the bis-diphenylphosphine oxide molecule. The crystal structures have been determined from single-crystal X-ray diffraction data, with the exception of 7 (which has been determined here from powder X-ray diffraction data) and 4 (which was known previously). The compounds with even n represent a systematic structural series, exhibiting characteristic, essentially linear P=O ... P=O ... P=O dipolar arrays, together with C-H ... O and C-H ... π interactions. For the compounds with odd n, on the other hand, uniform structural behaviour is not observed across the series, although certain aspects of these crystal structures contribute in a general sense to our understanding of the structural properties of bis-diphenylphosphine oxides. Importantly, for the compounds with odd n, there is "frustration" with regard to the molecular conformation, as the preferred all-anti conformation of the aliphatic chain gives rise to an unfavourable parallel alignment of the two P=O dipoles within the molecule. Clearly the importance of avoiding a parallel alignment of the P=O dipoles becomes greater as n decreases. Local structural aspects (investigated by high-resolution solid-state 31P NMR spectroscopy) and thermal properties of the bis-diphenylphosphine oxide materials are also reported.
Synthesis of enantiopure ω-functionalized C15 α-amino carboxylates
Markidis, Theodoros,Kokotos, George
, p. 1685 - 1688 (2007/10/03)
An efficient route for the synthesis of enantiopure ω-hydroxy, ω-carboxy, ω-oxo, and ω-amino α-amino acids and bis-α-amino acids was developed. The synthesis of ω-trityloxy δ,ε-unsaturated α-amino acids was based on the Wittig reaction of methyl (2S)-2-[bis(tert-butoxycarbonyl)-amino]-5-oxopentanoate with ω-trityloxy alkylidene triphenylphosphoranes. After hydrogenation, the ω-hydroxy α-amino acid was used as starting material for the synthesis of other ω-functionalized α-amino acids. The length of the side chain of α-amino acids or bis-α-amino acids depends on the starting alkanediol or dibromide used to prepare the phosphoranes.
Aliphatic phenylene vinylene copolymers: Tuning the color of luminescence through co-monomer feed ratios
Hay,Klavetter
, p. 7112 - 7118 (2007/10/02)
By introducing co-monomers with flexible linker groups into growth condensation route to poly-(phenylene-alt-vinylene (PPV), a series of solution-processible PPV copolymers is prepared. Peak photoluminescence of these copolymers systematically ranges from about 2.25 to 2.75 eV (yellow-green to blue), increasing in energy upon increasing flexible linker content. Length of the linker group does not significantly alter spectral properties but does influence solubility and film morphology. The statistical distibution of phenylene vinylene segements along the copolymer backbone is discussed in the context of the optical profiles expected. Quantitative quenching of the luminescense for the shortest phenylene vinylene segments strongly indicates that crossover of excited states is occurring. The trapping and recombination of these excited states is occurring on lower-energy "islands", confirmed to be the longer phenylene vinylene segments, which serve as ideal recombination sites for photogenerated species.
