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The solution properties of a novel soluble polydiacetylene, poly[1,6-bis(3,6-dihexadecyl-9H-carbazol-9-yl)hexa-\ud 2,4-diyne] (polyDCHD-HS), have been investigated by using UV–Vis absorption, fluorescence, and FT-Raman\ud spectroscopies. The polymer gives rise to stable, brilliant red solutions in aromatic solvents and in chloroform at\ud room temperature with no evidence of the colour transition to yellow that usually takes place by increasing the\ud temperature with other soluble polydiacetylenes. A particular role appears to be played by benzene–polyDCHD-HS\ud interactions, because in this solvent a very narrow and intense excitonic peak is observed at room temperature in the\ud electronic spectrum. Interestingly, these solutions show also a well-resolved fluorescence spectrum, with a very small\ud Stokes shift and a rather high quantum yield (≅102). Furthermore, a very efficient transfer of the excitation energy\ud from the carbazolyl substituents to the conjugated backbone is found to take place. On account of the observation\ud that by increasing the temperature of the benzene solutions up to 75 C the excitonic feature in both the absorption\ud and the emission spectra undergoes fully reversible broadening and intensity reduction accompanied by the increase\ud of the Stokes shift, without any dramatic colour change, it is likely that the rates of torsional motions in the polymer\ud chains are thermally activated without modifying the average conjugation length of the polymer chains. FT-Raman\ud measurements in benzene solutions in the same temperature range have confirmed this conclusion. The photophysical\ud properties of polyDCHD-HS in benzene around 60 C are quite similar to those observed in other aromatic solvents\ud at room temperature. By heating up the red solutions in toluene or in chlorobenzene, no spectral shift is observed but\ud only a limited increase of the absorption band broadening. All these findings strongly suggest that by the appropriate\ud choice of the substituents it is possible to obtain stable solutions of the red form of polydiacetylenes

A series of eight new organotin compounds derived from Schiff bases has been prepared by a multicomponent reaction from 2-hydroxy-1-naphthaldehyde or 4-substituted-2-hydroxybenzalhedyde, benzhydrazine, and the corresponding diorganotin oxide (R 2 SnO, R = n Bu or Ph). All of the compounds were fully characterized by NMR ( 1 H, 13 C, and 119 Sn), IR, UV/vis, elemental analyses and fluorescence spectroscopy. The crystal structures for some organotin compounds were determined by single crystal X-ray diffraction analysis. All of the compounds display fluorescence at room temperature with quantum yields of about 2 Â 10 À4 to 0.56. The cytotoxic activity and cellular imaging studies were carried out with the newly synthesized compounds. To the best of our knowledge, this is the first report of organotin compounds with Schiff base ligands investigated for fluorescence bioimaging (FBI).

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The interfacial region of surface-modified semiconducting nanoparticles and polymers contributes to the limited efficiency of hybrid photovoltaic cells and has been analyzed by molecular simulation at atomic resolution to complement experimental measurements.

The synthesis of the monomer 1,6-bis(3,6-dihexadecyl-N-carbazolyl)-2,4-hexadiyne, its polymerization and the puri® cation of the polymer, which is soluble in common organic solvents, are reported. Results from powder X-ray di raction studies carried out on the red form of the polymer are discussed. The red polymer chains self-assemble into cylindrical shapes which produce hexagonal columnar mesophases with a transition from a more (Col h o ) to a less ordered (Col h d ) structure around 85ß C. The role played by the long alkyl chains in the formation of the supramolecular hexagonal mesophase is emphasized by comparing these results with those obtained from an analogous polymer with dodecyl substituents which exhibits only the Col h d structure over the whole range of temperature explored.