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).
New rigid amphiphilic molecules based on a p-phenylene-ethynylene unit with hydrophilic side chains
were synthesized by a step by step method up to the heptamer. The two most interesting materials, the
pentamer and the heptamer, are amphiphilic enough in nature to produce stable Langmuir films on
hydrophilic substrates such as hydrophilic glass, ITO, or hydrophilic silicon. A transfer ratio of 1, observed
only by lifting, suggests a Z-type deposited film. The multilayer deposition can be carried out up to 36
layers. The films were analyzed by X-ray reflectivity and are revealed as well structured with a layering
period of 3.7 nm. This suggests a rearrangement in a Y-type bilayer occurring after transfer deposition
from the water surface. Using AFM, the surfaces of films deposited on glass or Si are shown to exhibit
steps of 3.6−3.7 nm height or multiples, which are coherent with a self-rearrangement of the single deposited
layer to a double layer during the drying process. The heptamer and pentamer show high photoluminescence
and large Stokes shifts with emission peaks at 516 and 504 nm. LED properties are demonstrated using
the ITO/oPEn/LiF/Al sandwich yielding photon emission at 516 nm for the heptamer. The luminescence−voltage characteristics of two diodes using 22 and 36 LB layers show threshold voltage at 4.5 and 6 V
respectively and in those conditions the electroluminescence yield is close to 10-3%. It is concluded that
the electroluminescence in a LB film of molecules aligned parallel to the substrate is interesting because
it confirms the possibility of tailoring conduction and emission properties of devices using a layer by layer
deposition technique.
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.
Change of the permanent molecular electric dipole moment, Δμ, in a series of nominally centrosymmetric and noncentrosymmteric ferrocene-phenyleneethynylene oligomers was estimated by measuring the two-photon absorption cross-section spectra of the lower energy metal-to-ligand charge-transfer transitions using femtosecond nonlinear transmission method and was found to vary in the range up to 12 D, with the highest value corresponding to the most nonsymmetric system. Calculations of the Δμ performed by the TD-DFT method show quantitative agreement with the experimental values and reveal that facile rotation of the ferrocene moieties relative to the organic ligand breaks the ground-state inversion symmetry in the nominally symmetric structures.
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