A new silole bearing an allyl group at silicon has been incorporated into previously-reported novel reactive polysiloxane
coatings made from polymethylhydrosiloxane (PMHS) polymers crosslinked by the sol-gel process allowing subsequent
functionalization by hydrosilylation of the SiH reactive groups. The thin films of crosslinked resin are covalently bonded
to the glass substrate and contain a very low concentration of silole groups. They exhibit the aggregation-induced
emission effect owing to restricted intramolecular rotation, and show enhanced sensitivity to nitroaromatic analytes
because of the very low concentration of silole groups. The films can be used to test for nitroaromatics present not only
in the vapour phase but also in many types of solvent because of the robust nature of the crosslinked network and
covalent bonding to the substrate. They can be made in thicknesses ranging from 20 nm up to 1 μm. The silole groups
are readily accessible, and the sensors can be regenerated by washing with solvents such as chloroform.
The preparation is described of a novel highly emissive ytterbium complex with a proposed unusual structure obtained
by reaction of tricyanovinylbenzene (TCNVB) with bis(indenyl)ytterbium(II) in THF. The reaction occurs under
extremely mild conditions, the tetraphenyltetracyanoporphyrazine macrocycle being assembled in high yield from
TCNVB building-blocks by Yb3+-template synthesis. The analytical, spectral and electrochemical investigations of the
obtained ytterbium complex indicate its existence in the form of a binuclear adduct with Yb(TCNVB)3 species in which a
one doubly reduced TCNVB molecule bridges two Yb3+ cations. The formation of a disordered polynuclear coordination
polymer network including a macrocyclic structure and metal cations bridged through the nitrile nitrogen atoms is
proposed. The complex is readily soluble and is compatible with a variety of polymeric matrices giving doped polymeric
glasses and films which are highly luminescent in the biologically relevant optical window covering the visible and near
infrared range (640-1000 nm). In addition, doped polymeric glasses and films highly emissive at the telecommunication
wavelength (1540 nm) including the novel ytterbium complex and originally not luminescent erbium chelate in an
equimolar ratio have been obtained. The compound is found to be an extraordinarily strong sensitizer of near-IR Er3+
emission. Use of the Yb complex as a fluorescent marker for biomedical in vitro investigations has been demonstrated.
The goal of the present study is to underline the relationships that may exist between the molecular arrangement in thin films and the OLED efficiency. For this purpose, we have synthesized three new silole derivatives with incrementally flexible structure to tune their packing ability. Moreover, these siloles were especially designed to possess both electron- and hole-transporting properties in order to be used in single-layer OLEDs. This architecture was chosen since the absence of organic layers interfaces allows a better evaluation of the role of the molecular arrangement in the active layer. The examination of the EL properties gives evidences of the prominent role of the molecular organization on the OLED efficiency. A crystalline-like organization of the molecules allows high current density but low luminance efficiency since an excessive electron current flow is involved compared to the hole one, and the recombination rate is poor. On the contrary, disordered assemblies of molecules allows better performances by avoiding unfavorable π-stacking, while keeping good intermolecular orbital overlaps to support charge carrier transport. Thus single-layer devices based on silole 9 exhibit luminance efficiency as high as 0.75 Cd/A associated with both good chemical and film stabilities that are very promising applications for long life OLED application.
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