4 research outputs found
Switching of Reverse Charge Transfers for a Rational Design of an OFFâON Phosphorescent Chemodosimeter of Cyanide Anions
A rational
approach to luminescence turn-on sensing of cyanide
by a dicyanovinyl-substituted acetylide PtÂ(II) complex, which primarily
relies on the nucleophilic addition reaction of cyanide anions to
the Îą-position of the dicyanovinyl group, is described. The
strategy used for the design of this cyanide-selective sensor takes
advantage of a switch of charge transfer from MLâ˛CT to MLCT/Lâ˛LCT
in this acetylide PtÂ(II) sensor. As a result, this chromophore that
exhibits almost no basal luminescence displays observable changes
in its UVâvisible spectrum and acquires strong phosphorescence
upon addition of cyanide anions. DFT computations reveal that the
frontier molecular orbitals of the anionic system obtained after addition
of CN<sup>â</sup> are drastically different from those of the
neutral initial species. TD-DFT computations permitted a full assignment
of the observed absorption bands and explained well the emissive properties
of the species under consideration
Enhancement of Two-Photon Initiating Efficiency of a 4,4â˛-Diaminostyryl-2,2â˛-bipyridine Derivative Promoted by Complexation with Silver Ions
We report on the two-photon-induced polymerization (TPIP)
ability
of a new class of free radical two-photon initiator based on a cationic
silverÂ(I) complex incorporating 4,4â˛-diaminostyryl-2,2â˛-bipyridine
(DES) derivatives as ligands. Coordination with Ag<sup>+</sup> induces
a strong increase of the charge transfer character at excited state,
which enhances the two-photon absorption properties of the complex
with respect to that of the free ligand. A comparative analysis of
the photophysical properties of DES and DES<sub>2</sub>Ag<sup>+</sup> shows that the presence of silver cation increases the efficiency
for the generation of radical cations (DES<sup>â˘+</sup>), which
can be used as hydrogen abstractor in free radical photopolymerization.
We show that the addition of an aliphatic amine used as hydrogen donor
also opens a parallel route for the regeneration of DES. The improvement
of the two-photon polymerization efficiency is then evidenced by the
fabrication of microstructures. We finally demonstrate that the use
of DES<sub>2</sub>Ag<sup>+</sup> as two-photon initiator offers new
opportunities for the fabrication of functional nanostructures composed
of metalâpolymer nanocomposites
Supramolecular RutheniumâAlkynyl Multicomponent Architectures: Engineering, Photophysical Properties, and Responsiveness to Nitroaromatics
A series of H-bonded
supramolecular architectures were built from
monofunctional MâCîźCâR and bifunctional RâCîźCâMâCîźCâR <i>trans</i>-alkynylbisÂ(1,2-bisÂ(diphenylphosphino)Âethane)ÂrutheniumÂ(II)
complexes and Ď-conjugated modules containing 2,5-dialkoxy-<i>p</i>-phenylene. Incorporation on each partner of a cyanuric
end and of the complementary Hamilton receptor provided the necessary
means to keep the constituents together via strong hydrogen bonding.
Characterization of all architectures has been performed on the basis
of NMR and photophysical methods. In particular, the formation of
a Hamilton receptor/cyanuric acid complex has been exemplified by
an X-ray single-crystal structure determination. Both self-assembly
and accurate modification of the complementary blocks were ensured
in such a way that the resulting materials maintain the responsiveness
of the electron-rich 2,5-dialkoxy-<i>p</i>-phenylene spacers
toward nitroaromatics
Supramolecular RutheniumâAlkynyl Multicomponent Architectures: Engineering, Photophysical Properties, and Responsiveness to Nitroaromatics
A series of H-bonded
supramolecular architectures were built from
monofunctional MâCîźCâR and bifunctional RâCîźCâMâCîźCâR <i>trans</i>-alkynylbisÂ(1,2-bisÂ(diphenylphosphino)Âethane)ÂrutheniumÂ(II)
complexes and Ď-conjugated modules containing 2,5-dialkoxy-<i>p</i>-phenylene. Incorporation on each partner of a cyanuric
end and of the complementary Hamilton receptor provided the necessary
means to keep the constituents together via strong hydrogen bonding.
Characterization of all architectures has been performed on the basis
of NMR and photophysical methods. In particular, the formation of
a Hamilton receptor/cyanuric acid complex has been exemplified by
an X-ray single-crystal structure determination. Both self-assembly
and accurate modification of the complementary blocks were ensured
in such a way that the resulting materials maintain the responsiveness
of the electron-rich 2,5-dialkoxy-<i>p</i>-phenylene spacers
toward nitroaromatics