Switching of Reverse Charge Transfers for a Rational Design of an OFF–ON Phosphorescent Chemodosimeter of Cyanide Anions

A rational approach to luminescence turn-on sensing of cyanide by a dicyanovinyl-substituted acetylide Pt­(II) complex, which primarily relies on the nucleophilic addition reaction of cyanide anions to the α-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 ML′CT to MLCT/L′LCT in this acetylide Pt­(II) sensor. As a result, this chromophore that exhibits almost no basal luminescence displays observable changes in its UV–visible 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^– 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 4,4′-Diaminostyryl-2,2′-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 silver­(I) complex incorporating 4,4′-diaminostyryl-2,2′-bipyridine (DES) derivatives as ligands. Coordination with Ag⁺ 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 DES₂Ag⁺ shows that the presence of silver cation increases the efficiency for the generation of radical cations (DES^•+), 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 DES₂Ag⁺ as two-photon initiator offers new opportunities for the fabrication of functional nanostructures composed of metal–polymer nanocomposites

Supramolecular Ruthenium–Alkynyl Multicomponent Architectures: Engineering, Photophysical Properties, and Responsiveness to Nitroaromatics

A series of H-bonded supramolecular architectures were built from monofunctional M–CC–R and bifunctional R–CC–M–CC–R <i>trans</i>-alkynylbis­(1,2-bis­(diphenylphosphino)­ethane)­ruthenium­(II) complexes and π-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 Ruthenium–Alkynyl Multicomponent Architectures: Engineering, Photophysical Properties, and Responsiveness to Nitroaromatics

A series of H-bonded supramolecular architectures were built from monofunctional M–CC–R and bifunctional R–CC–M–CC–R <i>trans</i>-alkynylbis­(1,2-bis­(diphenylphosphino)­ethane)­ruthenium­(II) complexes and π-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