Micropatterning of electrochemiluminescent polymers based on multipolar Ru-complex two-photon initiators.

In this work, we present an original stereolithography strategy based on multibranched Ru-complexes with a high two-photon initiating ability allowing the 'one-pot' direct laser writing of ECL-active materials deposited onto electro-active surfaces at the µm scale.

Unexpected disruption of the dimensionality-driven two-photon absorption enhancement within a multipolar polypyridyl ruthenium complex series.

The dimensionality-driven two-photon absorption (2PA) enhancement effect is investigated in a series of functionalized bipyridyl Ru-complexes. Our design strategy leads to very high 2PA responses up to ∼1500 GM. However, we highlight that the 2PA performance vs. dimensionality correlation reaches an unexpected limit stemming from 'anti-cooperative' interchromophoric couplings.

Liposomes for PET and MR Imaging and for Dual Targeting (Magnetic Field/Glucose Moiety): Synthesis, Properties, and in Vivo Studies.

We describe the potentiality of a new liposomal formulation enabling positron emission tomography (PET) and magnetic resonance MR() imaging. The bimodality is achieved by coupling a 68Ga-based radiotracer on the bilayer of magnetic liposomes. In order to enhance the targeting properties obtained under a permanent magnetic field, a sugar moiety was added in the lipid formulation. Two new phospholipids were synthesized, one with a specific chelator of 68Ga (DSPE-PEG-NODAGA) and one with a glucose moiety (DSPE-PEG-glucose). The liposomes were produced according to a fast and safe process, with a high radiolabeling yield. MR and PET imaging were performed on mice bearing human glioblastoma tumors (U87MG) after iv injection. The accumulation of the liposomes in solid tumor is evidenced by MR imaging and the amount is evaluated in vivo and ex vivo according to PET imaging. An efficient magnetic targeting is achieved with these new magnetic liposomes.

Photoisomerisation in Aminoazobenzene-Substituted Ruthenium(II) Tris(bipyridine) Complexes: Influence of the Conjugation Pathway.

Transition-metal complexes containing stimuli-responsive systems are attractive for applications in optical devices, photonic memory, photosensing, as well as luminescence imaging. Amongst them, photochromic metal complexes offer the possibility of combining the specific properties of the metal centre and the optical response of the photochromic group. The synthesis, the electrochemical properties and the photophysical characterisation of a series of donor-acceptor azobenzene derivatives that possess bipyridine groups connected to a 4-dialkylaminoazobenzene moiety through various linkers are presented. DFT and TD-DFT calculations were performed to complement the experimental findings and contribute to their interpretation. The position and nature of the linker (ethynyl, triazolyl, none) were engineered and shown to induce different electronic coupling between donor and acceptor in ligands and complexes. This in turn led to strong modulations in terms of photoisomerisation of the ligands and complexes.

Absorption and fluorescence signatures of 1,2,3-triazole based regioisomers: challenging compounds for TD-DFT.

In the continuous quest for improving TD-DFT methodologies as a tool to predict the photophysical features of solvated chromophores, we investigate two model regioisomers based on the 1,2,3-triazole moiety. Starting from their experimental absorption and emission spectra, key energy differences highlighting the main trends between the two isomers are extracted and used to gauge the accuracy of several levels of theory. RI-CC2 and EOM-CCSD calculations allow us to ascertain that the low energy spectra are not linked to double excitations. In a vacuum, none of these methods nor any of the implemented TD-DFT levels of theory, ranging from global hybrids (PBE0, B3LYP) to range-separated functionals without (CAM-B3LYP, ωB97X) or with dispersion corrections (ωB97X-D), are able to capture the key features that differentiate the two chromophores. Accounting for solvent within a specific PCM model allows us to recover experimental trends, but the dramatic changes occurring when moving from toluene to THF and/or when using different PCM approaches (LR, cLR, SS) suggest that this agreement is probably fortuitous. Even if the ωB97X-D functional combined with the SS-PCM scheme leads to quantitative agreement with experiment, TD-DFT results obtained for 1,2,3-triazole based chromophores need to be treated with caution. We also show that the SS-PCM approach may be useful to test current and novel exchange-correlation functionals against the charge transfer failure.

Cyclometalated platinum(II) with ethynyl-linked azobenzene ligands: an original switching mode.

The photophysical properties of 6-phenyl-2,2'-bipyridyl platinum(ii) complexes bearing different σ-alkynyl-linked azobenzene ancillary ligands were investigated. These complexes exhibited strong, broad, structureless charge-transfer bands in the visible region, which were red-shifted when the electron-donating ability of the para substituent on the azo-acetylide ligand increased. When excited at the charge-transfer absorption band, the complexes exhibited weak green emission, which was assigned to a triplet metal-to-ligand charge transfer/interligand charge transfer emission ((3)MLCT/(3)L'LCT). The presence of an amino substituent in the azobenzene moiety opened the possibility of protonation, which led to the formation of an azonium based derivative and resulted in drastic perturbations of the molecular orbitals and photophysical properties of the Pt-acetylide complex. These studies are fully supported by DFT and TD-DFT calculations.