Cyclometallated platinum(II) complexes containing pyridyl-acetylide ligands: the selective influence of lead binding on luminescence

International audienceThe design, synthesis, photophysical properties, and the ion-binding properties of cyclometallated platinum(II) complexes containing pyridyl-appended alkynyl ligands are described. When the pyridyl group is incorporated into an azamacrocycle, a specific response towards lead(II) cations involves a change in the nature of the excited charge transfer state, resulting in the appearance of a low-energy absorption band and a partial quenching of luminescence

Switching of excited states in cyclometalated platinum complexes incorporating pyridyl-acetylide ligands (Pt-C[triple bond, length as m-dash]C-py): a combined experimental and theoretical study

International audienceThis article presents the design of cyclometalated platinum(II) complexes incorporating pyridyl-appended acetylide ligands of the form Pt-C[triple bond, length as m-dash]C-py, acting either as sites for protonation or methylation reactions or as a host receptor for binding metal cations. The complexes studied are Pt(t-Bu2phbpy)(-C[triple bond, length as m-dash]C-py), 2, which can undergo protonation at the pyridyl N; its cationic N-methylated derivative [Pt(t-Bu2phbpy)(-C[triple bond, length as m-dash]C-pyMe)]+, 4, which serves as a model of the N-protonated species; and a derivative in which the pyridyl ring is incorporated into a macrocyclic diamide-crown ether ligand (3). The co-ligand t-Bu2phbpy is a cyclometalated, N[caret]N[caret]C-coordinated phenylbipyridine ligand carrying tert-butyl groups at the 4-positions of the pyridyl rings. The photophysical properties of the neutral compounds 2 and 3 have been compared to those of the pyridinium, methyl-pyridinium or metal-complexed species (namely 2-H+, 4 and 3-Pb2+). Detailed TD-DFT calculations provide a theoretical basis to account for the experimentally-observed changes upon protonation/methylation/complexation. The joint TD-DFT and experimental studies provide evidence for an unprecedented molecular switch in the nature of the excited state (from mixed L′LCT/MLCT to ML′CT) in which the acceptor ligand in the CT process switches from being the N[caret]N[caret]C ligand to the pyridyl acetylide

Database of pleistocene periglacial featuresin France: description of the online version

A database of Pleistocene periglacial features in France has been compiled from a review of academic literature and reports of rescue archaeology, the analysis of aerial photographs and new field surveys. Polygons, soil stripes, ice-wedge pseudomorphs, sand wedges and composite wedge pseudomorphs are included in the database together with their geographic coordinates, geological context, description and associated references. It is hoped that this database, which aim is to be integrated in broader studies, will stimulate further work on past permafrost reconstruction and will favour greater understanding of the climatic events that lead to the formation of the periglacial features. The database is available online on the AFEQ-CNF INQUA website (https://afeqeng.hypotheses.org/487). A folder that contains photographs and sketches of the features is also available on request.Une base de données des structures périglaciaires pléistocènes de France a été créée à partir d’une revue de la littérature scientifique, de rapports d’archéologie préventive, de l’analyse de photographies aériennes et de nouvelles prospections de terrain. Les polygones, les sols striés, les pseudomorphoses de coin de glace, les coins de sable et les pseudomorphoses de coin composite ont été répertoriés dans la base de données avec leurs coordonnées géographiques, le contexte géologique, leur description et les références bibliographiques associées. Nous espérons que cette base de données, dont le but est d’être intégrée dans des études plus larges, stimulera de prochains travaux sur la reconstitution du pergélisol pléistocène et favorisera une plus grande compréhension des événements climatiques qui ont conduit à la formation de ces structures périglaciaires. La base de données est disponible en ligne sur le site de l’AFEQ-CNF INQUA (https://afeqeng.hypotheses.org/487). Un dossier contenant les photographies et dessins des structures périglaciaires est également disponible sur demande

Ingénierie moléculaire de complexes de platine : application à la détection de cations métalliques par luminescence.

Cyclometallated platinum (II) acetylide complexes are known for their strong phosphorescence which is versatile to its chemical environment. The use of such complexes is in adequacy to the actual need in luminescent molecular. The acetylide ligand integrates the receptor which is able to coordinate transition metal cations. The choice of the receptor lies in both its fitness in the cation coordination and in contribution to the luminescence properties of the complex. Our strategy was successful; we report series of complexes which are selective, namely to lead cation. In addition, cation binding gives rise to a variety of unprecedented photoluminescent processes: improving or quenching the luminescence, switching phosphorescence to fluorescence. The origin of those processes is depicted through the different chapters of this thesis.Les complexes de platine (II) cyclométallés et à ligand acétylure ont une phosphorescence intense et sensible à l'environnement chimique. Leur utilisation en tant que sondes luminescentes est en accord avec le besoin actuel de nouveaux matériaux moléculaires. Nous avons choisi d'incorporer en position acétylénique un récepteur apte à la coordination de cations de métaux de transition. Le choix du motif a été motivé par ses aptitudes à la fois à la coordination de cations et à moduler les propriétés luminescentes. Notre stratégie s'est révélée être fructueuse avec le développement de sondes sélectives, notamment à l'ion plomb (II). La coordination du cation par le récepteur provoque des réponses très variées : exacerbation de l'émission, extinction de l'émission, basculement phosphorescence à fluorescence. Ces processus sont explicités au cours des différents chapitres de cette thèse

Ditopic bis-terdentate cyclometallating ligands and their highly luminescent dinuclear iridium(iii) complexes.

A new family of bridged cyclometallating ligands is reported, which incorporate two terdentate N(∧)C(∧)N-coordinating binding sites linked via pyrazine, pyrimidine or pyridazine units. Dinuclear Ir(iii) complexes of one ligand have been prepared and crystallographically characterised; they display intense red phosphorescence

Two photon photosensitizers for PDT: molecular engineering towards understanding of their excited state photophysics

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Neutral heteroleptic cyclometallated Platinum(II) complexes featuring 2-phenylbenzimidazole ligand as bright emitters in solid state and in solution

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Cover Picture: Theoretical and Experimental Study on Boron β-Diketonate Complexes with Intense Two-Photon-Induced Fluorescence in Solution and in the Solid State (ChemPhysChem 14/2016)

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Cyclometalated N-heterocyclic carbene iridium( iii ) complexes with naphthalimide chromophores: a novel class of phosphorescent heteroleptic compounds

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Water-soluble chromophores with star-shaped oligomeric arms: synthesis, spectroscopic studies and first results in bio-imaging and cell death induction

International audienceA simple polymerisation strategy allows water solubilisation of chromophores for biophotonics, with good conservation of their fluorescence quantum-yield. Preliminary investigations show that the resulting objects are valuable candidates for photodynamic therapy and two-photon fluorescence imaging