Perfluorocyclohexene bridges in inverse DiArylEthenes: synthesis through Pd-catalysed C-H bond activation, experimental and theoretical studies on their photoreactivity.

International audienceThe palladium-catalysed direct di-heteroarylation of 1,2-dichloroperfluorocyclohexene with a variety of heteroarenes gives rise in to a new family of 1,2-di(heteroaryl)perfluorocyclohexenes. These derivatives do not exhibit photoreactivity and this unexpected outcome is explained by calculations demonstrating the lack of reactive isomers

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

An unprecedented family of luminescent iridium(III) complexes bearing a six-membered chelated tridentate C^N^C ligand

C.H. acknowledges the Région Bretagne, France for funding. EZ-C acknowledges the University of St Andrews and EPSRC (EP/M02105X/1) for financial support. The authors thank the EPSRC UK National Mass Spectrometry Facility at Swansea University for analytical services. T.R. thanks the FEDER funds for financial support helping the acquisition of the D8Venture diffractometer of ISCR. D.J. acknowledges the European Research Council and the Région des Pays de la Loire for financial support in the framework of a Starting Grant (Marches - 278845) and the LUMOMAT RFI project, respectively. This research used computational resources of 1) the GENCI-CINES/IDRIS, 2) the CCIPL (Centre de Calcul Intensif des Pays de Loire), 3) a local Troy cluster.A new family consisting of three luminescent neutral Ir(III) complexes with the unprecedented [Ir(C^N^C)(N^N)Cl] architecture, where C^N^C is a bis(six-membered) chelating tridentate tripod ligand derived from 2-benzhydrylpyridine (bnpy) and N^N is 4,4'-ditert-butyl-2,2'-bipyridine (dtBubpy) is reported. X-ray crystallography reveals an unexpected and unusual double C-H bond activation of the two distal non-conjugated phenyl rings of the bnpy coupled with a very short Ir-Cl bond trans to the pyridine of the bnpy ligand. Depending on the substitution on the bnpy ligand, phosphorescence, ranging from yellow to red, is observed in dichloromethane solution. A combined study of density functional theory (DFT) and time-dependent DFT (TD-DFT) corroborates the mixed charge-transfer nature of the related excited-states.Publisher PDFPeer reviewe

Sequential double second-order nonlinear optical switch by an acido-triggered photochromic cyclometallated platinum(ii) complex.

International audienceAn unprecedented DTE-based Pt(II) complex, 2(o), which stands as the first example of a sequential double nonlinear optical switch, induced first by protonation and next upon irradiation with UV light is presented

Photoswitching of the second-order nonlinearity of a tetrahedral octupolar multi DTE-based copper(I) complex.

International audienceThe modulation of the quadratic NLO response of an octupolar metal-based chromophore featuring four photochromic dithienylethene units is reported. Quantum mechanical simulations are consistent with a full switching of the DTE units and reproduce the strong enhancement of the NLO response

Tunable double photochromism of a family of bis-DTE bipyridine ligands and their dipolar Zn complexes.

International audienceThe photoinduced ring-closure/ring-opening reactions of a series of bis-dithienylethene derivatives, as free ligands and Zn(II)-complexes, are investigated by resorting to theoretical (time-dependent density functional theory) and kinetic analyses in solution. The originality of the system stems from the tunability of the photoreaction quantum yields and conversion yields as a function of the electronic structure. The latter could be varied by modifying the electron-donating character of the DTE-end substituents L(a-d) (o,o) (a, D = H; b, D = OMe; c, D = NMe(2); d, D = NBu(2)) and/or the Lewis character of the metal ion center L(a-d)ZnX(2) (o,o) (L(a-c), X = OAc; L(d), X = Cl). The orbital description of the doubly-open form (o,o) and half-closed form (o,c) predicts that double closure to the form (c,c) would occur using UV irradiation. Photokinetic studies on the complete series demonstrate that photocyclization proceeds following a sequential ring closure mechanism. They clearly point out distinct quantum yields for the first and second ring closures, the latter being characterized by a significantly lower value. Dramatic decrease in both the quantum yields of the ring-closure and ring-opening processes is demonstrated for the complex L(d)ZnCl(2) exhibiting the strongest charge-transfer character in the series investigated. These studies show that this series of DTE derivatives provides an efficient strategy to tune the photochromic properties through the combination of the electron-donor and electron-acceptor (D-A) groups

Functionalized styryl iridium(III) complexes as active second-order NLO chromophores and building blocks for SHG polymeric films

International audienceWe studied the second-order NLO properties in solution of various Ir(III) acetylacetonate complexes bearing a substituted cyclometallated 4-styryl-2-phenylpyridine (ppy-4-styryl-R, with R = NEt2, OMe, H, NO2) with the EFISH technique. The dipole moments were evaluated by Density Functional Theory (DFT) calculations. We have also investigated the Second Harmonic Generation (SHG) of composite films based on the various cyclometallated Ir(III) complexes dispersed and oriented in a polymethylmethacrylate (PMMA) matrix

Modulating the luminescence of an iridium(III) complex incorporating a di(2-picolyl)anilino-appended bipyridine ligand with Zn2+ cations

International audienceA novel iridium complex incorporating a di(2-picolyl)anilino-appended bipyridine ligand was synthesized and its optical properties studied. The presence of Zn2+ ions specifically perturbs the excited state, giving rise to a blue-shifted absorption and emission, and a shorter luminescence lifetime

A "reverse interrupter": the novel molecular design of a fluorescent photochromic DTE-based bipyridine

International audienceAn original design of a fluorescent dithienylethene (DTE)-based bipyridine, where donor (D) and acceptor (A) groups are located on the same thiophene ring of the DTE unit, is reported; in non-polar solvents, UV or visible excitation triggers a photochromic reaction, disrupting the conjugation and quenching the fluorescence