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2-R-1H-1,3-Benzazaphospholes (R-BAPs) are an interesting class of fluorescent σ2P heterocycles containing PC bonds.

2-R-1

International audience; Adaptive coordination-driven supramolecular chemistry based on conformationally flexible pre-organized luminescent Cu(I) precursors paves the way to the ready formation of intricate supramolecular scaffold possessing intrinsic luminescence properties. A formal ring extension of a tetrametallic Cu(I) metallacycle bearing Thermally Activated Delayed Fluorescence (TADF) properties can thus be carried out, affording a new hexametallic Cu(I) metallacycle 1 bearing modulated solid-state TADF properties. Attempts to adapt this ring extension process to the formation of targeted heterometallic Au2Cu4 and Pt2Cu8 assemblies led to the unexpected and ready formation of the Au2Cu10 and Pt4Cu11 derivatives 2 and 3, respectively. These outcomes strengthen the scope and perspectives of adaptive coordination-driven supramolecular chemistry compared to those of conventional coordination-driven supramolecular chemistry. Indeed, it guides concerted intramolecular fragmentation and redistribution of the particular building blocks used, affording selectively supramolecular scaffolds of higher nuclearity and complexity. The study of the solid-state photophysical properties of the assemblies 2 and 3 highlights enhanced and original behaviors, in which the heavy metal spin-orbit coupling values significantly influence the relaxation processes centered on the Cu(I) metal centers.

International audience; The ditopic nitrile-capped 1,4-phenylenediacetonitrile linker L3 featuring partial conformational flexibility was reacted with a flexible pre-assembled Cu(I) dimer stabilized by the bis(diphenyl-phosphino)methane dppm ligand along adaptive coordination-driven supramolecular assembling processes. It resulted in the selective and unexpected formation of a compact tetrametallic assembly associating two bimetallic building blocks with three ditopic linkers. The solid-state photophysical studies of this original Cu(I)-based assembly were analysed and showed its attractive luminescence properties.

2-R-1,3-Benzoxaphospholes (R-BOPs) are examples of fluorescent conjugated materials possessing low coordinate phosphorus centers. A series of 2-(p-XC6H4)-BOPs (X = H, Cl, Br, Me, OMe) react with [W(CO)5(NCMe)] to produce the crystalline complexes [W(CO)5(2-Ar-BOP)] (2a-e). All complexes were characterized by NMR spectroscopy and by single crystal X-ray diffraction. The crystal structures all displayed extensive π-stacking of the BOP ligands and gear locking of the CO groups. Addition of the protecting [W(CO)5] group to the BOPs was discovered to significantly diminish fluorescence of the BOP moiety.

International audience; The reaction of the pre-assembled bimetallic Cu(i) [Cu-2(mu(2)-dppm)(2)](2+) fragment with the ligand 1,4-dicyanobenzeneB(0)in non-distilled CH(2)Cl(2)allowed the characterisation of an unexpected one-dimensional coordination polymerD, while no reaction occurred when dry CH(2)Cl(2)was used as the solvent. The X-ray crystal structure resolution performed on air-stable single crystals ofDrevealed that this coordination polymer contained the first reported bridging aqua ligand coordinated on Cu(i) bimetallic units connected byB(0)ligands within zig-zag chains. Consequently,Dwas obtained in very good yield when the synthesis was conducted in dry CH2Cl2, in which water was added as a reactant in excess. In the solid state at room temperature under UV lamp excitation,Dpresented blue-cyan eye-perceived luminescence that contrasted with the green-yellow eye-perceived luminescence emitted by single crystals ofDin the crystallisation solution. Related to this property, reversible luminescent vapochromic behaviour was observed upon the exposure of dry single crystals ofDto vapors of CH2Cl2, EtOH, CH(3)NO(2)and THF solvents. The X-ray crystal structure resolution analysis revealed that this vapochromic response occursviasingle crystal to single crystal transitions, along which the volatile solvent molecules are taken up in the very low porous dry single crystals ofD, leading to the formation of one-dimensional channels of included solvent molecules, which are mobile in the crystalline solid at room temperature. The detailed temperature -dependent photophysical studies suggest that this mobility impacts the relaxation processes within these molecular solids, resulting in luminescence vapochromic effects. The results also highlight the complexity of the relaxation processes that can take place in these heteroleptic polymetallic Cu(i) supramolecular assemblies, which are based on highly easy, affordable and quick synthetic procedures.

Fluorescent molecules and materials that exhibit emission changes in response to analytes are of great interest across multiple disciplines. Herein, we investigate the response of NH-containing fluorophores carbazole and 2-phenylbenzimidazole (Ph-BIM) with two representative isolable singlet carbenes. Specifically, N-heterocyclic carbene 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and cyclic (alkyl)(amino)carbene (2,6-diisopropylphenyl)-4,4-diethyl-2,2-dimethyl-pyrrolidin-5-ylidene (EtCAAC) were discovered to afford three different types of reaction products with carbazole and Ph-BIM. Depending on the reaction pair, hydrogen bonding (1), NH-insertion (2,3), or proton transfer (4) products can be isolated, each displaying variable photophysical responses. These products have been structurally authenticated by single crystal X-ray diffraction and NMR spectrometric methods. Studies of the solution state behavior of 1-4 reveals that these adducts are labile and can reversibly dissociate to free carbenes and fluorophores to varying extents. These equilibria produce concentration dependent solution state behavior as identified and quantified via UV-visible absorption, emission, 1H DOSY, and NMR spectroscopic measurements.

International audience; A thermally activated delayed fluorescence (TADF) tetrametallic Cu(I) metallacycle A behaves as a conformationally adaptive preorganized precursor to afford, through straightforward and rational coordination-driven supramolecular processes, a variety of room-temperature solid-state luminescent polymetallic assemblies. Reacting various cyano-based building blocks with A, a homometallic Cu(I) 1D-helical coordination polymer C and CuM discrete circular heterobimetallic assemblies D (M = Ni, Pd, Pt) are obtained. Their luminescence behaviors are studied, revealing notably the crucial impact of the spin-orbit coupling offered by the central M metal center on the photophysical properties of the heterobimetallic D derivatives.

International audience; The reaction between a preassembled CuI bimetallic molecular clip with a short intermetallic distance and a series of fully aliphatic cyano-capped ditopic linkers with increasing lengths was investigated. It is shown that, depending on the length of the ditopic linkers, the rational design of unprecedented supramolecular compact metallacycles containing fully aliphatic walls is possible. The specific preorganized molecular arrangement of the molecular clip used favors stabilizing interlinker London dispersion interactions, which allow, as the length of the linkers increases, the selective formation of discrete compact metallacycles at the expense of 1D coordination polymers. The generalizability of this approach was demonstrated by the reaction of fully aliphatic cyano-capped linkers with two other types of preassembled CuI bimetallic molecular clips that also had short intermetallic distances.

Date of Acceptance: 29/05/2014 There is presently a lack of efficient and stable blue emitters for light-emitting electrochemical cells (LEECs), which limits the development of white light emitting systems for lighting. Cyclometalated iridium complexes as blue emitters tend to show low photoluminescence efficiency due to significant ligand-centred character of the radiative transition. The most common strategy to blue-shift the emission is to use fluorine substituents on the cyclometalating ligand, such as 2,4-difluorophenylpyridine, dFppy, which has been shown to decrease the stability of the emitter in operating devices. Herein we report a series of four new charged cyclometalated iridium complexes using methoxy- and methyl-substituted 2,3′-bipyridine as the main ligands. The combination of donor groups and the use of a cyclometalated pyridine has been recently reported for neutral complexes and found electronically equivalent to dFppy. We describe the photophysical and electrochemical properties of the complexes in solution and use DFT and TDDFT calculations to gain insights into their properties. The complexes exhibit bluish-green emission with onsets around 450 nm, which correspond to the maximum emission at 77 K. Furthermore, photoluminescence quantum yields in solution are all above 40%, with the brightest in the series at 66%. Finally, LEECs were prepared using these complexes as the emissive material to evaluate the performance of this particular design. Compared to previously reported devices with fluorine-containing emitters, the emitted colours are slightly red-shifted due to methyl substituents on the coordinating pyridine of the main ligand and overall device performances, unfortunately including the stability of devices, are similar to those previously reported. Interestingly within the series of complexes there appears to be a positive effect of the methoxy-substituents on the stability of the devices. The poor stability is therefore attributed to the combination of cyclometalated pyridine and methoxy groups. Postprint

Herein we report the synthesis and optoelectronic characterisation of three deep blue-emitting cationic iridium complexes, of the form [Ir(dFppy)2(N^N)]PF6, bearing biimidazole-type N^N ancillary ligands (dFppyH = 2-(2,4-difluorophenyl)pyridine). Complex 1 contains the parent biimidazole, biim, while 2 contains a dimethylated analog, dMebiim, and 3 contains an ortho-xylyl-tethered biimidzole, o-xylbiim. We explore a strategy of tethering the biimidazole in order to rigidify the complex and increase the photoluminescent quantum yield, culminating in deep blue (λmax: 457 nm in MeOH at 298 K) ligand-centered emission with a very high photoluminescent quantum yield of 68% and microsecond emission lifetime. Density functional theory calculations elucidate the origin of such disparate excited state kinetics across this series, especially in light of virtually identical optoelectronic properties observed for these compounds.

The straightforward synthesis of a new Cu(I) metal-rich small metallacycle is presented. This compound is luminescent in the solid state with an emission quantum yield of 72% at room temperature and displays a pronounced reversible red-shift of its emission spectra upon cooling. Quantum chemical calculations reveal that these properties are governed by important geometrical relaxations that imply the formation of cuprophilic interactions at the excited states.