2-Azabutadiene complexes of rhenium(I): S,N-chelated species with photophysical properties heavily governed by the ligand hidden traits.

The reaction of [Re(CO)3(THF)(µ-Br)]2 or [Re(CO)5X] (X = Cl, Br, I) with the diaryl-2-azabutadienes [(RS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CAr2] containing two thioether arms at the 4,4-position forms the luminescent S,N-chelate complexes fac-[(OC)3ReX{(RS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CAr2}] (1a-h). The halide abstraction by silver triflate converts [(OC)3ReCl{(PhS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CPh2}] (1c) to [(OC)3Re(OS([double bond, length as m-dash]O)2CF3){(PhS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CPh2}] (1j) bearing a covalently bound triflate ligand. The cyclic voltammograms reveal reversible S^N ligand-centred reduction and irreversible oxidation waves for all complexes. The crystal structures of nine octahedral complexes have been determined along with that of (NaphtylS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CPh2 (L6). A rich system of weak non-covalent intermolecular secondary interactions through CHX(Cl, Br)Re, CHO, COπ(Ph), CHπCO, CHO and CHS contacts has been evidenced. The photophysical properties have been investigated by steady-state and time-resolved absorption (fs transient absorption, fs-TAS) and emission (ns-TCSPC and ps-Streak camera) spectroscopy in 2-MeTHF solution at 298 and 77 K. The emission bands are composed of either singlet (450 < λmax < 535 nm) and/or triplet emissions (at 77 K only, λmax < 640 nm, or appearing as a tail at λ > 600 nm), which decay in a multiexponential manner for the fluorescence (short ps (i.e.

A Platinum(II) Organometallic Building Block for the Design of Emissive Copper(I) and Silver(I) Coordination Polymers.

The tritopic organometallic ligand trans-MeSC6H4C≡CPt(PMe3)2(C≡N) (L1) was prepared from cis-PtCl2(PMe3)2 and p-ethynyl(methyl thioether)benzene. Its versatility was shown with the formation of [CuX(L1)]n coordination polymers (CPs) with CuX salts in MeCN (X = I (CP1), CN (CP2), SCN (CP3)). These CPs were characterized by X-ray crystallography, thermal gravimetric analysis (TGA), and IR and Raman spectroscopy. CP1 consists of a 1D head-to-tail chain formed by tricoordinated -C≡N-CuI(η2-C≡C)- linkages, whereas CP2 is built upon a central (CuCN)n zigzag chain bearing dangling L1s held by -C≡N-Cu bonds. Finally, CP3 exhibits 2D sheets secured by Cu-N≡C-/-(Me)S-Cu bondings and transversal Cu-S-C≡N-Cu bridges. Concurrently, the CPs formed with AgX (X = NO3- (CP4 and CP5), CF3CO2- (CP6) PF6- (CP7)) exhibits 2D sheets with guest molecules (anion, solvents) inside the tight pores or between layers. These new materials are emissive: L1 (λ0-0 ∼465 nm), CP1-CP7 (500 < λmax < 620 nm). Their photophysical properties (absorption and emission spectra, emission lifetimes (∼0.2 < τe < 120 µs), and quantum yields in the solid state at 77 and 298 K) were analyzed. The various natures of the emissive excited states were addressed by density functional theory (DFT) and time-dependent DFT (TDDFT) computations. For CP1, this state is a triplet halide or pseudohalide to ligand charge transfer 3XLCT (CT = charge transfer; X = I; L = L1) and for CP2, it is 3XLCT (X = CN; L = L1). However, for CP3, it is 3XLCT (X = SCN; L = L1). For CP4, the T1 state is described as a [MeSC6H4(η2-C≡C)-Ag(NO3)]2 → [Pt]/C≡CC6H4SMe CT.

A "Flexible" Rigid Rod, trans-Pt(PMe3)2(C≡CC6H4CN)2 (L1), to Form 2D [{Cu2(µ2-X)2}2(µ4-L1)] n Polymers (X = Br, I) Exhibiting the Largest Bathochromic Emissions.

The trans-Pt(PMe3)2(C≡CC6H4CN)2 organometallic ligand L1, which is prepared from 4-ethynylbenzonitrile and cis-Pt(PMe3)2Cl2, binds CuX salts to form two strongly luminescent two-dimensional coordination polymers (CPs) [{Cu2(µ2-X)2}2(µ4-L1)] n (X = I, CP1; X = Br, CP2). The emission quantum yields, Φe ≈ 30% at 298 K, are the largest ones for all CPs built upon the trans-Pt(PMe3)2(C≡CC6H4X)2 motifs (X = SMe, CN). X-ray crystallography reveals that, to accommodate these layered CPs, L1 must undergo major distortions of the C≡C-C angles (∼159°) and significant rotations about the Pt-CC bonds, so that the dihedral angles made by the two aromatic planes is 90° in a quasi-identical manner for both CPs. Together, these two features represent the largest distortion for trans-Pt(PMe3)2(C≡CC6H4X)2 complexes among all of the CPs built upon this type of ligand (2 of 16 entries). Concurrently, CP1 and CP2 also exhibit the most red-shifted emissions (λmax = 650 and 640 nm, respectively) known for this type of chromophore at room temperature. The {Cu2(µ2-X)2} rhomboids adopt the trans- (X = I, common) and cis-geometries (X = Br, extremely rare) making them "isomers" if excluding the fact that the halides are different. Density functional theory (DFT) and time-dependent DFT suggest that the triplet emissive excited state is metal/halide-to-ligand charge transfer in both cases despite this difference in rhomboid geometry.

Multiply "trapped" 3[trans-Pt(PR3)2(C[triple bond, length as m-dash]CC6H4X)2]* conformers in rigid media.

The complexes (R = Me, Et, Bu; X = H, SMe) exhibit well-defined multi-exponential emissions (2-4 components) in the solid state at 77 and 298 K and in 2MeTHF glasses at 77 K due to multiple frozen conformers exhibiting variable dihedral angles formed by the PtP2C2 and C6H4 planes. The demonstration was made using X-ray crystallography at various temperatures where different sites are present in the samples, and using geometry optimization (DFT computations) where various stable conformers are noted.

The trans-Bis(p-thioetherphenylacetynyl)bis(phosphine)platinum(II) Ligands: A Step towards Predictability and Crystal Design.

Two organometallic ligands L1 (trans-[p-MeSC6H4C≡C-Pt(PR3)2-C≡CC6H4SMe; R = Me]) and L2 (R = Et) react with CuX salts (X = Cl, Br, I) in MeCN to form one-dimensional (1D) or two-dimensional (2D) coordination polymers (CPs). The clusters formed with copper halide can either be step cubane Cu4I4, rhomboids Cu2X2, or simply CuI. The formed CPs with L1, which is less sterically demanding than L2, exhibit a crystallization solvent molecule (MeCN), whereas those formed with L2 do not incorporate MeCN molecules in the lattice. These CPs were characterized by X-ray crystallography, thermogravimetric analysis, IR, Raman, absorption, and emission spectra as well as photophysical measurements in the presence and absence of crystallization MeCN molecules for those CPs with the solvent in the lattice (i.e., [(Cu4I4)L1·MeCN] n (CP1), [(Cu2Br2)L1·2MeCN] n (CP3), and [(Cu2Cl2)L1·MeCN] n (CP5)). The crystallization molecules were removed under vacuum to evaluate the porosity of the materials by Brunauer-Emmett-Teller (N2 at 77 K). The 2D CP shows a reversible type 1 adsorption isotherm for both CO2 and N2, indicative of microporosity, whereas the 1D CPs do not capture more solvent molecules or CO2.

The 3D [(Cu2Br2){µ-EtS(CH2)4SEt}]n material: a rare example of a coordination polymer exhibiting triplet-triplet annihilation.

EtS(CH2)4SEt, L1, forms with CuI a luminescent 2D polymer [Cu4I4{µ-L1}2]n (CP1), which exhibits no triplet excitation energy migration, but with CuBr, it forms a 3D material (CP2), [(Cu2Br2){µ-L1}]n consisting of parallel (Cu2Br2S2)n layers bridged by L1's. CP2 shows T1-T1 annihilation at 298 K but not at 77 K.

Luminescent 1D- and 2D-Coordination Polymers Using CuX Salts (X = Cl, Br, I) and a Metal-Containing Dithioether Ligand.

The organometallic synthon trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1) reacts with CuX (X = Cl, Br, I) in PrCN and PhCN to form 1D- or 2D-coordination polymers (CP) with a very high degree of variability of features. The copper-halide unit can be either the rhomboids Cu2X2 fragments or the step cubane Cu4I4. The CP's may also incorporate a crystallization solvent molecule or not, which may be coordinated to copper or not. Their characterizations were performed by X-ray crystallography, thermal gravimetric analysis (TGA), and IR, absorption, and emission spectra as well as photophysical measurements in the presence and absence of solvent crystallization molecules. The nature of the singlet and triplet excited state was addressed using DFT and TDDFT computations, which turn out to be mainly ππ* with some minor MLCT (Cu4I4 → L1) contributions. The porosity of the materials has been evaluated by BET (N2 at 77 K). The solvent-free 1D CP's are not prone to capture solvent molecules or CO2, but the efficiency for CO2 absorption is best for the 2D CP, which exhibits the presence of clear cavities in the grid structure, after the removal of the crystallization molecules.

Can a highly flexible copper(i) cluster-containing 1D and 2D coordination polymers exhibit MOF-like properties?

The reaction of CuI with the highly flexible dithioether ligand p-TolS(CH2)8STol-p affords both in MeCN or in EtCN the 2D coordination polymers [Cu8I8{p-TolS(CH2)8STol-p}3(solvent)2]n (1·MeCN and 1·EtCN) containing octanuclear Cu8I8 clusters as connection nodes. In contrast, treatment of CuI with p-tBuC6H4S(CH2)8SC6H4But-p in EtCN solution leads to the formation of the luminescent 1D CP [Cu4I4{tBuC6H4S(CH2)8SC6H4-tBu}2(EtCN)2]n (2·EtCN) incorporating Cu4(µ3-I)4 clusters of the closed cubane type as secondary building units (SBUs). The 2D coordination polymers 1·MeCN and 1·EtCN demonstrate the ability to lose their solvent crystallisation molecules under vacuum and readsorb the same or a new one using vapor as monitored by powder X-ray diffraction, thermogravimetric, IR, chromaticity, emission spectra and emission lifetime measurements. Conversely, the 1D material 2·EtCN does not readsorb EtCN, likely due to the collapse of the macrocycles formed by the metal cluster nodes and flexible long-chained ArSC8SAr ligands but absorbs a smaller substrate such as CO2.