Unusual triplet-triplet annihilation in a 3D copper(i) chloride coordination polymer.

A new coordination polymer (CP) defined as [Cu2Cl2(EtS(CH2)4SEt)4]n (CP2) was prepared by reacting EtS(CH2)4SEt with CuCl in acetonitrile in a 1 : 2 stoichiometric ratio. The X-ray structure reveals formation of non-porous 3D material composed of parallel 2D-[Cu2Cl2S2]n layers of Cl-bridged Cu2(µ-Cl)2 rhomboids assembled by EtS(CH2)4SEt ligands. A weak triplet emission (Φe < 0.0001) is observed in the 400-500 nm range with τe of 0.93 (298 K) and 3.5 ns (77 K) as major components. CP2 is the only 2nd example of emissive thioether/CuCl-containing material and combined DFT/TDDFT computations suggest the presence of lowest energy M/XLCT excited states. Upon increasing the photon flux (i.e. laser power), a triplet-triplet annihilation (TTA) is induced with quenching time constants of 72 ps (kQ = 1.3 × 1010 s-1) and 1.0 ns (kQ = 7.1 × 108 s-1) at 298 and 77 K, respectively, proceeding through an excitation energy migration operating via a Dexter process. Two distinct (Io)1/2 (Io = laser power) dependences of the emission intensity are depicted, indicating saturation as the observed emission increases with the excitation flux. These findings differ from that previously reported isomorphous CP [Cu2Br2(µ-EtS(CH2)4SEt)4]n (CP1), which exhibits no TTA behaviour at 77 K, and only one (laser power)2 dependence at 298 K. The ∼18-fold increase in kQ upon warming CP2 from 77 to 298 K indicates a temperature-aided TTA process. The significant difference between the presence (slower, CP2) and absence (CP1) of TTA at 77 K is explained by the larger unit cell contraction of the former upon cooling. This is noticeable by the larger change in inter-rhomboid CuCu separation for CP2.

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.

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.

Reactivity of CuI and CuBr toward dialkyl sulfides RSR: from discrete molecular Cu4I4S4 and Cu8I8S6 clusters to luminescent copper(I) coordination polymers.

The 1D coordination polymer (CP) [(Me2S)3{Cu2(µ-I)2}]n (1) is formed when CuI reacts with SMe2 in n-heptane, whereas in acetonitrile (MeCN), the reaction forms exclusively the 2D CP [(Me2S)3{Cu4(µ-I)4}]n (2) containing "flower-basket" Cu4I4 units. The reaction product of CuI with MeSEt is also solvent-dependent, where the 1D polymer [(MeSEt)2{Cu4(µ3-I)2(µ2-I)2}(MeCN)2]n (3) containing "stepped-cubane" Cu4I4 units is isolated in MeCN. In contrast, the reaction in n-heptane affords the 1D CP [(MeSEt)3{Cu4(µ3-I)4}]n (4) containing "closed-cubane" Cu4I4 clusters. The reaction of MeSPr with CuI provides the structurally related 1D CP [(MeSPr)3{Cu4(µ3-I)4}]n (5), for which the X-ray structure has been determined at 115, 155, 195, 235, and 275 K, addressing the evolution of the metric parameters. Similarly to 4 and the previously reported CP [(Et2S)3{Cu4(µ3-I)4}]n (Inorg. Chem. 2010, 49, 5834), the 1D chain is built upon closed cubanes Cu4(µ3-I)4 as secondary building units (SBUs) interconnected via µ-MeSPr ligands. The 0D tetranuclear clusters [(L)4{Cu4(µ3-I)4}] [L = EtSPr (6), Pr2S (7)] respectively result from the reaction of CuI with EtSPr and n-Pr2S. With i-Pr2S, the octanuclear cluster [(i-Pr2S)6{Cu8(µ3-I)3}(µ4-I)2}] (8) is formed. An X-ray study has also been performed at five different temperatures for the 2D polymer [(Cu3Br3)(MeSEt)3]n (9) formed from the reaction between CuBr and MeSEt in heptane. The unprecedented framework of 9 consists of layers with alternating Cu(µ2-Br)2Cu rhomboids, which are connected through two µ-MeSEt ligands to tetranuclear open-cubane Cu4Br4 SBUs. MeSPr forms with CuBr in heptane the 1D CP [(Cu3Br3)(MeSPr)3]n (10), which is converted to a 2D metal-organic framework [(Cu5Br5)(µ2-MeSPr)3]n (11) incorporating pentanuclear [(Cu5(µ4-Br)(µ2-Br)] SBUs when recrystallized in MeCN. The thermal stability and photophysical properties of these materials are also reported.

Coordination RC6 H4 S(CH2 )8 SC6 H4 R/(CuI)n polymers (R (n) = H (4); Me (8)): an innocent methyl group that makes the difference.

Under identical conditions, CuI reacts with PhS(CH2 )8 SPh and p-TolS(CH2 )8 STol-p affording, respectively, a luminescent 1D coordination polymer [Cu4 I4 {µ2 -PhS(CH2 )8 SPh}2 ]n (1) and an unprecedented 2D network [Cu8 I8 {µ2 -p-TolS(CH2 )8 STol-p}3 (MeCN)2 ]n (2), which incorporate closed-cubane Cu4 I4 and octanuclear Cu8 I8 clusters of as connecting nodes. Their thermal and photophysical properties exhibit notable differences.

Slow and fast singlet energy transfers in BODIPY-gallium(III)corrole dyads linked by flexible chains.

Red (no styryl), green (monostyryl), and blue (distyryl) BODIPY-gallium(III) (BODIPY = boron-dipyrromethene) corrole dyads have been prepared in high yields using click chemistry, and their photophysical properties are reported. An original and efficient control of the direction of the singlet energy transfers is reported, going either from BODIPY to the gallium-corrole units or from gallium-corroles to BODIPY, depending upon the nature of the substitution on BODIPY. In one case (green), both directions are possible. The mechanism for the energy transfers is interpreted by means of through-space Förster resonance energy transfer (FRET).

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.

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.

Antenna effects in truxene-bridged BODIPY triarylzinc(II)porphyrin dyads: evidence for a dual Dexter-Förster mechanism.

The antenna process from an energy donor (BODIPY; 4',4'-difluoro-1',3',5',7'-tetramethyl-4'-bora-3a',4a'-diaza-s-indacene) in its singlet state to two acceptors (two zinc(II) 5,15-p-tolyl-10-phenylporphyrin) bridged by a central truxene residue (5',5'',10',10'',15',15''-hexabutyltruxene), 5, has been analysed by means of comparison of the energy transfer rates with those of a structurally similar ß-substituted BODIPY-(zinc(II) 5,10,15-p-tolyl-porphyrin), 6, where no conjugation is present between the donor and the two acceptors using the Förster resonance energy transfer (FRET) approximation. It is estimated that the energy transfer in operates mostly via a Dexter mechanism (>99%), and the remaining proceeds via a Förster mechanism (<1%). This information is useful for the design of future molecular devices aimed at harvesting light.

Formation of an unprecedented (CuBr)5 cluster and a zeolite-type 2D-coordination polymer: a surprising halide effect.

A unique pentanuclear cluster within a zeolite-type polymer ([Cu5(µ4-Br)(µ3-Br)2(µ2-Br)2](µ2-MeSPr)3)n (1; void space >81%) and a luminescent 1D ([Cu(µ3-I)]4(MeSPr)3)n polymer, 2, are formed when MeSPr reacts with CuBr and CuI.