From Short-Bite Ligand Assembled Ribbons to Nanosized Networks in Cu(I) Coordination Polymers Built Upon Bis(benzylthio)alkanes (BzS(CH2)nSBz; n = 1-9).

With the objective to establish a correlation between the spacer distance and halide dependence on the structural features of coordination polymers (CPs) assembled by the reaction between CuX salts (X = Cl, Br, I) and dithioether ligands BzS(CH2)nSBz (n = 1-9; Bz = benzyl), a series of 26 compounds have been prepared and structurally investigated. A particular attention has been devoted to the design of networks with extremely long and flexible methylene spacer units between the SBz donor sites. Under identical conditions, CuI and CuBr react with BzSCH2Bz (L1) affording respectively the one-dimensional (1D) CPs {Cu(µ2-I)2Cu}(µ-L1)2]n (CP1) and {Cu(µ2-Br)2Cu}(µ-L1)2] (CP2), which incorporate Cu(µ2-X)2Cu rhomboids as secondary building units (SBUs). The hitherto unknown architecture of two-dimensional (2D) layers obtained with CuCl (CP3) differs from that of CP1 and CP2, which bear inorganic -Cl-Cu-Cl-Cu-Cl- chains interconnected through bridging L1 ligands, thus forming a 2D architecture. The crystallographic characterization of a 1D CP obtained by reacting CuI with 1,3-bis(benzylthio)propane (L2) reveals that [{Cu(µ2-I)2Cu}(µ-L2)2]n (CP4) contains conventional Cu2I2 rhomboids as SBUs. In contrast, unusual isostructural CPs [{Cu(µ2-X)}(µ2-L2)]n (CP5) and (CP6) are obtained with CuX when X = Br and Cl, respectively, in which the isolated Cu atoms are bridged by a single µ2-Br or µ2-Cl ion giving rise to infinite [Cu(µ2-X)Cu]n ribbons. The crystal structure of the strongly luminescent three-dimensional (3D) polymer [{Cu4(µ3-I)3(µ4-I)(µ-L3)1.5]n (CP7) issued from reacting 2 equiv of CuI with BzS(CH2)4SBz (L3) has been redetermined. CP7 features unusual [(Cu4I3)(µ4-I)]n arrays securing the 3D connectivity. In contrast, mixing CuI with an excess of L3 provides the nonemissive material [{Cu(µ2-I)2Cu}(µ-L3)2]n (CP8). Treatment of CuBr and CuCl with L3 leads to [{Cu(µ2-Br)2Cu}(µ-L3)2]n (CP9) and the 0D complex [{Cu(µ2-Cl)2Cu}(µ-L3)2] (D1), respectively. The crystallographic particularity for CP9 is the coexistence of two topological isomers within the unit cell. The first one, CP9-1D, consists of simple 1D ribbons running along the a axis of the unit cell. The second topological isomer, CP9-2D, also consists of [Cu(µ2-Br)2Cu] SBUs, but these are interconnected in a 2D manner forming 2D sheets placed perpendicular to the 1D ribbons. Four 2D CPs, namely, [{Cu4(µ3-I)4}(µ-L4)2]n (CP10), [{Cu(µ2-I)2Cu}(µ-L4)2]n (CP11), [{Cu(µ2-Br)2Cu}(µ-L4)2]n (CP12), and [{Cu(µ2-Cl)2Cu}(µ-L4)2]n (CP13), stem from the self-assembly process of CuX with BzS(CH2)6SBz (L4). A similar series of 2D materials comprising [{Cu4(µ3-I)4}(µ-L5)2]n (CP14), [{Cu(µ2-I)2Cu}(µ-L5)2]n (CP15), [{Cu(µ2-Br)2Cu}(µ-L5)2]n (CP16), and [{Cu(µ2-Cl)2Cu}(µ-L5)2]n (CP17) result from the coordination of BzS(CH2)7SBz (L5) on CuX. Ligation of CuX with the long-chain ligand BzS(CH2)8SBz (L6) allows for the X-ray characterization of the luminescent 2D [{Cu4(µ3-I)4}(µ-L6)2]n (CP18) and the isostructural 1D series [{Cu(µ2-X)2Cu}(µ-L6)2]n CP19 (X = I), CP20 (X = Br) and CP21(X = Cl). Noteworthy, BzS(CH2)9SBz (L7) bearing a very flexible nine-atom chain generated the crystalline materials 2D [{Cu4(µ3-I)4}(µ-L7)2]n (CP22) and the isostructural 1D series [{Cu(µ2-X)2Cu}(µ-L6)2]n CP23 (X = I), CP24 (X = Br), and CP25 (X = Cl), featuring nanometric separations between the cubane- or rhomboid-SBUs. This comparative study reveals that the outcome of the reaction of CuX with the shorter ligands BzS(CH2)nSBz (n = 1-4) is not predictable. However, with more flexible spacer chains BzS(CH2)nSBz (n = 6-9), a clear structural pattern can be established. Using a 1:1 CuX-to-ligand ratio, [{Cu(µ2-X)2Cu}(µ-L4-7)2] CPs are always formed, irrespectively of L4-L7. Employing a 2:1 CuX-to-ligand ratio, only CuI is able to form networks incorporating Cu4(µ3-I)4 clusters as SBUs. All attempts to construct polynuclear cluster using CuBr and CuCl failed. The materials have been furthermore analyzed by powder X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis, and the photophysical properties of the emissive materials have been studied.

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.

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.

Luminescent P-chirogenic copper clusters.

P-chirogenic clusters of the cubanes [Cu4I4L4] (L = chiral phosphine) were prepared from (+)- and (-)-ephedrine with L = (S)- or (R)-(R)(Ph)(i-Pr)P (with R = CH3 (seven steps) or C17H35 (10 steps)) with e.e. up to 96%. The X-ray structure of [Cu4I4((R)-(CH3)(Ph)(i-Pr)P)4] confirmed the cubane structure with average Cu···Cu and Cu···I distances of 2.954 and 2.696 Å, respectively. The cubane structure of the corresponding [Cu4I4((S)-(CH3)(Ph)(i-Pr)P)4] was established by the comparison of the X-ray powder diffraction patterns, and the opposite optical activity of the (S)- and (R)-ligand-containing clusters was confirmed by circular dichroism spectroscopy. Small-angle X-ray scattering patterns of one cluster bearing a C17H35 chain exhibit a weak signal at 2θ ~ 2.8° (d ~ 31.6 Å), indicating some molecular ordering in the liquid state. The emission spectra exhibit two emission bands, both associated with triplet excited states. These two bands are assigned as follows: the high energy emission is due to a halide-to-ligand charge transfer, XLCT, state mixed with LXCT (ligand-to-halide-charge-transfer). The low energy band is assigned to a cluster-centered excited state. Both emissions are found to be thermochromic with the relative intensity changing between 77 and 298 K for the clusters in methylcyclohexane solution. Several differences are observed in the photophysical parameters, emission quantum yields and lifetimes for R = CH3 and C17H35. The measurements of the polarization along the emission indicate that the emission is depolarized, consistent with an approximate tetrahedral geometry of the chromophores.

Organometallic oligomers based on bis(arylacetylide)bis(P-chirogenic phosphine)platinum(II) complexes: synthesis and photonic properties.

A series of P-chirogenic oligomers of the type (-C≡C-aryl-C≡C-PtL2-)n [L = (R)- and (S)-P(Ph)(iPr)(C17H35); aryl = 1,4-benzene, 2,1,3-benzothiadiazole] along the corresponding achiral analogues (L = PBu3) and model complexes PhC≡CPtL2C≡CPh were prepared from the ephedrine strategy and were fully characterized [(1)H, (31)P NMR; IR; small-angle X-ray scattering (SAXS); gel permeation chromatography (GPC); thermal gravimetric analysis (TGA); circular dichroism, UV-vis, and luminescence spectroscopy; photophysics, and degree of anisotropy measurements]. From the CD measurements, the chiral environment of the phosphine ligands is modestly felt by the aryl moieties. Concurrently, the TGA shows that the P(C17H35)(Ph)(i-Pr)-containing materials are more stable than those containing the shorter chain ligand PBu3, and exhibits red-shifted absorption and emission bands compared to those including the PBu3 ligands. The presence of the long chain on the phosphorus atoms does not greatly alter the photophysical parameters, notably the emission lifetimes, and fast triplet energy transfer terminal* → central unit has been deduced from the absence of luminescence arising from the terminal units.

Construction of (CuX)2n cluster-containing (X = Br, I; n = 1, 2) coordination polymers assembled by dithioethers ArS(CH2)(m)SAr (Ar = Ph, p-Tol; m = 3, 5): effect of the spacer length, aryl group, and metal-to-ligand ratio on the dimensionality, cluster nuclearity, and the luminescence properties of the metal-organic frameworks.

Reaction of CuI with bis(phenylthio)propane in a 1:1 ratio yields the two-dimensional coordination polymer [{Cu(µ(2)-I)(2)Cu}{µ-PhS(CH(2))(3)SPh}(2)](n) (1). The 2D-sheet structure of 1 is built up by dimeric Cu(2)I(2) units, which are connected via four bridging 1,3-bis(phenylthio)propane ligands. In contrast, treatment of 2 equiv of CuI with 1,3-bis(phenylthio)propane in MeCN solution affords in a self-assembly reaction the strongly luminescent metal-organic 2D-coordination polymer [Cu(4)I(4){µ-PhS(CH(2))(3)Ph}(2)](n) (2), in which cubane-like Cu(4)(µ(3)-I)(4) cluster units are linked by the dithioether ligands. The crystallographically characterized one-dimensional (1D) compound [{Cu(µ(2)-Br)(2)Cu}{µ-PhS(CH(2))(3)SPh}(2)](n) (3) is obtained using CuBr. The outcome of the reaction of PhS(CH(2))(5)SPh with CuI also depends of the metal-to-ligand ratio employed. Mixing CuI and the dithioether in a 2:1 ratio results in formation of [Cu(4)I(4){µ-PhS(CH(2))(5)Ph}(2)](n) (4) in which cubane-like Cu(4)(µ(3)-I)(4) clusters are linked by the bridging dithioether ligand giving rise to a 1D necklace structure. A ribbon-like 1D-polymer with composition [{Cu(µ(2)-I)(2)Cu}{µ-PhS(CH(2))(5)SPh}(2)](n) (5), incorporating rhomboid Cu(2)I(2) units, is produced upon treatment of CuI with 1,5-bis(phenylthio)pentane in a 1:1 ratio. Reaction of CuBr with PhS(CH(2))(5)SPh produces the isomorphous 1D-compound [{Cu(µ(2)-Br)(2)Cu}{µ-PhS(CH(2))(5)SPh}(2)](n) (6). Strongly luminescent [Cu(4)I(4){µ-p-TolS(CH(2))(5)STol-p}(2)](n) (7) is obtained after mixing 1,5-bis(p-tolylthio)pentane with CuI in a 1:2 ratio, and the 2D-polymer [{Cu(µ(2)-I)(2)Cu}(2){µ-p-TolS(CH(2))(5)STol-p}(2)](n) (8) results from reaction in a 1:1 metal-to-ligand ratio. Under the same reaction conditions, 1D-polymeric [{Cu(µ(2)-Br)(2)Cu}{µ-p-TolS(CH(2))(5)STol-p}(2)](n) (9) is formed using CuBr. This study reveals that the structure of the self-assembly process between CuX and ArS(CH(2))(m)SAr ligands is hard to predict. The solid-state luminescence spectra at 298 and 77 K of 2 and 4 exhibit very strong emissions around 535 and 560 nm, respectively, whereas those for 1 and 5 display weaker ones at about 450 nm. The emission lifetimes are longer for the longer wavelength emissions (>1.0 µs arising from the cubane species) and shorter for the shorter wavelength ones (<1.4 µs arising from the rhomboid units). The Br-containing species are found to be weakly fluorescent.