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<b>aryl</b>CCPtL₂)<i>_n</i> [L = (<i>R</i>)- and (<i>S</i>)-P­(Ph)­(<i>i</i>Pr)­(C₁₇H₃₅); <b>aryl</b> = 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 [¹H, ³¹P 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>i</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

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}]_<i>n</i> (<b>1</b>) is formed when CuI reacts with SMe₂ in <i>n</i>-heptane, whereas in acetonitrile (MeCN), the reaction forms exclusively the 2D CP [(Me₂S)₃{Cu₄(μ-I)₄}]_<i>n</i> (<b>2</b>) 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]_<i>n</i> (<b>3</b>) containing “stepped-cubane” Cu₄I₄ units is isolated in MeCN. In contrast, the reaction in <i>n</i>-heptane affords the 1D CP [(MeSEt)₃{Cu₄(μ₃-I)₄}]_<i>n</i> (<b>4</b>) containing “closed-cubane” Cu₄I₄ clusters. The reaction of MeSPr with CuI provides the structurally related 1D CP [(MeSPr)₃{Cu₄(μ₃-I)₄}]_<i>n</i> (<b>5</b>), 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 <b>4</b> and the previously reported CP [(Et₂S)₃{Cu₄(μ₃-I)₄}]_<i>n</i> (<i>Inorg. Chem.</i> <b>2010</b>, <i>49</i>, 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 (<b>6</b>), Pr₂S (<b>7</b>)] respectively result from the reaction of CuI with EtSPr and <i>n</i>-Pr₂S. With <i>i</i>-Pr₂S, the octanuclear cluster [(<i>i</i>-Pr₂S)₆{Cu₈(μ₃-I)₃}­(μ₄-I)₂}] (<b>8</b>) is formed. An X-ray study has also been performed at five different temperatures for the 2D polymer [(Cu₃Br₃)­(MeSEt)₃]_<i>n</i> (<b>9</b>) formed from the reaction between CuBr and MeSEt in heptane. The unprecedented framework of <b>9</b> 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]_<i>n</i> (<b>10</b>), which is converted to a 2D metal–organic framework [(Cu₅Br₅)­(μ₂-MeSPr)₃]_<i>n</i> (<b>11</b>) incorporating pentanuclear [(Cu₅(μ₄-Br)­(μ₂-Br)] SBUs when recrystallized in MeCN. The thermal stability and photophysical properties of these materials are also reported

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}]_<i>n</i> (<b>1</b>) is formed when CuI reacts with SMe₂ in <i>n</i>-heptane, whereas in acetonitrile (MeCN), the reaction forms exclusively the 2D CP [(Me₂S)₃{Cu₄(μ-I)₄}]_<i>n</i> (<b>2</b>) 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]_<i>n</i> (<b>3</b>) containing “stepped-cubane” Cu₄I₄ units is isolated in MeCN. In contrast, the reaction in <i>n</i>-heptane affords the 1D CP [(MeSEt)₃{Cu₄(μ₃-I)₄}]_<i>n</i> (<b>4</b>) containing “closed-cubane” Cu₄I₄ clusters. The reaction of MeSPr with CuI provides the structurally related 1D CP [(MeSPr)₃{Cu₄(μ₃-I)₄}]_<i>n</i> (<b>5</b>), 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 <b>4</b> and the previously reported CP [(Et₂S)₃{Cu₄(μ₃-I)₄}]_<i>n</i> (<i>Inorg. Chem.</i> <b>2010</b>, <i>49</i>, 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 (<b>6</b>), Pr₂S (<b>7</b>)] respectively result from the reaction of CuI with EtSPr and <i>n</i>-Pr₂S. With <i>i</i>-Pr₂S, the octanuclear cluster [(<i>i</i>-Pr₂S)₆{Cu₈(μ₃-I)₃}­(μ₄-I)₂}] (<b>8</b>) is formed. An X-ray study has also been performed at five different temperatures for the 2D polymer [(Cu₃Br₃)­(MeSEt)₃]_<i>n</i> (<b>9</b>) formed from the reaction between CuBr and MeSEt in heptane. The unprecedented framework of <b>9</b> 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]_<i>n</i> (<b>10</b>), which is converted to a 2D metal–organic framework [(Cu₅Br₅)­(μ₂-MeSPr)₃]_<i>n</i> (<b>11</b>) incorporating pentanuclear [(Cu₅(μ₄-Br)­(μ₂-Br)] SBUs when recrystallized in MeCN. The thermal stability and photophysical properties of these materials are also reported

Luminescent P‑Chirogenic Copper Clusters

P-chirogenic clusters of the cubanes [Cu₄I₄L₄] (L = chiral phosphine) were prepared from (+)- and (−)-ephedrine with L = (<i>S</i>)- or (<i>R</i>)-(R)­(Ph)­(<i>i</i>-Pr)P (with R = CH₃ (seven steps) or C₁₇H₃₅ (10 steps)) with e.e. up to 96%. The X-ray structure of [Cu₄I₄((<i>R</i>)-(CH₃)­(Ph)­(<i>i</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((<i>S</i>)-(CH₃)­(Ph)­(<i>i</i>-Pr)­P)₄] was established by the comparison of the X-ray powder diffraction patterns, and the opposite optical activity of the (<i>S</i>)- and (<i>R</i>)-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° (<i>d</i> ∼ 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

Construction of (CuX)_2<i>n</i> Cluster-Containing (X = Br, I; <i>n</i> = 1, 2) Coordination Polymers Assembled by Dithioethers ArS(CH₂)_<i>m</i>SAr (Ar = Ph, <i>p</i>‑Tol; <i>m</i> = 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(μ₂-I)₂Cu}­{μ-PhS­(CH₂)₃SPh}₂]_<i>n</i> (<b>1</b>). The 2D-sheet structure of <b>1</b> is built up by dimeric Cu₂I₂ 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 [Cu₄I₄{μ-PhS­(CH₂)₃Ph}₂]_<i>n</i> (<b>2</b>), in which cubane-like Cu₄(μ₃-I)₄ cluster units are linked by the dithioether ligands. The crystallographically characterized one-dimensional (1D) compound [{Cu­(μ₂-Br)₂Cu}­{μ-PhS­(CH₂)₃SPh}₂]_<i>n</i> (<b>3</b>) is obtained using CuBr. The outcome of the reaction of PhS­(CH₂)₅SPh 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 [Cu₄I₄{μ-PhS­(CH₂)₅Ph}₂]_<i>n</i> (<b>4</b>) in which cubane-like Cu₄(μ₃-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(μ₂-I)₂Cu}­{μ-PhS­(CH₂)₅SPh}₂]_<i>n</i> (<b>5</b>), incorporating rhomboid Cu₂I₂ units, is produced upon treatment of CuI with 1,5-bis­(phenylthio)­pentane in a 1:1 ratio. Reaction of CuBr with PhS­(CH₂)₅SPh produces the isomorphous 1D-compound [{Cu­(μ₂-Br)₂Cu}­{μ-PhS­(CH₂)₅SPh}₂]_<i>n</i> (<b>6</b>). Strongly luminescent [Cu₄I₄{μ-<i>p</i>-TolS­(CH₂)₅STol-<i>p</i>}₂]_<i>n</i> (<b>7</b>) is obtained after mixing 1,5-bis­(<i>p</i>-tolylthio)­pentane with CuI in a 1:2 ratio, and the 2D-polymer [{Cu­(μ₂-I)₂Cu}₂{μ-<i>p</i>-TolS­(CH₂)₅STol-<i>p</i>}₂]_<i>n</i> (<b>8</b>) results from reaction in a 1:1 metal-to-ligand ratio. Under the same reaction conditions, 1D-polymeric [{Cu­(μ₂-Br)₂Cu}­{μ-<i>p</i>-TolS­(CH₂)₅STol-p}₂]_<i>n</i> (<b>9</b>) is formed using CuBr. This study reveals that the structure of the self-assembly process between CuX and ArS­(CH₂)_<i>m</i>SAr ligands is hard to predict. The solid-state luminescence spectra at 298 and 77 K of <b>2</b> and <b>4</b> exhibit very strong emissions around 535 and 560 nm, respectively, whereas those for <b>1</b> and <b>5</b> 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

Luminescent P‑Chirogenic Copper Clusters

P-chirogenic clusters of the cubanes [Cu₄I₄L₄] (L = chiral phosphine) were prepared from (+)- and (−)-ephedrine with L = (<i>S</i>)- or (<i>R</i>)-(R)­(Ph)­(<i>i</i>-Pr)P (with R = CH₃ (seven steps) or C₁₇H₃₅ (10 steps)) with e.e. up to 96%. The X-ray structure of [Cu₄I₄((<i>R</i>)-(CH₃)­(Ph)­(<i>i</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((<i>S</i>)-(CH₃)­(Ph)­(<i>i</i>-Pr)­P)₄] was established by the comparison of the X-ray powder diffraction patterns, and the opposite optical activity of the (<i>S</i>)- and (<i>R</i>)-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° (<i>d</i> ∼ 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

Construction of (CuX)_2<i>n</i> Cluster-Containing (X = Br, I; <i>n</i> = 1, 2) Coordination Polymers Assembled by Dithioethers ArS(CH₂)_<i>m</i>SAr (Ar = Ph, <i>p</i>‑Tol; <i>m</i> = 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(μ₂-I)₂Cu}­{μ-PhS­(CH₂)₃SPh}₂]_<i>n</i> (<b>1</b>). The 2D-sheet structure of <b>1</b> is built up by dimeric Cu₂I₂ 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 [Cu₄I₄{μ-PhS­(CH₂)₃Ph}₂]_<i>n</i> (<b>2</b>), in which cubane-like Cu₄(μ₃-I)₄ cluster units are linked by the dithioether ligands. The crystallographically characterized one-dimensional (1D) compound [{Cu­(μ₂-Br)₂Cu}­{μ-PhS­(CH₂)₃SPh}₂]_<i>n</i> (<b>3</b>) is obtained using CuBr. The outcome of the reaction of PhS­(CH₂)₅SPh 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 [Cu₄I₄{μ-PhS­(CH₂)₅Ph}₂]_<i>n</i> (<b>4</b>) in which cubane-like Cu₄(μ₃-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(μ₂-I)₂Cu}­{μ-PhS­(CH₂)₅SPh}₂]_<i>n</i> (<b>5</b>), incorporating rhomboid Cu₂I₂ units, is produced upon treatment of CuI with 1,5-bis­(phenylthio)­pentane in a 1:1 ratio. Reaction of CuBr with PhS­(CH₂)₅SPh produces the isomorphous 1D-compound [{Cu­(μ₂-Br)₂Cu}­{μ-PhS­(CH₂)₅SPh}₂]_<i>n</i> (<b>6</b>). Strongly luminescent [Cu₄I₄{μ-<i>p</i>-TolS­(CH₂)₅STol-<i>p</i>}₂]_<i>n</i> (<b>7</b>) is obtained after mixing 1,5-bis­(<i>p</i>-tolylthio)­pentane with CuI in a 1:2 ratio, and the 2D-polymer [{Cu­(μ₂-I)₂Cu}₂{μ-<i>p</i>-TolS­(CH₂)₅STol-<i>p</i>}₂]_<i>n</i> (<b>8</b>) results from reaction in a 1:1 metal-to-ligand ratio. Under the same reaction conditions, 1D-polymeric [{Cu­(μ₂-Br)₂Cu}­{μ-<i>p</i>-TolS­(CH₂)₅STol-p}₂]_<i>n</i> (<b>9</b>) is formed using CuBr. This study reveals that the structure of the self-assembly process between CuX and ArS­(CH₂)_<i>m</i>SAr ligands is hard to predict. The solid-state luminescence spectra at 298 and 77 K of <b>2</b> and <b>4</b> exhibit very strong emissions around 535 and 560 nm, respectively, whereas those for <b>1</b> and <b>5</b> 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

Copper(I) Halides (X = Br, I) Coordinated to Bis(arylthio)methane Ligands: Aryl Substitution and Halide Effects on the Dimensionality, Cluster Size, and Luminescence Properties of the Coordination Polymers

Bis­(phenylthio)­methane (<b>L1</b>) reacts with CuI to yield the 1D-coordination polymer [{Cu₄(μ₃-I)₄}­(μ-<b>L1</b>)₂]_<i>n</i> (<b>1</b>) bearing cubane Cu₄I₄ clusters as connecting nodes. The crystal structures at 115, 155, 195, and 235 K provided evidence for a phase transition changing from the monoclinic space group <i>C</i>2/<i>c</i> to <i>P</i>2₁/<i>c</i>. The self-assembly process of CuI with bis­(<i>p</i>-tolylthio)­methane (<b>L2</b>), bis­(4-methoxyphenylthio)­methane (<b>L3</b>), and bis­(4-bromo-phenylthio)­methane (<b>L4</b>) affords the 1D-coordination polymers [{Cu₄(μ₃-I)₄}­(μ-<b>L<i>x</i></b>)₂]_<i>n</i> (<i>x</i> = 2, 3, or 4). Compounds <b>2</b> and <b>4</b> are isostructural with <i>C</i>2/<i>c</i> low temperature polymorph of <b>1</b>, whereas the inversion centers and 2-fold axes are lost in <b>3</b> (space group <i>Cc</i>). The use of bis­(<i>m</i>-tolylthio)­methane (<b>L5</b>) has no impact on the composition and overall topology of the resulting 1D ribbon of [{Cu₄(μ₃-I)₄}­(μ-<b>L5</b>)₂]_<i>n</i> (<b>5</b>). Even the coordination of the sterically crowded dithioether bis­(5-<i>tert</i>-butyl-2-methylphenylthio)­methane (<b>L8</b>) does not alter the network topology generating the 1D polymer [{Cu₄(μ₃-I)₄}­(μ-<b>L8</b>)₂]_<i>n</i> (<b>8</b>). The 1D polymer [{Cu­(μ₂-Br)₂Cu}­(<b>L1</b>)₂] (<b>9</b>) results from the coordination of <b>L1</b> with CuBr in a 1:1 metal-to-ligand ratio. In contrast to the mean Cu···Cu distances, which are <2.8 Å noted for the Cu₄(μ₃-I)₄ clusters in the 1D polymers <b>1</b>–<b>8</b>, the Cu···Cu contact within the Cu­(μ₂-Br)₂Cu rhomboids of <b>9</b> [2.9194(8) Å] is above the sum of the van der Waals radii of two Cu atoms. The structural arrangement of 1D polymer [{Cu­(μ₂-Br)₂Cu}­(<b>L3</b>)₂]_<i>n</i> (<b>11</b>) is quite similar to that of <b>9</b>. While the reaction of CuBr with <b>L5</b> results in a similar 1D polymer [{Cu­(μ₂-Br)₂Cu}­(<b>L5</b>)₂]_<i>n</i> (<b>12</b>), the reaction of CuBr with <b>L2</b> leads to the dinuclear complex [{Cu­(μ₂-Br)₂Cu}­(η¹-<b>L2</b>)₄] (<b>10</b>) ligated by four pendent bis­(<i>p</i>-tolylthio)­methane ligands. The ligation of bis­(<i>o</i>-tolylthio)­methane, <b>L6</b>, on CuBr also yields a discrete complex [{Cu­(μ₂-Br)₂Cu}­(MeCN)₂(η¹-<b>L6</b>)₂] (<b>13</b>) bearing MeCN and dangling dithioether ligands. A strong luminescence is detected for all CuI polymers, all exhibiting emission lifetimes in the microsecond time scale (i.e., phosphorescence). The polymers containing the Cu₄I₄ core (<b>1</b>–<b>8</b>) exhibit the typically observed low-energy band and sometimes a weaker high-energy band. The nature of the low-energy band was proposed based on literature DFT and TDDFT computations and is predicted to be a mixture of cluster-centered (CC*) and metal/halide-to-ligand charger transfer (M/XLCT). An approximate relationship between the Cu···Cu distance and the emission maxima corroborates the CC* contribution to the nature of the excited states. The emission of the rhomboid-containing materials is assigned to M/XLCT based on literature works on similar motifs