Nickel-Catalyzed Suzuki Polycondensation for Controlled Synthesis of Ester-Functionalized Conjugated Polymers

Controlled synthesis of conjugated polymers with functional side chains is of great importance, affording well-defined optoelectronic materials possessing enhanced stability and tunability as compared to their alkyl-substituted counterparts. Herein, a chain-growth Suzuki polycondensation of an ester-functionalized thiophene is described using commercially available nickel precatalysts. Model compound studies were used to identify suitable catalysts, and these experiments provided guidance for the polymerization of the ester-substituted monomer. This is the first report of nickel-catalyzed Suzuki cross-coupling for catalyst-transfer polycondensation, and to further illustrate the versatility of this method, block and alternating copolymers with 3-hexyl­thiophene were synthesized. The presented protocol should serve as an entry point into the synthesis of other electron-deficient polymers and donor–acceptor copolymers with controlled molecular weights and low dispersity

Monoplatinum Doping of Gold Nanoclusters and Catalytic Application

We report single-atom doping of gold nanoclusters (NCs), and its drastic effects on the optical, electronic, and catalytic properties, using the 25-atom system as a model. In our synthetic approach, a mixture of Pt₁Au₂₄(SC₂H₄Ph)₁₈ and Au₂₅(SC₂H₄Ph)₁₈ was produced via a size-focusing process, and then Pt₁Au₂₄(SC₂H₄Ph)₁₈ NCs were obtained by selective decomposition of Au₂₅(SC₂H₄Ph)₁₈ in the mixture with concentrated H₂O₂ followed by purification via size-exclusion chromatography. Experimental and theoretical analyses confirmed that Pt₁Au₂₄(SC₂H₄Ph)₁₈ possesses a Pt-centered icosahedral core capped by six Au₂(SC₂H₄Ph)₃ staples. The Pt₁Au₂₄(SC₂H₄Ph)₁₈ cluster exhibits greatly enhanced stability and catalytic activity relative to Au₂₅(SC₂H₄Ph)₁₈ but a smaller energy gap (<i>E</i>_g ≈ 0.8 eV vs 1.3 eV for the homogold cluster)

Stability and Reactivity of 1,3-Benzothiaphosphole: Metalation and Diels–Alder Chemistry

The synthesis and functionalization of the parent 1,3-benzothiaphosphole is reported. The phosphole could not be isolated, but the compound could be manipulated in solution to produce several new phosphorus compounds. Metalation of the 2-position using lithium diisopropylamide proceeded smoothly according to ³¹P NMR spectroscopy, and quenching with trimethylsilyl chloride resulted in the desired 2-(trimethylsilyl)-1,3-benzothiaphosphole. The PC bond of the thiaphosphole was also explored as a dienophile in Diels–Alder reactions with isoprene, 2,3-dimethylbutadiene, 2,3-dibenzylbutadiene, and cyclopentadiene. The fused-ring structures were fully characterized, and a solid-state molecular structure of the 2,3-dimethylbutadiene cycloadduct was obtained. Residual dipolar coupling (RDC) NMR experiments were used to assign major and minor products for the isoprene and cyclopentadiene adducts

Stability and Reactivity of 1,3-Benzothiaphosphole: Metalation and Diels–Alder Chemistry

The synthesis and functionalization of the parent 1,3-benzothiaphosphole is reported. The phosphole could not be isolated, but the compound could be manipulated in solution to produce several new phosphorus compounds. Metalation of the 2-position using lithium diisopropylamide proceeded smoothly according to ³¹P NMR spectroscopy, and quenching with trimethylsilyl chloride resulted in the desired 2-(trimethylsilyl)-1,3-benzothiaphosphole. The PC bond of the thiaphosphole was also explored as a dienophile in Diels–Alder reactions with isoprene, 2,3-dimethylbutadiene, 2,3-dibenzylbutadiene, and cyclopentadiene. The fused-ring structures were fully characterized, and a solid-state molecular structure of the 2,3-dimethylbutadiene cycloadduct was obtained. Residual dipolar coupling (RDC) NMR experiments were used to assign major and minor products for the isoprene and cyclopentadiene adducts

Stability and Reactivity of 1,3-Benzothiaphosphole: Metalation and Diels–Alder Chemistry

The synthesis and functionalization of the parent 1,3-benzothiaphosphole is reported. The phosphole could not be isolated, but the compound could be manipulated in solution to produce several new phosphorus compounds. Metalation of the 2-position using lithium diisopropylamide proceeded smoothly according to ³¹P NMR spectroscopy, and quenching with trimethylsilyl chloride resulted in the desired 2-(trimethylsilyl)-1,3-benzothiaphosphole. The PC bond of the thiaphosphole was also explored as a dienophile in Diels–Alder reactions with isoprene, 2,3-dimethylbutadiene, 2,3-dibenzylbutadiene, and cyclopentadiene. The fused-ring structures were fully characterized, and a solid-state molecular structure of the 2,3-dimethylbutadiene cycloadduct was obtained. Residual dipolar coupling (RDC) NMR experiments were used to assign major and minor products for the isoprene and cyclopentadiene adducts

Crystal Structure of Barrel-Shaped Chiral Au₁₃₀(<i>p</i>‑MBT)₅₀ Nanocluster

We report the structure determination of a large gold nanocluster formulated as Au₁₃₀(<i>p</i>-MBT)₅₀, where <i>p</i>-MBT is 4-methylbenzene­thiolate. The nanocluster is constructed in a four-shell manner, with 55 gold atoms assembled into a two-shell Ino decahedron. The surface is protected exclusively by –S–Au–S– staple motifs, which self-organize into five ripple-like stripes on the surface of the barrel-shaped Au₁₀₅ kernel. The Au₁₃₀(<i>p-</i>MBT)₅₀ can be viewed as an elongated version of the Au₁₀₂(SR)₄₄. Comparison of the Au₁₃₀(<i>p-</i>MBT)₅₀ structure with the recently discovered icosahedral Au₁₃₃(<i>p-</i>TBBT)₅₂ nanocluster (where <i>p-</i>TBBT = 4-<i>tert</i>-butyl­benzene­thiolate) reveals an interesting phenomenon that a subtle ligand effect in the para-position of benzenethiolate can significantly affect the gold atom packing structure, i.e. from the 5-fold twinned Au₅₅ decahedron to 20-fold twinned Au₅₅ icosahedron

Crystal Structure of Barrel-Shaped Chiral Au₁₃₀(<i>p</i>‑MBT)₅₀ Nanocluster

We report the structure determination of a large gold nanocluster formulated as Au₁₃₀(<i>p</i>-MBT)₅₀, where <i>p</i>-MBT is 4-methylbenzene­thiolate. The nanocluster is constructed in a four-shell manner, with 55 gold atoms assembled into a two-shell Ino decahedron. The surface is protected exclusively by –S–Au–S– staple motifs, which self-organize into five ripple-like stripes on the surface of the barrel-shaped Au₁₀₅ kernel. The Au₁₃₀(<i>p-</i>MBT)₅₀ can be viewed as an elongated version of the Au₁₀₂(SR)₄₄. Comparison of the Au₁₃₀(<i>p-</i>MBT)₅₀ structure with the recently discovered icosahedral Au₁₃₃(<i>p-</i>TBBT)₅₂ nanocluster (where <i>p-</i>TBBT = 4-<i>tert</i>-butyl­benzene­thiolate) reveals an interesting phenomenon that a subtle ligand effect in the para-position of benzenethiolate can significantly affect the gold atom packing structure, i.e. from the 5-fold twinned Au₅₅ decahedron to 20-fold twinned Au₅₅ icosahedron

Tri-icosahedral Gold Nanocluster [Au₃₇(PPh₃)₁₀(SC₂H₄Ph)₁₀X₂]⁺: Linear Assembly of Icosahedral Building Blocks

The [Au₃₇(PPh₃)₁₀(SR)₁₀X₂]⁺ nanocluster (where SR = thiolate and X = Cl/Br) was theoretically predicted in 2007, but since then, there has been no experimental success in the synthesis and structure determination. Herein, we report a kinetically controlled, selective synthesis of [Au₃₇(PPh₃)₁₀(SC₂H₄Ph)₁₀X₂]⁺ (counterion: Cl^– or Br^–) with its crystal structure characterized by X-ray crystallography. This nanocluster shows a rod-like structure assembled from three icosahedral Au₁₃ units in a linear fashion, consistent with the earlier prediction. The optical absorption and the electrochemical and catalytic properties are investigated. The successful synthesis of this new nanocluster allows us to gain insight into the size, structure, and property evolution of gold nanoclusters that are based upon the assembly of icosahedral units (<i>i.e.</i>, <i>cluster of clusters</i>). Some interesting trends are identified in the evolution from the monoicosahedral [Au₁₃(PPh₃)₁₀X₂]³⁺ to the bi-icosahedral [Au₂₅(PPh₃)₁₀(SC₂H₄Ph)₅X₂]²⁺ and to the tri-icosahedral [Au₃₇(PPh₃)₁₀(SC₂H₄Ph)₁₀X₂]⁺ nanocluster, which also points to the possibility of achieving even longer rod nanoclusters based upon assembly of icosahedral building blocks