The synthesis and structural, photophysical, electrochemical, and electroluminescent properties of a class of platinum(II) complexes bearing σ-alkynyl ancillary ligands, namely [(C∧N∧N)Pt(C⋮C)nR] [H(C∧N∧N) = 6-aryl-2,2‘-bipyridine; n = 1−4; R = aryl, alkyl, or trimethylsilyl], have been studied. Substituents with different steric and electronic properties were introduced into the tridentate cyclometalating and arylacetylide ligands, and the π-conjugation length of the oligoynyl moiety was homologously extended from ethynyl to octatetraynyl. The X-ray crystal structures of several derivatives confirm the Pt−(C⋮C) ligation and reveal various intermolecular interactions, such as π−π, Pt···Pt, and C−H···F−C. The complexes display good thermal stability and intense phosphorescence in fluid and glassy solutions with high quantum yields and microsecond lifetimes. Their emission energies are sensitive to solvent polarity, the electronic affinities of the substituents on both the cyclometalating and arylacetylide ...

Light-Emitting Tridentate Cyclometalated Platinum(II) Complexes Containing σ-Alkynyl Auxiliaries: Tuning of Photo- and Electrophosphorescence

Carbon in one dimension: structural analysis of the higher conjugated polyynes.

With the Fritsch−Buttenberg−Wiechell rearrangement as a primary synthetic route, a series of conjugated, triisopropylsilyl end-capped polyynes containing 2−10 acetylene units has been assembled. In a few steps, significant quantities of the polyynes are made available, which allow for a thorough analysis of their structural, physical, and optical properties. Molecules in the series have been characterized in detail using 13C NMR spectroscopy, differential scanning calorimetry, mass spectrometry, and, for four derivatives including octayne 6, X-ray crystallography. UV−vis spectroscopy of the polyynes 1−7 shows a consistent lowering of the HOMO−LUMO gap (Eg) as a function of the number of acetylene units (n), fitting a power-law relationship of Eg ∼ n-0.379±0.002. The third-order nonlinear optical (NLO) properties of the polyyne series have been examined, and the nonresonant molecular second hyperpolarizabilities (γ) increase as a function of length according to the power-law γ ∼ n4.28±0.13. This result exh...

http://www.aaronslepkov.com/docs/Eisler%20et%20al,%20JACS%20127%202666%202005.pdf

Polyynes as a model for carbyne: synthesis, physical properties, and nonlinear optical response.

The field of electronics using single-molecule components has recently received much attention as a possible new design concept for the continued miniturisation of electronics. Molecular wires are the conceptually simplest components of such electronic systems and several different compound types have been used to produce molecular wires. Examples of some of the most promising families of molecular wires are presented, namely conjugated hydrocarbons, carbon nanotubes, porphyrin oligomers and DNA. Discussion centres around their potential use in functioning electronic architectures in terms of their electronic properties, ease and controllability of synthesis and potential for self-assembly.

A comparison of potential molecular wires as components for molecular electronics.

Coordination and organometallic chemistry of metal-NO complexes.

Reaction of the butadiynyl complex (η5-C5Me5)Re(NO)(PPh3)(C⋮CC⋮CH) (ReC4H) with Cu(OAc)2 (pyridine, 80 °C) gives the μ-octatetraynediyl complex ReC8Re (70%). Analogous cross-coupling of ReC4H and ReC2H gives (after chromatography) ReC4Re (14%), ReC6Re (44%), and ReC8Re (15%). Longer sp carbon chains are accessed by reactions of ReC4H with n-BuLi and CuI, which give ReC4Cu. This isolable species is treated in situ with BrC⋮CSiEt3 or BrC⋮CC⋮CSiMe3 (excess EtNH2, THF) to give ReC6SiEt3 or ReC8SiMe3 (84−77%). Desilylations (wet n-Bu4N+F-) yield ReC6H or ReC8H (88−73%). Then Cu(OAc)2 (pyridine, 50 °C) gives ReC12Re or ReC16Re (71−67%). The former is also available from ReC4Cu and BrC⋮CC⋮CBr (45%), and ReC10Re can be accessed by cross-coupling. ReC6H and ReC8H are similarly converted to ReC10SiR3 (R = Me, Et; 51−26%) and ReC12SiMe3 (43%). Desilylation of ReC10SiR3 gives labile ReC10H, but only black powder is obtained from ReC12SiMe3. In situ coupling of ReC10H gives ReC20Re (52−34%), which unlike lower homolog...

a Berit Bartik

Papers

Toward Metal-Capped One-Dimensional Carbon Allotropes: Wirelike C6−C20 Polyynediyl Chains That Span Two Redox-Active (η5-C5Me5)Re(NO)(PPh3) Endgroups