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We demonstrate a highly efficient thermal conversion of four differently substituted polydiacetylenes (PDAs 1 and 2a–c) into virtually indistinguishable N = 8 armchair graphene nanoribbons ([8]AGNR). PDAs 1 and 2a–c are themselves easily accessed through photochemically initiated topochemical polymerization of diynes 3 and 4a–c in the crystal. The clean, quantitative transformation of PDAs 1 and 2a–c into [8]AGNR occurs via a series of Hopf pericyclic reactions, followed by aromatization reactions of the annulated polycyclic aromatic intermediates, as well as homolytic bond fragmentation of the edge functional groups upon heating up to 600 °C under an inert atmosphere. We characterize the different steps of both processes using complementary spectroscopic techniques (CP/MAS 13C NMR, Raman, FT-IR, and XPS) and high-resolution transmission electron microscopy (HRTEM). This novel approach to GNRs exploits the power of crystal engineering and solid-state reactions by targeting very large organic structures th...

The synthesis and characterization of Ln-C4Ph4-K, [(NNTBS)Ln(η2-C4Ph4)][K(THF)x] (Ln = Sc, Y, Lu), rare-earth metal complexes supported by a ferrocene diamide ligand, NNTBS (NNTBS = fc(NSitBuMe2)2, fc = 1,1′-ferrocenediyl), were accomplished. The preparation of the half-sandwich compounds, Ln-naph-K, [(NNTBS)Ln(μ-C10H8)][K(THF)2] (Ln = Sc, Y, Lu, La), was necessary in order to obtain high yields of rare-earth metallacyclopentadienes. Unlike Y and Lu, La did not show the same reactivity toward PhCCPh. The characterization of the new metal complexes was accomplished by NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction.

DyIII single-ion magnets (SIMs) with strong axial donors and weak equatorial ligands are attractive model systems with which to harness the maximum magnetic anisotropy of DyIII ions. Utilizing a rigid ferrocene diamide ligand (NNTBS), a DyIII SIM, (NNTBS)DyI(THF)2, 1-Dy (NNTBS = fc(NHSitBuMe2)2, fc = 1,1′-ferrocenediyl), composed of a near linear arrangement of donor atoms, exhibits a large energy barrier to spin reversal (770.8 K) and magnetic blocking (14 K). The effects of the transverse ligands on the magnetic and electronic structure of 1-Dy were investigated through ab initio methods, eliciting significant magnetic axiality, even in the fourth Kramers doublet, thus demonstrating the potential of rigid diamide ligands in the design of new SIMs with defined magnetic axiality.

Solid-state electrolytes are the key to the development of lithium-based batteries with dramatically improved energy density and safety. Inspired by ionic channels in biological systems, a novel class of pseudo solid-state electrolytes with biomimetic ionic channels is reported herein. This is achieved by complexing the anions of an electrolyte to the open metal sites of metal-organic frameworks (MOFs), which transforms the MOF scaffolds into ionic-channel analogs with lithium-ion conduction and low activation energy. This work suggests the emergence of a new class of pseudo solid-state lithium-ion conducting electrolytes.

Herein, we present the intramolecular [2+2] cycloadditions of dienones promoted through sensitization, using a polypyridyl iridium(III) catalyst, to form bridged cyclobutanes. In contrast to previous examples of straight [2+2] cycloadditions, these efficient crossed additions were achieved under irradiation with visible light. The reactions delivered desired bridged benzobicycloheptanone products with excellent regioselectivity in high yields (up to 96%). This process is superior to previous syntheses of benzobicyclo[3.1.1]heptanones, which are readily converted to B-norbenzomorphan analogues of biological significance. Electrochemical, computational, and spectroscopic studies substantiated the mechanism of triplet energy transfer and explained the unusual regiocontrol.

There is significant interest in the development of methods to create hybrid materials that transform capabilities, in particular for Earth-abundant metal oxides, such as TiO2, to give improved or new properties relevant to a broad spectrum of applications. Here we introduce an approach we refer to as ‘molecular cross-linking’, whereby a hybrid molecular boron oxide material is formed from polyhedral boron-cluster precursors of the type [B12(OH)12]2–. This new approach is enabled by the inherent robustness of the boron-cluster molecular building block, which is compatible with the harsh thermal and oxidizing conditions that are necessary for the synthesis of many metal oxides. In this work, using a battery of experimental techniques and materials simulation, we show how this material can be interfaced successfully with TiO2 and other metal oxides to give boron-rich hybrid materials with intriguing photophysical and electrochemical properties.

Readily assembled mini-galvanic cells can be employed to compare their observed voltages with those predicted from the Nernst equation and to determine solubility products for silver halides and overall formation constants for metal–ammonia complexes. Results obtained by students in both an honors-level first-year course in general chemistry and an intermediate-level course for students majoring in chemistry, biochemistry, and biology agree well with data reported in the literature. In addition, these mini-galvanic cells can be used as concentration cells, together with a computer-generated calibration curve based on the Nernst equation, to determine the silver ion concentration in a dilute unknown solution of silver nitrate.

In the version of this Article originally published, Liban M. A. Saleh was incorrectly listed as Liban A. M. Saleh due to a technical error. This has now been amended in all online versions of the Article.

© 2015 American Chemical Society. The activity of several yttrium alkoxide and aryloxide complexes supported by a ferrocene-based ligand incorporating two thiol phenolates, thiolfan (1,1′-bis(2,4-di-tert-butyl-6-thiomethylenephenoxy)ferrocene), was studied. The tert-butoxide complex could only be isolated in the ate form, while a monophenoxide complex could be obtained for OAr = 2,6-di-tert-butylphenolate. The synthetic utility of these yttrium complexes has been demonstrated by the ring-opening polymerization of cyclic esters, with a high activity toward ε-caprolactone and -valerolactone being found for the yttrium phenoxide complex.

© 2015 American Chemical Society. The synthesis and characterization of two yttrium alkyl complexes supported by a bisphosphinimine ferrocene ligand, NPfc (1,1′-di(2,4-di-tert-butyl-6-diphenylphosphiniminophenoxy)ferrocene), were accomplished. Although (NPfc)Y(CH2Ph) and (NPfc)Y(CH2SiMe3) could be structurally characterized, these compounds are thermally sensitive and decompose at ambient temperature within hours. Their characterization was accomplished by NMR spectroscopy, electrochemical measurements, and elemental analysis. Reactivity studies were also carried out; however, the lack of prolonged thermal stability at ambient temperature of these molecules led to decomposition before a clean transformation to reaction products could be observed. (Chemical Equation Presented).

© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015. Reliable transformation of low-cost rare-earth metal oxides to organometallic rare-earth metal complexes is a prerequisite for the advancement of non-aqueous rare-earth metal chemistry. We have recently developed an in situ method to prepare rare-earth alkyl and halide precursors supported by a diamidoferrocene NNTBS, 1,1′-fc(NSiMe2tBu)2, as an ancillary ligand. Herein, we extended the scope of this method to other lanthanide ions including those that are redox active, such as cerium, praseodymium, samarium, terbium, thulium, and ytterbium. Specifically, samarium trisbenzyl could be generated in situ and then converted to the corresponding samarium benzyl or iodide complexes in good yield. However, it was found that ytterbium trisbenzyl could not be formed cleanly and the consequent conversion to ytterbium iodide complex was low yielding. By adapting an alternative route, the desired ytterbium chloride precursor could be obtained in good yield and purity.

The activity of several group 4 metal alkoxide complexes supported by ferrocene-based ligands was controlled using redox reagents during the ring-opening polymerization of l-lactide and ε-caprolactone. Switching in situ between the oxidized and reduced forms of a metal complex resulted in a change in the corresponding rate of polymerization. Opposite behavior was observed for each monomer used. One-pot copolymerization of the two monomers to give block copolymers was also achieved. © 2014 American Chemical Society.

A novel procedure has been devised for the synthesis of derivatives of 1H-indole that is based on the direct, room-temperature electrochemical reduction of substituted o-nitrostyrenes at carbon cathodes in N,N-dimethylformamide containing tetramethylammonium tetrafluoroborate as supporting electrolyte and in the presence of a 10-fold molar excess of a proton donor (phenol or methyl 3-oxobutanoate).