Rapid Electron Transport Phenomenon in the Bis(terpyridine) Metal Complex Wire: Marcus Theory and Electrochemical Impedance Spectroscopy Study

The authors reported previously that bis­(terpyiridne)­iron­(II) complex oligomer wires possess outstanding long-range intrawire electron transport ability. Here, molecular arrays of gold-electrode–bis­(terpyridine)­iron­(II)–ferrocene are constructed by stepwise coordination as simple models of the oligomer wire system. The fast electron transfer between the terminal ferrocene and the gold electrode through the bis­(terpyiridne)­iron­(II) complex unit is studied by potential step chronoamperometry (PSCA) and electrochemical impedance spectroscopy (EIS). Tafel plots derived from PSCA are analyzed based on Marcus theory. The plots reveal greater first-order electron transfer rate constant, weaker electronic coupling between the terminal ferrocene and the gold electrode, and smaller reorganization energy than shown by a conventional ferrocenylalkanethiol self-assembled monolayer. The electron transfer rate constants estimated by EIS agree with the PSCA results

Luminescent Heteroleptic Tris(dipyrrinato)indium(III) Complexes

To provide an improvement over the low fluorescence efficiencies often shown by homoleptic tris­(dipyrrinato)­indium­(III) complexes, luminescent heteroleptic tris­(dipyrrinato)­indium­(III) complexes bearing two types of dipyrrinato ligands are designed here by theoretical calculation and then synthesized. They possess frontier orbitals linked to suppression of the nonemissive charge-separated states; one shows a high fluorescence quantum yield (0.41) in toluene, which exceeds that of the corresponding BF₂ complex

Bis[(<i>E</i>)‑2,6-bis(1<i>H</i>‑pyrazol-1-yl)-4-styrylpyridine]iron(II) Complex: Relationship between Thermal Spin Crossover and Crystal Solvent

The crystal structures and thermal spin-crossover (SCO) behavior of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·X</b> [<i><b>E</b></i><b>-dpsp</b> = (<i>E</i>)-2,6-bis­(1<i>H</i>-pyrazol-1-yl)-4-styrylpyridine; <b>X</b> = crystal solvent] are investigated. The titled iron­(II) complex features polymorphology induced by crystal solvents, which is identified by means of single-crystal X-ray diffraction analysis: For <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b> and <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·4MeNO</b>_<b>2</b>, detailed analyses at various temperatures are conducted. The magnetic properties of bulk microcrystalline samples of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·X</b> are assessed using a SQUID magnetometer. Among the series, only <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b> undergoes peculiar thermal SCO, such as a precipitous and hysteretic spin-state change (<i>T</i>_1/2↑ = 179 K, <i>T</i>_1/2↓ = 164 K, and Δ<i>T</i>_1/2 = 15 K) and frozen-in effect. All single crystals of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·X</b> are free from intermolecular interaction except for <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b>: One of the phenyl rings in <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b> is twisted appreciably and features an intermolecular H–H short contact with one of the neighboring complexes to form a one-dimensional network. The twisted phenyl group also participates in π–π stacking with one of the pyrazolyl rings of another neighboring molecule, constructing a dimeric couple. These intermolecular interactions would induce cooperative effects, which leads to the good thermal SCO phenomenon of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b>

Bis[(<i>E</i>)‑2,6-bis(1<i>H</i>‑pyrazol-1-yl)-4-styrylpyridine]iron(II) Complex: Relationship between Thermal Spin Crossover and Crystal Solvent

The crystal structures and thermal spin-crossover (SCO) behavior of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·X</b> [<i><b>E</b></i><b>-dpsp</b> = (<i>E</i>)-2,6-bis­(1<i>H</i>-pyrazol-1-yl)-4-styrylpyridine; <b>X</b> = crystal solvent] are investigated. The titled iron­(II) complex features polymorphology induced by crystal solvents, which is identified by means of single-crystal X-ray diffraction analysis: For <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b> and <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·4MeNO</b>_<b>2</b>, detailed analyses at various temperatures are conducted. The magnetic properties of bulk microcrystalline samples of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·X</b> are assessed using a SQUID magnetometer. Among the series, only <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b> undergoes peculiar thermal SCO, such as a precipitous and hysteretic spin-state change (<i>T</i>_1/2↑ = 179 K, <i>T</i>_1/2↓ = 164 K, and Δ<i>T</i>_1/2 = 15 K) and frozen-in effect. All single crystals of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·X</b> are free from intermolecular interaction except for <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b>: One of the phenyl rings in <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b> is twisted appreciably and features an intermolecular H–H short contact with one of the neighboring complexes to form a one-dimensional network. The twisted phenyl group also participates in π–π stacking with one of the pyrazolyl rings of another neighboring molecule, constructing a dimeric couple. These intermolecular interactions would induce cooperative effects, which leads to the good thermal SCO phenomenon of <b>[Fe­(</b><i><b>E</b></i><b>-dpsp)</b>_<b>2</b><b>]­(BF</b>_<b>4</b><b>)</b>_<b>2</b><b>·acetone</b>

Ferrocene–Dithiolene Hybrids: Control of Strong Donor–Acceptor Electronic Communication to Reverse the Charge Transfer Direction

We prepared a novel class of ferrocene–dithiolene hybrid molecules, FcS₄dt­(Me)₂ and FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)] (where FcS₄dt indicates 2-(1,3-dithia[3]­ferrocenophane-2-ylidene)-1,3-dithiole-4,5-dithiolate and ^<i>t</i>Bu₂bpy indicates 4,4′-di-<i>tert</i>-butyl-2,2′-bipyridine), in which the ferrocene moiety was bound to the planar conjugated dithiolene skeleton via two sulfur atoms such that the cyclopentadienyl rings were perpendicular to the dithiolene backbone. The physical properties and electronic structures of the complexes and their oxidized species [FcS₄dt­(Me)₂]^•+ and [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]^•+ were investigated by means of single-crystal X-ray diffraction (XRD) analysis, cyclic voltammetry, electron paramagnetic resonance (EPR), and UV–vis near infrared (UV–vis–NIR) spectroscopy. The electron density distributions of the highest occupied molecular orbitals (HOMOs) of FcS₄dt­(Me)₂ and FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)] differed remarkably in that the HOMO of the former was ferrocene-based whereas that of the latter was dithiolene-based. The differences in the HOMO distributions originated from the energy level of the dithiolene-based π-orbital in each of the complexes, which was controlled by changing R in FcS₄dt­(R)₂ (R = Me for FcS₄dt­(Me)₂; 2R = Pt­(^<i>t</i>Bu₂bpy) for FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]). We succeeded in analyzing the crystal structure of [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]­(F₄TCNQ)·C₆H₁₄·CH₂Cl₂ (where F₄TCNQ indicates 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), which provided a rare example of the crystal structure of a [Pt­(diimine)­(dithiolate)]^•+ ion-based complex. A comparison of the bond lengths in FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)] and [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]^•+ suggested that the latter complex displayed a conjugated dithiolene-based π-radical character. These considerations agreed well with the electronic structures calculated using density functional theory (DFT) and time-dependent­(TD)-DFT methods. Significant electronic communication between the ferrocene and dithiolene moieties was detected for both [FcS₄dt­(Me)₂]^•+ and [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]^•+ in the appearance of an intramolecular charge transfer band, which was hardly observed for previously reported ferrocene–dithiolene hybrid molecules. The charge transfer direction was reversed between the two cations. The electron coupling parameter <i>H</i>_AB and the potential energy curves of the oxidized complexes were estimated based on the classical two-state Marcus–Hush theory. These results suggest that FcS₄dt-based metalladithiolenes can exhibit controllable electronic structures expressed as double-minimum potential energy curves

Ferrocene–Dithiolene Hybrids: Control of Strong Donor–Acceptor Electronic Communication to Reverse the Charge Transfer Direction

We prepared a novel class of ferrocene–dithiolene hybrid molecules, FcS₄dt­(Me)₂ and FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)] (where FcS₄dt indicates 2-(1,3-dithia[3]­ferrocenophane-2-ylidene)-1,3-dithiole-4,5-dithiolate and ^<i>t</i>Bu₂bpy indicates 4,4′-di-<i>tert</i>-butyl-2,2′-bipyridine), in which the ferrocene moiety was bound to the planar conjugated dithiolene skeleton via two sulfur atoms such that the cyclopentadienyl rings were perpendicular to the dithiolene backbone. The physical properties and electronic structures of the complexes and their oxidized species [FcS₄dt­(Me)₂]^•+ and [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]^•+ were investigated by means of single-crystal X-ray diffraction (XRD) analysis, cyclic voltammetry, electron paramagnetic resonance (EPR), and UV–vis near infrared (UV–vis–NIR) spectroscopy. The electron density distributions of the highest occupied molecular orbitals (HOMOs) of FcS₄dt­(Me)₂ and FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)] differed remarkably in that the HOMO of the former was ferrocene-based whereas that of the latter was dithiolene-based. The differences in the HOMO distributions originated from the energy level of the dithiolene-based π-orbital in each of the complexes, which was controlled by changing R in FcS₄dt­(R)₂ (R = Me for FcS₄dt­(Me)₂; 2R = Pt­(^<i>t</i>Bu₂bpy) for FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]). We succeeded in analyzing the crystal structure of [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]­(F₄TCNQ)·C₆H₁₄·CH₂Cl₂ (where F₄TCNQ indicates 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), which provided a rare example of the crystal structure of a [Pt­(diimine)­(dithiolate)]^•+ ion-based complex. A comparison of the bond lengths in FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)] and [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]^•+ suggested that the latter complex displayed a conjugated dithiolene-based π-radical character. These considerations agreed well with the electronic structures calculated using density functional theory (DFT) and time-dependent­(TD)-DFT methods. Significant electronic communication between the ferrocene and dithiolene moieties was detected for both [FcS₄dt­(Me)₂]^•+ and [FcS₄dt­[Pt­(^<i>t</i>Bu₂bpy)]]^•+ in the appearance of an intramolecular charge transfer band, which was hardly observed for previously reported ferrocene–dithiolene hybrid molecules. The charge transfer direction was reversed between the two cations. The electron coupling parameter <i>H</i>_AB and the potential energy curves of the oxidized complexes were estimated based on the classical two-state Marcus–Hush theory. These results suggest that FcS₄dt-based metalladithiolenes can exhibit controllable electronic structures expressed as double-minimum potential energy curves

Crystalline Graphdiyne Nanosheets Produced at a Gas/Liquid or Liquid/Liquid Interface

Synthetic two-dimensional polymers, or bottom-up nanosheets, are ultrathin polymeric frameworks with in-plane periodicity. They can be synthesized in a direct, bottom-up fashion using atomic, ionic, or molecular components. However, few are based on carbon–carbon bond formation, which means that there is a potential new field of investigation into these fundamentally important chemical bonds. Here, we describe the bottom-up synthesis of all-carbon, π-conjugated graphdiyne nanosheets. A liquid/liquid interfacial protocol involves layering a dichloromethane solution of hexaethynylbenzene on an aqueous layer containing a copper catalyst at room temperature. A multilayer graphdiyne (thickness, 24 nm; domain size, >25 μm) emerges through a successive alkyne–alkyne homocoupling reaction at the interface. A gas/liquid interfacial synthesis is more successful. Sprinkling a very small amount of hexaethynylbenzene in a mixture of dichloromethane and toluene onto the surface of the aqueous phase at room temperature generated single-crystalline graphdiyne nanosheets, which feature regular hexagonal domains, a lower degree of oxygenation, and uniform thickness (3.0 nm) and lateral size (1.5 μm)

Crystalline Graphdiyne Nanosheets Produced at a Gas/Liquid or Liquid/Liquid Interface

Synthetic two-dimensional polymers, or bottom-up nanosheets, are ultrathin polymeric frameworks with in-plane periodicity. They can be synthesized in a direct, bottom-up fashion using atomic, ionic, or molecular components. However, few are based on carbon–carbon bond formation, which means that there is a potential new field of investigation into these fundamentally important chemical bonds. Here, we describe the bottom-up synthesis of all-carbon, π-conjugated graphdiyne nanosheets. A liquid/liquid interfacial protocol involves layering a dichloromethane solution of hexaethynylbenzene on an aqueous layer containing a copper catalyst at room temperature. A multilayer graphdiyne (thickness, 24 nm; domain size, >25 μm) emerges through a successive alkyne–alkyne homocoupling reaction at the interface. A gas/liquid interfacial synthesis is more successful. Sprinkling a very small amount of hexaethynylbenzene in a mixture of dichloromethane and toluene onto the surface of the aqueous phase at room temperature generated single-crystalline graphdiyne nanosheets, which feature regular hexagonal domains, a lower degree of oxygenation, and uniform thickness (3.0 nm) and lateral size (1.5 μm)

By way of sea, the journey towards Alonso de Ercilla's ideal

Este artículo entra en el debate sobre La Araucana a partir de un análisis desde la experiencia del viaje y la metáfora de la vida como navegación, concebidas como un eje significativo de la obra. La poetización del periplo de Ercilla a América se propone como un centro irradiador de sugestivas significaciones de La Araucana. Para ello, se vincula La Araucana con la tradición ideológica sobre el viaje que los autores de la literatura áurea desarrollaron con profusión desde los tiempos de la conquista, con el fin de entroncar el poema con la tradición del humanismo cristiano, del erasmismo pacifista y de su desarrollo en la poesía moralista de su tiempo. El poeta filtró este contexto ideológico tomando de él aquello que le convino para plantear su particular visión de la Conquista; una visión que lo convierte en inaugurador de un discurso crítico americano en la poesía escrita en castellano.This article engages in the debate on La Araucana with an analysis of the experience of travel and the metaphor of life as navigation, both conceived as significant axis of the book. The poetization of Ercilla’s journey to America is proposed as an irradiating centre of suggestive signi?cances in La Araucana. As a result La Araucana is tied to the ideological tradition relating to the journey that authors of Golden Age literature developed abundantly from the times of the Conquest with the purpose of establishing a connection between La Araucana and the Christian humanism tradition and paci?st Erasmism, and their development in the moralist poetry of the time. The poet ?ltered this ideological context taking from it all that interested him in order to present his particular view of the Conquest; a vision that establishes him as the founder of a critical American discourse in poetry written in Castilian

Reactivity and Electronic Properties of a Ferrocene Molecule Bearing an N,C-Chelated BMes₂ Unit

A dimesitylboron-functionalized benzimidazolylferrocene, B­(2-ferrocenyl-<i>N</i>-Me-benzimidazolyl)­Mes₂ (<b>1</b>), has been synthesized and fully characterized. The B–N bond in <b>1</b> was found to undergo a dynamic dissociation/association process in solution, leading to a dynamic exchange of the two mesityls bound to the boron atom and slow hydrolysis of <b>1</b> under ambient conditions. The hydrolyzed product 2-BMes­(OH)-1-(<i>N</i>-methylbenzimidazol-2-yl)­ferrocene (<b>2</b>) was isolated and characterized, in which the boron center has a trigonal-planar geometry with one of the mesityls being replaced by an OH^– group. The photoisomerization process of the boron unit in <b>1</b> was fully inhibited by the low lying d–d/MLCT states of the ferrocene unit. Compound <b>1</b> can be oxidized readily by I₂, forming the ferrocenium species <b>[1</b>^<b>+</b><b>]­I</b>_<b>3</b>^<b>‑</b> (<b>3</b>). NMR and EPR data for <b>3</b> indicated a notable spin delocalization through space from the Fe­(III) center to a flanking mesityl group