Synthesis of Redox-Active Macrocyclic Diimine Ligands as Flexible Building Blocks

Conjugated coordination polymers attract attention as materials for electrochemical energy storage, mostly as cathode materials for supercapacitors. Faradaic capacity may be introduced to such materials using redox-active building blocks, metals, or ligands. Using this strategy, a novel hybrid cathode material was developed based on a Ni2+ metal-organic polymer. The proposed material, in addition to double-layer capacitance, shows high pseudocapacitance, which arises from the contributions of both the metal center and ligand. A tailoring strategy in the ligand design allows us to minimize the molecular weight of the ligand, which increases its gravimetric energy. According to computational results, the ligand makes the prevailing contribution to the pseudocapacitance of the material. Different approaches to metal–organic polymer (MOP) synthesis were implemented, and the obtained materials were examined by FTIR, Raman spectroscopy, powder XRD, SEM/EDX (energy-dispersive X-ray spectroscopy), TEM, and thermal analysis. Energy-storage performance was comparatively studied with cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD). As a result, materials with an excellent discharge capacity were obtained, reaching the gravimetric energy density of common inorganic cathode materials.

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Generation of Bis(ferrocenyl)silylenes from Siliranes

Molecules ◽

10.3390/molecules25245917 ◽

2020 ◽

Vol 25 (24) ◽

pp. 5917

Author(s):

Yang Pan ◽

Shogo Morisako ◽

Shinobu Aoyagi ◽

Takahiro Sasamori

Keyword(s):

Transition Metal ◽

Building Block ◽

Building Blocks ◽

Redox Behavior ◽

Organosilicon Compounds ◽

Design And Synthesis ◽

Mild Conditions ◽

Redox Active ◽

Electronic Perturbation ◽

Active Transition

Divalent silicon species, the so-called silylenes, represent attractive organosilicon building blocks. Isolable stable silylenes remain scarce, and in most hitherto reported examples, the silicon center is stabilized by electron-donating substituents (e.g., heteroatoms such as nitrogen), which results in electronic perturbation. In order to avoid such electronic perturbation, we have been interested in the chemistry of reactive silylenes with carbon-based substituents such as ferrocenyl groups. Due to the presence of a divalent silicon center and the redox-active transition metal iron, ferrocenylsilylenes can be expected to exhibit interesting redox behavior. Herein, we report the design and synthesis of a bis(ferrocenyl)silirane as a precursor for a bis(ferrocenyl)silylene, which could potentially be used as a building block for redox-active organosilicon compounds. It was found that the isolated bis(ferrocenyl)siliranes could be a bottleable precursor for the bis(ferrocenyl)silylene under mild conditions.

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cis-Bis(2,2′-bipyridine-κ2N,N′)bis(pyridin-4-amine-κN1)ruthenium(II) bis(hexafluoridophosphate) acetonitrile monosolvate

Acta Crystallographica Section E Structure Reports Online ◽

10.1107/s1600536812052002 ◽

2013 ◽

Vol 69 (2) ◽

pp. m77-m78

Author(s):

Mariana R. Camilo ◽

Felipe T. Martins ◽

Valéria R. S. Malta ◽

Javier Ellena ◽

Rose M. Carlos

Keyword(s):

Hydrogen Bonds ◽

Building Blocks ◽

Title Complex ◽

Screw Axis ◽

Complex Molecules ◽

Diimine Ligands ◽

Counter Ions ◽

Distorted Octahedral ◽

Solvent Molecules ◽

Octahedral Configuration

In the title complex, [Ru(C10H8N2)2(C5H6N2)2](PF6)2·CH3CN, the RuIIatom is bonded to two α-diimine ligands,viz.2,2′-bipyridine, in acisconfiguration and to two 4-aminopyridine (4Apy) ligands in the expected distorted octahedral configuration. The compound is isostructural with [Ru(C10H8N2)2(C5H6N2)2](ClO4)2·CH3CN [Duanet al.(1999).J. Coord. Chem.46, 301–312] and both structures are stabilized by classical hydrogen bonds between 4Apy ligands as donors and counter-ions and acetonitrile solvent molecules as acceptors. Indeed, N—H...F interactions give rise to an intermolecularly locked assembly of two centrosymmetric complex molecules and two PF6−counter-ions, which can be considered as the building units of both crystal architectures. The building blocks are connected to one another through hydrogen bonds between 4Apy and the connecting pieces made up of two centrosymmetric motifs with PF6−ions and acetonitrile molecules, giving rise to ribbons running parallel to [011]. 21-Screw-axis-related complex molecules and PF6−counter-ions alternate in helical chains formed along theaaxis by means of these contacts.

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Redox Activity as a Powerful Strategy to Tune Magnetic and/or Conducting Properties in Benzoquinone-Based Metal-Organic Frameworks

Magnetochemistry ◽

10.3390/magnetochemistry7080109 ◽

2021 ◽

Vol 7 (8) ◽

pp. 109

Author(s):

Noemi Monni ◽

Mariangela Oggianu ◽

Suchithra Ashoka Sahadevan ◽

Maria Laura Mercuri

Keyword(s):

Electrode Materials ◽

Metal Organic Frameworks ◽

Future Generation ◽

Building Blocks ◽

Redox Activity ◽

Semiquinone Radical ◽

Molecular Building Blocks ◽

Redox Active ◽

Metal Organic ◽

Selection Of

Multifunctional molecular materials have attracted material scientists for several years as they are promising materials for the future generation of electronic devices. Careful selection of their molecular building blocks allows for the combination and/or even interplay of different physical properties in the same crystal lattice. Incorporation of redox activity in these networks is one of the most appealing and recent synthetic strategies used to enhance magnetic and/or conducting and/or optical properties. Quinone derivatives are excellent redox-active linkers, widely used for various applications such as electrode materials, flow batteries, pseudo-capacitors, etc. Quinones undergo a reversible two-electron redox reaction to form hydroquinone dianions via intermediate semiquinone radical formation. Moreover, the possibility to functionalize the six-membered ring of the quinone by various substituents/functional groups make them excellent molecular building blocks for the construction of multifunctional tunable metal-organic frameworks (MOFs). An overview of the recent advances on benzoquinone-based MOFs, with a particular focus on key examples where magnetic and/or conducting properties are tuned/switched, even simultaneously, by playing with redox activity, is herein envisioned.

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Nickel-Catalyzed Site- and Stereoselective Reductive Alkylalkynylation of Alkynes

10.26434/chemrxiv.13182590 ◽

2020 ◽

Author(s):

Yi Jiang ◽

Jiaoting Pan ◽

Tao Yang ◽

Joel Jun Han Lim ◽

Yu Zhao ◽

...

Keyword(s):

Organic Chemistry ◽

Functional Groups ◽

Multicomponent Reaction ◽

Alkyl Group ◽

Crucial Role ◽

Building Blocks ◽

Radical Addition ◽

Active Esters ◽

Redox Active

Development of a catalytic multicomponent reaction by orthogonal activation of readily available substrates for the streamlined difunctionalization of alkynes is a compelling objective in organic chemistry. Alkyne carboalkynylation, in particular, offers a direct entry to valuable 1,3-enynes with different substitution patterns. Here, we show that the synthesis of stereodefined 1,3-enynes featuring a trisubstituted olefin is achieved by merging alkynes, alkynyl bromides and redox-active N-(acyloxy)phthalimides through nickel-catalyzed reductive alkylalkynylation. Products are generated in up to 89% yield as single regio- and E isomers. Transformations are tolerant of diverse functional groups and the resulting 1,3-enynes are amenable to further elaboration to synthetically useful building blocks. With olefin-tethered N-(acyloxy)phthalimides, a cascade radical addition/cyclization/alkynylation process can be implemented to obtain 1,5-enynes. The present study underscores the crucial role of redox-active esters as superior alkyl group donors compared to haloalkanes in reductive alkyne dicarbofunctionalizations.

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