Cyclic multiredox centered systems are currently of great interest, with new compounds being reported and developments made in understanding their behavior. Efficient, elegant, and high‐yielding (for macrocyclic species) synthetic routes to two novel alkynyl‐conjugated multiple ferrocene‐ and biferrocene‐containing cyclic compounds are presented. The electronic interactions between the individual ferrocene units have been investigated through electrochemistry, spectroelectrochemistry, density functional theory (DFT), and crystallography to understand the effect of cyclization on the electronic properties and structure.
Biferrocene systems offer a motif that incorporates multiple redox-active centres, enabling redox control, high levels of stability and near perfect conductance levels, and thus is an ideal participant within future molecular electronic systems. However, the incorporation of biferrocene can be restricted by current synthetic routes. Herein, we discuss a new method for the synthesis and incorporation of biferrocenyl motifs within
The ethynyl-phenylene substituted 2,2':6',2''-terpyridine (tpy) derivatives, 4-(phenyl-ethynyl)-2,2':6',2''-terpyridine (L(1)), 4-(methoxyphenyl-ethynyl)-2,2':6',2''-terpyridine (L(2)), 4-(tolyl-ethynyl)-2,2':6',2''-terpyridine (L(3)) and 4-(nitrophenyl-ethynyl)-2,2':6',2''-terpyridine (L(4)) have been used to synthesize four new [RuCl(2,2'-bipyridine)(L(n))]PF6 based complexes. Electronic absorption, resonance Raman, cyclic voltammetry and spectroelectrochemistry aided by DFT calculations were used to explore the influence of the alkynyl substituents on the electronic structures, photochemical and redox properties of the complexes. Furthermore, it is shown that the addition of ethynyl phenyl moieties to the 4-position of the tpy ligand does not have a detrimental effect on these complexes, or the analogous aqua complexes, with respect to their ability to photocatalyse the oxidation of 4-methoxybenzyl alcohol to the corresponding benzaldehyde.
Cyclic multiredoxc entered systems are currently of great interest, with new compounds being reported and developments made in understanding their behavior.Efficient, elegant, and high-yielding (for macrocyclic species) synthetic routes to two novel alkynyl-conjugated multiple ferrocene-and biferrocene-containing cyclic compounds are presented. The electronic interactions between the individual ferrocene units have been investigated through electrochemistry,s pectroelectrochemistry,density functional theory (DFT), and crystallography to understand the effect of cyclization on the electronic properties and structure.
Metallocenes are
a promising candidate for future spintronic devices
due to their versatile and tunable magnetic properties. However, single
metallocenes, e.g., ferrocene, sublimate below room temperature, and
therefore the implementation for future applications is challenging.
Here, a method to prepare biferrocene thin films using organic molecular
beam deposition (OMBD) is presented, and the effect of substrate and
deposition rate on the film structure and morphology as well as its
chemical and magnetic properties is investigated. On Kapton and Si
substrates, biferrocene interacts only weakly with the substrate,
and distinct grains scattered over the surface are observed. By incorporating
a 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) seeding layer
and depositing biferrocene at high deposition rates of 1.0 Å
s–1, it is possible to achieve a well-ordered densely
packed film. With spintronic applications in mind, the magnetic properties
of the thin films are characterized using superconducting quantum
interference device (SQUID) magnetometry. Whereas initial SQUID measurements
show weak ferromagnetic behavior up to room temperature due to oxidized
molecule fragments, measurements of biferrocene on PTCDA capped with
LiF show the diamagnetic behavior expected of biferrocene. Through
the successful deposition of biferrocene thin films and the ability
to control the spin state, these results demonstrate a first step
toward metallocene-based spintronics.
Ferrocenediyl systems offer a motif that incorporates multiple functionality and redox-active centers, enabling these units to be used as molecular scaffolds in linear and cyclic compounds. Herein, we discuss a new modular methodology for the synthesis and incorporation of ferrocenediyl motifs within extended conjugated systems. We have synthesized a family of compounds featuring ferrocenediyl-ethynyl units with various para-substituted aromatic linkages. Extended linear, open-chain species have been isolated and understanding towards the analogous cyclic compounds gained. The new compounds have been probed using NMR, mass spectrometry, cyclic voltammetry and X-ray crystallography to gain further understanding of their structural and electronic properties.
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