Synthesis, X‐ray Structure and Reactivity of a Sterically Protected Azobisphenol Ligand: On the Quest for New Multifunctional Active Ligands

Evangelio, Emi; Saiz‐Poseu, Javier; Maspoch, Daniel; Wurst, Klaus; Busquè, Félix; Ruiz‐Molina, Daniel

doi:10.1002/ejic.200701339

Cited by 10 publications

(13 citation statements)

References 65 publications

(25 reference statements)

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“…[11] DFT calculations performed on HL ("NH" and "OH" forms) confirm that the "NH" form is more stable. [12] Nevertheless, it should be pointed out that the calculated energy difference is only 3.0 kcal/mol, suggesting that the "OH" form may also be relevant (Figure 2).…”

Section: Resultsmentioning

confidence: 80%

Radicals of Free and Zinc(II)‐Coordinated α‐Azophenols

Kochem¹,

Orio²,

Philouze³

et al. 2010

Eur J Inorg Chem

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The tridentate 2-tert-butyl-4-methoxy-6-(quinolin-8-ylazo)phenol ligand HL has been synthesized and structurally characterized. Its redox activity has been investigated by electrochemical measurements and DFT calculations. Oxidation of HL (irreversible process) affords primarily a hydrogen-bonded phenoxyl radical, whereas its reduction affords an iminosemiquinonate radical species. The reaction of two equivalents of HL with Zn(OAc)₂ affords the zinc complex Zn(L)₂, which has been structurally characterized. Its oxidation is easier than that of HL and is reversible. The EPR spectrum of [Zn(L)(L^·)]⁺ shows an unresolved (S = 1/2) signal at g = 2.005, while [Zn(L^·)]²⁺ exhibits spin triplet resonances (|D| = 0.0118 cm^–1 and E/D = 0). The extra delocalization of spin density on the azo group contributes to a lowering of the D value relative to those of Schiff base derivatives. The temperature dependence of the EPR signal and DFT calculations reveal an excited state for the spin triplet and a weak exchange coupling constant J = –2.73 cm^–1

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Section: Resultsmentioning

confidence: 80%

Radicals of Free and Zinc(II)‐Coordinated α‐Azophenols

Kochem¹,

Orio²,

Philouze³

et al. 2010

Eur J Inorg Chem

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show abstract

“…Moreover, this compound also exhibits good reactivity with transition‐metal ions such as cobalt. Accordingly, combination of both the acid–base character and the complexation ability have been used to create a chromophoric array of three states with significantly different colours (enhanced by the presence of the azo group), which can interconvert reversibly between them 533. In addition to the studies on bulk solutions, these families of compounds have also been structured on surfaces for the development of a surface molecular sensor for the detection of acidity.…”

Section: Materials For Chemo‐/biosensingmentioning

confidence: 99%

Catechol‐Based Biomimetic Functional Materials

Saiz‐Poseu²,

et al. 2012

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Abstract.Catechols are found in nature taking part in a remarkably broad scope of biochemical processes and functions. Though not exclusively, such versatility may be traced back to several properties uniquely found together in the o -dihydroxyaryl chemical function; namely, its ability to establish reversible equilibria at moderate redox potentials and pHs and to irreversibly cross-link through complex oxidation mechanisms; its excellent chelating properties, greatly exemplifi ed by, but by no means exclusive, to the binding of Fe 3 + ; and the diverse modes of interaction of the vicinal hydroxyl groups with all kinds of surfaces of remarkably different chemical and physical nature. Thanks to this diversity, catechols can be found either as simple molecular systems, forming part of supramolacular structures, coordinated to different metal ions or as macromolecules mostly arising from polymerization mechanisms through covalent bonds. Such versatility has allowed catechols to participate in several natural processes and functions that range from the adhesive properties of marine organisms to the storage of some transition metal ions. As a result of such an astonishing range of functionalities, catechol-based systems have in recent years been subject to intense research, aimed at mimicking these natural systems in order to develop new functional materials and coatings. A comprehensive review of these studies is discussed in this paper.

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“…AB photochromic properties have been utilized as a light triggered switch in a variety of polymers, [9][10][11] surface-modified materials, [12][13][14] protein probes, [15][16][17][18] molecular machines, [19][20][21] holographic recording devices [22][23][24] and metal ion chelators. [25][26][27][28] The change in geometry upon isomerization orients the molecules to perform a task, [29][30][31] modulates interactions that change the structure of the bulk material, [32][33][34] changes the spectroscopic properties [35][36][37] or moves a substituent that blocks or unblocks activity. 16,[38][39][40] AB is also present as a chromophore in various pH 41,42 and metal ion indicators, 43,44 as well as industrial dyes and non-linear optical devices.…”

Section: Introductionmentioning

confidence: 99%

Photoisomerization in different classes of azobenzene

2012

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Azobenzene undergoes trans→cis isomerization when irradiated with light tuned to an appropriate wavelength. The reverse cis→trans isomerization can be driven by light or occurs thermally in the dark. Azobenzene's photochromatic properties make it an ideal component of numerous molecular devices and functional materials. Despite the abundance of application-driven research, azobenzene photochemistry and the isomerization mechanism remain topics of investigation. Additional substituents on the azobenzene ring system change the spectroscopic properties and isomerization mechanism. This critical review details the studies completed to date on the 3 main classes of azobenzene derivatives. Understanding the differences in photochemistry, which originate from substitution, is imperative in exploiting azobenzene in the desired applications.

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Synthesis, X‐ray Structure and Reactivity of a Sterically Protected Azobisphenol Ligand: On the Quest for New Multifunctional Active Ligands

Cited by 10 publications

References 65 publications

Radicals of Free and Zinc(II)‐Coordinated α‐Azophenols

Radicals of Free and Zinc(II)‐Coordinated α‐Azophenols

Catechol‐Based Biomimetic Functional Materials

Photoisomerization in different classes of azobenzene

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