Study of the correlations of the MLCT Vis absorption maxima of 4‐pentacyanoferrate‐ 4′‐arylsubstituted bispyridinium complexes with the Hammett substituent parameters and the solvent polarity parameters <i>E</i> and AN

Papadakis, Raffaello; Tsolomitis, Athanase

doi:10.1002/poc.1514

Cited by 22 publications

(19 citation statements)

References 29 publications

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“…In fact, the absorption maximum of the VHF does also give a straight line when plotting l max against the difference in s values. [23] The use of s pY gives a significantly poorer fit (R 2 = 0.91) compared with that obtained by using the through-conjugation values (R 2 = 0.97).…”

Section: Resultsmentioning

confidence: 91%

Linear Free‐Energy Correlations for the Vinylheptafulvene Ring Closure: A Probe for Hammett σ Values

Broman

Jevric

Nielsen

2013

Chemistry A European J

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Linear free-energy relationships, like Hammett correlations, are fundamental in physical organic chemistry for the elucidation of reaction mechanisms. In this work, we show that Hammett correlations exist for the ring closure of six different model systems of vinylheptafulvenes (VHFs) to their corresponding dihydroazulenes (DHAs). These first-order reactions were easily followed by UV/Vis absorption spectroscopy on account of the significantly different absorption characteristics between VHFs and DHAs. Opposing effects displayed by substituent groups at two different positions are conveniently accounted for by simply subtracting the two Hammett σ values of each group. The linear correlations readily allow us to obtain unknown and approximate Hammett σ values for previously uninvestigated substituents. We also show that they can provide alternative values to the standard ones. We present values for a variety of substituent groups ranging from alkynes, sulfones, sulfoxides, and different heteroaromatics. The electronic effects exerted by substituent groups on VHFs are also reflected in their absorption maxima. Thus, we have established an empirical relationship between the absorption maximum of the VHF and the Hammett σ values of its substituents. This fine-tuning of electronic properties is particularly important for the ongoing efforts of using the DHA/VHF molecular switch in molecular electronics devices.

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Section: Resultsmentioning

confidence: 91%

Linear Free‐Energy Correlations for the Vinylheptafulvene Ring Closure: A Probe for Hammett σ Values

Broman

Jevric

Nielsen

2013

Chemistry A European J

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“…When conducting a deep literature search, it is easily made obvious that there are not many examples of solvent-switchable supramolecular structures such as rotaxanes and catenanes exhibiting also solvatochromism. As mentioned above, solvatochromic supramolecular assemblies exhibit a strong change in position and sometimes the intensity of their absorption spectra, which is achieved by changing [28]; II, Reichardt's betaine [28]; III, betaine of N-aryl and N′-phenacetyl-4,4′-bipyridines [35,36]; and IV, pentacyanoferrate(II) complexes with N-aryl4,4′-bipyridines (monoquats) ligands (R = OMe, Me, H, Cl, Br, CN) [37,38]. Solvent Effects in Supramolecular Systems DOI: http://dx.doi.org/10.5772/intechopen.86981 the polarity of the solvent (solvatochromic effect).…”

Section: Supramolecules Involving Solvatochromic Entitiesmentioning

confidence: 99%

Solvent Effects in Supramolecular Systems

Papadakis¹,

Deligkiozi²

2020

Solvents, Ionic Liquids and Solvent Effects

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Today it is well-established that solvents demonstrate an important role in chemistry. Solvents are able to affect the reactivity, as well as the electronic, optical, and generally physicochemical properties of compounds in solution. Taking this into account, in this chapter we analyze the importance of solvent polarity in phenomena closely related to supramolecular systems as well as the aptitude of various supramolecules to interact with solvent molecules and thus to give rise to chromic effects such as solvatochromism. Main focus is placed on mechanically interlocked molecules, e.g., rotaxanes, catenanes, etc., exhibiting solvent-controlled shuttling movements, switching, and/or solvatochromism. The effect of solvents in various supramolecular architectures is a further focus of this chapter.

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“…Pinheiro et al [52] studied an intensely solvatochromic pentacyano ruthenium(II) complex with a 2,2 -bipyridine ligand and exploited its particularly high sensitivity to traces of water for its detection in aprotic solvents using merely UV-Vis spectrophotometry [47]. Dyes of this family have been used as solvatochromic probes [53,54]. Some studies by Coe et al brought 4,4 -bipyridine ligands to the fore [55].…”

Section: Solvatochromic Complexes Involving Monoquats As Ligandsmentioning

confidence: 99%

“…The MLCT energy differences between water and MeOH of complexes 31a-f were similar to the ones of complexes 28a-28d by Coe et al [55] (see Table 1). In a similar fashion, Papadakis and Tsolomitis utilized Zincke reaction to produce a number of monoquats in which the N-substituent was an aryl group (see Figure 14a) [53]. They then utilized these monoquats as ligands and synthesized six pentacyanoferrate(II) complexes, which were found to exhibit intense solvatochromism.…”

Section: Solvatochromic Complexes Involving Monoquats As Ligandsmentioning

confidence: 99%

“…A characteristic response to solvent polarity and preferential solvation effects occurring in water/MeOH mixtures are shown in Figure 14c. Due to their large solvatochromic shifts and their high solubilities in polar organic solvents and water, complexes 31a-f could be outstanding solvent polarity indicators and probes of solute-microenvironment effects, especially useful in cases of media of high polarity [53][54][55]57].…”

Section: Solvatochromic Complexes Involving Monoquats As Ligandsmentioning

confidence: 99%

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Mono- and Di-Quaternized 4,4′-Bipyridine Derivatives as Key Building Blocks for Medium- and Environment-Responsive Compounds and Materials

Papadakis

2019

Molecules

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Mono-and di-quaternized 4,4 -bipyridine derivatives constitute a family of heterocyclic compounds, which in recent years have been employed in numerous applications. These applications correspond to various disciplines of research and technology. In their majority, two key features of these 4,4 -bipyridine-based derivatives are exploited: their redox activity and their electrochromic aptitude. Contemporary materials and compounds encompassing these skeletons as building blocks are often characterized as multifunctional, as their presence often gives rise to interesting phenomena, e.g., various types of chromism. This research trend is acknowledged, and, in this review article, recent examples of multifunctional chromic materials/compounds of this class are presented. Emphasis is placed on solvent-/medium-and environment-responsive 4,4 -bipyridine derivatives. Two important classes of 4,4 -bipyridine-based products with solvatochromic and/or environment-responsive character are reviewed: viologens (i.e., N,N -disubstituted derivatives) and monoquats (i.e., monosubstituted 4,4 -bipyridine derivatives). The multifunctional nature of these derivatives is analyzed and structure-property relations are discussed in connection to the role of these derivatives in various novel applications.Molecules 2020, 25, 1 2 of 30 recent) underlining the high versatility of this class of compounds [9,10,[12][13][14][15]. Perhaps, the most reviewed subject regarding the viologens is their electrochromism [13,14,16]. Viologens are known to undergo one-electron reductions electrochemically ( Figure 2) yielding colorful radicals i.e., cations that are stable in the absence of O 2 . Yet, their chromism can also be triggered through various stimuli (including light, heat, solvents, presence of various chemical species, pressure, etc.). All these possibilities shape the very versatile "chromic character" of viologens and generally of 4,4 -bipyridine derivatives. Even though this "chromic character" has only recently started gaining more attention and there is an increasing number of research articles emphasizing on the alternative uses of 4,4 -bipyridine derivatives, there are no reviews in this growing area up until now. Such an attempt is presented in this review paper with an emphasis on medium-and environment-responsive compounds and materials based on 4,4 -bipyridine. Primary focus is placed on viologen-involving solvatochromic systems as well as materials and compounds of this class whose chromic behavior is dependent on various environment stimuli. Molecules 2018, 23, x 2 of 30 Figure 2. Schemes depicting (a) the electrochromic cycle (1) and (b) the photochromic cycle of paraquat (A, counter anion). Structure and Properties of Viologens The Strong Electron-Withdrawing Character of ViologensThe strong electron-withdrawing character of viologens has been widely exploited in numerous molecular architectures and materials. Viologens can undergo reversible one-electron reductions forming radical cations (Figure 2a), which are vividly colo...

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Study of the correlations of the MLCT Vis absorption maxima of 4‐pentacyanoferrate‐ 4′‐arylsubstituted bispyridinium complexes with the Hammett substituent parameters and the solvent polarity parameters E and AN

Cited by 22 publications

References 29 publications

Linear Free‐Energy Correlations for the Vinylheptafulvene Ring Closure: A Probe for Hammett σ Values

Linear Free‐Energy Correlations for the Vinylheptafulvene Ring Closure: A Probe for Hammett σ Values

Solvent Effects in Supramolecular Systems

Mono- and Di-Quaternized 4,4′-Bipyridine Derivatives as Key Building Blocks for Medium- and Environment-Responsive Compounds and Materials

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