A valence tautomeric cobalt–dioxolene complex with an anchoring group for prospective chemical grafting to metal oxides

Mörtel, Max; Seller, M.; Heinemann, Frank W.; Khusniyarov, Marat M.

doi:10.1039/d0dt03771k

Cited by 12 publications

(20 citation statements)

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“…The assignment of the transitions (Table S5) using TDA-DFT confirm the identity of the characteristic tautomeric bands for the [Co(dbdiox)-(dbsq)(N 2 L)] family. 23,32,66 Density Functional Theory Calculations. A pioneering DFT study on the VT complex [Co(dbdiox)(dbsq)(phen)] was reported by Noodleman, Hendrickson et al in 1997.…”

Section: ■ Introductionmentioning

confidence: 99%

A Convenient DFT-Based Strategy for Predicting Transition Temperatures of Valence Tautomeric Molecular Switches

et al. 2021

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The ability to identify promising candidate switchable molecules computationally, prior to synthesis, represents a considerable advance in the development of switchable molecular materials. Even more useful would be the possibility of predicting the switching temperature. Cobalt-dioxolene complexes can exhibit thermally induced valence tautomeric switching between low-spin CoIII-catecholate and high-spin CoII-semiquinonate forms, where the half-temperature (T 1/2) is the temperature at which there are equal amounts of the two tautomers. We report the first simple computational strategy for accurately predicting T 1/2 values for valence tautomeric complexes. Dispersion-corrected density functional theory (DFT) methods have been applied to the [Co(dbdiox)(dbsq)(N2L)] (dbdiox/dbsq•– = 3,5-di-tert-butyldioxolene/semiquinonate; N2L = diimine) family of valence tautomeric complexes, including the newly reported [Co(dbdiox)(dbsq)(MeO-bpy)] (1) (MeO-bpy = 4,4′-dimethoxy-2,2′-bipyridine). The DFT strategy has been thoroughly benchmarked to experimental data, affording highly accurate spin-distributions and an excellent energy match between experimental and calculated spin-states. Detailed orbital analysis of the [Co(dbdiox)(dbsq)(N2L)] complexes has revealed that the diimine ligand tunes the T 1/2 value primarily through π-acceptance. We have established an excellent correlation between experimental T 1/2(toluene) values for [Co(dbdiox)(dbsq)(N2L)] complexes and the calculated lowest unoccupied molecular orbital energy of the corresponding diimine ligand. The model affords accurate T 1/2(toluene) values for [Co(dbdiox)(dbsq)(N2L)] complexes, with an average error of only 3.7%. This quantitative and simple DFT strategy allows experimentalists to not only rapidly identify proposed VT complexes but also predict the transition temperature. This study lays the groundwork for future in silico screening of candidate switchable molecules prior to experimental investigation, with associated time, cost, and environmental benefits.

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Section: ■ Introductionmentioning

confidence: 99%

A Convenient DFT-Based Strategy for Predicting Transition Temperatures of Valence Tautomeric Molecular Switches

et al. 2021

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“…These changes confirm hs -Co II (SQ • ) 2 → ls -Co III (SQ • )(Cat) switching and thus the CIVT effect . The band in the SWIR region is assigned to the ligand-to-ligand intervalence charge transfer (LLIVCT) transition, which is a spectroscopic signature of the ls -Co III (SQ • )(Cat) state in complexes featuring two dioxolene ligands in different oxidation levels. ,, The evolution of absorption at 750 nm has been analyzed with our revised model (see the Experimental Section and Figure S2) yielding the association constant K a = 5.7(5) × 10 3 L mol –1 for stypy binding to 1 *HS , which is in excellent agreement with the previously obtained data (4(1)–6(2) × 10 3 L mol –1 ) …”

Section: Results and Discussionmentioning

confidence: 87%

Molecular Valence Tautomeric Metal Complexes for Chemosensing

et al. 2021

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Switchable valence tautomeric metal complexes have been long suggested for applications as chemosensors. However, no such molecular sensors have been yet reported. Here, we present a concept for sensing and the first prototype molecular sensor based on valence tautomeric cobalt-dioxolenes. A valence tautomeric cobalt-dioxolene complex [ls-CoIII(SQ•)(Cat)(stypy)2] ⇄ [hs-CoII(SQ•)2(stypy)2] 1 (ls = low spin, hs = high spin, Cat = 3,5-di-tert-butylcatecholate(2−), SQ = one-electron oxidized, benzosemiquinone(1−) form of Cat, stypy = trans-4-styrylpyridine) has been used as a molecular sensor. The lability of axial stypy ligands of 1 in solution allows us to exchange stypy ligands by dimethyl sulfoxide and simple pyridine analytes in a controllable way, which triggers colorimetric and magnetic responses.

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“…111 Similarly, in the complex [Co(BzOEt-phen)(t-Budiox) 2 ] (41; BzOEt-phen = ethyl 4-(1-10-phenanthrolin-5-yl)benzoate), T c shifts from 261-265 K to 230-231 K upon moving from DCM to toluene. 112 It is important to note that for several of these examples, solution-state equilibria were investigated in only two or three solvents. More detailed solvatochromic analyses can often be precluded by insolubility or dissociation/decomposition in certain solvents.…”

Section: Solvatochromism and Redox Isomerism: Valence Tautomerismmentioning

confidence: 99%

Switching metal complexesviaintramolecular electron transfer: connections with solvatochromism

Nadurata

Boskovic

2021

Inorg. Chem. Front.

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A valence tautomeric cobalt–dioxolene complex with an anchoring group for prospective chemical grafting to metal oxides

Abstract: Here we synthesized a valence tautomeric cobalt-dioxolene complex featuring a protected anchoring group. At room temperature, the complex reveals a nearly pure low-spin-Co(III)-catecholate state in the solid state, but a...

Cited by 12 publications

References 40 publications

A Convenient DFT-Based Strategy for Predicting Transition Temperatures of Valence Tautomeric Molecular Switches

A Convenient DFT-Based Strategy for Predicting Transition Temperatures of Valence Tautomeric Molecular Switches

Molecular Valence Tautomeric Metal Complexes for Chemosensing

Switching metal complexesviaintramolecular electron transfer: connections with solvatochromism

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