Ionic Liquids–Cobalt(II) Thermochromic Complexes: How the Structure Tunability Affects “Self-Contained” Systems

Billeci, Floriana; Gunaratne, H. Q. Nimal; Licence, Peter; Seddon, Kenneth R.; Plechkova, Natalia V.; D’Anna, Francesca

doi:10.1021/acssuschemeng.0c08586

Cited by 8 publications

(4 citation statements)

References 56 publications

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“…150 ppm/°C Δδ/Δ T for the 59 Co nucleus is larger than all other reported systems, many by at least an order of magnitude (Figure ). For example, the typical temperature dependence of the 59 Co NMR shift is between 1 and 3 ppm/°C, with the highest for a Co(III) complex belonging to Co(acac) 3 (acac = acetylacetonate) at 3.15 ppm/°C. , Relatively recently, a higher temperature dependence was reported for a putative Co(II) complex at 8.5 ppm/°C . The complexes here eclipse all of those.…”

Section: Resultssupporting

confidence: 46%

“…17,28 Relatively recently, a higher temperature dependence was reported for a putative Co(II) complex at 8.5 ppm/°C. 29 The complexes here eclipse all of those. A preliminary study of 2 in a 300 MHz NMR showed 131 ppm/°Cand our results here, which are even higher, suggest amplification of T sensitivity with the higher magnetic field.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Record Chemical-Shift Temperature Sensitivity in a Series of Trinuclear Cobalt Complexes

Üngör

Ozvat

et al. 2022

J. Am. Chem. Soc.

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Designing spins that exhibit long-lived coherence and strong temperature sensitivity is central to designing effective molecular thermometers and a fundamental challenge in the chemistry/quantuminformation space. Herein, we provide a new pathway to both properties in the same molecule by designing a nuclear spin, which possesses a robust spin coherence, to mimic the strong temperature sensitivity of an electronic spin. This design strategy is demonstrated in the group of trinuclear Co(III) spin-crossover compounds [(CpCo(OP(OR) 2 ) 3 ) 2 Co](SbCl 6 ) where Cp = cyclopentadienyl and R = Me (1), Et (2), i-Pr (3), and t-Bu (4). Nuclear magnetic resonance analyses of the 59 Co nuclear spins reveal 59 Co chemical-shift temperature sensitivity (Δδ/ΔT) values that span from 101(1) ppm/°C in 1 to 149(1) ppm/°C in 2 and 150(2) ppm/°C in 4, where the latter two are record temperature sensitivities for any nuclear spin. Additionally, complexes 2 and 4 have T 2 * values of 74 and 78 μs in solution at ambient temperatures surpassing those from electron-spin-based complexes, which typically display long coherence times only at extremely low temperatures. Our results suggest that spin-crossover phenomena can enable electron-spin-like temperature sensitivities in nuclear spins while retaining robust coherence times at room temperature.

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Section: Resultssupporting

confidence: 46%

Section: ■ Results and Discussionmentioning

confidence: 99%

Record Chemical-Shift Temperature Sensitivity in a Series of Trinuclear Cobalt Complexes

Üngör

Ozvat

et al. 2022

J. Am. Chem. Soc.

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“…Understanding how to deliberately design and manipulate thermochromic materials has driven technological innovation and progress for numerous applications requiring thermally sensitive smart glasses, temperature probes, and sensors, among others. − Materials with thermochromic properties are more likely to be commercially viable when the thermochromic transitions exhibit large spectral shifts, reversibility, and discreteness (i.e., occurring at a well-defined temperature). − ,, Here, we investigate the metal- dieten ( N , N -diethylethylenediamine) family of compounds (e.g., [M( dieten ) 2 ](X) 2 , where M = Cu 2+ , Ni 2+ and X = certain monovalent anions) as they exhibit those important thermochromic characteristics while also possessing tunable molecular properties and interactions that govern their thermochromic behavior. , …”

Section: Introductionmentioning

confidence: 99%

Manipulation of the Thermochromic Transition Temperature in a Classic Metal–Organic Complex by Selective Anion Doping

et al. 2022

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The origin of thermochromism displayed by the hybrid material [Ni(dieten)2](BF4)2 (dieten = N,N-diethylethylenediamine) is explored by anion substitution of the tetrafluoroborate anions (BF4 –) with varying percentages (0–25%) of bromide (Br–). Differential scanning calorimetry and variable-temperature diffuse reflectance spectroscopy indicate that the yellow-orange to orange-red thermochromic transition inherent to undoped [Ni(dieten)2](BF4)2 shifts from 100 to 90 °C as the doping concentration increases from 0 to 25%. Similarly, a 15 nm line broadening of the Kubelka–Munk transformed diffuse reflectance signal (proportional to the absorbance of the complex) and a broadening of the endothermic transition are observed with increasing Br– doping. The structure of the undoped [Ni(dieten)2](BF4)2, determined by single-crystal X-ray diffraction, is presented, and powder X-ray diffraction was used to confirm that the crystal structure and crystallinity of each doped sample remains unchanged from the BF4 – phase. We provide evidence for an underlying mechanism of thermochromism that is linked to hydrogen bonding within the crystal structure and which can be manipulated via targeted modulation of lattice anions. The mechanism proposed here is likely applicable to other materials within the family of dieten complexes ([M(dieten)2](X)2, where M = Ni2+, Cu2+ and X = BF4 –, ClO4 –, NO3 –).

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“…Therefore, extensive research on ionic liquids has been conducted in numerous fields, such as electrochemistry and organic synthesis. Ionic liquids are typically onium salts, although various functional ionic liquids containing metal complexes have been synthesized in recent years. − Our laboratory has synthesized several ionic liquids containing cationic sandwich or half-sandwich complexes, − which exhibit unique functionalities such as magnetism, chemical reactivity, and stimuli-responsiveness in addition to ionic conductivity. − …”

Section: Introductionmentioning

confidence: 99%

Photoinduced and Thermal Linkage Isomerizations of an Organometallic Ionic Liquid Containing a Half-Sandwich Ruthenium Thiocyanate Complex

2021

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Metal complexes with thiocyanate (SCN–) ligands typically exhibit S- or N-coordinated linkage isomers. In this study, to explore ionic liquids that exhibit stimuli-responsiveness based on linkage isomerization, we synthesized an ionic liquid containing a cationic half-sandwich thiocyanate complex, [Ru(C6H6)(NCS)L]Tf2N (L = N-hexyl-2-pyridinemethanimine, Tf2N = bis(trifluoromethanesulfonyl)amide anion). The as-synthesized ionic liquid was a 0.7:0.3 mixture of N- and S-coordinated isomers, presenting as an extremely viscous liquid exhibiting a glass transition at 0 °C. Isomerization from the N- to the S-coordinated isomer occurred upon UV photoirradiation or heating, although thermal isomerization was accompanied by significant decomposition. The N- and S-coordinated isomers were separated into brown and orange liquids, respectively, using gel permeation chromatography. Each isomer exhibited a small solvatochromic absorption shift in organic solvents, with different solvent dependences observed for the two isomers.

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Ionic Liquids–Cobalt(II) Thermochromic Complexes: How the Structure Tunability Affects “Self-Contained” Systems

Cited by 8 publications

References 56 publications

Record Chemical-Shift Temperature Sensitivity in a Series of Trinuclear Cobalt Complexes

Record Chemical-Shift Temperature Sensitivity in a Series of Trinuclear Cobalt Complexes

Manipulation of the Thermochromic Transition Temperature in a Classic Metal–Organic Complex by Selective Anion Doping

Photoinduced and Thermal Linkage Isomerizations of an Organometallic Ionic Liquid Containing a Half-Sandwich Ruthenium Thiocyanate Complex

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