RESUMEN
Owing to their high ionic conductivity and negligible vapor pressure, ionic liquids (ILs) find applications in various electronic devices. However, fabricating IL-based photocontrollable devices remains a challenge. In this study, we developed organometallic ILs with reversible light- and heat-controlled ionic conductivities for potential use in tunable devices. The physical properties and stimulus responses of ILs containing a cationic sandwich Ru complex with two coordinating substituents were investigated. UV photoirradiation of these ILs triggered cation photodissociation, resulting in their transformation into viscoelastic coordination polymers wherein the coordinating substituents bridged the Ru centers. Owing to the anion coordination, salts with coordinating anions such as CF3SO2NCN-, B(CN)4-, and BF2(CN)2- exhibited faster response and higher conversion than those with noncoordinating anions including (FSO2)2N- and (CF3SO2)2N-. All photoproducts reverted to their original ILs upon heating, except for the photoproduct of the BF2(CN)2 salt, which decomposed upon heating. Light- and heat-induced reversible changes occur in most cases between the high-ionic-conductive IL state and low-ionic-conductive coordination polymer state. Unlike previously reported ILs with three or one cation substituent, the current ILs exhibited both high reactivity and large ionic conductivity changes.
RESUMEN
We synthesized several protic ionic liquids (ILs) composed of onium cations and the (trifluoromethylsulfonyl)(vinylsulfonyl)amide anion. The addition of a base catalytically facilitated their transformation into zwitterions (ZIs) under solvent-free conditions, which is a convenient method for synthesizing ZIs from ILs.
RESUMEN
Cationic rhodium complexes with 1,5-cyclooctadiene (cod) ligands are important organometallic compounds that are useful as precatalysts; however, their solid-state structures and thermal properties have not been adequately investigated. In this study, we synthesized [Rh(cod)L]X (L = cod, C6H6, PhMe; X = SbF6, (FSO2)2N (= FSA), CF3BF3, CB11H12) and investigated their phase behaviors, crystal structures, and reactivities. The phase transitions of these salts result in disordered solid-state structures. Moreover, the structural disorder increases with a decrease in the cation symmetry in the SbF6 salts; [Rh(cod)(PhMe)]SbF6 exhibits a rotator phase, and the cations in other salts exhibit a dynamic rotational disorder. In contrast, a lower crystal symmetry with less cation disorder is observed for FSA salts. The thermal stabilities and reactivities of these salts were further investigated. FSA salts with arene ligands produce anion-coordinated complexes upon melting, and SbF6 salts with arene ligands produce [Rh(cod)L'2]SbF6 (L' = MeCN and SMe2) via an in situ single-crystal-to-single-crystal ligand-exchange reaction.
RESUMEN
Several meltable coordination polymers (CPs) that possess substantial advantages attributable to their high flexibility and processability have been developed recently; however, the melting mechanism and vitrification conditions of these materials are not yet fully understood. In this study, we synthesized meltable CPs [A][K(TCM)2] (A = onium cation, TCM = C(CN)3-) incorporating ionic liquid components and investigated their crystal structures and melting behaviors in detail. These CPs feature two- or three-dimensional anionic [K(TCM)2]n- frameworks incorporating onium cations. Each CP was found to undergo incongruent melting at a temperature between 73 and 192 °C to produce a heterogeneous mixture of the ionic liquid ([A][TCM]) and microcrystalline K[TCM]. Furthermore, they formed homogeneous liquids upon further heating to â¼240 °C. The melting points of these CPs were linearly correlated with those of their constituent ionic liquids. The vitrification of these materials upon rapid cooling from the molten state was further investigated. The cooling rates required for vitrification differed greatly between the CPs and were correlated with the cation flexibility.
RESUMEN
The reversible formation of ionic liquid gels, or ionogels, upon external stimuli could improve their versatility and expand their application scope in electronic, biomedical, and micro-engineering systems. Herein, we developed organometallic compounds that release low-molecular-weight gelators upon photoirradiation, which facilitate the on-demand photogelation of ionic liquids (ILs). The chemical formulae of the gelator-coordinated complexes are [Ru(C5H5)L]X (L = C6H5NHCONHC12H25; X = PF6, B(CN)4). Each of the complexes were ILs that are easy to synthesize and miscible in ILs. By adding a small amount of the complex, various ILs were transformed to gels upon UV photoirradiation. The PF6 salt allowed the photogelation of ILs with coordinating substituents, whereas the B(CN)4 salt allowed the photogelation of non-coordinating ILs, albeit the reaction was slower. These gels underwent the reverse reaction and liquefied back when heated, and the photogelation was repeatable for ILs with coordinating cations.
RESUMEN
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.
RESUMEN
To investigate the effects of chirality on the phase behavior of ionic plastic crystals and ionic liquids, salts of a chiral sandwich complex with various anions were synthesized. The synthesized salts have the general chemical formula [Ru(C5H5)(C6H5CHCH3OCH3)]X (X = CB11H12, CF3BF3, PF6, CPFSA (= [double bond, length as m-dash]CF2(SO2CF2)2N)), where the ruthenium complex possesses a chiral substituent. The racemates of the salts with the CB11H12, CF3BF3, and PF6 anions crystallized as a solid solution, racemic compound, and conglomerate, respectively. The (S)-enantiomer and the racemate of the CB11H12 salt exhibited phase transitions to the ionic plastic phase and melted at high temperatures. Further, this salt exhibited polymorphism, as crystallographically investigated. Most of the other salts were ionic liquids exhibiting no plastic phase. The CPFSA salt was liquid and exhibited glass transition at low temperatures.
RESUMEN
The reversible switching of bonding modes in coordination polymers through the application of external stimuli leads to versatile mechanical and electronic functions. However, the exploration of such a system remains a great challenge. In this study, we designed liquid mixtures comprising a photoreactive organometallic ionic liquid and a bridging ligand, which form intermolecular coordination bonds upon photoirradiation. The liquid mixture of an ionic liquid [Ru(C5H5){Ph(CH2)3CN}][(SO2F)2N] (1) and a tridentate ligand N(C2H4CN)3 was transformed into an elastomer of an amorphous coordination polymer upon ultraviolet photoirradiation. By contrast, the photoirradiation of the mixture of 1 and a bidentate ligand NC(CH2)4CN produced a highly viscous liquid comprising coordination-bonded oligomers. In these reactions, photoirradiation causes dissociation of the organometallic cation, followed by the formation of intermolecular coordination bonds via the bridging ligands. The photoproducts underwent reverse reactions thermally. Based on coordination transformation, the ionic conductivity and viscoelasticity of these materials were reversibly controlled by the application of light and heat.
RESUMEN
Ru-containing ionic liquids [Ru(C5H5){C6H3(OC6H12CN)3}][N(SO2F)2] (1) and [Ru(C5H5){C6H5(OC3H6CN)}][N(SO2F)2] (2), having different numbers of substituents, were reversibly converted to coordination polymer solids and oligomeric liquids, respectively, by UV photoirradiation and heating. This feature enabled the control of their ionic conductivities and viscoelastic properties.
RESUMEN
To explore the structural transformation of cyclopentadienyl ruthenium (CpRu) complexes in response to external stimuli, the reaction of [RuCp(MeCN)3][X] (X = PF6, (FSO2)2N [= FSA]) and tris(alkylthio)benzenes (1,3,5-C6H3(SR)3; L 1 : R = Pr, L 2 : R = Me) was investigated, and the crystal structures and thermal properties of the products were examined. The reaction produced the sandwich complexes [RuCpL n ][X] or dinuclear complexes [Ru2Cp2(µ-L n )2(CH3CN) m ][X]2 (X = PF6, FSA) depending on the reaction conditions. The sandwich complex [RuCpL 1 ][FSA] was an ionic liquid. The solids of dinuclear complexes transformed into the thermodynamically stable sandwich complexes upon heating accompanied by acetonitrile loss. This change resulted in a transformation from crystal to ionic liquid for complexes with the FSA anion. UV irradiation of the sandwich complex [RuCpL 1 ][PF6] in methanol produced the dinuclear complex [Ru2Cp2(µ-L 1 )2 L 1 2][PF6]2. The complex transformed into the sandwich complex upon heating.
