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Oxide-derived copper (OD-Cu) has attracted considerable attention due to its exceptional electrocatalytic performance toward various reactions, including the reduction of nitrate (NO 3 - ) to ammonia (NH 3 ). Furthermore, numerous techniques have been developed to synthesize copper oxides with well-defined surface orientations. However, the relationship between the surface orientation of the precursor and the NO 3 - reduction performance of the resulting OD-Cu catalyst remains unclear. In this study, two types of OD-Cu electrodes, prepared by reducing copper oxide (Cu 2 O) with exposed (100) and (111) facets grown on Cu substrates, were employed for NO 3 - reduction. The OD-Cu catalyst derived from Cu 2 O(111) exhibited a lower overpotential for initiating NO 3 - reduction and achieved a higher current density compared to the catalyst derived from Cu 2 O(100). Conversely, the catalyst prepared from Cu 2 O(100) demonstrated superior Faradaic efficiency for NH 3 production. These differences are attributed to variations in the preferential reaction steps of NO 3 - reduction on each catalyst., (© 2025 The Author(s). Chemistry - An Asian Journal published by Wiley-VCH GmbH.)

Although coordination polymers generally do not melt, several that do melt have been synthesized recently and have drawn much attention. In this study, two- and three-dimensional coordination polymers that melt were synthesized, [Ru(Cp)(C 6 H 5 R)][M{C(CN) 3 } 2 ] (R=H, Me, Et; M=K, Rb; Cp=C 5 H 5 ), which are complex salts comprising M[C(CN) 3 ] and organometallic ionic liquids [Ru(Cp)(C 6 H 5 R)][C(CN) 3 ]. They have anionic [M{C(CN) 3 } 2 ] n coordination polymer frameworks, whose dimensionalities depend on the size of the organometallic cation inside. Their melting points decreased with increasing cation substituent length and size of the alkali metal ion (T - coordination polymer frameworks, whose dimensionalities depend on the size of the organometallic cation inside. Their melting points decreased with increasing cation substituent length and size of the alkali metal ion (T m =102-239 °C), and these low-melting-point coordination polymers exhibited incongruent melting, forming mixtures of solid M[C(CN) 3 ] and ionic liquid upon melting. Using the same method, coordination polymers were synthesized with various bridging ligands, [Co(Cp) 2 ][MX 2 ] (X=B(CN) 4 , C(CN) 3 , N(CN) 2 ; M=K, Na), as well as a paramagnetic coordination polymer, [Fe(Cp) 2 ][K{C(CN) 3 } 2 ]., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first example of an asymmetric cyclization-dimerization of (ortho-alkynyl phenyl) (methoxymethyl) sulfides with a palladium(II) bisoxazoline (box) catalyst has been developed. The box ligand enhances the alkynophilicity of benzothienyl palladium(II) intermediate A and thus promotes coordination of the second alkyne substrate, leading to the dimerization. The characteristic properties of the box ligand were supported by density functional theory (DFT) calculations of the intermediate. Axially chiral bibenzothiophenes were obtained in good yields with good enantioselectivities., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ruthenium-containing organometallic ionic liquids with the B(CN) 4 anion were developed that generate microporous amorphous coordination polymers upon UV irradiation. UV light irradiation of [Ru(C 5 H 5 )(C 6 H 5 R)][B(CN) 4 ] (R=butyl, ethyl, octyl) quantitatively generated a yellow powder of a coordination polymer with the formula [Ru(C 5 H 5 ){B(CN) 4 }] n . In this reaction, the arene ligand is eliminated by UV irradiation and coordination polymer is formed by coordination of the cyano groups of the anion to the Ru ion. The photogenerated solids exhibited nitrogen absorption properties due to their microporous structure. This paper proposes a method to fabricate functional coordination polymers by photoirradiation of liquids., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Square-planar rhodium(I) isocyanide complexes exhibit unique chemical reactivities such as the formation of Rh-Rh bonds and oxidative addition. This paper details the syntheses and properties of multifunctional ionic liquids containing Rh I isocyanide complexes [Rh(nBuNC) 4 ]X (X=Tf 2 N (=N(SO 2 CF 3 ) 2 - ), Nf 2 N (=N(SO 2 C 4 F 9 ) 2 - ), FSA (=N(SO 2 F) 2 - ), CF 3 BF 3 - ). Salts with Tf 2 N and Nf 2 N were liquids, whereas those with FSA and CF 3 BF 3 were solids at room temperature. The salts exhibited thermochromism in the liquid state, changing from orange at high temperatures to blue-purple at lower temperatures. This is based on the equilibrium between monomer, dimer, and other oligomers associated with Rh-Rh bond formation. The salts also exhibited fluorescence. Exposure of the Tf 2 N salt to methyl iodide vapor produced ionic liquid mixtures [Rh(nBuNC) 4 ] x [Rh(nBuNC) 4 IMe] (1-x) [Tf 2 N], concomitant with a color change from purple to red, orange, and yellow, extending the thermochromic color range. The reaction of the Tf 2 N salt and iodine produced mononuclear and polynuclear iodine adducts. Thus, these liquids exhibit thermochromism, fluorescence, vapochromism, chemical reactivities, and characteristic properties of ionic liquids., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Among the various thermochromic materials, liquid thermochromic materials are comparatively rare. To produce functional thermochromic liquids, we have designed ionic liquids based on cationic nickel complexes with ether side chains, [Ni(acac)(Me 2 NC 2 H 4 NR 1 R 2 )]Tf 2 N ([1]Tf 2 N: R 1 =C 3 H 6 OEt, R 2 =Me; [2]Tf 2 N: R 1 =C 3 H 6 OMe, R 2 =Me; [3]Tf 2 N: R 1 =R 2 =C 3 H 6 OMe), where acac=acetylacetonate and Tf 2 N=(F 3 CSO 2 ) 2 N - . The side chains (R 1 , R 2 ) can moderately coordinate to the metal center, enabling temperature-dependent coordination equilibria in the liquid state. [1]Tf 2 N is a liquid at room temperature. [2]Tf 2 N is obtained as a solid (T m =352.7 K) but remains liquid at room temperature after melting. [3]Tf 2 N is a solid with a high melting point (T m =422.3 K). These salts display thermochromism in the liquid state, appearing red at high temperatures and orange, light-blue, or bluish-green at lower temperatures, and exhibiting concomitant changes in their magnetic properties. This phenomenon is based on temperature-dependent equilibrium between a square-planar diamagnetic species and a paramagnetic species with intramolecular ether coordination., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Sandwich compounds often exhibit various phase transitions, including those to plastic phases. To elucidate the general features of the phase transitions in metallocenium salts, the thermal properties and crystal structures of [Fe(C 5 Me 5 ) 2 ]X ([1]X), [Co(C 5 Me 5 ) 2 ]X ([2]X), and [Fe(C 5 Me 4 H) 2 ]X ([3]X) have been investigated, where the counter anions (X) are Tf 2 N (=(CF 3 SO 2 ) 2 N - ), OTf (=CF 3 SO 3 - ), PF 6 , and BF 4 . The Tf 2 N salts commonly undergo phase transitions from an ordered phase at low temperatures to an anion-disordered phase, followed by a plastic phase and finally melt at high temperatures. All these salts exhibit a phase transition to a plastic phase, and the transition temperature generally decreases with decreasing cation size and increasing anion size. The crystal structures of these salts comprise an alternating arrangement of cations and anions. About half of these salts exhibit phase transitions at low temperatures, which are mostly correlated with the order-disorder of the anion., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Unprecedented anionic Fe(III) spin crossover (SCO) complexes involving a weak-field O,N,O-tridentate ligand were discovered. The SCO transition was evidenced by the temperature variations in magnetic susceptibility, Mössbauer spectrum, and coordination structure. The DFT calculations suggested that larger coefficients on the azo group in the HOMO-1 of a ligand might contribute to the enhancement of a ligand-field splitting energy. The present anionic SCO complex also exhibited the light- induced excited-spin-state trapping effect., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

To develop solvent-recognition films, Nafion membranes incorporating cationic nickel-chelate complexes, that is, [Ni(L(1))(L(2))](+) (HL(1) = acetylacetone, 2,2,6,6-tetramethyl-3,5-heptanedione; L(2) = N,N-diethylethylenediamine, N-butyl-N,N',N'-trimethylethylenediamine), were prepared. Immersion of the films in various solvents effected the color changes varying from red to pale blue green depending on the donor number of the solvents. The color change is based on an equilibrium shift between square-planar and solvent-coordinated octahedral geometries of the cations. The degree of the color change depended on the affinity of the incorporated complex to the solvent molecules. The films were robust and exhibited a reversible solvent response. The films exhibited thermochromism when a small amount of appropriate solvents were incorporated and changed from pale blue green at low temperatures to red at high temperatures., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

To introduce halogen-bond interactions between a cation and an anion, a novel Fe(III) complex from iodine-substituted ligands involving a paramagnetic nickel dithiolene anion was prepared and characterized. The compound exhibited the synergy between a spin-crossover transition and a spin-Peierls-like singlet formation. The halogen-bond interactions between the iodine and the sulfur atoms stabilized the paramagnetic state of π-spins and played a crucial role in the synergistic magnetic transition between d- and π-spins. In addition, the compound showed the light-induced excited spin state trapping effect., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Palladium and CO: Carbonylation of 1 with [Pd(tfa)2(±)-L1] (tfa = trifluoroacetate) affords the spirofuranone 2 with inversion of the stereochemistry at C17 in 96 % yield. C17-epi-1 also gave the same product 2 with retention of the stereochemistry at C17. Labelling studies show that (13)CO was incorporated into the C5' position of the furanone ring. The first asymmetric version of this new reaction was achieved., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Crystal structures and thermal properties of cobaltocenium salts with bis(perfluoroalkylsulfonyl)amide (C(n)F2(n+1)SO2)2N anions [n = 0 (1), 1 (1 a), 2 (1 b), 3 (1 c), and 4 (1 d)] and the 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonylamide anion (2) were investigated. In these solids, the cations are surrounded by four anions around their C5 axis, and stacking of these local structures forms two kinds of assembled structures. In the salts with even n (1, 1 b, and 1 d), the cation and anion are arranged alternately to form mixed-stack columns in the crystal. In contrast, in the salts with odd n (1 a and 1 c), the cations and anions independently form segregated-stack columns. An odd-even effect was also observed in the sum of the phase-change entropies from crystal to melt. All of the salts exhibited phase transitions in the solid state. The phase transitions to the lowest-temperature phase in 1, 1 a, and 2 are accompanied by order-disorder of the anions and symmetry lowering of the space group, which results in the formation of an ion pair. Solid-state (13)C NMR measurements on 1 a and 1 b revealed enhanced molecular motions of the cation in the higher-temperature phases., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Vapor- and gas-responsive ionic liquids (ILs) comprised of cationic metal-chelate complexes and bis(trifluoromethanesulfonyl)imide (Tf(2)N) have been prepared, namely, [Cu(acac)(BuMe(3)en)][Tf(2)N] (1 a), [Cu(Bu-acac)(BuMe(3)en)][Tf(2)N] (1 b), [Cu(C(12)-acac)(Me(4)en)][Tf(2)N] (1 c), [Cu(acac)(Me(4)en)][Tf(2)N] (1 d), and [Ni(acac)(BuMe(3)en)][Tf(2)N] (2 a) (acac = acetylacetonate, Bu-acac = 3-butyl-2,4-pentanedionate, C(12)-acac = 3-dodecyl-2,4-pentanedionate, BuMe(3)en = N-butyl-N,N',N'-tetramethylethylenediamine, and Me(4)en = N,N,N',N'-trimethylethylenediamine). These ILs exhibited reversible changes in color, thermal properties, and magnetic properties in response to organic vapors and gases. The Cu(II)-containing ILs are purple and turn blue-purple to green when exposed to organic vapors, such as acetonitrile, methanol, and DMSO, or ammonia gas. The color change is based on the coordination of the vapor molecules to the cation, and the resultant colors depend on the coordination strength (donor number, DN) of the vapor molecules. The vapor absorption caused changes in the melting points and viscosities, leading to alteration in the phase behaviors. The IL with a long alkyl chain (1 d) transitioned from a purple solid to a brown liquid at its melting point. The Ni(II)-containing IL (2 a) is a dark red diamagnetic liquid, which turned into a green paramagnetic liquid by absorbing vapors with high DN. Based on the equilibrium shift from four- to six-coordinated species, the liquid exhibited thermochromism and temperature-dependent magnetic susceptibility after absorbing methanol., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The piano-stool half-metallocenium cations [Fe(C(5)R(5))(CO)(2)L](+) (C(5)R(5) = C(5)H(5), C(5)Me(5), C(5)Me(4)Et; L = 1-pentene, nBuCN, MeCN, Me(2)S, NH(3), NMe(3), pyridine) provide ionic liquids (ILs) with the bis(trifluoromethanesulfonyl)imide (Tf(2)N) anion without introducing long alkyl chains. Their melting points are affected by molecular symmetry, and their thermal stabilities reflect the strength of the metal-ligand bonding. These are reactive liquids that show solventless ligand exchange reactions by gas absorption. The direction of the ligand-exchange reaction is correlated with the stabilities. Based on the variation of the melting points, these ILs undergo transformations between the liquid and solid phases associated with the reaction., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Simple cationic sandwich complexes that contained alkyl- or halogen substituents provided ionic liquids (ILs) with the bis(perfluoroalkanesulfonyl)imide anion. Ferrocenium- and cobaltocenium ILs [M(C(5)H(4)R(1))(C(5)H(4)R(2))][Tf(2)N] (M=Fe, Co) and arene-ferrocenium ILs [Fe(C(5)H(4)R(1))(C(6)H(5)R(2))][Tf(2)N] were prepared and their physical properties were investigated. A detailed comparison of their thermal properties revealed the effects of molecular symmetry and substituents on their melting points. Their viscosity increased on increasing the length of the substituent on the cation and the perfluoroalkyl chain length on the anion. Upon cooling, ILs with low viscosities exhibited crystallization, whereas those with higher viscosities tended to exhibit glass transitions. Most of these salts showed phase transitions in the solid state. A magnetic-switching phenomenon was observed for the paramagnetic ferrocenium IL, which was associated with a liquid/solid transformation, based on the magnetic anisotropy of the ferrocenium cation. (57)Fe Mössbauer spectroscopy was applied to [Fe(C(5)H(4)nBu)(2)][Tf(2)N] to investigate the vibrational behavior of the iron atom in the crystal and glassy states of the ferrocenium IL., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Bis(oxazoline)-palladium(II) catalyzed carbonylation of homopropargyl alcohols afforded acyclic methoxyacrylate 2 and 6-membered lactone 3a-k in good combined yield. In the case of propargyl alcohols, 5-membered lactones 3p, 3q, 16 were obtained in moderate yields. The one-pot synthesis of kawa lactones 3a, 3r, 3s and formal synthesis of dihydroxycystothiazole A and dihydroxycystothiazole C are presented. To elucidate the stereochemistry of (+)-annularin G and (-)-annularin H, the first asymmetric syntheses of these natural products were achieved.

Boxing clever: Direct conversion of a terminal alkyne group into a beta-methoxyacrylate is realized with the aid of the bis(oxazoline) ligand (box). Acetyl and ketal protecting groups, free hydroxy groups, and acid-sensitive glycosidic bonds are not affected under the reaction conditions. The one-pot synthesis of (+/-)-dihydrokawain from the homopropargyl alcohol is also achieved. tfa = trifluoroacetate.

The crystal architecture, magnetic properties, and thermodynamic properties of [n-butylferrocene][Ni(mnt)2] (1), [tert-butylferrocene][Ni(mnt)2] (2), [1,1'-diethylferrocene][Ni(mnt)2] (3), and [1,1'-diisopropylferrocene][Ni(mnt)2] (4) were investigated (mnt=maleonitriledithiolate). These complexes exhibit a unique supramolecular structure in which the ferrocenium cations constitute honeycomb-like assembled structures surrounding columns of the anions. For 1, the cations form a dimer through a very short intermolecular ferrocene-ferrocene distance of 3.28 A, which mediates an antiferromagnetic interaction with a singlet-triplet energy gap of 5 K. First-order phase transitions occur in 1-3 at 364, 361, and 350 K, respectively, accompanied by thermal hysteresis.