Copper(II) solvatochromic complexes [Cu(acac)(N^N)(ligand)]BPh4 with various axial ligands. Correlation between coordination geometries and d–d transition energies (acac=acetylacetonato, N^N=1,10-phenanthoroline, 2,2′-bipyridyl)

Organometallic Ionic Liquids Containing Sandwich Complexes: Molecular Design, Physical Properties, and Chemical Reactivities

Ionic liquids (ILs) are salts with low melting points and are useful as electrolytes and solvents. We have developed ILs containing cationic metal complexes, which form a family of functional liquids that exhibit unique physical properties and chemical reactivities originating from metal complexes. Our study explores the liquid chemistry in the field of coordination chemistry, where solid-state chemistry is currently the main focus. This review describes the molecular design, physical properties, and reactivities of organometallic ILs containing sandwich or half-sandwich complexes. This paper mainly covers stimuli-responsive ILs, whose magnetic properties, solvent polarities, colors, or structures change by the application of external fields, such as light, heat, and magnetic fields, or by reaction with coordinating molecules.

Sonochemical synthesis of a trinuclear Cu(ii) complex with open coordination sites for the differentiable optical detection of volatile amines

A discrete trinuclear Cu(ii) complex, namely, [Cu₃(pzdc)₂(dpyam)₂(H₂O)₄] (1) (H₃pzdc = pyrazole-3,5-dicarboxylic acid, dpyam = 2,2′-dipyridylamine) was simply synthesized by the sonochemical process and structurally characterized. The single-crystal X-ray diffraction analysis revealed that three adjacent Cu(ii) centers are linked via two bridging pzdc ligands to form a trinuclear Cu(ii) unit. Each trinuclear Cu(ii) unit contains open coordination sites with two trigonal bipyramidal Cu(ii) centers and one elongated octahedral geometry. Moreover, the open coordination site of 1 was occupied by a small molecule, leading to the guest-induced structural transformation with chromism that was verified by FT-IR, UV-vis diffuse reflectance spectra, elemental analysis, PXRD, and SEM techniques. Compound 1 exhibits color change along with structural transformation in methanol media and after the dehydration process. Also, 1 shows different color responses after exposure to different amine vapors. In addition, compound 1 was conveniently deposited onto a filter paper by a sonochemical method used as a portable test strip for the discriminative qualitative detection of amines.

A trinuclear Cu(ii) complex with open coordination sites for the differentiable optical detection of volatile amines.

Cobalt(ii) liquid metal salts for high current density electrodeposition of cobalt

Cobalt-containing liquid metal salts were synthesized and characterized. Reversible thermochromism was observed and the electrodeposition of cobalt layers with different morphologies was investigated.

Cobalt(ii) containing liquid metal salts for electrodeposition of cobalt and electrochemical nanoparticle formation

Cobalt(ii) containing ionic liquids were used as electrolytes for the electrodeposition of cobalt thin films and cobalt nanoparticles.

Coordination abilities of polycyano anions in the solid state: coordination geometries and d–d transition energies of mixed-ligand solvatochromic copper(ii) complexes with B(CN)4, C(CN)3, and N(CN)2 anions

Crystal structures and electronic spectra of the adducts of polycyano anions with cationic solvatochromic Cu(ii) complexes were investigated.

Unique trapping of paddlewheel copper(ii) carboxylate by ligand-bound {Cu2} fragments for [Cu6] assembly

Trapping of paddlewheel {Cu₂(carboxylate)₄} by ligand-bound {Cu₂(μ-H₂L)}³⁺ units resulted in dumbbell-shaped [Cu₆] complexes modulating the tetracarboxylate bridged Cu⋯Cu separations.

Ionic liquids from cationic palladium(II) chelate complexes: preparation, thermal properties, and crystal structures

Metal-containing ionic liquids comprising cationic Pd(II) chelate complexes and the bis(trifluoromethanesulfonyl)amide (Tf2N) anion were prepared: [Pd(acac)(Me4en)]Tf2N (1), [Pd(acac)(BuMe3en)]Tf2N (2), and [Pd(C8-acac)(Me4en)]Tf2N (3) (acac = 2,4-pentanedionate, C8-acac = 3-octyl-2,4-pentanedionate, Me4en = N,N,N',N'-tetramethylethylenediamine, BuMe3en = N-butyl-N,N',N'-trimethylethylenediamine). These salts were yellow solids with melting points of 85.2 °C, 71.1 °C, and 62.3 °C, respectively. During cooling from the liquid state, complex 1 exhibited crystallization, whereas 2 and 3 exhibited only glass transitions at approximately -40 °C. X-ray structure determination revealed that the cations in 1 and 3 form dimer-like arrangements and that there were no direct contacts between the charged moieties of the cations and anions in the solid state.

1D hacksaw chain bipyridine–sulfonate Schiff base-dicopper(ii) as a host for variable solvent guests

The current study related to five solvatomorphs containing the 1D hacksaw chain of bipyridine–sulfonate Schiff base-dicopper(ii) as a host provides the first example of a polymeric copper(ii) system with five interconvertible solvatomorphic forms.

Naked-eye detection and thermochromic properties of Cu(ii)-3,3′-thiodipropionate complexes with benzimidazole

Two novel coordination complexes were synthesized and characterized. Solvent sensing and their thermochromic properties were studied. Complex 1 can be used as a naked-eye sensor for methanol. Complex 2 may be used as a DMF sensor. The thermochromic behaviors of complexes 1 and 2 were investigated.

Colorimetric solvent indicators based on Nafion membranes incorporating nickel(II)-chelate complexes

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.