Cold and Liquid Crystal Properties of Square-Planar Copper(II) Versus Nickel(II)- Iminophenolate/Naphthalen-2-Olate Schiff Base Complexes.

Reaction of the phenolate or naphthalen-2-olate based Schiff base ligands, (E)-1-((2-ethylphenylimino)methyl)phenol (HL1) or (E)-1-((2-ethylphenylimino)methyl)naphthalen-2-ol (HL2) with nickel(II) and copper(II) acetate provides the complexes bis[(E)-1-((2-ethylphenylimino)methyl)phenolato-ĸN,O]Ni/Cu(II), [Ni(L1)] (1) and [Cu(L1)] (2), or bis[(E)-1-((2-ethylphenylimino)methyl)naphthalen-2-olato-ĸN,O]Ni/Cu(II), [Ni(L2)] (3) and [Cu(L2)] (4), respectively. Single crystal X-ray structure determinations for 1, 3 and 4 reveal N,O-metal coordination of two chelating Schiff base ligands in a square-planar geometry. Powder X-ray diffractograms confirm the phase purity of the bulk microcrystalline samples.

Schiff Base in Ketoamine Form and Rh(η-cod)-Schiff Base Complex with Z' = 2 Structure from Pairwise C-H···Metallochelate-π Contacts.

Condensation of 2-hydroxybenzaldehyde (salicylaldehyde) or 2-hydroxy-1-naphthaldehyde with 2-ethylaniline yields the Schiff base compound of ()-2-(((2-ethylphenyl)imino)methyl)phenol (HL) or ()-1-(((2-ethylphenyl)imino)methyl)naphthalen-2-ol (HL), which in turn react with the dinuclear complex of [Rh(η-cod)(µ-OCCH)] (cod = cycloocta-1,5-diene) to afford the mononuclear (η-cod){()-2-(((2-ethylphenyl)imino)methyl)phenolato-κN,O}rhodium(I), [Rh(η-cod)(L)] () or (η-cod){()-1-(((2-ethylphenyl)imino)methyl)naphthalen-2-olato-κN,O}rhodium(I), [Rh(η-cod)(L)] () (L or L = deprotonated Schiff base ligand). The X-ray structure determination revealed that the HL exists in the solid state not as the usual (imine)N···H-O(phenol) form (enolamine form) but as the zwitterionic (imine)N-H···O(phenol) form (ketoamine form). H NMR spectra for HL in different solvents demonstrated the existence of keto-enol tautomerism (i.

Pseudotetrahedral Zn(II)-( or )-dihalogen-salicylaldiminato complexes with Λ- or Δ-chirality induction at-metal.

Reactions of enantiopure ( or )--1-(phenyl)ethyl-2,4-X,X-salicylaldimine (-H or -H; X, X = dihalogen) with Zn(II)-nitrate give bis[( or )--1-(phenyl)ethyl-2,4-X,X-salicylaldiminato-κN,O]-zinc(II), (Δ-Zn or Λ-Zn) with Δ/Λ-chirality induction at-metal in the -symmetric molecules. EI-mass spectra show parent ion peaks. X-ray structures indicate that two phenolate-oxygen and two imine-nitrogen atoms from two molecules of the Schiff bases coordinate to the Zn(II) ion in a pseudotetrahedral geometry.

Synthesis and Characterization of Bis[( or )--1-(X-CH)ethyl-2-oxo-1-naphthaldiminato-κ,]-Λ/Δ-cobalt(II) (X = H, -CHO, -Br) with Symmetry- and Distance-Dependent Vibrational Circular Dichroism Enhancement and Sign Inversion.

The enantiopure Schiff bases ( or )--1-(X-CH)ethyl-2-hydroxy-1-naphthaldimine {X = H [( or )-HL1], -CHO [( or )-HL2], and -Br [(- or )-HL3]} react with cobalt(II) acetate to give bis[( or )--1-(X-CH)ethyl-2-oxo-1-naphthaldiminato-κ,]-Λ/Δ-cobalt(II) {X = H [Λ/Δ-Co-( or )-L1], -CHO [Λ/Δ-Co-( or )-L2], and -Br [Λ/Δ-Co-( or )-L3]} (-), respectively. Induced Λ and Δ chirality originates at the metal center of the -symmetric molecule in pseudotetrahedral geometry. Differential scanning calorimetry analyses explored the thermal stability of the complexes, which undergo reversible phase transformation from crystalline solid to isotropic liquid phase for and but irreversible phase transformation for .

Pseudotetrahedral copper(II)-complexes with enantiopure ( or )-2-(((aryl)ethylimino)ethyl)phenolate Schiff base ligands.

Condensation of 2-hydroxy-benzophenone (HL') with (R or S)-(Ar)ethylamine yields the enantiopure Schiff bases (S or R)-2-((E)-1-(1-(Ar)ethylimino)ethyl)phenol {Ar = C6H5 (S- or R-HL1), p-CH3OC6H4 (S- or R-HL2)}. These Schiff bases react with copper(ii) acetate under reflux to give green microcrystals of bis[(R or S)-2-((E)-1-(1-(Ar)ethylimino)ethyl)phenolato-κ2N,O]-Λ/Δ-copper(ii), {Ar = C6H5 (Λ/Δ-Cu-R- or S-L1), p-CH3OC6H4 (Λ/Δ-Cu-R- or S-L2)} with induction of Λ/Δ-chirality at-metal. The presence of Schiff base ligands in the paramagnetic green microcrystals is confirmed by decomplexation reaction with NaCN via reduction of Cu(ii) to Cu(i) in DMSO-d6 solution.

Solid-state to solution helicity inversion of pseudotetrahedral chiral copper(ii) complexes with 2,4-dihalo-salicylaldiminate ligands.

The enantiopure Schiff bases (R or S)-N-1-(phenyl)ethyl-2,4-X1,X2-salicylaldimine (X1, X2 = Cl, Br, I) coordinate to copper(ii) and provide pseudotetrahedral bis[(S or R)-N-1-(phenyl)ethyl-(2,4-X1,X2-salicylaldiminato-κ2N,O)]-Δ/Λ-Cu(ii) (Λ/Δ-Cu-R or Δ/Λ-Cu-S). An induced Λ and Δ-chirality at-metal centre has been launched along the C2-axis of the molecule. Steric constraints brought by halogen substituents on the coordinating salicylal ring provide diastereoselectively Λ-Cu-R or Δ-Cu-S as major and Δ-Cu-R or Λ-Cu-S as minor diastereomers at solid-state, as evidenced by X-ray crystal structures and PXRD analyses.

Transport properties of RuV-based half-Heusler semiconductors for thermoelectric applications: a computational study.

A systematic study of electronic structure, mechanical and transport properties of RuV-based half-Heusler alloys (RuVZ, Z = As, P, Sb) have been presented using ab initio density functional and Boltzmann transport theory. The electronic structures are obtained using generalized gradient approximation with Perdew-Burke-Ernzerhof functional. All the compounds are crystallized in face centered cubic phase with space group #216.

Transition metal substituted FeP: potential candidate for MRAM application.

We propose transition metal substituted FeP as a new promising material for spin-transfer torque magnetic random-access memory (STT-MRAM) application. Using first-principles calculations based on density functional theory and Monte Carlo simulations, we demonstrate that this material can be used as a ferromagnetic electrode in the magnetic tunnel junction (MTJ) of STT-MRAM due to its moderate perpendicular magnetic anisotropy, high ferromagnetic transition temperature, and large tunnel magnetoresistance. This work is expected to provide a basis for the development of a new class of FeP-based electrode materials for STT-MRAM devices.

Broad-Range Spectral Analysis for Chiral Metal Coordination Compounds: (Chiro)optical Superspectrum of Cobalt(II) Complexes.

Chiroptical broad-range spectral analysis extending from UV to mid-IR was employed to study a family of Co(II) N-(1-(aryl)ethyl)salicylaldiminato Schiff base complexes with pseudotetrahedral geometry associated with chirality-at-metal of the Δ/Λ type. While common chiral organic compounds have well-separated absorption and circular dichroism spectra (CD) in the UV/vis and IR regions, chiral Co(II) complexes feature an almost unique continuum of absorption and CD bands, which cover in sequence the UV, visible, near-IR (NIR), and IR regions of the electromagnetic spectrum. They can be collected in a single (chiro)optical superspectrum ranging from the UV (230 nm, 5.

Synthesis, X-ray, and Spectroscopic Study of Dissymmetric Tetrahedral Zinc(II) Complexes from Chiral Schiff Base Naphthaldiminate Ligands with Apparent Exception to the ECD Exciton Chirality.

Bidentate enantiopure Schiff base ligands, (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminate (R- or S-N^O), diastereoselectively provide Λ- or Δ-chiral-at-metal four-coordinated Zn(R- or S-N^O)2 {Ar = C6H5; Zn-1R or Zn-1S and p-C6H4OMe; Zn-2R or Zn-2S}. Two R- or S-N^O-chelate ligands coordinate to the zinc(II) in a tetrahedral mode and induce Λ- or Δ-configuration at the zinc metal center. In the solid state, the R- or S-ligand diastereoselectively gives Λ- or Δ-Zn configuration, respectively, and forms enantiopure crystals.

Chirality at metal and helical ligand folding in optical isomers of chiral bis(naphthaldiminato)nickel(II) complexes.

Enantiopure bis[{(R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminato-κ(2)N,O}]nickel(ii) complexes {Ar = C6H5 ( or ), p-OMeC6H4 ( or ), and p-BrC6H4 ( or )} are synthesized from the reactions between (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldimine and nickel(ii) acetate. Circular-dichroism spectra and their density-functional theoretical simulation reveal the expected mirror image relationship between the enantiomeric pairs / and / in solution. CD spectra are dominated by the metal-centered Λ- or Δ-chirality of non-planar four-coordinated nickel, this latter being in turn dictated by the ligand chirality.

Induced chirality-at-metal and diastereoselectivity at Δ/Λ-configured distorted square-planar copper complexes by enantiopure Schiff base ligands: combined circular dichroism, DFT and X-ray structural studies.

Bidentate enantiopure Schiff base ligands, (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminato-κ(2)N,O, diastereoselectively yield Δ/Λ-chiral four-coordinated, non-planar Cu(N^O)2 complexes [Ar = C6H5 R/S-L1, m-C6H4OMe R-L2, p-C6H4OMe R/S-L3, and p-C6H4Br R/S-L4]. Two N,O-chelate ligands coordinate to the copper(II) atom in distorted square-planar mode, and induce metal-centered Δ/Λ-chirality at the copper atom in the C2-symmetric complexes. In the solid state, the R-L1 (or R-L4) ligand chirality diastereoselectively induces a Λ-Cu configuration in Λ-Cu-R-L1 (or Λ-Cu-R-L4), the S-L1 ligand a Δ-Cu configuration in Δ-Cu-S-L1, forming enantiopure crystals upon crystallization.

Polymorphs, enantiomorphs, chirality and helicity in [Rh{N,O}(eta4-cod)] complexes with {N,O}=salicylaldiminato Schiff base or aminocarboxylato ligands.

The dimeric complex acetato(eta4-cycloocta-1,5-diene)rhodium(I), [Rh(O2CMe)(eta4-cod)]2 (cod = cycloocta-1,5-diene) reacts with N,O-chelating Schiff-base ligands or with N-phenylglycine to afford the diminato- or aminocarboxylato(4-cycloocta-1,5-diene)rhodium(I) complexes [{Rh(eta4-cod)}2(salen)] (1), [{Rh(eta4-cod)}2(salophen)] (2), [Rh((S)-N-phenylglycinato)(eta4-cod)] (3S), [Rh(rac-N-phenylglycinato)(eta4-cod)] (3rac), [Rh((R)-N-(4-methoxphenyl)ethyl-2-oxo-1-naphthaldiminato)(eta4-cod)] (4) and [Rh(N-(o-tolyl)-2-oxo-1-naphthaldiminato)(eta4-cod)] (5) [salen2- = N,N-ethylene-bis(salicylaldiminato), salophen2- = N,N-(1,2-phenylene)-bis(salicylaldiminato)]. The complexes are characterized by IR-, UV/Vis-, 1H/13C-NMR- and mass-spectroscopy. Complexes 1, 2, 4 and 5 contain six-membered metallaaromatic Rh-(N-CCC-O)-chelate rings which accept C-H.