Diazine based ligand supported CoII3 and CoII4 coordination complexes: role of the anions

We report the synthesis and characterisation of a family of three CoII4, two CoII3 complexes from an symmetrical diazine ligand, H2hyda = N,N−bis(3−methoxy salicylidene) hydrazine). The metallic skeletons of all complexes describe a nearly linear arrangement of CoII centers. The present results highlight the profound influence of the anions on the structural outcome of a complex. Furthermore, the distortion imposed by the twisted nature of the diazine based ligand depends on the use of associated anions which results in triple helical CoII4 and double helical CoII3 entities. The CoII ions in complexes 1−3 are antiferromagnetically coupled leading to diamagnetic ground state. In contrast, complexes 4 and 5 exhibit a magnetic ground state, but exhibit different behaviour at low temperatures due to differences in crystal packing and hence intermolecular interactions

Diazine based ligand supported CoII3 and CoII4 coordination complexes: role of the anions

We report the synthesis and characterisation of a family of three CoII4, two CoII3 complexes from an symmetrical diazine ligand, H2hyda = N,N−bis(3−methoxy salicylidene) hydrazine). The metallic skeletons of all complexes describe a nearly linear arrangement of CoII centers. The present results highlight the profound influence of the anions on the structural outcome of a complex. Furthermore, the distortion imposed by the twisted nature of the diazine based ligand depends on the use of associated anions which results in triple helical CoII4 and double helical CoII3 entities. The CoII ions in complexes 1−3 are antiferromagnetically coupled leading to diamagnetic ground state. In contrast, complexes 4 and 5 exhibit a magnetic ground state, but exhibit different behaviour at low temperatures due to differences in crystal packing and hence intermolecular interactions

Inhomogeneous polarization evolution resolves a fundamental issue in non-Hermitian transverse optical beam shifts

Depending on the system parameters, the transverse optical beam shift in reflection can be non-Hermitian with real eigenvalues and non-orthogonal eigenstates. We reveal that such an unusual resemblance with typical PT (parity-time)-symmetric systems originates from the beam's momentum domain polarization evolution. Specifically, for partial reflection, the momentum domain inhomogeneous polarization evolution of the beam is at the heart of all the peculiarities in the corresponding eigenspectrum of the transverse shift operator. These findings put forward the notion of novel non-Hermitian spin-orbit photonics and enable common polarization optical elements to act as PT-symmetric non-Hermitian systems

Self-assembly of a ``cationic-cage'' via the formation of Ag-carbene bonds followed by imine condensation

A new strategy for the synthesis of a ``cationic-cage'' (CC-Ag) has been developed via metal-carbene (M-CNHC) bond formation followed by imine bond condensation. Reaction of a trigonal trisimidazolium salt H3L(PF6)(3) functionalized with three flexible N-phenyl-aldehyde pendants with silver oxide yielded a trinuclear tricationic organometallic cage (OC-Ag). Subsequent treatment of the organometallic cage (OC-Ag) with 1,4-diaminobutane links the two tris-NHC ligands via imine bond condensation, which thus generates a 3D `cationiccage' (CC-Ag). Furthermore, post-synthetic replacement of the Ag(I) with Au(I) leading to the formation of CC-Au was achieved via trans-metalation, with the retention of the molecular architecture

Co^II₄, Co^II₇, and a Series of Co^II₂Ln^III (Ln^III = Nd^III, Sm^III, Gd^III, Tb^III, Dy^III) Coordination Clusters: Search for Single Molecule Magnets

We report herein the syntheses and investigation of the magnetic properties of a Co^II₄ compound, a series of trinuclear Co^II₂Ln^III (Ln^III = Nd^III, Sm^III, Gd^III, Tb^III, Dy^III) complexes, and a Co^II₇ complex. The homometallic Co^II₄ core was obtained from the reaction of Ln­(NO₃)₃<b>·</b><i>x</i>H₂O/­Co­(NO₃)₂<b>·</b>6H₂O/­H₂vab/Et₃N in a 0.5:0.5:1:2 ratio in methanol. Variation in synthetic conditions was necessary to get the desired Co^II–Ln^III complexes. The Co^II–Ln^III assembly was synthesized from Ln­(NO₃)₃<b>·</b><i>x</i>H₂O/­Co­(OAc)₂<b>·</b>4H₂O/­H₂vab/NaOMe in a 0.4:0.5:1:1 ratio in methanol. The isostructural Co^II₂Ln^III complexes have a core structure with the general formula [Co₂Ln­(Hvab)₄­(NO₃)]­(NO₃)₂<b>­·</b>MeOH<b>·</b>H₂O, (where H₂vab = 2-[(2-hydroxymethyl-phenylimino)-methyl]-6-methoxy-phenol) with simultaneous crystallization of Co^II₇ complex in each reaction. The magnetic investigation of these complexes reveals that both homometallic complexes and four Co^II–Ln^III complexes (except Co^II–Nd^III) display behavior characteristic of single molecule magnets

Syntheses, crystal structures, spectral studies, and DFT calculations of two new square planar Ni(II) complexes derived from pyridoxal-based Schiff base ligands

<div><p>Two new complexes based on a Schiff base derived from pyridoxal N,N-dimethylethylenediamine (HL¹) and N,N-diethylethylenediamine (HL²), [Ni(L¹)SCN] (<b>1</b>) and [Ni(L²)SCN] (<b>2</b>), have been synthesized and structurally characterized by single-crystal X-ray diffraction along with other physical techniques, including elemental analyses, IR spectra, cyclic voltammetry, UV–vis, and luminescence studies. X-ray studies suggest that in both the complexes nickel lies in a slightly distorted square planar environment occupied by the tridentate ONN ligand and an isothiocyanate moiety. Density functional theory computations have been carried out to characterize the complexes.</p></div

Doubly chloro bridged dimeric copper(II) complex: magneto-structural correlation and anticancer activity

We have synthesized and structurally characterized a new doubly chloro bridged dimeric copper(II) complex, [Cu2(μ-Cl)2(HL)2Cl2] (1) based on a Schiff base ligand, 5-[(pyridin-2-ylmethylene)-amino]-pentan-1-ol). Single crystal X-ray diffraction shows the presence of dinuclear copper(II) centres in a square pyramidal geometry linked by obtuse double chloro bridge. The magnetic study illustrated that weak antiferromagnetic interactions (J = −0.47 cm−1) prevail in complex 1 which is well supported by magneto-structural correlation. This compound adds to the library of doubly chloro bridged copper(II) complexes in the regime of spin state cross over. DFT calculations have been conducted within a brokensymmetry(BS) framework to investigate the exchange interaction further which depicts that the approximate spin projection technique yields the best corroboration of the experimental J value. Spin density plots show the presence of an ∼0.52e charge residing on the copper atom along with a substantial charge on bridging and peripheral chlorine atoms. The potential of complex 1 to act as an anticancer agent is thoroughly examined on a series of liver cancer cell lines and screening shows the HepG2 cell line exhibits maximum cytotoxicity by phosphatidyl serine exposure in the outer cell membrane associated with ROS generation and mitochondrial depolarization with increasing time in the in vitro model system

Heterometallic Cu^II–Dy^III Clusters of Different Nuclearities with Slow Magnetic Relaxation

The synthesis, structures, and magnetic properties of two heterometallic Cu^II–Dy^III clusters are reported. The first structural motif displays a pentanuclear Cu^II₄Dy^III core, while the second one reveals a nonanuclear Cu^II₆Dy^III₃ core. We employed <i>o</i>-vanillin-based Schiff base ligands combining <i>o</i>-vanillin with 3-amino-1-propanol, H₂vap, (2-[(3-hydroxy-propylimino)-methyl]-6-methoxy-phenol), and 2-aminoethanol, H₂vae, (2-[(3-hydroxy-ethylimino)-methyl]-6-methoxy-phenol). The differing nuclearities of the two clusters stem from the choice of imino alcohol arm in the Schiff bases, H₂vap and H₂vae. This work is aimed at broadening the diversity of Cu^II–Dy^III clusters and to perceive the consequence of changing the length of the alcohol arm on the nuclearity of the cluster, providing valuable insight into promising future synthetic directions. The underlying topological entity of the pentanuclear Cu₄Dy cluster is reported for the first time. The investigation of magnetic behaviors of <b>1</b> and <b>2</b> below 2 K reveals slow magnetic relaxation with a significant influence coming from the variation of the alcohol arm affecting the nature of magnetic interactions