Indolenine meso-Substituted Dibenzotetraaza[14]annulene and Its Coordination Chemistry toward the Transition Metal Ions MnIII, FeIII, CoII, NiII, CuII, and PdII

Highly interface-dependent spin transport in an Fe-Mn(DBTAA)-Fe single molecule spintronic device

Understanding the spinterface between magnetic electrodes and molecules, and realizing the controllable spin filtering effect, are crucial for the development of high-performance molecular devices, but both still face big challenges. Here, based on first-principles calculations of an Fe-Mn(DBTAA)-Fe single molecule spintronic device, we unveil that spin filtering efficiency is highly dependent on interface configurations, which can modulate and even reverse the spin polarization of tunnelling electrons. For Fe-Mn(DBTAA)-Fe, a varied spin filtering from -93% to +75% is observed. The underlying mechanism could be attributed to the distinct magnetic and electronic couplings between the Fe electrode and the Mn(DBTAA) molecule in different interface configurations. This work not only highlights the importance of a magnetic electrode-molecule interface, but also implies that through suitable interface design, the performance, e.g., of the spin filtering channel of single molecule spintronic devices, can be flexibly tuned.

Synthesis, Characterization, Solution Behavior and Theoretical Studies of Pd(II) Allyl Complexes with 2-Phenyl-3H-indoles as Ligands

The study of the reactivity of three 2-phenyl-3H-indole ligands of general formulae C8H3N-2-(C6H4-4-R1)-3-NOMe-5-R2 (1) [with R1 = H, R2 = OMe (a); R1 = R2 = H (b) or R1 = Cl, R2 = H (c)] with [Pd(η3-1-R3C3H4)(μ-Cl)]2 (R3 = H or Ph) has allowed us to isolate two sets of new Pd(II)-allyl complexes of general formulae [Pd(η3-1-R3C3H4)(1)Cl] {R3 = H (2) or Ph (3)}. Compounds 2a–2c and 3a–3c were characterized by elemental analyses, mass spectrometry and IR spectroscopy. The crystal structures of 2a, 3a and 3b were also determined by X-ray diffraction. 1H-NMR studies reveal the coexistence of two (for 2a–2c) or three (for 3a–3c) isomeric forms in CD2Cl2 solutions at 182 K. Additional studies on the catalytic activity of mixtures containing [Pd(η3-C3H5)(μ-Cl)]2 and the parent ligand (1a–1c) in the allylic alkylation of (E)-3-phenyl-2-propenyl (cinnamyl) acetate with sodium diethyl 2-methylmalonate as well as the stoichiometric reaction between compounds 3a and 3c with the nucleophile reveal that in both cases the formation of the linear trans- derivative is strongly preferred over the branched product. Computational studies at a DFT level on compound 3a allowed us to compare the relative stability of their isomeric forms present in solution and to explain the regioselectivity of the catalytic and stoichiometric processes.

Structural and Electronic Effects Due to Fluorine Atoms on Dibenzotetraaza-Annulenes Complexes

The preparation and characterization of Ni(II) (1F) and Cu(II) (2F) complexes of the ligand 15,16,17,18,19,20,21,22-octafluoro-dibenzotetraaza[14]annulene (L_F) are here reported. These compounds have been characterized by elemental analysis, mass and UV-vis spectroscopies, single-crystal X-ray diffraction, and computational studies. The effects due to the presence of fluorine atoms have been highlighted by comparison with the analogous complexes of the ligand L_H (Ni: 1H; Cu: 2H), which bears hydrogen atoms at the benzenoid rings instead of fluorine. 1F and 2F are isostructural, with the metal ions bound to the four nitrogen atoms in a square-planar geometry and where the planar molecules are arranged in a herringbone motif in the crystal lattice. Remarkable differences in the intermolecular interactions between 1F and 2F and the corresponding H-complexes are shown by Hirshfeld surface calculations. Moreover, the effects of fluorination on the electronic structures have been investigated by density functional theory (DFT) and time-dependent DFT calculations. The compounds with L_F and L_H ligands present corresponding molecular orbitals (MOs) with similar shapes. Furthermore, while the presence of F-atoms lowers the energy of the MOs in comparison with those of the L_H complexes, it does not remarkably affect the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) and HOMO-LUMO + 1 gaps, in agreement with the UV-vis results.

Proton Control of the Lanthanoid Single-Ion Magnet Behavior of a Double-Decker Complex with an Indolenine-Substituted Annulene Ligand

Two double-decker complexes with annulene ligands functionalized with indolenine groups were synthesized and characterized. The position of the proton acting as a counterion on one of the four indolenine nitrogen atoms was determined by using DFT calculations. Deprotonation and protonation of the complex induced by adding a base and an acid, respectively, were monitored by using NMR spectroscopy. Moreover, a correlation among the degree of protonation of the complex, the opening of the hysteresis, and the slow relaxation time is discussed.

Antimicrobial activity of aroylhydrazone-based oxido vanadium(v) complexes: in vitro and in silico studies

A series of oxido vanadium(v) complexes have been synthesized and evaluated from the point of experimental and theoretical antimicrobial activity.

Spin transport of dibenzotetraaza[14]annulene complexes with first row transition metals

We investigate the spin transport properties of DBTAA complexes involving first row transition metals. The results show that Fe– and Co–DBTAA exhibit perfect spin filtering effect, which is dependent on the connected position of anchoring group.