Cobalt(III) α-Dimethylglyoximates [Co(DH)2(Py)2]2SiF6 · 10H2O and [Co(DH)2(Thio)2]2SiF6 · 2H2O · C2H5OH: Synthesis and Structure

[Co(DH)₂(Py)₂]₂SiF₆ · 10H₂O and [Co(DH)₂(Thio)₂]₂SiF₆ · 2H₂O · C₂H₅OH complexes are synthesized and characterized by X-ray diffraction analysis. Two radicals of -glyoxime linked by hydrogen O–H···O bonds lie in the equatorial plane of the octahedral Co(III) complexes. Intramolecular (– and N–H···O) and intermolecular (O–H···F, O–H···O, N–H···F, N–H···O, N–H···S) interactions are discovered in the crystal. The influence of nonvalence interactions on the structures is discussed.     

Delocalization in platinum-alkynyl systems: a metal-bridged organic mixed-valence compound

A complex featuring two triarylamine redox centers bridged by Pt, trans-bis(triethylphosphine)-bis{4-[bis(4-methoxyphenyl)amino]phenylethynyl} platinum(II), has been synthesized as a model system for pi-conjugated Pt-containing polymers. Analysis of the intervalence charge-transfer band displayed by its mixed-valence monocation affords a quantitative assessment of electronic delocalization through the Pt bridge; this is found to be only slightly smaller than that determined for a benzene-bridged analogue. These results are supported by density functional theory calculations, which show that the active orbitals involved in the electron-transfer process in both cases have similar delocalization through the bridging unit.     

Two ZnII mononuclear coordination compounds with pyridinedicarboxylate and auxiliary N‐(pyridin‐4‐ylmethylidene)hydroxylamine ligands

Two new mononuclear coordination compounds, bis{4‐[(hydroxyimino)methyl]pyridinium} diaquabis(pyridine‐2,5‐dicarboxylato‐κ²N,O²)zincate(II), (C₆H₇N₂O)₂[Zn(C₇H₃NO₄)₂(H₂O)₂], (1), and (pyridine‐2,6‐dicarboxylato‐κ³O²,N,O⁶)bis[N‐(pyridin‐4‐ylmethylidene‐κN)hydroxylamine]zinc(II), [Zn(C₇H₃NO₄)(C₆H₆N₂O)₂], (2), have been synthesized and characterized by single‐crystal X‐ray diffractometry. The centrosymmetric Zn^II cation in (1) is octahedrally coordinated by two chelating pyridine‐2,5‐dicarboxylate ligands and by two water molecules in a distorted octahedral geometry. In (2), the Zn^II cation is coordinated by a tridentate pyridine‐2,6‐dicarboxylate dianion and by two N‐(pyridin‐4‐ylmethylidene)hydroxylamine molecules in a distorted C₂‐symmetric trigonal bipyramidal coordination geometry.     

From 1D to 2D Cd(II) and Zn(II) Coordination Networks by Replacing Monocarboxylate with Dicarboxylates in Partnership with Azine Ligands: Synthesis,Crystal Structures,Inclusion, and Emission Properties

Eight mixed-ligand coordination networks, [Cd(2-aba)(NO₃)(4-bphz)_3/2]_n·n(dmf) (1), [Cd(2-aba)₂(4-bphz)]_n·0.75n(dmf) (2), [Cd(seb)(4-bphz)]_n·n(H₂O) (3), [Cd(seb)(4-bpmhz)]_n·n(H₂O) (4), [Cd(hpa)(3-bphz)]_n (5), [Zn(1,3-bdc)(3-bpmhz)]_n·n(MeOH) (6), [Cd(1,3-bdc)(3-bpmhz)]_n ·0.5n(H₂O)·0.5n(EtOH) (7), and [Cd(NO₃)₂(3-bphz)(bpe)]_n·n(3-bphz) (8) were obtained by interplay of cadmium nitrate tetrahydrate or zinc nitrate hexahydrate with 2-aminobenzenecarboxylic acid (H(2-aba)), three dicarboxylic acids, sebacic (decanedioic acid, H₂seb), homophthalic (2-(carboxymethyl)benzoic acid, H₂hpa), isophthalic (1,3-benzenedicarboxylic acid, H₂(1,3-bdc)) acids, bis(4-pyridyl)ethane (bpe) and with four azine ligands, 1,2-bis(pyridin-4-ylmethylene)hydrazine (4-bphz), 1,2-bis(1-(pyridin-4-yl)ethylidene) hydrazine (4-bpmhz), 1,2-bis(pyridin-3-ylmethylene)hydrazine (3-bphz), and 1,2-bis(1-(pyridin-3-yl) ethylidene)hydrazine (3-bpmhz). Compounds 1 and 2 are 1D coordination polymers, while compounds 3–8 are 2D coordination polymers. All compounds were characterized by spectroscopic and X-ray diffraction methods of analysis. The solvent uptakes and stabilities to the guest evacuation were studied and compared for 1D and 2D coordination networks. The de-solvated forms revealed a significant increase of emission in comparison with the as-synthesized crystals.     

Design of efficient ambipolar host materials for organic blue electrophosphorescence: theoretical characterization of hosts based on carbazole derivatives

Density functional theory calculations were carried out to investigate the electronic structures of representative ambipolar hosts for blue electroluminescence, based on two carbazole end groups and meta-terphenyl (mTP)-like bridges. The bridge molecular segments include mTP, 2,6-bisphenylpyridine, 3,5-bisphenylpyridine, and 2,6-bisphenylpyrimidine. While the ionization potentials and electron affinities of these molecules are mainly determined by their hole- and electron-transport subunits, respectively, each subunit impacts the electronic properties of the other upon their binding, mainly in an inductive way. Importantly, the lowest triplet state of the hosts is determined to be confined into the mTP-like bridges since these are the subunits with lowest individual triplet energy. Extension of the phenyl-based π-conjugated system via meta linkages is found to be effective in modulating the electron affinity value while maintaining a high triplet energy.     

Electronic structure of the pentacene–gold interface: A density-functional theory study

The structural and electronic properties of a pentacene monolayer adsorbed on the Au(1 1 1) surface have been studied with a density-functional theory (DFT) approach. A thermally stable adsorption geometry of the pentacene monolayer on the gold surface is found, from which the adsorption energy per pentacene molecule can be evaluated. Our results illustrate how the electron charge distribution initially present over the clean gold surface is pushed back upon adsorption of the pentacene monolayer; this push-back (pillow effect) leads to a significant work-function decrease for the modified gold surface. The electronic couplings between the highest occupied molecular orbital of pentacene and the Au(1 1 1) surface and between adjacent pentacene molecules within the monolayer, were extracted from the calculated band structures; the pentacene–gold surface electronic coupling is found to be about five times smaller than the electronic coupling between pentacene molecules.     

Coordination Polymers of Zn and Cd Based on Two Isomeric Azine Ligands: Synthesis,Crystal Structures,and Luminescence Properties

Russian Journal of Coordination Chemistry - Metal-organic 1D coordination polymers of Zn(II) and Cd(II), [{Zn(3-Bphz)(H2O)4}(3-Bphz)(NO3)2]n (I), [Zn(3-Bphz)I2]n (II), [Cd(3-Bphz)I2]n (III),...     

Synthesis and Crystal Structure of [Co(DmgH)2(Thio)2]2F[PF6]. The Effect of Fluorine-Containing Co(III) Dioximates on the Physiological Processes of the Microalga Porphyridium cruentum

Russian Journal of Coordination Chemistry - New fluorine-containing cobalt(III) dioximates [Co(DmgH)2(Thio)2]2F[PF6] (I) and [Co(DmgH)2(Sam)2]2[TiF6] · 4H2O (II) (DmgH = dimethylglyoxime...     

Theoretical description of the geometric and electronic structures of organic-organic interfaces in organic solar cells: a brief review

We review some of the computational methodologies used in our research group to develop a better understanding of the geometric and electronic structures of organic-organic interfaces present in the active layer of organic solar cells. We focus in particular on the exciton-dissociation and charge-transfer processes at the pentacene-fullerene interface. We also discuss the local morphology at this interface on the basis of molecular dynamics simulations.