Search

A series of crown ether substituted vinylogous tetrathiafulvalenes (TTFVs) is synthesized via oxidative coupling of bisdithiafulvenes. The rigidification of the crown ether ring after complexation has appeared as a decrease of the apparent electron-transfer kinetics and has little effect on the thermodynamics as the crown ether is far from the redox center.

The synthesis and the chelating ability of the tetrathiafulvenyl-acerylacetonate anion are investigated in regard to metal M(super H) cation (M(super h) = Ni, Zn) giving rise to the first metal complexes involving such rodox-active ligands. Electrochemical investigation, associated with the structural analysis of these complexes, evidence intramolecular interactions between two tetrathiafulvalene (TTF) cores of a complex.

Research describes the synthesis of porphyrazinediols, their conversion into solitaire complexes, and chemical oxidation of the polydentate noninnocent macrocycles. Results demonstrate that porphyrazinediols are a novel class of redox-active ligands whose diol chelating group is directly attached at the beta-positions of the macrocycle.

The chemoselective reduction of vinylmercury chlorides with tributylstannane and a radical inhibitor produced several vinylmercury hydrides. The vinylmercury hydrides are composed of a mercury unit with a bonding angle of 180 degrees. The HgH bond of the methylmercury hydride has the lowest harmonic frequency among the vinylmercury hydrides. Diethenylmercury has the largest Hg-C bond shortening compared to the monosubstituted compounds.

A single component molecular conductor is isolated from electrocrystallization of the monoanionic gold bis(dithiolene) complex based on the N-ethyl-1,3-thiazoline-2-thione-4,5-dithiolate (Et-thiazdt) ligand. First-principles density functional theory (DFT) calculations have shown that the ground state is antiferromagnetic with a very small band gap.

Tetrathiafulvalenes (TTF) and bis(cyclopentadienyl) molybdenum dithiolene complexes, Cp2Mo(dithiolene) complexes, are known separately to act as good electron donor molecules. For an investigation of the interaction between both electrophores, two types of complexes were synthesized and characterized. The first type has one Cp2Mo fragment coordinated to one TTF dithiolate ligand, and the second type has one TTF bis(dithiolate) bridging two Cp2Mo fragments. Comparisons of the electrochemical properties of these complexes with those of models of each separate electrophore provide evidence for their mutual influence. All of these complexes act as very good electron donors with a first oxidation potential 430 mV lower than the tetrakis(methylthio)TTF. DFT calculations suggest that the HOMO of the neutral complex and the SOMO of the cation are delocalized across the whole TTF dithiolate ligand. The X-ray crystal structure analyses of the neutral and the mono-oxidized Cp2Mo(dithiolene)(bismethylthio)TTF complexes are consistent with the delocalized assignment of the highest occupied frontier molecular orbitals. UV-vis-NIR spectroelectrochemical investigations confirm this electronic delocalization within the TTF dithiolate ligand. [ABSTRACT FROM AUTHOR]

A complete series of dianionic, monoanionic, and neutral dithiolene complexes formulated as [Ni(Et-thiazdt)2]n, with n = -2, -1, 0, and Et-thiazdt: N-ethyl-1,3-thiazoline-2-thione-4,5-dithiolate, is prepared using an optimized procedure described earlier for the N-Me derivatives. Electrochemical and spectroscopic properties confirm the electron-rich character of the Et-thiazdt dithiolate ligand. The three complexes are structurally characterized by single-crystal X-ray diffraction. The paramagnetic anionic complex [Ni(Et-thiazdt)2]-1, as Ph4P+ salt, exhibits side-by-side lateral interactions leading to a Heisenberg spin chain behavior. The solid-state structure of the neutral, diamagnetic [Ni(Et-thiazdt)2]0 complex shows a face-to-face organization with a large longitudinal shift, at variance with the structure of its radical and neutral gold dithiolene analogue described earlier and formulated as [Au(Et-thiazdt)2]. Comparison of the two structures, and those of the other few structurally characterized pairs of Ni/Au dithiolene complexes, demonstrates the important role played by overlap interactions between gold dithiolene radical species. Despite its closed-shell character, the neutral nickel complex [Ni(Et-thiazdt)2]0 exhibits a semiconducting behavior with a room-temperature conductivity σRT ≈ 0.014 S cm-1. [ABSTRACT FROM AUTHOR]

On the basis of the reported radical neutral complex [Au(Et-thiazdt)2] (Et-thiazdt = N-ethyl-1,3-thiazoline -2-thione-4,5-dithiolate), a series of single-component conductors derived from [Au(Et-thiazdt)2], also noted as [AuS4(-S)2], has been developed, by replacing the outer sulfur atoms of the thiazoline-2-thione rings by oxygen atoms and/or by replacing the coordinating sulfur atoms by selenium atoms toward the corresponding diselenolene complexes. Comparison of the X-ray crystal structures and transport properties of the four isostructural complexes, noted as [AuS4(-S)2], [AuS4(-O)2], [AuSe4(-S)2], and [AuSe4(-O)2], shows that the oxygen substitution on the outer thiazoline ring actually decreases the conductivity by a factor of 100, despite a contracted unit cell volume reflecting a positive chemical pressure effect. On the other hand, the S/Se substitution increases the conductivity by a factor of 100, and the pressure needed to transform these semiconductors into the metallic state is shifted from 13 kbar in [AuS4(-S)2] to only ≈6 kbar in [AuSe4(-S)2]. Analysis of unit cell evolutions and ab initio band structure calculations demonstrates the strongly anisotropic nature of this chemical pressure effect and provides an explanation for the observed changes in conductivity. The greater sensitivity of these neutral single-component conductors to external pressure, as compared with "classical" radical salts, is also highlighted. [ABSTRACT FROM AUTHOR]

New thermosensitive liposomes with a phase transition at 42 °C, containing nickel-bis(dithiolene) complexes as efficient and stable photothermal agents, have been formulated and characterized. These liposomes are highly stable and keep their contents at 37 °C for more than 30 days. On the contrary, the mild hyperthermia generated by the nickel-bis(dithiolene) complex under 940 nm NIR irradiation allows for the fine controlled release of the liposome contents, making such liposomes highly suitable for on-demand drug delivery in the human body under NIR laser irradiation. These liposomes can also be directly used, as shown here, as nanoagents for photothermal therapy. In fact, strong cell death can be generated under laser irradiation in the presence of these photothermally active nanocargos containing less than 10% w/w of metal complex. We also demonstrate, for the first time, that nickel-bis(dithiolene) complexes are good photoacoustic agents, generating easily detectable ultrasonic signals directly proportional to the concentration of complexes and the used laser power.

Molecular metals have been essentially obtained with tetrathiafulvalene (TTF)-based precursors, either with multicomponent ionic materials or, in a few instances, with single-component systems. In that respect, gold bis(dithiolene) complexes, in their neutral radical state, provide a prototype platform toward such single-component conductors. Herein we report the first single-component molecular metal under ambient pressure derived from such Au complexes without any TTF backbone. This complex exhibits a conductivity of 750 S·cm -1 at 300 K up to 3800 S·cm -1 at 4 K. First-principles electronic structure calculations show that the striking stability of the metallic state finds its origin in sizable internal electron transfer from the SOMO-1 to the SOMO of the complex as well as in substantial interstack and interlayer interactions.

The complete characterization of novel electropolymerizable organometallic complexes is presented. These are newly synthesized cyclometalated complexes of general formula (PPy)M(O ∧ N)(n) (H(PPy) = 2-phenylpyridine, M = Pd(II) or Pt(II), H(O ∧ N)(n) = Schiff base). Polymeric thin films have been obtained from these complexes by electropolymerization of the triphenylamino group grafted onto the H(O ∧ N)(n) ancillary ligand. The redox behavior and the photoconductivity of both of the monomers (PPy)M(O ∧ N)(n) and the electropolymerized species have been investigated. The polymeric films of (PPy)M(O ∧ N)(n) have shown a very significant enhancement of photoconductivity when compared to their monomeric amorphous counterparts. The high stability of the obtained films strongly suggests that electropolymerization of cyclometalated complexes represents a viable deposition technique of quality thin films with improved photoconduction properties, hence opening the door to a new class of materials with suitable properties for optoelectronic applications.

A novel redox active macrocycle including two vinylogous tetrathiafulvalenes (TTFVs) and two molybdenum tetracarbonyl fragments has been synthezised thanks to the coordination-driven self-assembly of complementary angular derivatives. Pyridyl vinylogous TTFVs have been deliberately elaborated for that purpose, using the oxidative coupling of pyridyldithiafulvenes (DTF). Cyclic voltammetry, IR and NMR spectroscopies, and single-crystal X-ray crystallography of the target molecules have been investigated.