Heteroleptic Pt(II)-dithiolene-based Colorimetric Chemosensors: Selectivity Control for Hg(II) Ion Sensing.

Hg2+ ions can accumulate in the natural environment and in organisms, where they cause damage to the central nervous system. Therefore, the detection of Hg2+ ions is essential for monitoring environmental contamination and human health. Herein, we demonstrate a simple method for tuning chemosensor signal ratios that significantly increased chemosensor selectivity for Hg2+ detection. Selectivity tuning was accomplished for chemosensors of the type (diphosphine)Pt(dmit), bearing the two different terminal groups 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis[bis(pentafluorophenyl)phosphino]ethane) (dfppe) due to the modulation of specific intermolecular interactions between the dmit ligand and Hg2+ ion. The structure exhibited a large pseudo-Stokes shift, which was advantageous for the internal reference signal and for eliminating potential artifacts. Straightforward chain-end manipulation enabled the tuning of chemosensor properties without additional chemical alterations. Based on these findings, we propose a new platform for improving the selectivity and sensitivity of colorimetric cation sensors. The results of this study will facilitate the designing of organic materials whose certain properties can be enhanced through precise control of the materials' chemical hybridization by simple functional end-group manipulation.

Electrochemical fabrication of (TMTSF)2X (X = PF6, BF4, CIO4) nanowires.

TMTSF-based (TMTSF = tetramethyltetraselenafulvalene = C10H12Se4) charge-transfer salt nanowires were fabricated using the galvanostatic deposition technique that was assisted by an anodic aluminum oxide (AAO) template. By applying a low current density of 1-2 microA/cm2 for more than one month, nanowire arrays with diameters of approximately 150 nm and lengths of approximately 6 microm were obtained. The length of nanowires can be controlled by the duration of the constant current application. Energy-dispersive X-ray spectroscopic (EDX) analysis confirmed that selenium is one of the main components of the nanowires. The micro-Raman (v3C == C) and FT-IR spectra (v3PF6-, v3BF4-, v3CIO4-) indicated that the nanowire arrays had the (TMTSF)2X (X = PF6, BF4, CIO4) phase. The TEM images and the selected area electron diffraction (SAED) patterns indicate that the nanowires were not single crystals, but the current-voltage characteristic that was measured with the four-terminal method showed the conductivity of the (TMTSF)2PF6 single crystals (sigmaRT = 1.6 S/cm) at room temperature.

Redox multifunctionality in a series of Pt(II) dithiolene complexes of a tetrathiafulvalene-based diphosphine ligand.

The redox-active and chelating diphosphine, 3,4-dimethyl-3',4'-bis(diphenylphosphino)-tetrathiafulvalene, denoted as P2, is engaged in a series of platinum complexes, [(P2)Pt(dithiolene)], with different dithiolate ligands, such as 1,2-benzenedithiolate (bdt), 1,3-dithiole-2-thione-4,5-dithiolate (dmit), and 5,6-dihydro-1,4-dithiin-2,3-dithiolate (dddt). The complexes are structurally characterized by X-ray diffraction, together with a model compound derived from bis(diphenylphosphino)ethane, namely, [(dppe)Pt(dddt)]. Four successive reversible electron-transfer processes are found for the [(P2)Pt(dddt)] complex, associated with the two covalently linked but electronically uncoupled electrophores, that is, the TTF core and the platinum dithiolene moiety. The assignments of the different redox processes to either one or the other electrophore is made thanks to the electrochemical properties of the model compound [(dppe)Pt(dddt)] lacking the TTF redox core, and with the help of theoretical calculations (DFT) to understand the nature and energy of the frontier orbitals of the [(P2)Pt(dithiolene)] complexes in their different oxidation states. The first oxidation of the highly electron-rich [(P2)Pt(dddt)] complex can be unambiguously assigned to the redox process affecting the Pt(dddt) moiety rather than the TTF core, a rare example in the coordination chemistry of tetrathiafulvalenes acting as ligands.

Heteroleptic binuclear palladium(II) and platinum(II) complexes containing 1,2-bis(diphenylphosphino)acetylene and 1,2-benzenedithiolates: syntheses, crystal structures, electrochemistry and photoluminescence properties.

A series of heteroleptic binuclear Pd(ii) and Pt(ii) complexes, [M(bdts)](2)(micro-dppa)(2) (M = Pd () and Pt (); dppa = 1,2-bis(diphenylphosphino)acetylene = Ph(2)PC[triple bond, length as m-dash]CPPh(2); bdts = 1,2-benzenedithiolate (bdt: a), 3,4-toluenedithiolate (tdt: b) and 1,4-dichloro-2,3-benzenedithiolate (Cl(2)bdt: c), containing two square-planar MP(2)S(2) cores were prepared using (MCl(2))(2)(micro-dppa)(2) (M = Pd () and Pt ()) and the corresponding 1,2-benzenedithiols, and characterized by spectroscopic methods including FT-IR, Raman, UV-vis, MALDI-TOF-MS, (31)P{(1)H} and/or (195)Pt{(1)H} NMR spectroscopy. X-Ray crystal structure analyses for complexes and revealed that C1C2C4C3 is twisted in two ways with a torsion angle of 21.6-30.7 degrees for 3a, 4a, and 4b and about 42 degrees for 3c and 4c, and that their crystals are racemic mixtures. Due to the more electronegative chloride atoms in the ligand, complexes and show higher nu(M-S) vibrational frequencies in their Raman spectra, smaller spin-spin coupling constants (J(Pt-P)) in their (195)Pt{(31)P} NMR spectra and higher anodic potentials (E(pa)) in their cyclic voltammograms than complexes 3a, 3b, 4a and 4b. Moreover, only complex containing the chlorinated ligand and Pt(ii) ion exhibits luminescence (lambda(ob) = 610 nm and lambda(ex) = 440 nm) in the solid state at 298 K. This emissive transition can be assigned as the d-pi(dithiolate) metal-to-ligand charge transfer (MLCT) and the feasibility of this spin-forbidden transition is ascribed to the effective spin-orbit coupling of ligand c containing heavy chloride atoms and the large spin-orbit coupling in Pt(ii).

Redox bifunctionality in a Pt(ii) dithiolene complex of a tetrathiafulvalene diphosphine ligand.

The Pt(ii) dithiolene complex of a tetrathiafulvalene diphosphine ligand exhibits two reversible redox systems at close potentials, localized on the weakly interacting TTF (tetrathiafulvalene) and Pt(dmit) moieties.

Charge-transfer interaction in single-walled carbon nanotubes with tetrathiafulvalene and their applications.

We observed that single-walled carbon nanotube (SWNT) was aligned in the presence of TTF This alignment was induced by a specific interaction between SWNT and tetrathiafulvalene (TTF), a well-known organic donor. The interaction between the two molecules can be explained by a charge-transfer, which was confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The binding energies of S (2P1/2) and S (2P3/2) were shifted from 163.0 eV and 164.1 eV to 163.9 eV and 165.1 eV, respectively. In Raman spectra of the SWNT-TTF, three peaks of SWNT in radial breathing mode were also upshifted by 4-5 cm(-1). The charge-transfer interaction also contributed in modifying the electronic structure of SWNT and furthermore enhanced the electrical conductivity of SWNT. A more conductive thin film was fabricated using the SWNT-TTF Four-probe measurement revealed that the surface resistance of the SWNT-TTF film was reduced to 4.359 omega at room temperature while that of SWNT film was 6.894 omega. These results enable carbon nanotubes to be utilized more for practically for industrial applications in fabricating peculiar nano-sized building blocks.

New 1:3 type nickel-bis(dithiolene) salt (FcCHCHPymCH3)[Ni(dmit)2]3 (dmit: 2-thioxo-1,3-dithiole-4,5-dithiolate): its electrocrystallization, crystal structure, electrical properties, and electronic band structure analysis.

Black single crystals of Ni(dmit)(2) complex (dmit: 2-thioxo-1,3-dithiole-4,5-dithiolate) with trans-4-[2-(1-ferrocenyl)vinyl]-1-methylpyridinium chromophore as a countercation, (FcCHCHPymCH(3))[Ni(dmit)(2)](3), were prepared by the electrocrystallization technique. In the triclinic structure of the complex (P, a = 11.430(5) A, b = 13.349(2) A, c = 19.355(6) A, alpha = 75.15(2) degrees , beta = 79.19(3) degrees , gamma = 82.12(2) degrees , Z = 2), Ni(dmit)(2) anion layers are separated by the cations with a relatively rare 1:3 cation-to-anion ratio. Detailed crystal and electronic structure analysis revealed that the anions are stacked in the layers to form alternating dimers and monomers rather than trimers. The measured electrical conductivity indicates a semiconducting property of the compound with an estimated energy gap of 0.06 eV. The calculated LUMO bands are very narrow, and the semiconducting behavior is more likely due to the electron localization mainly on the dimers, consistent with the observed longer Ni-S bond distances in the dimers.