Role of the coordination center in photocurrent behavior of a tetrathiafulvalene and metal complex dyad.

Small organic molecule-based compounds are considered to be promising materials in photoelectronics and high-performance optoelectronic devices. However, photoelectron conversion research based on functional organic molecule and metal complex dyads is very scarce. We design and prepare a series of compounds containing a tetrathiafulvalene (TTF) moiety substituted with pyridylmethylamide groups of formulas [Ni(acac)2L]·2CH3OH (1), [Cu2I2L2]·THF·2CH3CN (2), and [MnCl2L2]n·2nCH3CH2OH (3) (L = 4,5-bis(3-pyridylmethylamide)-4',5'-bimethylthio-tetrathiafulvalene, acac = acetylacetone) to study the role of the coordination center in photocurrent behavior. Complex 1 is a mononuclear species, and complex 2 is a dimeric species. Complex 3 is a two-dimensional (2-D) coordination polymer. Spectroscopic and electrochemical properties of these complexes indicate that they are electrochemically active materials. The tetrathiafulvalene ligand L is a photoelectron donor in the presence of electron acceptor methylviologen. The effect of metal coordination centers on photocurrent response behavior is examined. The redox-active metal coordination centers should play an important role in improvement of the photocurrent response property. The different morphologies of the electrode films reflect the dimensions in molecular structures of the coordination compounds.

Effect of metal coordination on photocurrent response properties of a tetrathiafulvalene organogel film.

Organic low molecular weight gelators with a tetrathiafulvalene (TTF) unit have received considerable attention because the formed gels usually exhibit redox active response and conducting or semiconducting properties. However, to our knowledge, metal coordination systems have not been reported for TTF-derived gels up to date. We have designed and synthesized a series of TTF derivatives with a diamide-diamino moiety that can coordinate to specific metal ions with square coordination geometry. Gelation properties and morphologies of the films prepared by the gelators in different hydrophobic solvents are characterized. The TTF derivative with a dodecyl group shows effective gelation properties, and electrodes with the organogel films are prepared. The effect of the Ni(II) and Cu(II) coordination on the photocurrent response property of the electrodes is examined. The metal square coordination significantly increases the photocurrent response. This gel system is the first metal coordination related TTF-gel-based photoelectric material. The mechanism of the metal coordination-improved photocurrent response property is discussed based on the crystal structural analysis and theoretical calculations.

Metal centered oxidation or ligand centered oxidation of metal dithiolene? Spectral, electrochemical and structural studies on a nickel-4-pyridine-1,2-dithiolate system.

The complex Et(4)N[Ni(4-pedt)(2)] (1) (4-pedt = 1-(pyridine-4-yl) ethylene-1,2-dithiolate) was synthesized to investigate the behaviour of metal dithiolene compounds upon protonation and oxidation by absorption spectroscopy, electrochemistry and structural analyses and to further understand the electronic states of the dithiolene compounds. It is unexpected that the 915 nm NIR transition band is not shifted when H(+) is added, and it is only affected (blue-shifted) when the compound is oxidized. All the evidence of electronic spectra indicates that the NIR band is relevant to the central [Ni(edt)(2)] moiety (edt = ethylenedithiolate), not the behaviour of individual Ni ions or ligands. It is also not the band of intermolecular interaction of a dimer. The moderately intense band appearing at 655 nm upon protonation is assigned to the intramolecular charge-transfer band between the [Ni(edt)(2)] moiety and the pyridine. The redox potentials of the metal dithiolene are sensitive to the protonation of the pyridyl group. The structures of monocationic complex and the protonated compounds [Ni(4-Hpedt)(2)]·ClO(4)·H(2)O (2) and [Ni(4-Hpedt)(2)]·PhSO(3)·2DMF (3) were characterized by single crystal X-ray determination. The structural data demonstrate that the oxidation of the monoanionic dithiolene complex to neutral does not change the Ni-S bond distances obviously, which further indicates that the process is not only the metal centered oxidation.

A redox active proton transfer and hydrogen-bonding system of tetrathiafulvalene-dicarboxylic acid and pyridine bases.

Hydrogen bonds are important in supramolecular chemistry and responsible for proton transfer processes. This manuscript reports new hydrogen-bonding systems of redox-active acid-base assemblies consisting of dimethylthio-tetrathiafulvalene dicarboxylic acid (H(2)L) coupled with pyridine (py), 2,2'-bipyridine (2,2'-bpy), and 4,4'-bipyridine (4,4'-bpy). The (1)H NMR chemical shifts of the pyridines and the redox potential shifts of the tetrathiafulvalene moiety indicate that proton-transfer and strong hydrogen-bonding interactions exist between the acid and the bases in aprotic solvents. The results of cyclic voltammetry show a two-step square reaction with a redox and proton transfer coupled mechanism. The nature of the hydrogen bonds was characterized by X-ray single crystal analysis. In contrast to the mono-carboxyl-py system, in this ortho-substituted dicarboxyl-py system one proton of the H(2)L transfers completely from the carboxyl to the py group. The conjugated intramolecular and intermolecular hydrogen bonds are responsible for the proton transfer.

[An introduction of different positioning tests of benign paroxysmal positional vertigo and their clinical values].

OBJECTIVE: To explore the clinical value of different positioning tests for different benign paroxysmal positional vertigo (BPPV). METHOD: This research applies Dix-Hallpike test and Side-lying test for PC-BPPV, Roll test and WRW test for HC-BPPV, Dix-Hallpike test, Side-lying test and Rahko T maneuvers for SC-BPPV. Six hundred and thirteen cases, who were tested with different positioning tests in the sequence of firstly PC-BPPV then HC-BPPV and finally SC-BPPV, were randomly divided into 2 groups. The order of positioning tests for PC-BPPV and HC-BPPV in the two groups was reversed. RESULT: There's no significant difference between the detection rate of Dix-Hallpike test and Side-lying test for PC-BPPV (P > 0.05). Similarly, there's no difference in statistics between the detection rate of Roll test and WRW test for HC-BPPV (P > 0.05). However, the detection rate of Rahko T maneuver was higher than the other two tests for SC-BPPV and the differences were statistically significant (P < 0.05). The detection rates of different positioning tests for PC-BPPV and HC-BPPV between the two groups were not different in statistics (P > 0.05), which implies that the different order had no effect on the sensitivity of each positioning test. CONCLUSION: Dix-Hallpike test is recommended as the first choice for PC-BPPV for its more efficient stimulus to the posterior semicircular canal, and Side-lying test is recommended as a prior choice to the patients with suspected PC-BPPV but unable to receive Dix-Hallpike test because of its similar sensitivity and more convenient manipulation. The detection rate of Both Roll test and WRW test were higher than 90% and there's no significant difference between the two tests. In addition, Roll test is easier to perform and helpful for the therapy, so its considered as the preferred test for HC-BPPV with WRW test as the supplement test. Nevertheless, for SC-BPPV the sensitivity of Rahko T maneuver was higher than that of the other two tests, so it can be used to confirm the suspected SC-BPPV patients detected or missed diagnosed by the two other tests. To avoid misdiagnosis or missed diagnosis, the judgment of affected semicircular canal is determined not only by positioning test but also by the feature of nystagmus.

Malformation of the external ear and facial paralysis caused by megatemperature hydro-aluminum.

We present a case of right lateral auricle contracture malformation, auricular canal atresia, and complete facial paralysis (House-Brackmann grade VI) caused by a megatemperature hydro-aluminum injury at work. The diastrophic auricle and auricular canal atresia were reshaped. The complete facial paralysis was reanimated to House-Brackmann grade III after surgical hypoglossal-facial end-to-end anastomosis. These outcomes indicate that hypoglossal-facial end-to-end anastomosis is an effective surgical option for successful reanimation of complete facial paralysis.

The treatment for postirradiation otitis media with effusion: a study of three methods.

OBJECTIVE: To explore treatments for postirradiation otitis media with effusion (OME) in patients with nasopharyngeal carcinoma. STUDY DESIGN: This study is a prospective quasi-randomized clinical trial. METHODS: Ninety-six patients (135 ears) with OME after the first course of radiotherapy for nasopharyngeal carcinoma were divided into three groups: simple auripuncture plus aspiration, tympanic membrane fenestration with cauterization, and myringotomy plus grommet insertion. Cure rates and incidences of complications were compared. RESULTS: Two deaths occurred. The other 94 patients (132 ears) finished a 2-year follow-up. In group 1, four ears (8.9%) were cured after the first treatment and 17 ears overall (37.8%) were cured by the end of the follow-up. Twenty ears (44.4%) had persistent fluid, two ears (4.4%) developed chronic suppurative otitis media, and five ears (11.1%) developed dry eardrum perforation. In group 2, seven ears (15.6%) were cured after the first treatment and 21 ears overall (46.7%) were cured by the end of the follow-up. Fourteen ears (31.1%) had persistent fluid, three ears (6.7%) developed chronic suppurative otitis media, and seven ears (15.6%) developed dry eardrum perforation. In group 3, eight ears (17.8%) were cured after the first treatment and 23 ears overall (51.1%) were cured by the end of the follow-up. Seven ears (15.6%) had persistent fluid, five ears (11.1%) developed chronic suppurative otitis media, three ears (6.7%) developed eardrum perforation with effusion, and five ears (11.1%) developed dry eardrum perforation. CONCLUSION: The methods each have advantages and disadvantages. We believe that a step by step approach should be used when choosing the treatment method for postirradiation OME. That is, first apply auripuncture plus aspiration, and then the other methods if this approach is inadequate. Enhanced local care after grommet insertion can effectively reduce the incidence of complications.