Studies of New Iridium Catalysts Supported on Modified Silicalite-1—Their Structure and Hydrogenating Properties

This paper investigates the catalytic properties of the iridium catalysts supported on modified silicalite-1. Post-synthesis modification of silicalite-1, with solutions of ammonium compounds (NH₄F and NH₄OH), appeared to be an efficient method to generate the acidic sites in starting support. The modification of support led not only to changes in its acidity but also its porosity—formation of additional micro- and mesopores. The novel materials were used as supports for iridium. The iridium catalysts (1 wt.% Ir) were characterized by N₂ adsorption/desorption measurements, temperature-programmed reduction with hydrogen (TPR-H₂), H₂ chemisorption, transmission electron microscopy (TEM), temperature-programmed desorption of ammonia (TPD-NH₃), X-ray photoelectron spectroscopy (XPS) and tested in the hydrogenation of toluene reaction. The catalytic activity of iridium supported on silicalite-1 treated with NH₄OH (higher porosity of support, better dispersion of active phase) was much higher than that of Ir supported on unmodified and modified with NH₄F silicalite-1.     

The New Reliable pH Sensor Based on Hydrous Iridium Dioxide and Its Composites

The new reliable sensor for pH determination was designed with the use of hydrous iridium dioxide and its composites. Three different hIrO₂-based materials were prepared and applied as solid-contact layers in pH-selective electrodes with polymeric membrane. The material choice included standalone hydrous iridium oxide; composite material of hydrous iridium oxide, carbon nanotubes, and triple composite material composed of hydrous iridium oxide; carbon nanotubes; and poly(3-octylthiophene-2,5-diyl). The paper depicts that the addition of functional material to standalone metal oxide is beneficial for the performance of solid-state ion-selective electrodes and presents the universal approach to designing this type of sensors. Each component contributed differently to the sensors’ performance—the addition of carbon nanotubes increased the electrical capacitance of sensor (up to 400 µF) while the addition of conducting polymer allowed it to increase the contact angle of material changing its wetting properties and enhancing the stability of potentiometric response. Hydrous iridium oxide contacted electrodes exhibit linear response in wide linear range of pH (2–11) and stable potentiometric response (the lowest potential drift of 0.036 mV/h is attributed to the electrode with triple composite material).     

Applied IrO2 Buffer Layer as a Great Promoter on Ti-Doping V2O5 Electrode to Enhance Electrochromic Device Properties

Electrochromic devices (ECDs) are a promising material for smart windows that are capable of transmittance variation. However, ECDs are still too expensive to achieve a wide market reach. Reducing fabrication cost remains a challenge. In this study, we inserted an IrO₂ buffer layer on Ti-doped V₂O₅ (Ti:V₂O₅) as a counter electrode using various Ar/O₂ gas flow ratios (1/2, 1/2.5, 1/3 and 1/3.5) in the fabrication process. The buffered-ECD resulted in a larger cyclic voltammetry (CV) area and the best surface average roughness (Ra = 3.91 nm) to promote electrochromic performance. It was fabricated using the low-cost, fast deposition process of vacuum cathodic arc plasma (CAP). This study investigates the influence of the IrO₂ buffer/Ti:V₂O₅ electrode on ECD electrochemical and optical properties, in terms of color efficiency (CE) and cycle durability. The buffered ECD (glass/ITO/WO₃/liquid electrolyte/IrO₂ buffer/Ti:V₂O₅/ITO/glass) demonstrated excellent optical transmittance modulation; ∆T = 57% (from T_bleaching (67%) to T_coloring (10%)) at 633 nm, which was higher than without the buffer (ITO/WO₃/liquid electrolyte/Ti:V₂O₅/ITO) (∆T = 36%). In addition, by means of an IrO₂ buffer, the ECD exhibited high coloration efficiency of 96.1 cm²/mC and good durability, which decayed by only 2% after 1000 cycles.     

An improved bidentate complex of iridium as a catalyst for hydrogen isotope exchange

Iridium(I) complexes 1 , containing bidentate phosphines, and 3 , with arsine ligands, are generated in situ. These species mediate hydrogen isotope exchange in a variety of aromatic substrates including benzyl ketones. Although the catalytic activities of complexes 1 and 3 are generally unexceptional, a logical step leads to the use of [ethylene‐1,2‐bis(diphenylarsine)](cyclooctadiene)iridium(I) tetrafluoroborate ( 5 ), which is an efficient catalyst for both aryl and benzyl ketones, and mediates exchange to a substantial extent in other substrates also. Copyright © 2005 John Wiley & Sons, Ltd.     

铱-芴主链型共聚物的合成与光致发光性能

合成以2-(4-溴苯基)苯并咪唑为环金属配体、乙酰丙酮为辅助配体的铱配合物客体单元,并通过Suzuki缩聚方法将客体引入聚芴(PFO)主体中,合成了主链型共聚物。通过元素分析、红外光谱、¹H-NMR等分析手段对产物进行了结构表征,通过紫外吸收光谱、稳态和瞬态荧光光谱对铱配合物、共聚物的光物理性能进行了研究。结果表明:铱配合物最大发射峰位于505 nm和535 nm,为绿光发射;共聚物同时呈现蓝光主体PFO和绿光客体铱配合物的发射,且随铱配合物含量提高,绿光强度明显增强,显示了主客体能量的部分转移,通过调节共聚物中铱配合物单元的含量,使共聚物的发光颜色从蓝光向绿光转移;当铱配合物的物质的量分数为2%时,蓝色荧光强度大于绿色磷光,共聚物色坐标刚好处于蓝绿交界处,当铱配合物物质的量分数大于2%时,共聚物呈现绿色发光;与铱配合物的荧光量子效率(2.7%)相比,共聚物的荧光量子效率均有显著增加;共聚物热稳定性良好。     

An interstitial hyperthermia system at 27 MHz

An interstitial hyperthermia system using thin, flexible wires operating at a frequency of 27 MHz has been evaluated for possible use in combination with (iridium) brachy-therapy applications employing flexible nylon afterloading catheters. This method of interstitial heating is argued to be a variation of local-current-field heating, however with the direct galvanic contact between electrode and tissue replaced by a capacitive coupling between wire and tissue. Through a special design of the wire the length of the heated area along the catheter can be chosen freely. Standard non-prepared implantation catheters can be used, so that no change from the established implantation techniques is required. Possible advantages of these 27 MHz wires over coaxial dipole antennas at higher frequencies are simplicity and low cost of the heating system, free choice of effective heating length for each wire and uniformity of heating along this effective heating length up to the tip of the wire. Flexibility of the wires is maintained, enabling application in curved (even U-shaped) catheters, e.g. for head and neck implantations. Impedance matching of the wires to the generator, necessary for an optimal transfer of power, appears possible by means of a variable air coil. Care should be taken to avoid stray capacitances of the connecting cables with respect to ground or among the different cables used. Measurements in muscle-equivalent split phantoms with infrared thermography have been performed with both single and multiple wires. The resulting SAR distributions confirm the working principle of these low-frequency wires (resistive heating) and illustrate the difference with radiative antennas at higher frequencies. The system is being applied both in experimental animal studies and in a clinical pilot study.     

巨块型宫颈癌术前组织间插植放疗的疗效观察

目的探讨巨块型宫颈癌术前组织间插植放疗的治疗效果。方法收集Ⅰb～Ⅱb期巨块型宫颈癌58例,其中术前放疗组（A组）30例,行术前Ir^192后装腔内组织问插植放疗1～2次,总剂量10～20Gy,每周1次,放疗结束后1～2周行宫颈癌根治术;直接手术组（B组）28例,直接行宫颈癌根治术。观察A组放疗前后宫颈肿瘤退缩情况,比较A、B组术中、术后情况,判断巨块型宫颈癌术前组织间插植放疗的疗效。结果A组放疗后肿瘤直径较放疗前明显缩小（P〈0．05）,临床有效率高达90％,近期随访无明显不良反应。A组的手术时间、术中出血量较B组明显减少（P〈0．05）。2组在术后胃肠道功能恢复时间、膀胱功能恢复时间及术后高危病理因素发生率方面差别无统计学意义（P〉0．05）。结论术前适当剂量的腔内组织间插植放疗可使宫颈肿瘤缩小,利于手术,不影响术后恢复,无高危病理因素出现。     

INTRALUMINAL BRACHYTHERAPY IN BILE DUCT CARCINOMAS

Background: Cholangiocarcinoma of the biliary tract is a rare tumour which has been treated with surgery, radiotherapy, chemotherapy, bypass procedures and stenting. Surgery remains the only curative treatment for these tumours, but a large proportion are unresectable. Intraluminal brachytherapy has been reported as an effective treatment for localized cholangiocarcinoma of the biliary tract. The purpose of our study was to analyse the survival of patients with biliary tract carcinoma treated with iridium-192 brachytherapy. Methods: A retrospective review of patients treated at Peter MacCallum was undertaken. From 1989 to 1994, 16 patients underwent brachytherapy via a transhepatic approach for cholangiocarcinoma. There were 12 male and four female patients. The median age was 65 (range 40–83). All patients had cholangiocarcinoma. Prior treatment included complete resection in three, partial resection in one, bypass procedures in eight, endoscopic stents in five and external biliary drainage in 15 of the 16 patients. One patient had received external beam irradiation. Results: The median survival was 23 months and 61% survived 1 year. The most common acute complication was cholangitis seen in four patients and the most common late complications were duodenal ulcer seen in two patients and cholangitis seen in two patients. Conclusions: We conclude that iridium-192 brachytherapy is a safe effective treatment for biliary tract carcinoma but a comparison between surgery and stenting would be of value. However, the cost of brachytherapy is not cheap and its value in this regard should be carefully analysed.     

Application of 1‐butyl‐3‐methylimidazolium hexafluorophosphate to Ir(I)‐catalyzed hydrogen isotope exchange labelling of substrates poorly soluble in dichloromethane

Substrate solubility remains a major limitation in Ir(I)‐catalyzed isotopic hydrogen exchange labelling. In the search for an alternative to the solvent dichloromethane, which is critical to the success of the reaction, we examined a series of ionic liquids for their suitability. Commercially available 1‐butyl‐3‐methylimidazolium hexafluorophosphate (abbreviated to [BMI][PF₆]) was found to support efficient deuterium and tritium exchange labelling of N‐(4‐methoxyphenyl)‐N‐methyl benzamide 1 under standard conditions. The solvent dissolves both polar hydroxyl and carboxylic acid substituted acetanilides, providing isotopomers in unprecedentedly high deuterium incorporation as compared to dichloromethane. We report the application of [BMI][PF₆] and its potential for extending the scope of Ir(I)‐catalyzed H/T exchange to more polar compounds. Copyright © 2003 John Wiley & Sons, Ltd.     

The neighboring group effect of fluorine in the tritium labeling of organic substrates with [Cp*(PMe3)IrMe(CH2Cl2)]+[BArf]−, a cationic iridium(III) complex

The cationic Ir(III) complex, [Cp*(PMe₃)IrMe(CH₂Cl₂)][BAr_f] ( 1 , Cp*=η⁵‐C₅Me₅, BAr_f=MeB(C₆F₅)₃), has been shown to be a useful reagent in the tritium and deuterium labeling of organic substrates. During a recent reaction of 1 with a fluorinated molecule, we observed an unusually high incorporation of tritium ortho to the aromatic fluorines. To probe whether this was an isolated incident or a more general phenomenon, we have investigated the application of 1 towards the tritiation of simple fluorinated organic substrates. Our results indicate that aromatic fluorine indeed does exhibit a neighboring group effect in terms of directing ortho H/T exchange. The directing influence appears to be at least as strong as the hydroxyl moiety reported in previous works. Copyright © 2006 John Wiley & Sons, Ltd.