Nai-Mu Hsu

Protein Tyrosine Phosphatases and their Inhibitors

Protein tyrosine phosphatase (PTP) is the family of enzymes that are key players in cellular signal transduction system and perturbation in their functioning is implicated in many disease-states. Diverse chemical compounds are being synthesized and evaluated as PTP inhibitors. This review presents a brief account of various enzymes of the PTP family and their inhibitors. Peculiar features of these enzymes and their roles in various diseases are summarized along with important inhibitors developed in recent years.

Carbene-based ruthenium photosensitizers

A new series of N-heterocyclic carbene (NHC)-pyridine ruthenium complexes incorporating a carbene unit as an ancillary ligand were designed and successfully synthesized by using simple synthetic methods. The photophysical, electrochemical and photovoltaic properties of these NHC-pyridine based ruthenium complexes were investigated. These complexes showed photoelectric conversion efficiencies in the range of 6.43 ∼ 7.24% under the illumination of AM 1.5 (100 mW cm(-2)). Interestingly, the modifications on the ancillary ligand of these sensitizers by removal of an alkoxyl group and replacement of the octyl chain with a 3,5-difluorobenzyl group showed a 13% increase in the conversion efficiency for the CifPR dye. These results demonstrated that structural modifications on the NHC-pyridine ancillary ligand of ruthenium complexes results in dye-sensitized solar cells exhibiting a comparable cell performance to that obtained using the standard N719 dye.

Preparation and characterization of pure rutile TiO 2 nanoparticles for photocatalytic study and thin films for dye-sensitized solar cells

Pure rutile-phase TiO2 (r-TiO2) was synthesized by a simple one pot experiment under hydrothermal condition using titanium (IV) n-butoxide as a Ti-precursor and HCl as a peptizer. The TiO2 products were characterized by XRD, TEM, ESCA, and BET surface area measurement. The r-TiO2 were rodlike in shape with average size of ∼61 × 32nm at hydrothermal temperature of 220°C for 10 h. Hydrothermal treatment at longer reaction time increased the tendency of crystal growth and also decreased the BET surface area. The degradation of methylene blue was selected as a test reaction to confer the photocatalytic activity of as-obtained r-TiO2. The results showed a strong correlation between the structure evolution, particle size, and photocatalytic performance of r-TiO2. Furthermore, the r-TiO2-based solar cell was prepared for the photovoltaic characteristics study, and the best efficiency of ∼3.16% was obtained.

Preparation of Nanoporous TiO2 Electrodes for Dye-Sensitized Solar Cells

Nano-porous thin films have been widely used as the working electrodes in dye-sensitized solar cells (DSSCs). In this work, the phase-pure anatase (a-) and rutile (r-) have been prepared using hydrothermal processes. The investigation of photo-to-electron conversion efficiency of DSSCs fabricated from mixed- with a- and r- ratio of 80 : 20 (A8R2) was performed and compared to that from commercial (DP-25). The results showed higher efficiency of DSSC for A8R2 cells with same dependence of cell efficiency on the film thickness for both A8R2 and DP-25 cells. The best efficiency obtained in this work is 5.2% from A8R2 cell with film thickness of 12.0 . The correlation between the films thickness and photoelectron chemical properties of DSSCs fabricated from A8R2 and DP-25 was compared and discussed.

Preparation of nanoporous TiO 2 electrodes for dye-sensitized solar cells

Nano-porous thin films have been widely used as the working electrodes in dye-sensitized solar cells (DSSCs). In this work, the phase-pure anatase (a-) and rutile (r-) have been prepared using hydrothermal processes. The investigation of photo-to-electron conversion efficiency of DSSCs fabricated from mixed- with a- and r- ratio of 80 : 20 (A8R2) was performed and compared to that from commercial (DP-25). The results showed higher efficiency of DSSC for A8R2 cells with same dependence of cell efficiency on the film thickness for both A8R2 and DP-25 cells. The best efficiency obtained in this work is 5.2% from A8R2 cell with film thickness of 12.0 . The correlation between the films thickness and photoelectron chemical properties of DSSCs fabricated from A8R2 and DP-25 was compared and discussed.

Preparation of Nanoporous TiO2Electrodes for Dye-Sensitized Solar Cells

Nano-porous thin films have been widely used as the working electrodes in dye-sensitized solar cells (DSSCs). In this work, the phase-pure anatase (a-) and rutile (r-) have been prepared using hydrothermal processes. The investigation of photo-to-electron conversion efficiency of DSSCs fabricated from mixed- with a- and r- ratio of 80 : 20 (A8R2) was performed and compared to that from commercial (DP-25). The results showed higher efficiency of DSSC for A8R2 cells with same dependence of cell efficiency on the film thickness for both A8R2 and DP-25 cells. The best efficiency obtained in this work is 5.2% from A8R2 cell with film thickness of 12.0 . The correlation between the films thickness and photoelectron chemical properties of DSSCs fabricated from A8R2 and DP-25 was compared and discussed.

Development of a novel oxidatively removable and recyclable linker for combinatorial solid phase synthesis

An appropriately derivatized phenanthridine is shown to behave as a novel, reusable linker which is based on a disubstituted amide anchorage and forms an acid group on oxidative cleavage, but tolerates exposure to acidic, basic and reductive reaction conditions.

Preparation and Optimization of Iridium Complexes with Quinazolinone Ligands on Solid Supports

Solid-phase combinatorial techniques are tremendously useful in the search for new drugs for the treatment of a wide variety of ailments. Materials discovery, however, has yet to benefit significantly from combinatorial methodology. Indeed, only a few exceptional attempts have been made to apply combinatorial approaches to the discovery of materials possessing novel photophysical properties. Moreover, even among these few reports, most of the materials prepared have been organic compounds. Several researchers have reported the immobilization of organometallic complexes onto functionalized polymer supports. Leadbeater attached ruthenium complexes to polymer supports to improve their catalytic efficiencies; Reedijk and coworkers developed methodologies to prepare platinum complexes on solid supports. Nevertheless, it remains rare for solid-phase combinatorial methods to be used for the synthesis of organometallic materials. In this paper, we describe a rapid and efficient parallel solid phase method for the synthesis of iridium complexes. This methodology allows the modification of three different functionalities on the template of the iridium complexes to optimize and finetune their photophysical properties for application in organic light-emitting diodes (OLEDs). OLEDs are advanced alternatives to inorganic lightemitting diodes and liquid-crystal displays. Because of their excellent properties (flexibility, self-luminescence, rapid response, good contrast, low energy consumption), they hold great potential for application in flat-panel displays. In recent decades, much attention has been focused on organometallic complexes of various heavy metals, including Ir, Os, Ru, and Pt, for their potential use as phosphorescent dopants in OLEDs. Iridium complexes, in particular, are excellent emitters for OLED applications. In 2006, we used a combinatorial organometallic solid phase synthesis and high throughput screening methodology to identify a novel iridium complex having two cyclometallating ligands and a single monoanionic, bidentate ancillary ligand. The optimization of lead organometallic materials using this library approach, however, remains in its nascent stages. As part of a continuing effort toward the development of organometallic materials exhibiting desired properties, we are aiming to optimize the properties of organometallic complexes through structural modifications using solid phase synthesis. So far, the key ligands we have used have been limited mostly to derivatives of o-pyridylarenes and o-pyridylheterocycles. Therefore, to extend our optimization studies, for this present study we selected iridium complexes featuring quinazolinone-based cyclometallating ligands. In this Report, we demonstrate the versatility of using a combinatorial parallel approach, applying solid phase synthesis, for the preparation and optimization of iridium complexes incorporating quinazolinone ligands as luminescent emitters. The parallel solid-phase syntheses of the iridium complexes 1 were carried out using Wang resin (1% DVB, 1.0 mmol/g, Scheme 1). Initially, Mitsunobu alkylation was tested to obtain resin 2 by reacting methyl 4-hydroxybenzoate with Wang resin under standard conditions. In these cases, the reactions afforded poor yields and resulted in several side products. Instead, we first activated the Wang resin as a mesylate and then alkylated it with methyl 4-hydroxybenzoate in DMF using NaH to afford the resin 2 * Towhomcorrespondenceshouldbeaddressed.E-mail:ch01@ncu.edu.tw. Fax: +886-3-427-7972.  Copyright 2009 by the American Chemical Society