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1. Honokiol Exhibits Anti-NLRP3 Inflammasome and Antimicrobial Properties in Neisseria gonorrhoeae-Infected Macrophages

Author

Hua KF, Hsu HT, Huang MS, Chiu HW, Wong WT, Peng CH, Lin YB, Chen A, Wang CC, Hsu CH, Wu CH, Lin WY, Ho CL, and Li LH

Subjects
neisseria gonorrhoeae, honokiol, nlrp3 inflammasome, mitochondria, bactericiide, Pathology, RB1-214, Therapeutics. Pharmacology, RM1-950
Abstract

Kuo-Feng Hua,1,2,* Hsien-Ta Hsu,3,4,* May-Shu Huang,5,6 Hsiao-Wen Chiu,1 Wei-Ting Wong,1 Chien-Hsiu Peng,1 Yu-Bei Lin,1 Ann Chen,7 Chien-Chun Wang,8,9 Chung-Hua Hsu,10,11 Chun-Hsien Wu,12 Wen-Yu Lin,1,12 Chen-Lung Ho,13 Lan-Hui Li14 1Department of Biotechnology and Animal Science, National Ilan University, Ilan, Taiwan; 2Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; 3Division of Neurosurgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan; 4School of Medicine, Buddhist Tzu Chi University, Hualien, Taiwan; 5Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; 6Department of Laboratory Medicine, Mackay Memorial Hospital, Taipei, Taiwan; 7Department of Pathology, Hualien Tzu Chi Hospital, Hualien, Taiwan; 8Infectious Disease Division, Linsen, Chinese Medicine and Kunming Branch, Taipei City Hospital, Taipei, Taiwan; 9Kunming Prevention and Control Center, Taipei City Hospital, Taipei, Taiwan; 10Linsen, Chinese Medicine and Kunming Branch, Taipei City Hospital, Taipei, Taiwan; 11Institute of Traditional Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; 12Division of Cardiology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; 13Division of Wood Cellulose, Taiwan Forestry Research Institute, Taipei, Taiwan; 14Department of Laboratory Medicine, Linsen, Chinese Medicine and Kunming Branch, Taipei City Hospital, Taipei, Taiwan*These authors contributed equally to this workCorrespondence: Lan-Hui Li, Department of Laboratory Medicine, Linsen, Chinese Medicine and Kunming Branch, Taipei City Hospital, 100, Kunming Street, Wanhua District, Taipei City, 108203, Taiwan, Tel +886-2-23703739 # 1438, Fax +886-2-23885259, Email A1525@tpech.gov.twPurpose: The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, crucial in infectious and inflammatory diseases by regulating IL-1β, presents a target for disease management. Neisseria gonorrhoeae causes gonorrhea in over 87 million people annually, with previous research revealing NLRP3 inflammasome activation in infected macrophages. No natural products have been reported to counteract this activation. Exploring honokiol, a phenolic compound from Chinese herbal medicine, we investigated its impact on NLRP3 inflammasome activation in N. gonorrhoeae-infected macrophages.Methods: Honokiol’s impact on the protein expression of pro-inflammatory mediators was analyzed using ELISA and Western blotting. The generation of intracellular H2O2 and mitochondrial reactive oxygen species (ROS) was detected through specific fluorescent probes (CM-H2DCFDA and MitoSOX, respectively) and analyzed by flow cytometry. Mitochondrial membrane integrity was assessed using specific fluorescent probes (MitoTracker and DiOC2(3)) and analyzed by flow cytometry. Additionally, the effect of honokiol on the viability of N. gonorrhoeae was examined through an in vitro colony-forming units assay.Results: Honokiol effectively inhibits caspase-1, caspase-11 and GSDMD activation and reduces the extracellular release of IL-1β, NLRP3, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) in N. gonorrhoeae-infected macrophages. Detailed investigations have demonstrated that honokiol lowers the production of H2O2 and the phosphorylation of ERK1/2 in N. gonorrhoeae-infected macrophages. Importantly, the phosphorylation of JNK1/2 and p38 and the activation of NF-κB remain unaffected. Moreover, honokiol reduces the N. gonorrhoeae-mediated generation of reactive oxygen species within the mitochondria, preserving their integrity. Additionally, honokiol suppresses the expression of the pro-inflammatory mediator IL-6 and inducible nitric oxide synthase induced by N. gonorrhoeae independently of NLRP3. Impressively, honokiol exhibits in vitro anti-gonococcal activity against N. gonorrhoeae.Conclusion: Honokiol inhibits the NLRP3 inflammasome in N. gonorrhoeae-infected macrophages and holds great promise for further development as an active ingredient in the prevention and treatment of symptoms associated with gonorrhea.Keywords: Neisseria gonorrhoeae, honokiol, NLRP3 inflammasome, mitochondria, bactericiide

Published
2024

2. Leptin Induces MMP-1 Expression Through the RhoA/ERK1/2/NF-κB Axis in Human Intervertebral Disc Cartilage Endplate-Derived Stem Cells

Author

Hua KF, Li LH, Yu HC, Wong WT, and Hsu HT

Subjects
intervertebral disc degeneration, leptin, matrix metalloproteinase, intervertebral disc cartilage endplate-derived stem cells, rhoa, erk1/2, Pathology, RB1-214, Therapeutics. Pharmacology, RM1-950
Abstract

Kuo-Feng Hua,1,2,* Lan-Hui Li,3,* Hsin-Chiao Yu,4 Wei-Ting Wong,1 Hsien-Ta Hsu4,5 1Department of Biotechnology and Animal Science, National Ilan University, Yilan, 26047, Taiwan; 2Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, 404333, Taiwan; 3Department of Laboratory Medicine, Linsen, Chinese Medicine and Kunming Branch, Taipei City Hospital, Taipei, 108, Taiwan; 4Division of Neurosurgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, 231, Taiwan; 5School of Medicine, Buddhist Tzu Chi University, Hualien, 970, Taiwan*These authors contributed equally to this workCorrespondence: Hsien-Ta Hsu, Division of Neurosurgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, No. 289, Jianguo Road, Xindian Dist, New Taipei City, 231016, Taiwan, Tel +866-2-6628-9779, Email j1208192@ms45.hinet.netPurpose: Intervertebral disc (IVD) degeneration, associated with aging, may cause low back pain and disability, with obesity as a significant risk factor. In a prior study, we found a positive correlation between IVD degeneration and levels of matrix metalloproteinase-1 (MMP-1) and leptin. Yet, the interaction between MMP-1 and leptin in IVD degeneration is unclear. Our research seeks to explore leptin’s influence on MMP-1 expression and the underlying mechanisms in human intervertebral disc cartilage endplate-derived stem cells, specifically SV40 cells.Methods: The mRNA and protein expression in leptin-stimulated SV40 cells were assessed using RT-real-time PCR and Western blotting or ELISA, respectively. We examined leptin-mediated RhoA activation through a GTP-bound RhoA pull-down assay. Furthermore, the phosphorylation levels of mitogen-activated protein kinases and AKT in leptin-stimulated SV40 cells were analyzed using Western blotting. The activation of NF-κB by leptin was investigated by assessing phosphorylation of IKKα/β, IκBα, and NF-κB p65, along with the nuclear translocation of NF-κB p65. To understand the underlying mechanism behind leptin-mediated MMP-1 expression, we employed specific inhibitors.Results: Leptin triggered the mRNA and protein expression of MMP-1 in SV40 cells. In-depth mechanistic investigations uncovered that leptin heightened RhoA activity, promoted ERK1/2 phosphorylation, and increased NF-κB activity. However, leptin did not induce phosphorylation of JNK1/2, p38, or AKT. When we inhibited RhoA, ERK1/2, and NF-κB, it resulted in a decrease in MMP-1 expression. Conversely, inhibition of reactive oxygen species and NADPH oxidase did not yield the same outcome. Additionally, inhibiting RhoA or ERK1/2 led to a reduction in leptin-induced NF-κB activation. Moreover, inhibiting RhoA also decreased leptin-mediated ERK1/2 phosphorylation.Conclusion: These results indicated that leptin induced MMP-1 expression in SV40 cells through the RhoA/ERK1/2/NF-κB axis. This study provided the pathogenic role of leptin and suggested the potential therapeutic target for IVD degeneration. Keywords: intervertebral disc degeneration, leptin, matrix metalloproteinase, intervertebral disc cartilage endplate-derived stem cells, RhoA, ERK1/2

Published
2023

3. Antrodia cinnamomea May Interfere with the Interaction Between ACE2 and SARS-CoV-2 Spike Protein in vitro and Reduces Lung Inflammation in a Hamster Model of COVID-19

Author

Li LH, Chiu HW, Wong WT, Huang KC, Lin TW, Chen ST, and Hua KF

Subjects
coronavirus disease 2019, angiotensin-converting enzyme-2, severe acute respiratory syndrome coronavirus 2, antrodia cinnamomea, the intracellular sensor nacht, lrr, and pyd domain-containing protein 3 inflammasome, cytokine., Pathology, RB1-214, Therapeutics. Pharmacology, RM1-950
Abstract

Lan-Hui Li,1 Hsiao-Wen Chiu,2 Wei-Ting Wong,2 Ko-Chieh Huang,3 Tzu-Wen Lin,3 Shui-Tein Chen,3 Kuo-Feng Hua2,4 1Department of Laboratory Medicine, Linsen, Chinese Medicine and Kunming Branch, Taipei City Hospital, Taipei, Taiwan; 2Department of Biotechnology and Animal Science, National Ilan University, Yilan, Taiwan; 3ALPS Biotech Co. Ltd, Taipei, Taiwan; 4Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, TaiwanCorrespondence: Kuo-Feng Hua, Department of Biotechnology and Animal Science, National Ilan University, No. 1, Sec. 1, Shennong Road, Yilan, 260, Taiwan, Tel +886 3 931 7626, Fax +886 3 935 4794, Email kuofenghua@gmail.comPurpose: Coronavirus disease 2019 (COVID-19) poses a global health challenge with widespread transmission. Growing concerns about vaccine side effects, diminishing efficacy, and religious-based hesitancy highlight the need for alternative pharmacological approaches. Our study investigates the impact of the ethanol extract of Antrodia cinnamomea (AC), a native medicinal fungus from Taiwan, on COVID-19 in both in vitro and in vivo contexts.Methods: We measured the mRNA and protein levels of angiotensin-converting enzyme-2 (ACE2) in human lung cells using real-time reverse transcriptase-polymerase chain reaction and Western blotting, respectively. Additionally, we determined the enzymatic activity of ACE2 using the fluorogenic peptide substrate Mca-YVADAPK(Dnp)-OH. To assess the impact of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, we used SARS-CoV-2 pseudovirus infections in human embryonic kidney 293T cells expressing ACE2 to measure infection rates. Furthermore, we evaluated the in vivo efficacy of AC in mitigating COVID-19 by conducting experiments on hamsters infected with the Delta variant of SARS-CoV-2.Results: AC effectively decreased ACE2 mRNA and protein levels, a critical host receptor for the SARS-CoV-2 spike protein, in human lung cells. It also prevented the spike protein from binding to human lung cells. Dehydrosulphurenic acid, an isolate from AC, directly inhibited ACE2 protease activity with an inhibitory constant of 1.53 μM. In vitro experiments showed that both AC and dehydrosulphurenic acid significantly reduced the infection rate of SARS-CoV-2 pseudovirus. In hamsters infected with the Delta variant of SARS-CoV-2, oral administration of AC reduced body weight loss and improved lung injury. Notably, AC also inhibited IL-1β expression in both macrophages and the lung tissues of SARS-CoV-2-infected hamsters.Conclusion: AC shows potential as a nutraceutical for reducing the risk of SARS-CoV-2 infection by disrupting the interaction between ACE2 and the SARS-CoV-2 spike protein, and for preventing COVID-19-associated lung inflammation.Graphical Abstract: Keywords: coronavirus disease 2019, angiotensin-converting enzyme-2, severe acute respiratory syndrome coronavirus 2, Antrodia cinnamomea, the intracellular sensor NACHT, LRR, PYD domain-containing protein 3 inflammasome, cytokine

Published
2023

4. A protocol for an international, multicentre pharmacokinetic study for Screening Antifungal Exposure in Intensive Care Units: The SAFE-ICU study

Author

Roberts, JA, Sime, F, Lipman, J, Hernandez-Mitre, MP, Baptista, JP, Brueggemann, RJ, Darvall, J, Waele, JJD, Dimopoulos, G, Lefrant, J-Y, Nor, MBM, Seoane, L, Slavin, MA, Valkonen, M, Venditti, M, Wong, WT, Zeitlinger, M, Roger, C, Roberts, JA, Sime, F, Lipman, J, Hernandez-Mitre, MP, Baptista, JP, Brueggemann, RJ, Darvall, J, Waele, JJD, Dimopoulos, G, Lefrant, J-Y, Nor, MBM, Seoane, L, Slavin, MA, Valkonen, M, Venditti, M, Wong, WT, Zeitlinger, M, and Roger, C

Abstract

OBJECTIVE: To describe whether contemporary dosing of antifungal drugs achieves therapeutic exposures in critically ill patients that are associated with optimal outcomes. Adequate antifungal therapy is a key determinant of survival of critically ill patients with fungal infections. Critical illness can alter an antifungal agents' pharmacokinetics, increasing the risk of inappropriate antifungal exposure that may lead to treatment failure and/or toxicity. DESIGN SETTING AND PARTICIPANTS: This international, multicentre, observational pharmacokinetic study will comprise adult critically ill patients prescribed antifungal agents including fluconazole, voriconazole, posaconazole, isavuconazole, caspofungin, micafungin, anidulafungin, and amphotericin B for the treatment or prophylaxis of invasive fungal disease. A minimum of 12 patients are targeted for enrolment for each antifungal agent, across 12 countries and 30 intensive care units to perform descriptive pharmacokinetics. Pharmacokinetic sampling will occur during two dosing intervals (occasions): firstly, between days 1 and 3, and secondly, between days 4 and 7 of the antifungal course, collecting three samples per occasion. Patients' demographic and clinical data will be collected. MAIN OUTCOME MEASURES: The primary endpoint of the study is attainment of pharmacokinetic/pharmacodynamic target exposures that are associated with optimal efficacy. Thirty-day mortality will also be measured. RESULTS AND CONCLUSIONS: This study will describe whether contemporary antifungal drug dosing achieves drug exposures associated with optimal outcomes. Data will also be used for the development of antifungal dosing algorithms for critically ill patients. Optimised drug dosing should be considered a priority for improving clinical outcomes for critically ill patients with fungal infections.

Published
2023

6. Development and evaluation of pH-responsive single-walled carbon nanotube-doxorubicin complexes in cancer cells

Author

Gu YJ, Cheng J, Jin J, Cheng SH, and Wong WT

Subjects
Medicine (General), R5-920
Abstract

Yan-Juan Gu1,2,*, Jinping Cheng2,*, Jiefu Jin3, Shuk Han Cheng2, Wing-Tak Wong11Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, 2Department of Biology and Chemistry, The City University of Hong Kong, 3Department of Chemistry, The University of Hong Kong, Hong Kong, China*These authors contributed equally to this workAbstract: Single-walled carbon nanotubes (SWNTs) have been identified as an efficient drug carrier. Here a controlled drug-delivery system based on SWNTs coated with doxorubicin (DOX) through hydrazone bonds was developed, because the hydrazone bond is more sensitive to tumor microenvironments than other covalent linkers. The SWNTs were firstly stabilized with polyethylene glycol (H2N-PEG-NH2). Hydrazinobenzoic acid (HBA) was then covalently attached on SWNTs via carbodiimide-activated coupling reaction to form hydrazine-modified SWNTs. The anticancer drug DOX was conjugated to the HBA segments of SWNT using hydrazine as the linker. The resulting hydrazone bonds formed between the DOX molecules and the HBA segments of SWNTs are acid cleavable, thereby providing a strong pH-responsive drug release, which may facilitate effective DOX release near the acidic tumor microenvironment and thus reduce its overall systemic toxicity. The DOX-loaded SWNTs were efficiently taken up by HepG2 tumor cells, and DOX was released intracellularly, as revealed by MTT assay and confocal microscope observations. Compared with SWNT-DOX conjugate formed by supramolecular interaction, the SWNT-HBA-DOX featured high weight loading and prolonged release of DOX, and thus improved its cytotoxicity against cancer cells. This study suggests that while SWNTs have great potential as a drug carrier, the efficient formulation strategy requires further study.Keywords: carbon nanotubes, drug delivery, controlled release, SWNTs

Published
2011

7. Nanotherapeutics in angiogenesis: synthesis and in vivo assessment of drug efficacy and biocompatibility in zebrafish embryos

Author

Cheng J, Gu YJ, Wang YJ, Cheng SH, and Wong WT

Subjects
Medicine (General), R5-920
Abstract

Jinping Cheng1*, Yan-Juan Gu2*, Yajun Wang3, Shuk Han Cheng1, Wing-Tak Wong21Department of Biology and Chemistry, The City University of Hong Kong, Kowloon, 2Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, 3Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China *These authors contributed equally to this work Background: Carbon nanotubes have shown broad potential in biomedical applications, given their unique mechanical, optical, and chemical properties. In this pilot study, carbon nanotubes have been explored as multimodal drug delivery vectors that facilitate antiangiogenic therapy in zebrafish embryos. Methods: Three different agents, ie, an antiangiogenic binding site (cyclic arginine-glycine-aspartic acid), an antiangiogenic drug (thalidomide), and a tracking dye (rhodamine), were conjugated onto single-walled carbon nanotubes (SWCNT). The biodistribution, efficacy, and biocompatibility of these triple functionalized SWCNT were tested in mammalian cells and validated in transparent zebrafish embryos. Results: Accumulation of SWCNT-associated nanoconjugates in blastoderm cells facilitated drug delivery applications. Mammalian cell xenograft assays demonstrated that these antiangiogenic SWCNT nanoconjugates specifically inhibited ectopic angiogenesis in the engrafted zebrafish embryos. Conclusion: This study highlights the potential of using SWCNT for generating efficient nanotherapeutics. Keywords: carbon nanotubes, drug delivery, antiangiogenic therapy

Published
2011

16. Fibroblast growth factor 21 in cardio-metabolic disorders: a systematic review and meta-analysis

Author

Lakhani, I, Gong, M, Wong, WT, Bazoukis, G, Lampropoulos, K, Wong, SH, Wu, WKK, Wong, MCS, Ong, KL, Liu, T, Tse, G, Lakhani, I, Gong, M, Wong, WT, Bazoukis, G, Lampropoulos, K, Wong, SH, Wu, WKK, Wong, MCS, Ong, KL, Liu, T, and Tse, G

Abstract

Background: Fibroblast growth factor 21 is a signalling protein involved in cell differentiation, morphogenesis, proliferation and metabolism. Recent studies have associated increased levels of FGF21 in the development of cardiovascular diseases, whereas others have reported no significant associations. Therefore, this systematic review and meta-analysis evaluated the value in predicting the risk of cardio-metabolic disorders and mortality. Methods: PubMed and EMBASE were searched until 5th September 2017 for studies that evaluated the roles of FGF21 levels in cardio-metabolic disorders. Results: A total of 183 and 301 entries were retrieved; 24 studies met the inclusion criteria. Four studies were identified by an additional search. Therefore, 28 studies were included in the final meta-analysis. High FGF21 levels significantly predicted the incidence of coronary artery disease (hazard ratio [HR]: 1.29; 95% confidence interval [CI]: 1.06–1.55; P < 0. 01; I2 = 48%) and the risk of metabolic syndrome (HR: 1.70, 95% CI: 1.35–2.15; P < 0.0001 I2 = 24%). In diabetes mellitus, FGF21 predicted disease incidence or progression (HR: 1.35, 95% CI: 1.06–1.72, P < 0.05, I2 = 69%) and worsening renal failure (HR: 1.06, 95% CI: 1.03–1.09, P < 0.0001, I2 = 47%). FGF21 also predicted all-cause mortality (HR: 3.00, 95% CI: 1.23–7.33; P < 0.05; I2 = 51%), and cardiovascular mortality (HR: 2.33, 95% CI: 1.08–4.99, P < 0.05, I2 = 75%). Conclusion: FGF21 significantly predicts the incidence of coronary artery disease, the risks of metabolic syndrome, diabetes mellitus and renal progression in diabetes. It also predicted all-cause and cardiovascular mortality.

Published
2018

17. Exploring the scope of communication content of mechanically ventilated patients

Author

Leung, CCH, Pun, J, Lock, G, Slade, D, Gomersall, CD, Wong, WT, Joynt, GM, Leung, CCH, Pun, J, Lock, G, Slade, D, Gomersall, CD, Wong, WT, and Joynt, GM

Abstract

© 2017 Purpose: Ineffective communication during mechanical ventilation (MV) and critical illness is distressing to many patients. This study aimed to describe the scope of communication content of ventilated critically ill patients. Materials and methods: We performed a prospective qualitative interview study in a multidisciplinary intensive care unit. Ten alert, orientated adult patients who previously underwent MV for at least 24 h and were able to speak at the time of interview were recruited. Semi-structured interviews with stimulated recall technique were conducted. A descriptive thematic analysis was performed of the patient-generated content using a free coding technique, where recurrent themes and subthemes were noted, coded and analyzed. Results: Patients' communication content included medical discussions with clinicians; communication with family to provide advice or comfort, make requests and plans, express feelings and convey personal perspectives on medical care; and expression of their own psychoemotional needs. Conclusions: The scope of communication content of ventilated ICU patients was broad, extending far beyond task-focused subject matter. Content ranged from conveying symptom-related messages to active participation in medical discussions, to conversing with family about a range of complex multi-dimensional issues, to sharing their own psychoemotional experiences. These patient-centered needs should be recognized and addressed in communication strategies.

Published
2018

20. Evolutionary conservation of the Eps8 gene and its mapping to human-chromosome 12q23-q24

Author

WONG WT, DRUCK T, BARLETTA C, CROCE CM, HEUBNER K, KRAUS MH, DI FIORE PP, CARLOMAGNO, Francesca, Wong, Wt, Carlomagno, Francesca, Druck, T, Barletta, C, Croce, Cm, Heubner, K, Kraus, Mh, and DI FIORE, Pp

Abstract

We have previously isolated the coding sequence for a novel substrate for tyrosine kinases, eps8, from NIH3T3 fibroblasts. Eps8 was phosphorylated in vivo by several receptor tyrosine kinases (RTKs) and, upon overexpression, was able to enhance EGFR-mediated mitogenic signaling in NIH3T3 cells. To gain understanding of eps8 function as well as its role in normal and neoplastic proliferation, we cloned the human eps8 coding sequence and studied expression of the human RNA and protein, evolutionary conservation, and chromosomal location. In addition to a previously identified SH3 domain, the predicted amino acid sequence of human eps8 revealed a non-random distribution of prolines, clustered in a way to suggest SH3-binding sites and a putative PH domain. Eps8 was expressed in all epithelial and fibroblastic lines examined and in some, but not all, hematopoietic cells. An essential function of eps8 in cell growth regulation was underscored by its conservation during evolution, where eps8-related sequences were detected as early as in Saccharomyces cerevisiae. Finally, the human EPS8 locus was mapped to chromosome 12q23-q24.

Published
1994

21. The Human Eps15 gene encoding a tyrosine kinase substrate is conserved in evolution and map to 1p31-1p32

Author

WONG WT, KRAUS MH, ZELANO A, DRUCK T, CROCE CM, HEUBENER K, DI FIORE PP, CARLOMAGNO, Francesca, Wong, Wt, Kraus, Mh, Carlomagno, Francesca, Zelano, A, Druck, T, Croce, Cm, Heubener, K, and DI FIORE, Pp

Abstract

Employing an expression cloning approach for tyrosine kinase substrates, we have previously isolated the coding sequence for a novel putative EGFR substrate, eps15, from NIH3T3 fibroblasts. Eps15 displayed a receptor-specific pattern of tyrosine phosphorylation in vivo and was able to transform NIH3T3 cells upon overexpression. To gain understanding of eps15 function as well as its role in normal and neoplastic proliferation, we cloned the human eps15 coding sequence and studied expression of the human RNA and protein, evolutionary conservation, and chromosomal location. The close structural similarity of human eps15 with the murine homologue is indicated by 89% and 90% identity of nucleotide and predicted amino acid sequences, respectively. Using the human eps15 coding sequence as probe, we demonstrate that eps15 is member of a gene family that is highly conserved during evolution. An essential function of eps15 in cell growth regulation is underscored by our observation of ubiquitous expression at the transcript and the protein level in normal and malignant human cells. The human EPS15 locus maps to chromosome 1p31-p32, a region involved in deletion in neuroblastoma, translocations in acute lymphoblastic leukemia, and exhibiting a fragile site.

Published
1994

23. Synthesis, crystal structure, and photophysical and magnetic properties of dimeric and polymeric lanthanide complexes with benzoic acid and its derivatives

Author

Lam, AWH, Wong, WT, Gao, S., Wen, GH, Zhang, XX, Lam, AWH, Wong, WT, Gao, S., Wen, GH, and Zhang, XX

Abstract

A new family of lanthanide carboxylate complexes with benzoic acid and its derivatives was synthesised and characterised. The structures of the complexes were established by X-ray crystallography, which revealed that various chelating modes of the carboxylate ligands are present on the metal ion, resulting in the formation of dimeric and polymeric skeletons. The photophysical properties of the Eu and Tb complexes were studied: the complexes exhibited sensitised luminescence in the visible spectral region, but the luminescence intensities and lifetimes were very sensitive to quenching by the OH groups of methanol molecules. The solid-state magnetic properties of the Gd and Tb complexes demonstrated the presence of weak antiferromagnetic exchange interactions at very low temperatures, caused by interaction between the neighbouring ions along the chain. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2003)

Published
2003

24. Half-Sandwich Titanium(IV) Complexes with Kläui's Tripod Ligand

Author

Lam, Tony C.H., Chan, Eddie Y.Y., Mak, Wing Leung, Lo, Samuel M.F., Williams, Ian Duncan, Wong, WT, Leung, Wa Hung, Lam, Tony C.H., Chan, Eddie Y.Y., Mak, Wing Leung, Lo, Samuel M.F., Williams, Ian Duncan, Wong, WT, and Leung, Wa Hung

Abstract

Treatment of [Ti(O-i-Pr)(2)Cl-2] with NaLOEt (L-OEt-= [CpCo{P(O)(OEt)(2)}(3)](-) Cp = eta(5)-C5H5) afforded [LOEtTi(O-i-Pr)(2)Cl] that reacted with HCl in ether to give [LOETTiCl3] (1). The average Ti-O and Ti-Cl distances in 1 are 1.975 and 2.293 Angstrom, respectively. Reaction of titanyl sulfate with NaLOEt in water followed by addition of HBF4 afforded [LOEtTiF3] (2), the Ti-O and Ti-F distances of which are 2.020(2) and 1.792(2) Angstrom, respectively. The Zr(IV) analogue [LOEtZrF3] (3) was prepared similarly from zirconyl nitrate, NaLOet, and HBF4 in water. The Zr-O and average Zr-F distances in 3 are 2.139(2) and 1.938(2) Angstrom, respectively. Treatment of 1 with tetrachlorocatechol (H(2)Cl(4)cat) afforded [LOEtTi(Cl(4)cat)Cl] (4). The average Ti-O(P), Ti-O(C), and Ti-Cl distances in 4 are 1.972, 1.926, and 2.334 Angstrom, respectively. Hydrolysis of 4 in the presence of Et3N yielded the mu-oxo dimer [(L-OEt)(2)Ti-2(Cl(4)cat)(2)(mu-O)] (5). The average Ti-O(P), Ti-O(C), and Ti-O(Ti) distances in 5 are 2.027, 1.926, and 1.7977(9) Angstrom. Treatment of 1 with 1,1'-binaphthol (BINOLH2) in the presence of Et3N afforded [(L-OEt)(2)Ti-2(mu-O)(2)(mu-BINOL)].2BINOLH(2) (6.2BINOLH(2)). Complex 1 is capable of catalyzing ring opening of epoxides with Me3SiN3 under solvent-free conditions presumably via a Ti-azide intermediate.

Published
2003

25. Bridged dinitrogen complexes of iron and chromium porphyrins

Author

Zhang, Qianfeng, Chim, JLC, Lai, W., Wong, WT, Leung, Wa Hung, Zhang, Qianfeng, Chim, JLC, Lai, W., Wong, WT, and Leung, Wa Hung

Abstract

Reactions of [M(OEP)(OTf)] (M = Fe or Cr, OEP = octaethylporphyrinate, OTf = triflate) with [Re(N-2)(PMe2Ph)(4)Cl] afford [(OEP)M(N-2)Re(PMe2Ph)(4)Cl] [OTf]. The structure of the heterometallic Fe/Re dinitrogen complex has been established by X-ray crystallography.

Published
2001

26. The metal-carbon stretching frequencies in methyl complexes of Rh, Ir, Ga and In with porphyrins and a tetradentate pyridine-amide ligand

Author

Lai, W., Lau, MK, Chong, V., Wong, WT, Leung, Wa Hung, Yu, NT, Lai, W., Lau, MK, Chong, V., Wong, WT, Leung, Wa Hung, and Yu, NT

Abstract

Interactions of trans -[Rh(bpb)(CH3)(H2O)] (1) [bpb = 1,2-bis(2-pyridinecarboxamido)benzene] with Lewis bases L afford the respective adducts trans-[Rh(bpb)(CH3)(L)], where L = 4-substituted pyridine 4-Xpy (X = H (2), `Bu (3), NMe2 (4) CN (5)), PMe2Ph (6) or benzimidazole (7), The structures of complexes 3 and 6 have been established by X-ray crystallography. The Rh-C distance in complex 6 (2.095(6) Angstrom) is longer than that in complex 3 (2.02(1) Angstrom), indicating that PMe2Ph has a stronger trans influence than 4-'Bupy. The metal-carbon stretching frequencies for trans -[Rh(bpb)(CH3)(L)] and [M(TTP)(CH3)] [TTP = 5,10,15,20-tetrakis(4-methylphenyl)porphyrin dianion; M = Rh, Ir, Ga, In] have been determined by near IR FT-Roman spectroscopy. Complex 1 exhibits v(Rh-C) at 562 cm(-1), which downshifts to 532 cm(-1) upon deuteriation of the axial methyl group. Replacement of the aquo ligand in complex 1 with nitrogen ligands or phosphine resulted in downshift in v(Rh-C). The v(Rh-C) for trans-[Rh(bpb)(CH3)(L)] was found to decrease in the order L: PMe2Ph much greater than 4-Xpy similar to BzIm > H2O, consistent the order of trans influence of L. For [M(TTP)(CH3)] (M = Co, Rh, Ir, Ga, or In) the M-C force constant was found to decrease in the orders Ir > Rh > Co and Ga > In, consistent with the trends of metal-carbon bond strength for these metals. For trans[Rh(bpb)(CH3)(4-Xpy)] and trans-[Rh(TTP)(CH3)(4-Xpy)], the v(Rh-C) were found to be not very sensitive to the nature of X, suggesting that the electronic factors of the axial pyridine ligand do not have a significant effect on the Rh-C bonds for these rhodium alkyl complexes. (C) 2001 Published by Elsevier Science B.V.

Published
2001

27. Direct functionalisation of sigma-aryl ligands: preparation of homoleptic functionalised aryls of osmium(II)

Author

Lau, MK, Zhang, Qianfeng, Chim, JLC, Wong, WT, Leung, Wa Hung, Lau, MK, Zhang, Qianfeng, Chim, JLC, Wong, WT, and Leung, Wa Hung

Abstract

The osmium(rv) tetraaryl complex [Os(C8H9)(4)] (C8H9 = 2,5-dimethylphenyl) reacts with pyridinium tribromide in the presence of Fe powder to give [Os(C8H8Br)(4)], which undergoes Suzuki coupling with arylboronic acids to afford a series of homoleptic functionalised aryls of osmium(IV).

Published
2001

28. Synthesis and molecular structures of monooxo aryl complexes of osmium(VI)

Author

Lau, MK, Chim, JLC, Wong, WT, Williams, Ian Duncan, Leung, Wa Hung, Lau, MK, Chim, JLC, Wong, WT, Williams, Ian Duncan, and Leung, Wa Hung

Abstract

Reaction of [OsO4] with C7H7MgBr (C7H7 = 2-methylphenyl) followed by column chromatography afforded the reported osmium tetraaryl [Os(C7H7)(4)] along with the oxo-osmium(VI) ([OsO(C7H7)(4)]) (1) (13\%) and the dioxo-osmium(VI) ([OsO2(C7H7)(2)]) (2) (25\%) complexes. Treatment of [OsO4] with C8H9MgBr (C8H9 = 2,5-dimethylphenyl) gave a mixture of [Os(C8H9)(4)] (3) (34\%) and [OsO(C8H9)(4)] (4) (4\%) while that with C8H9OMgBr (C8H9O = 4-methoxy-2-methylphenyl) afforded [OsO(C8H9O)(4)] (5) in 20\% yield. Oxidation of 3 with 3-chloroperoxybenzoic acid afforded 4 in good yield. The solid-state structures of 1 and 4 have been established by X-ray crystallography. Crystals of 1 are tetragonal with a = 13.080(1) and c = 6.6506(5) Angstrom, V = 1137.9(1) Angstrom (3), Z = 2, and space group of P4/n; while those of 4 are tetragonal with a = 13.593(2) and c = 7.377(2) Angstrom, V = 1363.0(5) Angstrom (3), Z = 4, and space group of P4/n. The geometry around osmium in both complexes is square pyramidal with the oxo ligand occupying apical position. The Os-O and Os-C distances in 1 are 1.652(2) and 2.084(1) Angstrom, respectively, while those in 4 are 1.688(7) and 2.088(4) Angstrom, respectively. The cyclic voltammograms of the monooxo aryl osmium(VI) compounds show reversible Os(VI/V) couple at around -1.4 V vs. ferrocene/ferrocenium couple.

Published
2001

32. Ruthenium complexes with N(SPR2)(2)(-) (R = Ph or Pr-i)

Author

Leung, Wa Hung, Zheng, HG, Chim, JLC, Chan, J., Wong, WT, Williams, Ian Duncan, Leung, Wa Hung, Zheng, HG, Chim, JLC, Chan, J., Wong, WT, and Williams, Ian Duncan

Abstract

Reactions of [Ru(PPh3)(3)Cl-2], [Ru(CO)(2)Cl-2](x), or [Ru(dmso)(4)Cl-2] (dmso=dimethyl sulfoxide) with KLR [L-R=N(SPR2)(2), R=Ph or Pr-i] afforded [Ru(L-R)(2)(PPh3)] (R=Ph 1 or Pr-i 2), cis-[Ru(L-R)(2)(CO)(2)] (L=Ph 3 or Pr-i 4), or cis-[Ru(L-Ph)(2)(dmso)(2)] 5, respectively. The crystal structures of complexes 1 and 2 have been determined. They show weak agostic interaction between Ru and L-R with calculated Ru ... H-C separations of 3.37 and 2.91 Angstrom, respectively. The Ru-P and average Ru-S distances in 1 are 2.218(1) and 2.400 Angstrom, respectively. The corresponding bond lengths for 2 are 2.210(2) and 2.404 Angstrom. Treatment of 2 with (BuNC)-N-t afforded trans-[Ru(L-Pr)(2)((BuNC)-N-t)(2)] 6, the average Ru-S and Ru-C distances of which are 2.453 and 1.990(3) Angstrom, respectively. Reaction of RuCl3 with KLR in methanol gave the homoleptic complexes [Ru(L-R)(3)] (L=Ph 7 or Pr-i 8). The average Ru-S distance and S-Ru-S angle in 7 are 2.414 Angstrom and 97.41 degrees, respectively. While complex 1 reacts with pyridine (py) to give [Ru(L-Ph)(2)(PPh3)(py)] 9, reaction of 2 with py led to isolation of structurally characterised [Ru(L-Pr)(2)(SO)] 10. The Ru-S(O) and S-O bond lengths in 10 are 2.0563(11) and 1.447(3) Angstrom, respectively, the Ru-S-O angle being 125.5(2)degrees. Treatment of 1 with SO2 afforded structurally characterised cis-[Ru(L-Ph)(2)(PPh3)(SO2)] 11. The SO2 ligand binds to Ru in 11 in a eta(1)-S mode and the Ru-S(O) distance is 2.140(4) Angstrom. Complex 2 reacted with SO2 to give the mu-sulfato-bridged ruthenium(III) dimer [{Ru(L-Pr)(PPh3)}(2)(mu-SO4)(2)] 12, which has been characterised by X-ray crystallography. The Ru-P and average Ru-S and Ru-O distances in 12 are 2.294(2), 2.321 and 2.133 Angstrom, respectively. Complex 1 is capable of catalysing hydrogenation of styrene in the presence of Et3N presumably via a ruthenium hydride intermediate.

Published
2000

33. Heterobimetallic mu-nitrido complexes containing ruthenium(II) dithiocarbamate

Author

Zheng, HG, Leung, Wa Hung, Chim, JLC, Lai, W., Lam, CH, Williams, Ian Duncan, Wong, WT, Zheng, HG, Leung, Wa Hung, Chim, JLC, Lai, W., Lam, CH, Williams, Ian Duncan, and Wong, WT

Abstract

Interaction of [Ru(Co)H(Et(2)dtc) with triflic acid (HOTf) afforded [Ru(Co)H(Et(2)dtc)(PPh3)(2)(OTf) (1), which has been characterized by X-ray crystallography. The Ru-C, Ru-O, average Ru-S and average Ru-P distances in 1 an 1.811(5), 2.216(3), 2.433 and 2.423 Angstrom, respectively. Reaction of 1 with amines L results in the formation of adducts trans-[Ru(CO)(Et(2)dtc)(PPh3)(2)L](OTf) (L = N2H4 (2) and NH2OH (3)). The Ru-C, Ru-N, average Ru-S and average Ru-P distance in 3 are 1.85(1), 2.179(8), 2.433 and 2.393, respectively; the Ru-N-O angle being 119.7(5)degrees. Treatment of 1 with [(NBu4)-Bu-n][OsN(C7H6S2)(2)] ([C7H6S2](2-) =3,4-toluenedithiolate(2-)), and [ReN(Et(2)dtc)(2)] (Et(2)dtc = N,N-diethyldithiocarbamate) gave the corresponding mu-nitrido complexes [Ru(CO)(Et(2)dtc)(PPh3)(2)(NOsO3)] (4), [Ru(CO)(Et(2)dtc)(PPh3)(2){NOs(C7H6S2)(2)}] (5) and [Ru(CO)(Et(2)dtc)(PPh3)(2){NRe(Et(2)dtc)(2)}] (6). The structures of complexes 4-6 have been established by X-ray crystallography. The Os-N and Ru-N distances, and Os-N-Ru angle in 4 are 1.719(7) and 2.075(7) Angstrom, and 155.1(4)degrees, respectively. The Os-N and Ru-N distances and Os-N-Ru angle in 5 are 1.680(6) and 2.068(6) Angstrom, and 166.2(3)degrees, respectively. The Re-N and Ru-N distances, and Re-N-Ru angle for 6 are 1.670(3) and 2.108(3) Angstrom, and 170.9(2)degrees, respectively. The bond lengths and angles for these mu-nitrido complexes are indicative of asymmetric bridging mode of nitride, i.e. M=N --> Ru(II) (M = Os(VIII), Os(VI), Re(V)). (C) 2000 Elsevier Science S.A. All rights reserved.

Published
2000

34. Dioxo- and nitrido-osmium complexes with imidodiphosphinochalcogenido ligands [N(QPR(2))(2)](-) (Q = S or Se; R = Ph or Pr-i)

Author

Zhang, Qianfeng, Lau, KK, Chim, JLC, Wong, TKT, Wong, WT, Williams, Ian Duncan, Leung, Wa Hung, Zhang, Qianfeng, Lau, KK, Chim, JLC, Wong, TKT, Wong, WT, Williams, Ian Duncan, and Leung, Wa Hung

Abstract

Reactions of trans-K-2[(OsO2)-O-VI(OH)(4)] with 2 equivalents of HN(QPR(2))(2) yielded the dioxoosmium(VI) complexes trans-[OsO2{N(QPR(2))(2)}(2)] (Q=S, R=Ph 1 or Pr-i 2; Q=Se, R=Ph 3). Complexes 1-3 have been characterised by X-ray crystallography. The Os-O distances in 1-3 are 1.739, 1.734 and 1.748 Angstrom, respectively. trans-[OsN{N(QPR(2))(2)}(2)Cl] (R=Pr-i, Q=S; R=Ph, Q=Se) were obtained by reactions of [NBu4n][OsNCl4] with K[N(QPR(2))(2)]. Treatment of [OsN{N(SPPh2)(2)}(2)][BF4] with [NBu4n][OsO3N] resulted in formation of a mu-nitrido Os-VIII-Os-VI complex [OsN{N(SPPh2)(2)}(2)(NOsO3)], in which the [NOsO3](-) is trans to the terminal nitride ligand. The Os-VI-N, Os-VI-N(Os) and Os-VIII-N distances are 1.617(12), 2.318(11), and 1.719(11) Angstrom, respectively; the Os(1)-N(4)-Os(2) angle being 159.2(7)degrees. Treatment of [OsN{N(SPPh2)(2)}(2)][BF4] with [NBu4n][ReO4] or [NBu4n](2)[M6O19] gave heterometallic mu-oxo complexes trans-[OsN{N(SPPh2)(2)}(2)(OReO3)] or trans-[{OsN[N(SPPh2)(2)](2)}(2)(M6O19)] (M=Mo or W), respectively. Reaction of [NH4](2)[OsCl6] with K[N(SPPh2)(2)] in the presence of PPh3 or treatment of 3 with C6F5SH led to isolation of the osmium(III) homoleptic complexes [Os{N(SPR2)(2)}(3)] (R=Pr-i or Ph). The geometry around Os in the latter is pseudo octahedral, and the average S-Os-S angle and average Os-S distance are 96.06(5)degrees and 2.450 Angstrom, respectively. Osmium(III) phosphoraniminate complexes [Os(NPMePh2)(PMePh2){N(SPPh2)(2)}(2)] and trans-[Os(NPPh3)(PPh3){N(SePPh2)(2)}(2)] were prepared by the respective nitridoosmium(VI) complex with PMePh2 or PPh3. Reaction of complex 1 or 2 with hydrazine hydrate afforded air-sensitive osmium(II) dinitrogen species, presumably [Os{N(SPR2)(2)}(2)(N-2)] (R=Ph or Pr-i), which exhibit IR nu(N-2) at 2060 and 2040 cm(-1), respectively.

Published
2000

35. Synthesis and crystal structure of an imidochromium(V) complex with a thioether macrocyclic ligand

Author

Leung, Wa Hung, Wu, MC, Wong, TKT, Wong, WT, Leung, Wa Hung, Wu, MC, Wong, TKT, and Wong, WT

Abstract

Reaction of [Cr(NBut)Cl-3(dme)] (dme = 1,2-dimethoxyethane) with 1,4,7-trithiacyclononane ([9]aneS(3)) followed by treatment with Ag(CF3SO3) leads to the isolation of [Cr((NBu)-Bu-t)([9]aneS(3))Cl-2(CF3SO3), which has been characterized by X-ray crystallography. The Cr-N, average Cr-S, and average Cr-Cl distances are 1.640(4), 2.431, and 2.273 Angstrom, respectively; the Cr-N-C angle being 173.2(4)degrees. (C) 2000 Elsevier Science S.A. All rights reserved.

Published
2000

36. Ruthenium benzylidene and vinylidene complexes in a sulfur-rich coordination environment

Author

Leung, Wa Hung, Lau, KK, Zhang, Qianfeng, Wong, WT, Tang, Benzhong, Leung, Wa Hung, Lau, KK, Zhang, Qianfeng, Wong, WT, and Tang, Benzhong

Abstract

Interaction of Ru(=CHPh)(PCy3)(2)Cl-2 (Cy = cyclohexyl) with K[N(PPh2S)(2)] affords air-stable Ru(=CHPh)[N(PPh2S)(2)](2), 1, which has been characterized by X-ray diffraction. The Ru-C-alpha and average Ru-S distance for 1 are 1.88(2) and 2.377 Angstrom, respectively. Reaction of 1 with CO gives cis-Ru(CO)(2)[N(PPh2S)(2)](2). Complex 1 undergoes metathesis with ethyl vinyl ether to give the methoxycarbene complex Ru(=CHOEt)[N(PPh2S)(2)](2), 3. Treatment of Ru(=CHPh)(PCy3)(2)Cl-2 with K[N(PPh2Se)(2)] affords Ru(=CHPh)[PPh2NP(Se)Ph-2](2), 4, which has been characterized by X-ray crystallography The Ru-C, average Ru-P, and average Ru-Se distances are 1.873(8), 2.383, and 2.450 A, respectively. Reactions of Ru(=CHPh)(PCy3)(2)Cl-2 with K[P(OR)(2)S-2] afford cis-Ru(=CHPh)(PCy3)[P(OR)(2)S-2](2) (R = Et (6) and i-Pr (7)). Reaction of Ru(=CHPh)(PCy3)(2)Cl-2 with 1,4,7-trithiacyclononane ([9]aneS(3)) gives [([9]aneS(3))Ru(=CHPh)(PCy3)Cl]Cl, 8. Treatment of Ru(=C=CHPh)(PCy3)(2)Cl-2 with K[N(PPh2S)(2)] or [9]aneS(3) affords cis-Ru(=C=CHPh)(PCy3)[N(PPh2S)(2)](2) (9) or ([9]aneS(3))Ru(PCy3)Cl-2 (10), respectively. The Ru-C, Ru-P, and average Ru-S distances in 9 are 1.80(1), 2.420(3), and 2.479 Angstrom, respectively. Complexes 1 and 8 are active catalysts for ring-opening metathesis polymerization of norbornene.

Published
2000

37. Synthesis and reactivity of nitrido-rhenium and -osmium complexes with an oxygen tripod ligand

Author

Leung, WH, Chan, EYY, Lai, TCY, Wong, WT, Leung, WH, Chan, EYY, Lai, TCY, and Wong, WT

Abstract

Interaction of [ReNCl3(PPh3)(2)] or [ReOCl2(PPh3)(3)] with NaLOEt (L-OEt=[Co(eta(5)-C5H5){PO(OEt)(2)}(3)]) afforded [ReLOEtN(PPh3)Cl] 1 and [ReLOEtOCl2] 2, respectively. Reaction of 1 with AgBF4 gave the nitridorhenium(VI) complex [ReLOEtN(PPh3)Cl]BF4 1 . BF4, which has a mu(eff) of 1.8 mu(B). Treatment of 1 with MeOSO2CF3, PhCH2Br or [Ph3C]BF4 afforded the respective organoimido species [ReLOEt(NMe)(PPh3)Cl][CF3SO3] 3, [ReLOEt(NCH2Ph)(PPh3)Cl]Br 4, and [ReLOEt(NCPh3)(PPh3)Cl] 5. Reaction of 1 with [Au(PPh3)(CF3SO3)], [Ru(Et(2)dtc)(PPh3)(2)(CO)(CF3SO3)], or [ReMeO3] yielded the bimetallic nitrido complexes [Au(PPh3){NReLOEt(PPh3)Cl}][CF3SO3] 6, [Ru(Et(2)dtc)(PPh3)(H2O)(CO){NReLOEt(PPh3)Cl}][CF3SO3] 7 or [ReMeO3{NReLOEt(PPh3)Cl}] 8, respectively. Treatment of [NBu4n][OsNCl4] with NaLOEt gave [OsLOEtNCl2] 9. The average Os-O, Os-Cl and Os-N distances in 9 are 2.066, 2.289 and 2.58(1) Angstrom, respectively. Reaction of 9 with PPh3 afforded the osmium(IV) phosphoran iminate species [OsLOEt(NPPh3)Cl-2] 10, which has a mu(eff) of 2.0 mu(B). The average Os-O, Os-Cl and Os-N distances in 10 are 2.099, 2.342, 1.893(5) Angstrom, respectively, the Os-N-P angle being 137.5(3)degrees. The formal potentials of the L-OEt-Re and -Os complexes have been determined by cyclic voltammetry. On the basis of the Re-VI-Re-V formal potential, the pi-donor strength was found to decrease in the order N3->[NAu(PPh3)](2-)> NMe2-.

Published
2000

38. Ruthenium(II) ammine and hydrazine complexes with [N(Ph(2)PQ)(2)](-) (Q = S, Se) ligands

Author

Zhang, Qianfeng, Zheng, HG, Wong, WY, Wong, WT, Leung, Wa Hung, Zhang, Qianfeng, Zheng, HG, Wong, WY, Wong, WT, and Leung, Wa Hung

Abstract

Reactions of coordinatively unsaturated Ru[N(Ph(2)PQ)(2)](2)(PPh3) (Q = S (1), Se (2)) with pyridine (py), SO2, and NH3 afford the corresponding 18e adducts Ru[N(Ph(2)PQ)(2)](2)(PPh3)(L) (Q = S, L = NH3 (5); Q = Se, L = py (3), SO2 (4), NH3 (6)). The molecular structures of complexes 2 and 6 are determined. The geometry around Ru in 2 is pseudo square pyramidal with PPh3 occupying the apical position, while that in 6 is pseudooctahedral with PPh3 and NH3 mutually cis. The Ru-P distances in 2 and 6 are 2.2025(11) and 2.2778(11) Angstrom, respectively. The Ru-N bond length in 6 is 2.185(3) Angstrom. Treatment of 1 or 2 with substituted hydrazines L or NH2OH yields the respective adducts Ru[N(Ph(2)PQ)(2)](2)(PPh3)(L) (Q = S, L = NH2NH2 (12), t-BuNHNH2 (14), l-aminopiperidine (C5H10NNH2) (15); Q = Se, L = PhCONHNH2 (7), PhNHNH2 (8), NH2OH (9), t-BuNHNH2 (10), C5H10NNH2 (11), NH2NH2 (13)), which are isolated as mixtures of their trans and cis isomers. The structures of cis-14 and cis-15 are characterized by X-ray crystallography. In both molecular structures, the ruthenium adopts a pseudooctahedral arrangement with PPh3 and hydrazine mutually cis. The Ru-N bond lengths in cis-14 . CH2Cl2 and cis-15 are 2.152(3) and 2.101(3) Angstrom, respectively. The Ru-N-N bond angles in cis-14 . CH2Cl2 and cis-15 are 120.5(4) and 129.0(2)degrees, respectively. Treatment of 1 with hydrazine monohydrate leads to the isolation of yellow 5 and red trans-Ru[N(Ph2PS)(2)](2)(NH3)(H2O) (16), which are characterized by mass spectrometry, H-1 NMR spectroscopy, and elemental analyses. The geometry around ruthenium in 16 is pseudooctahedral with the NH3 and H2O ligands mutually trans. The Ru-O and Ru-N bond distances are 2.118(4) and 2.142(6) Angstrom, respectively. Oxidation reactions of the above ruthenium hydrazine complexes are also studied.

Published
2000

39. Synthesis and characterization of oxidized products of CuX (X = Cl, Br) and N,N-dimethylbenzeneethanethioamide

Author

Zheng, HG, Chen, TN, Ye, XR, Xin, XQ, Wong, WT, Leung, Wa Hung, Zheng, HG, Chen, TN, Ye, XR, Xin, XQ, Wong, WT, and Leung, Wa Hung

Abstract

The binuclear complexes Cu-2(C10H12ONS)(2)X-2, where X = Cl, Br, have been synthesized and characterized and the X-ray structure determination of Cu-2(C10H12ONS)(2)Br-2 is reported. The ligand originally prepared has been oxidized (along with the metal ion) and changed into a bidentate ligand. Copper(II) has a distorted square planar coordination with Cu-S 2.242(2) Angstrom and Cu-Br 2.318(1) Angstrom. In the structure, two Cu atoms are linked by bridging oxygen atoms with Cu-O 1.908(4) Angstrom and Cu-Cu 3.042 Angstrom.

Published
1999

40. Synthesis and electrochemistry of ruthenium complexes with an oxygen tripod ligand

Author

Leung, Wa Hung, Chan, EYY, Wong, WT, Leung, Wa Hung, Chan, EYY, and Wong, WT

Abstract

Reaction of [Ru(COD)Cl-2](x) (COD = 1,5-cyclooctadiene) with NaLOEt afforded L-OEt(COD)RuCl (1). The average Ru-O, average Ru-C and Ru-Cl distances in 1 are 2.129, 2.164, and 2.398(3) Angstrom, respectively. Treatment of 1 with AgBF4 in acetone/H2O afforded [L-OEt(COD)Ru(OH2)]BF4 (2), which reacts with L to give the respective adducts [L-OEt(COD)RuL]BF4 (L = t-BuNH2 (3), p-MeC6H4NH2 (4), NH3 (5), N2H4 (6), pyridine (7), 4,4'-bipyridine (8), MeCN (9), Et2S (10), and Me2SO (11)). The structures of 3 and 4 have been characterized by X-ray crystallography. The average Ru-O, Ru-C, and Ru-N distances in 3 are 2.115, 2.162, and 2.197(6) Angstrom, respectively. The corresponding bond distances for 4 are 2.113, 2.160 and 2.174(5) Angstrom. Reaction of 8 with 2 afforded the 4.4'-bipyridine-bridged binuclear complex [{L-OEt(COD)Ru}(2)(mu-4,4'-bipy)](PF6)(2) (12). Deprotonation of complexes 2 and 4 gave the hydroxide L-OEt(COD)RuOH (13) and the amide L-OEt(COD)Ru(NUC6H4Me-p) (14). respectively. The structure of [L-OEt(CO)(PPh3)Ru(OH2)]BF4 (15) has been characterized by X-ray crystallography. The average Ru-O(L-OEt), Ru-C, Ru-P, and Ru-O(aquo) distances in 15 are 2.118, 1.83(1), 2.285(3), and 2.091(7) Angstrom, respectively. Interaction of 15 with p-MeC6H4NH2, PPh3, and NaN3 gave [L-OEt(CO)-(PPh3)Ru(p-MeC6H4NH2)]BF4 (16), [L-OEt(PPh3)(2)Ru(CO)]PF6 (17), and L-OEt(CO)(PPh3)RuN3 (18). respectively. Deprotonation of 15 and 16 afforded the hydroxide L-OEt(CO)(PPh3)Ru(OH) (19) and amide LOEt(CO)-(PPh3)Ru(NHC6H4Me-p) (20), respectively. Treatment of Ru(CO)Cl(H)(PPh3), with NaLOEt afforded the hydride L-OEt(CO)(PPh3)RuH (21), which reacts with tosyl azide to give the Ru(II) tosylamide L-OEt(CO)(PPh3)Ru-(NHSO2C6H4Me-p) (22). Reaction of [L-OEt(PPh3)(2)Ru(MeOH)](+) with t-BuNC, CNpy (4-cyanopyridine), Me2SO, (26)), isolated as their PF6 salts. The cyclic voltammograms for the Ru-L-OEt complexes show reversible oxidation couples assignable to Ru(III/II) couples. The availability of electr

Published
1999

41. Heterobimetallic nitrido-bridged Ru(II)NOs(VIII) and Ru(II)NOs(VI) complexes containing ruthenium porphyrins

Author

Leung, Wa Hung, Chim, JLC, Lai, W., Lam, L., Wong, WT, Chan, WH, Yeung, CH, Leung, Wa Hung, Chim, JLC, Lai, W., Lam, L., Wong, WT, Chan, WH, and Yeung, CH

Abstract

Treatment of Ru(por)(NO)(OTf) (por=dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin H-2(OEP) or 5,10,15,20-tetra(p-tolyl)porphyrin H-2(TTP), OTf=triflate) with [(NBu4)-Bu-n][OsO3N] afforded the nitrido-bridged Ru(II)-Os(VIII) complexes [(por)(NO)RuNOsO3] (por=OEP (3) or TTP (4)). The structure of 3 has been established by X-ray crystallography. The Ru-N(O), Ru-N(Os and Os-N distances in 3 are 1.83(2, 2.03(1) and 1.79(1) Angstrom, respectively; the Ru-N-O and Ru-N-Os angles are 153(1) and 138.4(8)degrees, respectively. Reaction of Ru(por)(NO)(OTf) with [(NBu4)-Bu-n]OsNL2] (H2L = 3,4-toluenedithiol) gave the nitrido-bridged Ru(II)-Os(VI) complexes (por)(NO)RuNOsL2 (por = OEP (5), TTP (6)). Treatment of Ru(OEP)(NO)(OTf) with ReN(Et(2)dtc)(2) (Et(2)dtc = N,N-diethyldithiocarbamate) afforded the Ru(IT)-Re(V) complex (OEP)(NO)RuNRe(Et(2)dtc)(2)(OTf) (7). Complexes 3 and 4 exhibit porphyrin-centered oxidation along with Os(VIII)-Os(VIT) and Ru(II)-Ru(I) reductions. Complexes 5 and 6 exhibit Os(VII)-Os(VI) and porphyrin ring oxidation along with Ru(II)-Ru(I) reduction. (C) 1999 Elsevier Science S.A. All rights reserved.

Published
1999

42. Reactions of nitridorhenium(V) and -osmium(VI) complexes with acylating agents

Author

Leung, Wah Hung, Chim, JLC, Williams, Ian D., Wong, WT, Leung, Wah Hung, Chim, JLC, Williams, Ian D., and Wong, WT

Abstract

Interaction of Re(N)L-2 [L = N(PSPh2)(2)] 1 with (CF3CO)(2)O or RCOCl afforded air-sensitive acylimido-Re(V) complexes trans-Re[NC(O)CF3](OCOCF3)L-2 2 or trans-Re[NC(O)R]ClL2 (R = CCl2H 3,CClH2 4, CH3 5), respectively. Treatment of 1 with (CX3CO)(2)O followed by recrystallization from CH2Cl2/hexane in air led to the formation of the corresponding parent imido complexes trans-Re(NH)(OCOCX3)L-2 (X = F 6, Cl 7). The structure of 7 has been characterized by X-ray crystallography. The Re-N, average Re-S, and Re-O distances are 1.664(3), 2.441, and 2.116(3) Angstrom, respectively. Deprotonation of 6 or 7 with Et3N gave 1. Recrystallization of 3 from CH2Cl2/hexane in air resulted in oxo-imido exchange and the isolation of the oxo-Re(V) species trans-Re(O)ClL2. Treatment of 1 with tosyl anhydride gave trans-Re(NH)(OTs)L-2 (OTs = tosyl) 8. Reaction of [n-Bu4N][OsNCl4] with KL afforded trans-Os(N)ClL2 9, which has been characterized by X-ray crystallography. The Os-N, Os-Cl, and average Os-S bond distances in 9 are 1.64(1), 2.577(4), and 2.429 Angstrom, respectively. Treatment of 10 with (CF3CO)(2)O, Ag(CF3CO2), or CF3CO2H resulted in chloride substitution and the formation of trans-Os(N)(OCOCF3)L-2 10. The Os-N, Os-O, and average Os-S distances in 10 are 1.643(5), 2.271(4), and 2.419 Angstrom respectively. Treatment of 1 with [Ph3C]BF4 resulted in the isolation of trans-Re(NCPh3)(F)L-2 11, presumably via the cationic tritylimido intermediate [Re(NCPh3)L-2](+). Reaction of 9 with [Ph3C]BF4 led to chloride abstraction and the formation of five-coordinate [Os(N)L-2]BF4 12. The Os-Nand average Os-S distances in 12 are 1.646(5), and 2.364 Angstrom, respectively.

Published
1999

43. Methoxycarbene and allenylidene complexes of ruthenium with an oxygen tripod ligand

Author

Leung, Wa Hung, Chan, EYY, Wong, WT, Leung, Wa Hung, Chan, EYY, and Wong, WT

Abstract

Interaction of L-OEt(PPh3)(2)RuCl (L-OEt = (eta(5)- C5H5) Co[P(OEt)(2)=O)(3)] with Me3SiC=CH and 2-phenyl-3-butyn-2-ol in the presence of NH4PF6 in MeOH/THF afforded the structurally characterized methoxycarbene [L-OEt(PPh3)(2)Ru=C(OMe)Me]PF6 (1) and the allenylidene complex [L-OEt(PPh3)(2)Ru=C=C=CPhMe]PF6 (2), respectively. The Ru-C distances in 1 and 2 are 1.876(6) and 1.86(2) Angstrom, respectively. The cyclic voltammograms of 1 and 2 exhibit reversible Ru(III/II) couples at 0.58 and 0.64 V vs Cp2Fe+/0 respectively.

Published
1998

44. Tosylimido complexes of tungsten(VI)

Author

Leung, Wa Hung, Wu, MC, Chim, JLC, Wong, WT, Leung, Wa Hung, Wu, MC, Chim, JLC, and Wong, WT

Abstract

Treatment of W(CO)(6) with N,N-dichloro-p-toluenesulfonamide affords [W(NTs)(2)Cl-2](x) 1, which reacts with bipy (2,2'-bipyridine) to give the adduct W(NTs)(2)Cl-2(bipy) 2. The average W-N(imido), W-Cl and W-N (bipy) distances are 1.782, 2.352 and 2.284 Angstrom, respectively. Reaction of [W(NTs)(2)Cl-2](n) with NaTp [Tp = hydrido(trispyrazolyl)borate] gives TpW(NTs)(2)Cl 4. These tungsten(VI) tosylimido complexes undergo imido transfer reactions with tertiary phosphine to give W(IV) and the N-tosyl phosphinimine. (C) 1998 Elsevier Science Ltd. All rights reserved.

Published
1998

46. Syntheses and crystal structures of bi- and tri-metallic complexes containing a trioxoosmium(VIII) moiety

Author

Leung, Wa Hung, Chim, JLC, Wong, WT, Leung, Wa Hung, Chim, JLC, and Wong, WT

Abstract

Interaction of cis-[Pt(dppm)(2)(O3SCF3)(2) [dppm = bis(diphenylphosphino)methane], cis-[Pt(Bupy)(O3SCF3)(2)] (Bupy = 4-tert-butylpyridine), (Ir(CO)(PPh3)(2)(O3SCF3)], and [Rh(cod)(OH2)(OTs)] (cod = cycloocta-1,5-diene, OTs = tosylate) with [NBu(4)(n)l[NOsO3] afforded bimetallic nitrido-bridged complexes cis-[Pt(dppm)(NOsO3)(2)] 3. trans-[Pt(Bupy)(2)(NOsO3)(2)] 4, [Ir(CO)(PPh3)(2)(NOsO3)] 5 and [{Rh(cod)(NOsO3)}(2) 6, respectively. Complex 4 crystallises in the P (1) over bar space group with a = 7.936(1), b = 10.758(2), c = 7.738(1) Angstrom, alpha = 100,02(1), beta = 99.75(1), gamma = 101.75(1)degrees, U=622.5(2) Angstrom(3) for Z = 1. The Pt-N (Os), Os-N and the mean Os-O distances are 1.958(7), 1.681(7) and 1.724 Angstrom, respectively. Complex 5 crystallises in the P2(1)/n space group with a = 10.124(1). b = 15.564(2), c = 22.623(3) Angstrom, beta = 100.08(2)degrees, U = 3509.7(7) Angstrom(3) for Z = 4. The Ir-N, Os-N and the mean Os-O distances are 1.998(7) 1.710(7) and 1.718 Angstrom, respectively. Treatment of [Au(PPh3)(NOsB3)] 1 with Ph3P=NPh gave the N-phosphinimine complex [Au(PPh3){N(=PPh3)Ph}][NOsO3] 7. Complex 7 crystallises in the P2(1)/n space: group with a = 8.780(1), b = 20.781(2), c = 20.711(5) Angstrom, beta = 91.23(1)degrees, U = 3788.0(9) Angstrom(3) for Z = 4. The Au-N distance is 2.091(8) Angstrom and the C-N-P angle in the phosphinimine is 127.0(7)degrees. Reaction of 1 with Bupy led to substitution of Bupy for [NOsO3] and formation of [Au(PPh3)(Bupy)][NOsO3] 8. Reaction of [Pt(dppf)(O3SCF3)Cl] [dppf= 1,1'-bis(diphenylphosphino)ferrocene] with [NBuO4n][NOsO3] afforded the trimetallic complex [Pt(dppf)(NOsO3)Cl] 11. Complex 11 crystallizes in the P2(1)/c space group with a = 20.058(2), b = 14.899(1), c = 23.943(1) Angstrom, beta = 114.57(2)degrees, U = 6508(1) Angstrom(3) for Z = 8. The mean Pt-N, Os-N and Os-O distances are 2.06, 1.66 and 1.67 Angstrom, respectively.

Published
1997

47. Oxidation reactions of dithiocarbamate complexes of ruthenium(II)

Author

Leung, Wa Hung, Chim, JLC, Hou, HW, Hun, TSM, Williams, Ian Duncan, Wong, WT, Leung, Wa Hung, Chim, JLC, Hou, HW, Hun, TSM, Williams, Ian Duncan, and Wong, WT

Abstract

The reaction of Ru(Et(2)dtc)(2)(DMSO) (Et(2)dtc = N,N-diethyldithiocarbamate; DMSO = dimethyl sulfoxide) with t-BuNC gave trans-Ru(Et(2)dtc)(2)(CN-t-Bu)(2), 1. Complex 1 crystallizes in the monoclinic space group P2(1)/n with 9.753(2) Angstrom, b = 11.583(2) Angstrom, c = 12.974(2) Angstrom, and beta = 91.8(2)degrees for Z = 2. The crystal structure of 1 shows the trans disposition of the two isocyanides; the mean Ru-S and Ru-C distances are 2.409 and 1.477(2) Angstrom, respectively. Treatment of [Ru(diene)Cl-2](n) with Na(Et(2)dtc) afforded Ru(Et(2)dtc)(2)(diene) (diene = bicyclo[2.2.1]-hepta-2,5-diene (NBD), 2, 1,5-cyclooctadiene (COD), 3). Complex 2 crystallizes in the triclinic space group P (1) over bar with a 7.316(1) Angstrom, b = 10.346(1) Angstrom, c = 15.123(2) Angstrom, alpha = 103.69(2)degrees, beta = 93.54(2)degrees, and gamma = 100.61(2)degrees for Z = 2. The mean Ru-S and Ru-C distances in 2 are 2.416 and 2.137 Angstrom, respectively. The reaction of cis-Ru(Et(2)dtc)(2)(CO)(2) with iodine gave the 2:1 molecular iodine complex cis-Ru(Et(2)dtc)(2)(CO)(2).1/2 I-2 4, which crystallizes in the monoclinic space group P2(1)/c with a = 7.347(2), b = 22.227(2) Angstrom, c = 12.891(2) Angstrom, and beta =95.98 (2)degrees for Z = 4. The mean Ru-S and Bu-C and the I-l distances in complex 4 are 2.427, 1.903, and 2.745(1) Angstrom, respectively. Treatment of Ru(Et(2)dtc)(2)(DMSO)(2) with I-2 gave the linear Ru(II)-Ru(III)-Ru(III) trimer [Ru-3(Et(2)dtc)(6)(DMSO)(2)](I-3)(2), 5, which crystallizes in the triclinic space group P (1) over bar with a = 14.125(3) Angstrom, b = 20.829(6) Angstrom, c = 13.658(3) Angstrom, alpha = 97.57(2)degrees, beta = 110.01(2)degrees, and gamma = 71.25(2)degrees for Z = 2. The structure of complex 6 can be viewed as consisting of a {Ru-2(III)(Et(2)dtC)(4)}(2+) Core and a (Ru-II(Et(2)dtc)2(DMSO)(2)\} moiety, which are linked together via the two dithiocarbamate sulfurs of the latter. While the two Ru(III) centers are connected by a Ru-R

Published
1997

48. Organometallic compounds of ruthenium containing an anionic oxygen tripod ligand

Author

Leung, Wa Hung, Chan, EYY, Williams, Ian Duncan, Wong, WT, Leung, Wa Hung, Chan, EYY, Williams, Ian Duncan, and Wong, WT

Abstract

Reaction of NaLOEt (L-OEt = (eta(5)-C5H5)Co{P(O)(OEt)(2)}(3)) with Ru(PPh3)(3)Cl-2, Ru(DMSO)(4)Cl-2 (DMSO = dimethyl sulfoxide), and Ru(PPh3)(2)(CO)Cl(CH=CHPh) afforded LOEtRu(PPh3)(2)Cl (1), LOEtRu(DMSO)(2)Cl (2), and LOEtRu(PPh3)(CO)(CH=CHPh) (3), respectively. The structures of complexes 1 and 2 have been established by X-ray crystallography. The mean Ru-O, Ru-P, and Ru-Cl bond distances in 1 are 2.183, 2.267, and 2.393(3) Angstrom, respectively. The mean Ru-O, Ru-S, and Ru-Cl distances in 2 are 2.118, 2.188, and 2.362(2) Angstrom, respectively. Treatment of 3 with HBF4 yielded the olefin complex [LOEtRu(PPh3)(CO)(eta(2)-PhCH=CH2)]BF4 (4). Reaction of complex 1 with PhC=CH in the presence of NH4PF6 gave the vinylidene complex [LOEtRu(PPh3)(2)(=C=CHPh)](PF6) (6). The mean Ru-O, Ru-P, and Ru-C distances in 6 are 2.127, 2.344, and 1.80(2) Angstrom, respectively. Deprotonation of 6 with NaOH gave the acetylide complex LOEtRu(PPh3)(2)(C=CPh) (7). Reaction of complex 1 with 3-butyn-1-ol in the presence of NH4PF6 afforded the cyclic carbene complex [LOEtRu(PPh3)(2)- {=C(CH2)(3)O}]PF6 (8). The mean Ru-O, Ru-P, and Ru-C distances in 8 are 2.175, 2.335, and 1.87(1) Angstrom, respectively. Reaction of LOEtRu(PPh3)(2)Cl with I-2 afforded the cation [LOEtRu(PPh3)(2)Cl](+) (1(+)), isolated as the I-3 and PF6 salts. The mean Ru-O, Ru-P, and Ru-Cl distances in 1(+) are 2.095, 2.380, and 2.300(3) Angstrom, respectively. The cyclic voltammogram of 1 in CH2Cl2 exhibits a reversible Ru(III/II) couple at -0.021 V vs Cp2Fe+/0 .

Published
1997

49. Epoxide ring opening catalysed by imidochromium complexes

Author

Leung, Wa Hung, Wu, MC, Chim, JLC, Yu, MT, Hou, HW, Yeung, Lam Lung, Wong, WT, Wang, Y., Leung, Wa Hung, Wu, MC, Chim, JLC, Yu, MT, Hou, HW, Yeung, Lam Lung, Wong, WT, and Wang, Y.

Abstract

tert-Butylimidochromium complexes catalysed ring opening of epoxides by SiMe3(N-3) to give azidohydrins in good yields. The proposed mechanism for the chromium-mediated epoxide azidolysis involves the intermediacy of a chromium-azide species which delivers nucleophilic azide to the epoxide substrate. The azido complexes [{Cr(NBut)(2)Cl}(2)(mu-N-3)(2)] I and [Cr((BuN)-N-t=NN=NSiMe3)(N-3)Cl-2] 2 have been isolated in the reactions of SiMe3(N-3) with [Cr(NBut)(2)Cl-2] and [Cr(NBut)Cl-3(dme)] (dme = 1,2-dimethoxyethane), respectively. The structure of complex 1 has been established by X-ray crystallography. The mean Cr-N (imide) and Cr-N (azide) distances are 1.605 and 2.061 Angstrom, respectively Reaction of [Cr(NBut)Cl-3(thf)(2)] (thf = tetrahydrofuran) with (S,S)-diop {4,5-[bis(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxolane} gave the dimeric complex [{Cr(NBut)Cl-3}(2){mu-(S,S)-diop}], which has been characterised by X-ray crystallography. The Cr-N and Cr-P distances are 1.593(9) and 2.449(4) Angstrom, respectively.

Published
1997

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