Examination of Acid-Fast Bacilli in Sputum Using Modified Light Microscope with Homemade Light Emitting Diode Additional Attachment

Typical clinical symptoms and chest X-ray is a marker of Tuberculosis (TB) sufferers. However, the diagnosis of TB in adults should be supported by microscopic examination. Currently, Bacilli microscopic examination of acid-fast bacilli (AFB) in sputum by Ziehl-Neelsen (ZN) coloring is the most widely used. However, for reasons of convenience, especially for laboratories with a considerable amount of smear samples, and due to higher sensitivity compared with ZN staining, the World Health Organization (WHO) has recommended the use of auramine-O-staining (fluorochrome  staining), which is visualized by light emitting diode (LED) fluorescence microscopy. The aim of this study was to evaluate the performance of modified light microscope with homemade LED additional attachment for examination of AFB in sputum using auramine-O-staining method. We compared the sensitivity and specificity of 2 kinds of AFB in sputum methods: ZN and fluorochrome, using culture on Lowenstein-Jensen media as the gold standard. The results showed auramine-O-staining gives more proportion of positive findings (81%) compared to the ZN method (70%). These results demonstrated that the sensitivity of auramine-O-staining was higher than ZN, however it gives more potential false positive results than ZN. The sensitivity of auramine-O-staining in detecting AFB in sputum was 100% while the specificity was 88%

Stoichiometric and Catalytic Reactions of Thermally Stable Nickel(0) NHC Complexes

Although there are many organic reactions that are catalyzed by either Ni⁰ or Pd⁰ complexes, in comparison with the case for Pd⁰ there has been significantly less work studying coordinatively unsaturated Ni⁰ complexes. Here, we develop a simple synthetic route for preparing a number of thermally stable NHC-supported Ni⁰ hexadiene complexes in good yield. We examine the stoichiometric reactivity of one of these species and demonstrate that the coordinated hexadiene moiety is labile and can be replaced with a variety of different ligands, including CO, phosphines, isonitriles, and olefins. In addition, we show that the Ni⁰ hexadiene complexes are relatively rare examples of homogeneous first-row transition-metal catalysts for the hydrogenation of olefins

Stoichiometric and Catalytic Reactions of Thermally Stable Nickel(0) NHC Complexes

Although there are many organic reactions that are catalyzed by either Ni⁰ or Pd⁰ complexes, in comparison with the case for Pd⁰ there has been significantly less work studying coordinatively unsaturated Ni⁰ complexes. Here, we develop a simple synthetic route for preparing a number of thermally stable NHC-supported Ni⁰ hexadiene complexes in good yield. We examine the stoichiometric reactivity of one of these species and demonstrate that the coordinated hexadiene moiety is labile and can be replaced with a variety of different ligands, including CO, phosphines, isonitriles, and olefins. In addition, we show that the Ni⁰ hexadiene complexes are relatively rare examples of homogeneous first-row transition-metal catalysts for the hydrogenation of olefins

Synthesis and Structure of Six-Coordinate Iron Borohydride Complexes Supported by PNP Ligands

The preparation of a number of iron complexes supported by ligands of the type HN­{CH₂CH₂(PR₂)}₂ [R = isopropyl (^ⁱPrPNP) or cyclohexyl (^CyPNP)] is reported. This is the first time this important bifunctional ligand has been coordinated to iron. The iron­(II) complexes (^ⁱPrPNP)­FeCl₂(CO) (<b>1a</b>) and (^CyPNP)­FeCl₂(CO) (<b>1b</b>) were synthesized through the reaction of the appropriate free ligand and FeCl₂ in the presence of CO. The iron(0) complex (^ⁱPrPNP)­Fe­(CO)₂ (<b>2a</b>) was prepared through the reaction of Fe­(CO)₅ with ^ⁱPrPNP, while irradiating with UV light. Compound <b>2a</b> is unstable in CH₂Cl₂ and is oxidized to <b>1a</b> via the intermediate iron­(II) complex [(^ⁱPrPNP)­FeCl­(CO)₂]Cl (<b>3a</b>). The reaction of <b>2a</b> with HCl generated the related complex [(^ⁱPrPNP)­FeH­(CO)₂]Cl (<b>4a</b>), while the neutral iron hydrides (^ⁱPrPNP)­FeHCl­(CO) (<b>5a</b>) and (^CyPNP)­FeHCl­(CO) (<b>5b</b>) were synthesized through the reaction of <b>1a</b> or <b>1b</b> with 1 equiv of ⁿBu₄NBH₄. The related reaction between <b>1a</b> and excess NaBH₄ generated the unusual η¹-HBH₃ complex (^ⁱPrPNP)­FeH­(η¹-HBH₃)­(CO) (<b>6a</b>). This complex features a bifurcated intramolecular dihydrogen bond between two of the hydrogen atoms associated with the η¹-HBH₃ ligand and the N–H proton of the pincer ligand, as well as intermolecular dihydrogen bonding. The protonation of <b>6a</b> with 2,6-lutidinium tetraphenylborate resulted in the formation of the dimeric complex [{(^ⁱPrPNP)­FeH­(CO)}₂(μ₂,η¹:η¹-H₂BH₂)]­[BPh₄] (<b>7a</b>), which features a rare example of a μ₂,η¹:η¹-H₂BH₂ ligand. Unlike all previous examples of complexes with a μ₂,η¹:η¹-H₂BH₂ ligand, there is no metal–metal bond and additional bridging ligand supporting the borohydride ligand in <b>7a</b>; however, it is proposed that two dihydrogen-bonding interactions stabilize the complex. Complexes <b>1a</b>, <b>2a</b>, <b>3a</b>, <b>4a</b>, <b>5a</b>, <b>6a</b>, and <b>7a</b> were characterized by X-ray crystallography

Synthesis and Structure of Six-Coordinate Iron Borohydride Complexes Supported by PNP Ligands

The preparation of a number of iron complexes supported by ligands of the type HN­{CH₂CH₂(PR₂)}₂ [R = isopropyl (^ⁱPrPNP) or cyclohexyl (^CyPNP)] is reported. This is the first time this important bifunctional ligand has been coordinated to iron. The iron­(II) complexes (^ⁱPrPNP)­FeCl₂(CO) (<b>1a</b>) and (^CyPNP)­FeCl₂(CO) (<b>1b</b>) were synthesized through the reaction of the appropriate free ligand and FeCl₂ in the presence of CO. The iron(0) complex (^ⁱPrPNP)­Fe­(CO)₂ (<b>2a</b>) was prepared through the reaction of Fe­(CO)₅ with ^ⁱPrPNP, while irradiating with UV light. Compound <b>2a</b> is unstable in CH₂Cl₂ and is oxidized to <b>1a</b> via the intermediate iron­(II) complex [(^ⁱPrPNP)­FeCl­(CO)₂]Cl (<b>3a</b>). The reaction of <b>2a</b> with HCl generated the related complex [(^ⁱPrPNP)­FeH­(CO)₂]Cl (<b>4a</b>), while the neutral iron hydrides (^ⁱPrPNP)­FeHCl­(CO) (<b>5a</b>) and (^CyPNP)­FeHCl­(CO) (<b>5b</b>) were synthesized through the reaction of <b>1a</b> or <b>1b</b> with 1 equiv of ⁿBu₄NBH₄. The related reaction between <b>1a</b> and excess NaBH₄ generated the unusual η¹-HBH₃ complex (^ⁱPrPNP)­FeH­(η¹-HBH₃)­(CO) (<b>6a</b>). This complex features a bifurcated intramolecular dihydrogen bond between two of the hydrogen atoms associated with the η¹-HBH₃ ligand and the N–H proton of the pincer ligand, as well as intermolecular dihydrogen bonding. The protonation of <b>6a</b> with 2,6-lutidinium tetraphenylborate resulted in the formation of the dimeric complex [{(^ⁱPrPNP)­FeH­(CO)}₂(μ₂,η¹:η¹-H₂BH₂)]­[BPh₄] (<b>7a</b>), which features a rare example of a μ₂,η¹:η¹-H₂BH₂ ligand. Unlike all previous examples of complexes with a μ₂,η¹:η¹-H₂BH₂ ligand, there is no metal–metal bond and additional bridging ligand supporting the borohydride ligand in <b>7a</b>; however, it is proposed that two dihydrogen-bonding interactions stabilize the complex. Complexes <b>1a</b>, <b>2a</b>, <b>3a</b>, <b>4a</b>, <b>5a</b>, <b>6a</b>, and <b>7a</b> were characterized by X-ray crystallography

Organometallic Ni Pincer Complexes for the Electrocatalytic Production of Hydrogen

Nonplatinum metals are needed to perform cost-effective water reduction electrocatalysis to enable technological implementation of a proposed hydrogen economy. We describe electrocatalytic proton reduction and H₂ production by two organometallic nickel complexes with tridentate pincer ligands. The kinetics of H₂ production from voltammetry is consistent with an overall third order rate law: the reaction is second order in acid and first order in catalyst. Hydrogen production with 90–95% Faradaic yields was confirmed by gas analysis, and UV–vis spectroscopy suggests that the ligand remains bound to the catalyst over the course of the reaction. A computational study provides mechanistic insights into the proposed catalytic cycle. Furthermore, two proposed intermediates in the proton reduction cycle were isolated in a representative system and show a catalytic response akin to the parent compound

Organometallic Ni Pincer Complexes for the Electrocatalytic Production of Hydrogen

Nonplatinum metals are needed to perform cost-effective water reduction electrocatalysis to enable technological implementation of a proposed hydrogen economy. We describe electrocatalytic proton reduction and H₂ production by two organometallic nickel complexes with tridentate pincer ligands. The kinetics of H₂ production from voltammetry is consistent with an overall third order rate law: the reaction is second order in acid and first order in catalyst. Hydrogen production with 90–95% Faradaic yields was confirmed by gas analysis, and UV–vis spectroscopy suggests that the ligand remains bound to the catalyst over the course of the reaction. A computational study provides mechanistic insights into the proposed catalytic cycle. Furthermore, two proposed intermediates in the proton reduction cycle were isolated in a representative system and show a catalytic response akin to the parent compound