This work was supported by the World Premier International Research Center (WPI) Initiative on Materials Nanoarchitectonics and a Grant-in-Aid for Challenging Exploratory Research (No. 26620139), both of which were provided from MEXT, Japan.

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The authors have nothing to disclose.

הסרה מושלמת של כימיקלים לא הרצויים מן השרף לא תמיד אפשר פשוט על ידי שטיפה עם ממסים שיכולים לפזר אותם כימיקלים בקלות. טכניקת מפתח לשטוף את השרף ביעילות היא לגרום לו להתנפח ולהתכווץ שוב ושוב כך הכימיקלים שנותרו בתוך ייאלצו החוצה. זו הסיבה מדוע שרף בהליך שלנו מטופל עם CH 2 Cl 2 ו MeOH לסירוגין כפי שהוא נשטף (למשל, פרוטוקול 2.1.4). כתוצאה מכך של תגובות צימוד רצופות שאינם כמותיים מרובים, בסך של מערך ממוקד בתערובת כמו-בקעה בסוף הסינתזה-השלב המוצק יכול להיות קטן. למרות כל תגובה בסינתזה-השלב המוצק היא בדרך כלל רק נערכה פעם, אותה תגובת הצימוד ניתן לחזור מספר פעמים, כפי שהודגמה בפרוטוקול 2.6, אם יש צורך לשפר את תשואת הצימוד הכוללת של צעד התגובה המתאים. על ידי חזרה על אותו coupling תגובת שתי פעמים, ~ 10% תשואה גדולה יותר של תגובת הצימוד המתאימה יכולה להתממש. בניגוד מונומרים חומצות אמיניות Fmoc מוגנים נפוצים לסינתזת פוליפפטיד מוצק שלב, אלה מונומרים נושאות קומפלקס מתכת עבור מערכי peptidic multimetallic בדרך כלל להראות תשואה של לא יותר מ -80% בתגובות הצימוד שלהם על פני השטח של השרף. אפקט סטרי בשל נוכחותם של מחצית מורכבת מתכת מגושמת לשחק תפקיד, כמו החדרת יחידת חומצה אמינית אחת על-מסוף C של מונומר לפעמים משפרת תשואת הצימוד שלה באופן דרסטי. עם זאת, אפילו שינויים כאלה של מבנה מונומר עדיין לא מספיק כדי לייעל את תגובות צימוד כמותית. זוהי סוגיה לטפל בעתיד, במיוחד לייצור התפוקה הגבוהה של מערכי peptidic multimetallic באמצעות האוטומציה של התהליך כולו של מתודולוגיה זו, כפי שכבר הוקמה בשינה במקרה של סינתזת פוליפפטיד מוצק שלב. </p&gt; בהשוואת סינתזת פתרון פאזיים, אחד היתרונות החשובים של סינתזה מוצק שלב היא ההפרדה הקלה של מוצרים המחוברים שרף מכימיקלים אחרים את הפתרון על ידי סינון ושטיפה עם ממסים שיכולים לפזר אותם. 11 תכונה זו שימושית במיוחד עבור הסינתזה של מיני multimetallic שאת ההפרדה / טיהור לא קלה עם שיטות אחרות. לפיכך, הפרוטוקול מודגש כאן הוא הבחירה המעשית היחידה לעשות מערכי peptidic multimetallic שיש רצף קבוע מראש של שלוש או יותר מתכות שונות. יתר על כן, בשל הפשטות של שיטה זו, הפרוטוקול יכול לכסות את הייצור של מגוון רחב יותר של מתחמי heteronuclear multimetallic מאלה נגישים כבר קיימים סינתטי גישות 1,2,3. כפי שמרכיבים המיוצרים על ידי שיטה זו יש רצף מושלם מבוקר של מרכזי מתכת לאורך עמוד שדרת פפטיד, הם ערעורing מועמדים כדי לחקור את ההשפעות של מבני רצף מוסדר כגון על האינטראקציות עם מולקולות ביו קשור (למשל, פפטידים, חלבונים, חומצות גרעין, סוכרים, אשר גם להן יש רצף מוסדר במבנה שלהם). זהו התמריץ שלנו כדי להפוך את המוצרים מסיסים במים.

סינתזה מבוקרת של מבנים מולקולריים מורכבים מאז ומתמיד אחד הנושאים המרכזיים בתחום הכימיה סינתטי. מתוך נקודת מבט זו, לסנתז מתחמי multinuclear heterometallic באופן designable עדיין נושא ראוי להיות לערער בתחום כימיה לא אורגנית בגלל המספרים של תוצאות מבניות אפשריות מהגישה-metallation המבוסס ליגנד כי הוא נפוץ עבור הכנת מתחמי מתכת monomeric. למרות כמה דוגמאות של מתחמי heterometallic multinuclear דווחו עד כה 1,2,3, במשפט והטעייה או הטבע מפרך של הסינתזה שלהם מחייבים פיתוח של שיטה פשוטה כי הוא ישים עבור מגוון רחב של מבנים. כתוצאת גישה חדשה כדי לטפל בבעיה זו, בשנת 2011 דיווחנו מתודולוגיה סינטטי 4,5 שבו מתחמי mononuclear מתכת שונים בעלי מחצית אמינו חומצת Fmoc מוגנת הם מצמידים ברצף לתת רבמתכתיים מערכי peptidic באמצעות הפרוטוקולים של סינתזת פוליפפטיד מוצק שלב 6. בשל אופיו הרצוף של סינתזת פוליפפטיד, רצף מסוים של מרכזי מתכת המרובים הוא designable באופן רציונלי על ידי שליטה על המספר וההסדר של תגובות הצימוד של מונומרים יצמידו המתכתיים אלה. בהמשך, גישה זו הייתה עוד modularized לעשות שונים גדולים ו / או מסועף מבני מערך על ידי שילוב עם ההצמדה קוולנטי בין שני מערכים קצרים 7. כאן אנו מראים כיצד סינתזה של מערכים multimetallic peptidic כזה מופעל בדרך כלל על ידי בחירת WSMOCA דיווחה לאחרונה (1 8 CAS RN 1827663-18-2; איור 1) בתור דוגמה מייצגת. למרות הסינתזה של מערך מסוים מתוארת בפרוטוקול זה, אותם ההליכים החלות על הסינתזה של מגוון רחב של רצפים שונים, כולל איזומרים 9. אנו צופים כי זה פרוטוcol תעורר יותר חוקר להשתתף המדע של תרכובות שבשליטת רצף, שבו המולקולות נחקרו עד כה בדרך כלל יש biopolymers היה אך לעתים רחוקות לכלול דוגמאות של מינים מבוססי מתכת מורכבת.

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synthesis of a water-soluble metal&#8211;organic complex array

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as Ru(II), Pt(II), and Rh(III). The compound, named as a water-soluble metal-organic complex array (WSMOCA), is obtained through 1) the conventional solution-chemistry-based preparation of the corresponding metal complex monomers having a 9-fluorenylmethyloxycarbonyl (Fmoc)-protected amino acid moiety and 2) their sequential coupling together with other water-soluble organic building units on the surface-functionalized polymeric resin by following the procedures originally developed for the solid-phase synthesis of polypeptides, with proper modifications. Traces of reactions determined by mass spectrometric analysis at the representative coupling steps in stage 2 confirm the selective construction of a predetermined sequence of metal centers along with the peptide backbone. The WSMOCA cleaved from the resin at the end of stage 2 has a certain level of solubility in aqueous media dependent on the pH value and/or salt content, which is useful for the purification of the compound.

איור 1 מציג את המבנים המולקולריים של המתחם, מבשרי היעד הסופי, ביניים. איור 2 מראה את התמונות של שרף איור 3 מציג את ספקטרה המונית MALDI-TOF של דגימות ב צעדים ההליך שנבחר. תמונות מתוך איור 2 א ל 2H מוצגות שינויים את הצבע והמראה של השרף שהוא עובר במהלך שלבי התגובה בסעיף 2 של הפרוטוקול. MALDI-TOF ספקטרומטריית מסה משמשת להתחקות אחר התגובות כדי לאשר את קיומו של מין היעד כצפוי. <img alt="איור 1" src="/files/ftp_upload/54513/54513fig1.jpg" /> איור 1. מבנה מולקולרי של WSMOCA, מבשרים, ביניים (1) WSMOCA הממוקד.; (2, 3, 4) Ruמונומרים, Pt, ו Rh, בהתאמה; (5) מבשר אורגני עבור מונומר Ru 2; (6) מבשר אורגני עבור מונומר Pt 3 ו Rh מונומר 4; (7) Glu; (8) חומצת TEG; (9, 10, 11) ביניים סינתטי כדי להתגלות ב 2.3.3, 2.5.2, 2.7.2, בהתאמה. <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54513/54513fig1large.jpg" target="_blank">לחץ כאן כדי לצפות בגרסה גדולה יותר של דמות זו.</a> <img alt="איור 2" src="/files/ftp_upload/54513/54513fig2.jpg" /> איור 2. הופעות של השרף על הצעדים הסינתטיים שנבחרו תמונות (א) כפי שנרכש שרף TG סבר בבית הזכוכית לסינתזה מוצק שלב ב 2.1.1.; (ב) שרף תפח ב CH 2 Cl 2 </sUB&gt; ב 2.1.2; (ג) שרף שטף לאחר deprotection של קבוצות Fmoc ב 2.1.4; (ד) שרף המרחפים פתרון והעמסת מונומר Ru 2 ב 2.2.1; (ה) שרף המרחפים פתרון והעמסת Glu ב 2.3.1; (ו) שרף המרחפים פתרון והעמסת מונומר Pt 3 ב 2.4.1; (ז) שרף המרחפים פתרון והעמסת מונומר Rh 4 ב 2.6.1; (ח) שרף המרחפים פתרון עבור התגובה מחשוף ב 2.9.4. <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54513/54513fig2large.jpg" target="_blank">אנא לחץ כאן כדי לצפות בגרסה גדולה יותר של דמות זו.</a> <img alt="איור 3" src="/files/ftp_upload/54513/54513fig3.jpg" /> איור 3. עקבות של הכנת 1 determ. שאינו עומד ידי ניתוח ספקטרומטריה ספקטרה המונית MALDI-TOF של דגימות כמו-בקעו מן שרף ליד המדרגות הנבחרות הסינתזה-השלב המוצק (פרוצדורות (א) 2.3.3 כדי לאשר את קיומו של 9; (ב) 2.5.2 כדי לאשר את קיומו של 10; (ג) 2.7.2 כדי לאשר את קיומו של 11; (ד) 2.9.5 כדי לאשר את קיומו של 1) ואלה של דגימות ב את השלבים הבאים (נהלים (ה) 2.9.7 כדי לאשר את deprotection קבוצות המלא Bu t על שאריות הצד של 1;. (ו) 2.10.5 לאשר בהעדר אותות גדולים אחרים מזו של 1) <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54513/54513fig3large.jpg" target="_blank">נא ללחוץ כאן כדי לצפות בגרסה גדולה יותר של דמות זו.</a>

Watch this Scientific Journal Video about Synthesis of a Water-soluble MetalÃ¢â‚¬â€œOrganic Complex Array at JoVE.com

Synthesis of a Water-soluble Metal&#8211;Organic Complex Array

A potential general method for the synthesis of water-soluble multimetallic peptidic arrays containing a predetermined sequence of metal centers is presented.

סינתזה של מערך מורכב מתכת-אורגנית נמס במים

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as ...

synthesis-of-a-water-soluble-metalorganic-complex-array

Nanyang Technological University

Research

JoVE Journal

Chemistry

9.8K Views.  National Institute for Materials Science. A potential general method for the synthesis of water-soluble multimetallic peptidic arrays containing a predetermined sequence of metal centers is presented.

Video: Synthesis of a Water-soluble Metal–Organic Complex Array

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

The development of fluorescent indicators represented a revolution for life sciences. Genetically encoded and synthetic fluorophores with sensing abilities allowed the visualization of biologically relevant species with high spatial and temporal resolution. Synthetic dyes are of particular interest thanks to their high tunability and the wide range of measureable analytes. However, these molecules suffer several limitations related to small molecule behavior (poor solubility, difficulties in targeting, often no ratiometric imaging allowed). In this work we introduce the development of dendrimer-based sensors and present a procedure for pH measurement in vitro, in living cells and in vivo. We choose dendrimers as ideal platform for our sensors for their many desirable properties (monodispersity, tunable properties, multivalency) that made them a widely used scaffold for several biomedical devices. The conjugation of fluorescent pH indicators to the dendrimer scaffold led to an enhancement of their sensing performances. In particular dendrimers exhibit reduced cell leakage, improved intracellular targeting and allow ratiometric measurements. These novel sensors were successfully employed to measure pH in living HeLa cells and in vivo in mouse brain.

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

Fluorescence sensors are powerful tools in life science. Here we describe a methodology to synthesize and use dendrimer-based fluorescent sensors to measure pH in living cells and in vivo. The dendritic scaffold enhances the properties of conjugated fluorescent dyes leading to improved sensing properties.

סינתזה, משלוח נייד ו<em&gt; בvivo</em&gt; יישום של חיישני pH מבוססי dendrimer

The development of  fluorescent indicators represented a revolution for life sciences. Genetically  encoded and synthetic fluorophores with sensing ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

תבניות מוגדרות אטומי לEpitaxial צמיחה של תחמוצת המורכבת Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Water in Oil Emulsions: A New System for Assembling Water-soluble Chlorophyll-binding Proteins with Hydrophobic Pigments

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. Their functionality critically depends on their specific organization within large and elaborate multisubunit transmembrane protein complexes. In order to understand at the molecular level how these complexes facilitate solar energy conversion, it is essential to understand protein-pigment, and pigment-pigment interactions, and their effect on excited dynamics. One way of gaining such understanding is by constructing and studying complexes of Chls with simple water-soluble recombinant proteins. However, incorporating the lipophilic Chls and BChls into water-soluble proteins is difficult. Moreover, there is no general method, which could be used for assembly of water-soluble proteins with hydrophobic pigments. Here, we demonstrate a simple and high throughput system based on water-in-oil emulsions, which enables assembly of water-soluble proteins with hydrophobic Chls. The new method was validated by assembling recombinant versions of the water-soluble chlorophyll binding protein of Brassicaceae plants (WSCP) with Chl a. We demonstrate the successful assembly of Chl a using crude lysates of WSCP expressing E. coli cell, which may be used for developing a genetic screen system for novel water-soluble Chl-binding proteins, and for studies of Chl-protein interactions and assembly processes.

This manuscript describes a simple and high-throughput method for assembling water-soluble proteins with hydrophobic pigments that is based on water-in-oil emulsions. We demonstrate the effectiveness of the method in the assembly of native chlorophylls with four variants of recombinant water-soluble-chlorophyll binding proteins (WSCPs) of Brassica plants expressed in E. coli.

המים אמולסיות שמן: מערכת חדשה להרכבת חלבונים מסיסים במים כלורופיל מחייב עם פיגמנטים הידרופובי

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. ...

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

סינתזת קילוף של פוספטים זירקוניום Discotic להשיג קריסטלים קולואיד נוזלים

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important structural element found in many complex natural products and pharmaceuticals. Owing to the continual discovery of new guanidine-containing natural products and designed small molecules, rapid and efficient guanidinylation methods are of keen interest to synthetic and medicinal organic chemists. Because the nucleophilicity and basicity of guanidines can affect subsequent chemical transformations, traditional, indirect guanidinylation is typically pursued. Indirect methods commonly employ multiple protection steps involving a latent amine precursor, such as an azide, phthalimide, or carbamate. By circumventing these circuitous methods and employing a direct guanidinylation reaction early in the synthetic sequence, it was possible to forge the linear terminal guanidine containing backbone of clavatadine A to realize a short and streamlined synthesis of this potent factor XIa inhibitor. In practice, guanidine hydrochloride is elaborated with a carefully constructed protecting array that is optimized to survive the synthetic steps to come. In the preparation of clavatadine A, direct guanidinylation of a commercially available diamine eliminated two unnecessary steps from its synthesis. Coupled with the wide variety of known guanidine protecting groups, direct guanidinylation evinces a succinct and efficient practicality inherent to methods that find a home in a synthetic chemist&#39;s toolbox.

Here, we present a protocol for direct, early stage guanidinylation that enables rapid total synthesis of aminoguanidine-containing small organic molecules. An advanced synthetic intermediate used in the synthesis of a blood coagulation factor XIa inhibitor was prepared using this protocol.

ישיר, בשלבים מוקדמים Guanidinylation פרוטוקול לסינתזה של מוצרים טבעיים Aminoguanidine המכיל קומפלקס

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

סינתזה ואפיון של קולואידים מולקולריים

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Chemo-enzymatic Synthesis of N-glycans for Array Development and HIV Antibody Profiling

We present a highly efficient way for the rapid preparation of a wide range of N-linked oligosaccharides (estimated to exceed 20,000 structures) that are commonly found on human glycoproteins. To achieve the desired structural diversity, the strategy began with the chemo-enzymatic synthesis of three kinds of oligosaccharyl fluoride modules, followed by their stepwise &#945;-selective glycosylations at the 3-O and 6-O positions of the mannose residue of the common core trisaccharide having a crucial &#946;-mannoside linkage. We further attached the N-glycans to the surface of an aluminum oxide-coated glass (ACG) slide to create a covalent mixed array for the analysis of hetero-ligand interaction with an HIV antibody. In particular, the binding behavior of a newly isolated HIV-1 broadly neutralizing antibody (bNAb), PG9, to the mixture of closely spaced Man5GlcNAc2 (Man5) and 2,6-di-sialylated bi-antennary complex type N-glycan (SCT) on an ACG array, opens a new avenue to guide the effective immunogen design for HIV vaccine development. In addition, our ACG array embodies a powerful tool to study other HIV antibodies for hetero-ligand binding behavior.

Chemo-enzymatic Synthesis of N-glycans for Array Development and HIV Antibody Profiling

A modular approach to the synthesis of N-glycans for attachment to an aluminum oxide-coated glass slide (ACG slide) as a glycan microarray has been developed and its use for the profiling of an HIV broadly neutralizing antibody has been demonstrated.

כימותרפיה-אנזימטי סינתזה של N- glycans עבור מערך פיתוח נוגדן HIV פרופיל

We present a highly efficient way for the rapid preparation of a wide range of N-linked oligosaccharides (estimated to exceed 20,000 structures) that are ...

Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction

A highly efficient transition metal catalyst removal method is developed. The water-soluble catalyst contains a newly-designed NHC ligand for the catalyst removal via host-guest interactions. The new NHC ligand possesses an adamantyl (guest) tethered linear ethylene glycol units for hydrophobic inclusion into the cavity of a &#946;-cyclodextrin (&#946;-CD) host compound. The new NHC ligand was applied to a Ru-based olefin metathesis catalyst. The Ru catalyst demonstrated excellent activity in representative ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) reactions in aqueous media as well as organic solvent, CH2Cl2. After the reaction was complete, the lingering Ru residue was removed from the aqueous solution with the efficiency of more than 99% (53 ppm of Ru residue) by simple filtration utilizing a host-guest interaction between insoluble silica-grafted &#946;-CD (host) and the adamantyl moiety (guest) on the catalyst. The new Ru catalyst also demonstrated high removal efficiency via extraction when the reaction is run in organic solvent by partitioning the crude reaction mixture between layers of diethyl ether and water. In this way, the catalyst stays in aqueous layer only. In organic layer, the residual Ru amount was only 0.14 ppm in the RCM reactions of diallyl compounds.

A removable water-soluble N-heterocyclic carbene (NHC) ligand in aqueous media via host-guest interaction has been developed. We demonstrated representative olefin metathesis reactions in water as well as in dichloromethane. Via either host-guest interaction or extraction, the residual ruthenium (Ru) catalyst was as low as 0.14 ppm after the reaction.

הסרת הטרוגנית רותניום מסיסים במים אולפין זרז שיכול עיצורים ממדיה מימית באמצעות אינטראקציה מארח-אורח

A highly efficient transition metal catalyst removal method is developed. The water-soluble catalyst contains a newly-designed NHC ligand for the catalyst ...

Negative Additive Manufacturing of Complex Shaped Boron Carbides

Boron carbide (B4C) is one of the hardest materials in existence. However, this attractive property also limits its machineability into complex shapes for high wear, high hardness, and lightweight material applications such as armors. To overcome this challenge, negative additive manufacturing (AM) is employed to produce complex geometries of boron carbides at various length scales. Negative AM first involves gelcasting a suspension into a 3D-printed plastic mold. The mold is then dissolved away, leaving behind a green body as a negative copy. Resorcinol-formaldehyde (RF) is used as a novel gelling agent because unlike traditional hydrogels, there is little to no shrinkage, which allows for extremely complex molds to be used. Furthermore, this gelling agent can be pyrolyzed to leave behind ~50 wt% carbon, which is a highly effective sintering aid for B4C. Due to this highly homogenous distribution of in situ carbon within the B4C matrix, less than 2% porosity can be achieved after sintering. This protocol highlights in detail the methodology for creating near fully dense boron carbide parts with highly complex geometries.

A method called negative additive manufacturing is used to produce near fully dense complex shaped boron carbide parts of various length scales. This technique is possible via the formulation of a novel suspension involving resorcinol-formaldehyde as a unique gelling agent that leaves behind a homogenous carbon sintering aid after pyrolysis.

הייצור מוספים שלילי של קומפלקס בצורת Carbides בורון

Boron carbide (B4C) is one of the hardest materials in existence. However, this attractive property also limits its machineability into complex shapes for ...

Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. Here, we introduce the molten-salt synthesis (MSS) method for making metal oxide nanomaterials. Advantages over other methods include its simplicity, greenness, reliability, scalability, and generalizability. Using pyrochlore lanthanum hafnium oxide (La2Hf2O7) as a representative, we describe the MSS protocol for the successful synthesis of complex metal oxide nanoparticles (NPs). Furthermore, this method has the unique ability to produce NPs with different material features by changing various synthesis parameters such as pH, temperature, duration, and post-annealing. By fine-tuning these parameters, we are able to synthesize highly uniform, non-agglomerated, and highly crystalline NPs. As a specific example, we vary the particle size of the La2Hf2O7&#160;NPs by changing the concentration of the ammonium hydroxide solution used in the MSS process, which allows us to further explore the effect of particle size on various properties. It is expected that the MSS method will become a more popular synthesis method for nanomaterials and more widely employed in the nanoscience and nanotechnology community in the upcoming years.

Here, we demonstrate a unique, relatively low-temperature, molten-salt synthesis method for preparing uniform complex metal oxide lanthanum hafnate nanoparticles.

מלח מותכת סינתזה של חלקיקי תחמוצת מתכת מורכבים

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. ...