Name: controlled photoredox ring-opening polymerization of o-carboxyanhydrides mediated by ni/zn complexes
Uploaded: 2017-11-21T15:00:00
Description: Watch this Scientific Journal Video about Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes at JoVE.com

Dette arbeidet ble støttet av oppstart finansiering fra Virginia Polytechnic Institute og State University. Q.F. anerkjenner støtte fra National Natural Science Foundation i Kina (21504047), Natural Science Foundation i Jiangsu provinsen (BK20150834), Nanjing University of innlegg og telekommunikasjon vitenskapelige Foundation NUPTSF (NY214179).

Forsiktig: Se alle relevante materialer Produktdatablad (MSDS) før bruk. Mange kjemikalier som brukes i syntesen er akutt giftige og kreftfremkallende. Kan bruke alle nødvendige sikkerhets praksis når reaksjon inkludert bruk av engineering kontroller (avtrekksvifte og glovebox) og personlig verneutstyr (vernebriller, hansker, laboratoriefrakk, full lengde bukser, lukket-toe sko, blått lys blokkere sikkerhet beskyttelsesbriller). Følgende fremgangsmåter innebærer standard luft-fri behandling teknikker i en hanskero...

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Det kritiske trinnet innenfor protokollen er å opprettholde temperaturen reaksjon-15 ± 5 ° C. Alle katalysatorer løsninger og OCA monomerer må lagres i en hanskerommet fryser ved-35 ° C før polymerisasjon. Reaksjon hetteglass må være pre-avkjølt i kalde fellen. I reaksjon, fordi LED-lys avleder varme, er det nødvendig å overvåke reaksjonen hver 15-20 minutter. Når temperaturen er hevet opp til-10 ° C, flytende nitrogen bør legges i dewar avkjøles fellen. Grunnen til lav temperatur er dannelsen av Ni(CO) ...

Poly (α-hydroxy acid) (PAHA) er en viktig klasse av biologisk nedbrytbart og biokompatible polymerer med programmer mellom biomedisinsk enheter emballasje. 1 , 2 selv om PAHAs kan tilberedes direkte av polycondensation av α-hydroxy syrer, molekylvekt (MWs) av de resulterende PAHAs er generelt lave. 3 ring-åpning polymerisasjon (ROPS) av lactones (f.eks lactide og glycolide) er en alternativ syntetiske tilnærming som gir bedre kontroll mø og molekylvekt distribusjon (Đ) enn polycondensation. Men mangel på side-kjeden funksjonaliteten i PAHAs og i lactones begrense mangfoldet av fysiske og kjemiske egenskaper og deres programmer. 4 , 5 siden 2006, 1,3-dioxolane-2,4-diones, såkalte O- carboxyanhydrides (OCAs), som kan være forberedt med et rikt utvalg av side-kjeden funksjonaliteten,6,7,8, 9 , 10 , 11 , 12 , 13 har framstått som en alternativ klasse av høyaktiv monomerer for polyester polymerisasjon. 14 , 15
Katalytisk systemer for ROP av OCAs kan kategoriseres i organocatalysts,8,12,16,17 organometalliske katalysatorer12,18,19 ,20,21 og biocatalysts. 22 vanligvis ROP av OCAs fremmet av organocatalyst fortsetter på en mer eller mindre ukontrollert måte, for eksempel epimerization (dvs. mangel på stereoregularity) for OCAs bærer uttak av elektron grupper,8,17 uforutsigbare mø, eller langsom polymerisasjon kinetics. 13 for å løse disse problemene, en aktiv Zn-alkoxide komplekset ble utviklet for ROP av OCAs. 12 well-controlled ROPs ble oppnådd på en lav grad av polymerisasjon (DP) uten epimerization. Men kan ikke dette emnet katalysator Zn-alkoxide effektivt produsere polymerer med en høy grad av polymerisasjon (DP ≥ 300). 13
Vi har nylig rapportert en lovende tilnærming som forbedrer customizability og effektiviteten av PAHA syntese (figur 1). 13 vi flette photoredox Ni/Ir katalysatorer som fremmer OCA dekarboksylering med sink alkoxide å megle ring-åpning polymerisering av OCAs. Bruk av lav temperatur (-15 ° C) og photoredox Ni/Ir katalyse akselererer synergi ring-åpning og dekarboksylering av OCA for kjeden overføring og unngå uønskede side reaksjoner, f.eks dannelsen av Ni-karbonyl. 23 , 24 på transmetalation med Ni komplekse den aktive Zn-alkoxide ligger på kjeden terminus for kjeden overføring. 13
I denne protokollen, legger vi til fersk tilberedt (bpy)Ni(COD) (bpy = 2, 2-bipyridyl, COD = 1,5-cyclooctadiene), Zn(HMDS)2 (HMDS = hexamethyldisilazane),25 benzylalkohol (BnOH) og Ir [dF (CF3) ppy]2(dtbbpy) PF6 ( Ir-1, dF (CF3) ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl) pyridine, dtbbpy = 4, 4' - di -tert- butyl-2, 2-bipyridine) i monomer l-1 løsning26 i et hanskerom med en kald felle, i nærvær av en blå LED-lyset (400-500 nm) og en fan å opprettholde temperatur (figur 1). Temperaturen holdes på-15 ° C ± 5 ° C i løpet av polymerisasjon. Konvertering av OCA overvåkes av Fourier-transform infrarødspektroskopi. Den resulterende polymer mø og Đs er preget av en gel gjennomtrengning kromatografi (GPC). Homodecoupling 1H-NMR studie avgjør om den fått polymer er isotactic eller ikke. Som de fleste kjemikalier er svært sensitiv for fuktighet, er detaljert video protokollen ment å hjelpe nye utøvere unngå fallgruvene knyttet photoredox ROP av OCAs.

<table>
	<tbody>
		<tr>
			<td>Ni(COD)2</td>
			<td>Strem</td>
			<td>28-0010</td>
			<td>Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>2,2&#8242;-bipyridine</td>
			<td>Strem</td>
			<td>07-0290</td>
			<td>Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>Zn(HMDS)2</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Synthesized following reported procedures.25 Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>Benzyl alcohol</td>
			<td>Sigma-Aldrich</td>
			<td>402834</td>
			<td>Stored with 4&#197; molecular sieve</td>
		</tr>
		<tr>
			<td>Ir[dF(CF3)ppy]2(dtbbpy)PF6</td>
			<td>Strem</td>
			<td>77-0425</td>
			<td>Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>THF</td>
			<td>Sigma-Aldrich</td>
			<td>34865</td>
			<td>Dried by alumina columns and stored with 4&#197; molecular sieve in the dark bottle in the glove box.</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma-Aldrich</td>
			<td>793175</td>
			<td></td>
		</tr>
		<tr>
			<td>GPC with an isocratic pump</td>
			<td>Agilent</td>
			<td>Agilent 1260 series</td>
			<td></td>
		</tr>
		<tr>
			<td>Dawn Heleos II Light Scatterer</td>
			<td>Wyatt</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Optilab rEX differential refractive index detector</td>
			<td>Wyatt</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Size exclusion columns</td>
			<td>Phenomenex</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Scintillation Vials - 7 ml</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FTIR spectrometer</td>
			<td>Agilent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stir bars</td>
			<td>VWR</td>
			<td>58948-091</td>
			<td></td>
		</tr>
		<tr>
			<td>Balance</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glove box</td>
			<td>Mbraun</td>
			<td>Labstar Pro</td>
			<td></td>
		</tr>
	</tbody>
</table>

controlled photoredox ring-opening polymerization of o-carboxyanhydrides mediated by ni/zn complexes

Her beskriver vi en effektiv protokoll som kombinerer photoredox Ni/Ir katalyse med bruk av en Zn-alkoxide for effektiv ring-åpning polymerisasjon, tillater for syntese av isotactic poly (α-hydroxy syrer) med forventet molekylvekt (> 140 kDa) og smale molekylvekt distribusjoner (Mm/Mn < 1.1). Denne ringen-åpning polymerisasjon er formidlet av Ni og Zn komplekser i nærvær av en alkohol initiator og en photoredox Ir katalysator, bestrålt av en blå LED (400-500 nm). Polymerisasjon utføres ved lav temperatur (-15 ° C) å unngå uønskede side reaksjoner. Komplett monomer forbruket kan oppnås innen 4-8 timer, gir en polymer nær den forventede Molekylvekten smale molekylvekt distribusjon. Den resulterte mange middels Molekylvekten viser en lineær sammenheng med graden av polymerisasjon opp til 1000. Homodecoupling 1H-NMR studien bekrefter at den fått polymer isotactic uten epimerization. Denne polymerisasjon rapporterte her tilbyr en strategi for å oppnå rask, kontrollert O- carboxyanhydrides polymerisasjon for å forberede stereoregular poly (α-hydroxy syrer) og dens copolymers bærer ulike funksjonelle side-kjede grupper.

Konvertering av OCA overvåkes av Fourier-transform infrarød spektroskopi, som vist i figur 2. Høyden på 1805 cm-1 er tildelt som anhydride bond strekningen i OCA; høyden på 1760 cm-1 tilsvarer dannelsen av ester bond i polymer. Når monomer's peak på 1805 cm-1 forsvinner helt, er polymerisasjon ferdig.
MW og Đ av den resulterende polymer er preget av...

Watch this Scientific Journal Video about Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes at JoVE.com

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

En protokoll for kontrollert photoredox ring-åpning polymerisasjon av O- carboxyanhydrides formidlet av Ni/Zn komplekser vises.

Kontrollert Photoredox Ring-åpning polymerisering av O- Carboxyanhydrides formidlet av Ni/Zn komplekser

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...

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Chemistry

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies

Produksjon av disulfide-stabilisert transmembrane Peptid Komplekser for Strukturelle studier

Physical  interactions among the lipid-embedded alpha-helical domains of membrane  proteins play a crucial role in folding and assembly of membrane ...

Anticancer Metal Complexes: Synthesis and Cytotoxicity Evaluation by the MTT Assay

Anticancer Metal Komplekser: Syntese og Cytotoksisitet Evaluering av MTT analysen

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; ...

Facile and Efficient Preparation of Tri-component Fluorescent Glycopolymers via RAFT-controlled Polymerization

Lettvinte og effektiv Utarbeidelse av Tri-komponent Fluorescent Glycopolymers via RAFT-kontrollerte Polymerisering

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and ...

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

Etylen Polymerisasjoner parallellTrykk reaktorer og et Kinetic Analysis of Chain Transfer Polymerisering

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel ...

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

Atom Transfer radikalpolymerisering av Funksjon vinylmonomerer Bruke perylen som en synlig lys Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Facile Synthesis of Worm-lignende Miceller av synlig lys mediert dispersjonspolymeriseringen Bruke Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by &#960;-&#960; Stacking Interactions

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by ÃƒÆ’Ã‚ÂÃƒÂ¢Ã¢â‚¬Å¡Ã‚Â¬-ÃƒÆ’Ã‚ÂÃƒÂ¢Ã¢â‚¬Å¡Ã‚Â¬ Stacking Interactions

Anioniske polymerisering av en amfifil copolymer for forberedelse av blokk-kopolymer Miceller stabilisert av π-rc stabling Interactions

In this study, an amphiphilic copolymer that includes a core-forming block with phenyl groups was synthesized by living anionic polymerization of phenyl ...

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

En enkel og effektiv protokoll for katalytisk Insertion Polymerisering av funksjonelle norbornener

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic ...

Extraction of Ramie Fiber in Alkali Hydrogen Peroxide System Supported by Controlled-release Alkali Source

Utvinning av Rami Fiber i lut hydrogenperoksid systemet støttes av kontrollert-release Alkali kilde

This protocol demonstrates a method for ramie fiber extraction by scouring raw ramie in an alkali hydrogen peroxide system supported by a ...

Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

Utarbeidelse av hul polystyren partikler og Microcapsules ved radikale polymerisering av Janus dråper bestående av hydrokarboner og Fluorocarbon oljer

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...