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

This work was supported by start-up funding from Virginia Polytechnic Institute and State University. Q.F. acknowledges support from National Natural Science Foundation of China (21504047), Natural Science Foundation of Jiangsu Province (BK20150834), Nanjing University of Posts and Telecommunications Scientific Foundation NUPTSF (NY214179).

Caution: Please consult all relevant materials safety data sheets (MSDS) before use. Many chemicals used in the synthesis are acutely toxic and carcinogenic. Please use all appropriate safety practices when performing reaction including the use of engineering controls (fume hood and glovebox) and personal protective equipment (safety glasses, gloves, lab coat, full-length pants, closed-toe shoes, blue-light blocking safety goggles). Following procedures involve standard air-free handling techniques in a glove box. All so...

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The critical step within the protocol is maintaining the reaction temperature at -15 &#177; 5 &#176;C. All catalysts solutions and OCA monomers have to be stored in a glove box freezer at -35 &#176;C before the polymerization. The reaction vials have to be pre-cooled in the cold trap. During the reaction, because the LED light dissipates heat, it is necessary to monitor the reaction every 15 - 20 minutes. Once the temperature is raised up to -10 &#176;C, liquid nitrogen should be added into the dewar to cool the trap. Th...

पॉली (α-hydroxy acid) (PAHA) जैव चिकित्सा उपकरणों से लेकर पैकेजिंग सामग्रियों तक के आवेदनों के साथ biodegradable और संगत पॉलिमर का एक महत्वपूर्ण वर्ग है । 1 , २ यद्यपि पहस α-hydroxy अम्ल के polycondensation द्वारा सीधे तैयार किया जा सकता है, परिणामस्वरूप मेगावाट के आणविक भार (पहस) सामान्यतः कम होते हैं. lactones (जैसे, lactide और glycolide) के 3 रिंग-ओपनिंग बहुलकीकरण (ROP) एक वैकल्पिक सिंथेटिक दृष्टिकोण है जो मेगावाट और आणविक भार वितरण (Đ) पर बेहतर नियंत्रण प्रदान करता है । हालांकि, पहस में पक्ष श्रृंखला कार्यक्षमता की कमी और lactones में भौतिक और रासायनिक गुणों और उनके अनुप्रयोगों की विविधता की सीमा । 4 , 5 के बाद से २००६, 1, 3-dioxolane-2, 4-दिोनों, तथाकथित O-carboxyanhydrides (OCAs), जो कि सुसाइड-चेन कार्यक्षमताओं के साथ-साथ,6, 7,8 9 , 10 , 11 , 12 , 13 पॉलिएस्टर बहुलकीकरण के लिए अत्यधिक सक्रिय मोनोमर के एक वैकल्पिक वर्ग के रूप में उभरा है । 14 , 15
OCAs के ROP के लिए उत्प्रेरक प्रणालियों organocatalysts में वर्गीकृत किया जा सकता है,8,12,16,17 organometallic उत्प्रेरक12,18,19 ,20,21 और मंहगे हैं । 22 आम तौर पर, एक अधिक या कम अनियंत्रित तरीके से organocatalyst आय में OCAs के ROP, जैसे epimerization (यानी, stereoregularity की कमी के रूप में) OCAs असर इलेक्ट्रॉन के लिए वापस लेने समूहों,8,17 अप्रत्याशित मेगावाट, या स्लो बहुलकीकरण कैनेटीक्स. 13 इन समस्याओं को हल करने के लिए, एक सक्रिय Zn-alkoxide जटिल OCAs के ROP के लिए विकसित किया गया था । epimerization के बिना बहुलकीकरण (डीपी) की कम डिग्री पर 12 अच्छी तरह नियंत्रित रॉप हासिल किए गए । हालांकि, इस Zn-alkoxide उत्प्रेरक कुशलता से बहुलकीकरण (डीपी ≥ ३००) के एक उच्च डिग्री के साथ पॉलिमर का उत्पादन नहीं कर सकते । 13
हमने हाल ही में एक होनहार दृष्टिकोण है कि काफी अनुकूलन और PAHA संश्लेषण की दक्षता में सुधार की सूचना दी है (चित्रा 1) । 13 हम photoredox Ni/आईआर उत्प्रेरक है कि जस्ता alkoxide के साथ OCA decarboxylation को बढ़ावा देने के लिए मध्यस्थता अंगूठी खोलने बहुलकीकरण के OCAs विलय । कम तापमान का उपयोग (-15 डिग्री सेल्सियस) और photoredox नी/आईआर catalysis synergistically की अंगूठी खोलने और श्रृंखला के प्रसार के लिए OCA के decarboxylation में बढ़ौतरी करते हुए अवांछित पक्ष प्रतिक्रियाओं से परहेज, जैसे, नी-carbonyl के गठन । 23 , 24 transmetalation पर नी परिसर के साथ सक्रिय Zn-alkoxide चेन प्रचार के लिए चेन टर्मिनस पर स्थित है । 13
इस प्रोटोकॉल में, हम नए सिरे से तैयार (bpy) नी जोड़ने (कॉड) (bpy = 2, 2 '-bipyridyl, कॉड = 1, 5-cyclooctadiene), Zn (HMDS)2 (HMDS = hexamethyldisilazane),25 benzyl अल्कोहल (BnOH) और Ir [dF (CF3) ppy]2(dtbbpy) कत6 ( Ir-1, dF (CF3) ppy = 2-(2, 4-difluorophenyl)-5-(trifluoromethyl) pyridine, dtbbpy = 4, 4 '-di-टर्ट-butyl-2, 2 '-bipyridine) में मोनोमर एल-1 समाधान26 एक दस्ताने बॉक्स में एक ठंडे जाल के साथ, एक की उपस्थिति में नीला एलईडी लाइट (400-500 एनएम) और एक प्रशंसक तापमान (चित्रा 1) बनाए रखने के लिए । तापमान बहुलकीकरण के दौरान-15 ° c ± 5 ° c में रखा जाता है । OCA के रूपांतरण का रूपान्तर-रूपांतर इन्फ्रारेड स्पेक्ट्रोस्कोपी द्वारा मॉनीटर किया जाता है. परिणामस्वरूप बहुलक मेगावाट और Đएस एक जेल permeation क्रोमैटोग्राफी (GPC) की विशेषता है । homodecoupling 1एच एनएमआर अध्ययन निर्धारित करता है कि प्राप्त बहुलक isotactic है या नहीं । के रूप में सबसे अधिक रसायनों नमी के प्रति संवेदनशील हैं, विस्तृत वीडियो प्रोटोकॉल नए चिकित्सकों OCAs के photoredox ROP के साथ जुड़े नुकसान से बचने में मदद करने के लिए करना है ।

<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

यहां, हम एक प्रभावी प्रोटोकॉल का वर्णन है कि एक Zn के उपयोग के साथ photoredox नी/आईआर catalysis को जोड़ती है-कुशल अंगूठी खोलने बहुलकीकरण के लिए alkoxide, isotactic पाली के संश्लेषण के लिए अनुमति (α-hydroxy एसिड) की उंमीद आणविक भार के साथ (> 140 केडीए) और संकीर्ण आणविक भार वितरण (एमडब्ल्यू/एमएन < १.१). इस अंगूठी-खोलने बहुलकीकरण एक शराब सर्जक और एक photoredox Ir उत्प्रेरक, विकिरणित द्वारा एक नीली एलईडी (४००-५०० एनएम) की उपस्थिति में एनआई और Zn परिसरों से मध्यस्थता है । बहुलकीकरण अवांछित साइड प्रतिक्रियाओं से बचने के लिए एक कम तापमान (-15 डिग्री सेल्सियस) पर किया जाता है । पूरा मोनोमर खपत 4-8 घंटे के भीतर प्राप्त किया जा सकता है, एक बहुलक संकीर्ण आणविक वजन वितरण के साथ उंमीद की आणविक वजन के करीब प्रदान । परिणामस्वरूप संख्या-औसत आणविक वजन १००० तक बहुलकीकरण की डिग्री के साथ एक रैखिक संबंध से पता चलता है । homodecoupling 1एच एनएमआर अध्ययन की पुष्टि करता है कि प्राप्त बहुलक epimerization के बिना isotactic है । इस बहुलकीकरण इस के साथ साथ रिपोर्ट तेजी से प्राप्त करने के लिए एक रणनीति प्रदान करता है, नियंत्रित ओ-carboxyanhydrides बहुलकीकरण stereoregular पाली तैयार करने के लिए (α-hydroxy एसिड) और इसके copolymers असर विभिन्न कार्यात्मक पक्ष श्रृंखला समूहों.

The conversion of OCA is monitored by Fourier-transform infrared spectroscopy, as shown in Figure 2. The peak at 1805 cm-1 is assigned as the anhydride bond stretch in OCA; the peak at 1760 cm-1 corresponds to the formation of the ester bond in the polymer. Once the monomer&#39;s peak at 1805 cm-1 completely disappears, the polymerization is finished.
The MW and ...

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

A protocol for the controlled photoredox ring-opening polymerization of O-carboxyanhydrides mediated by Ni/Zn complexes is presented.

नियंत्रित Photoredox अंगूठी-खोलने के बहुलकीकरण ओ-Carboxyanhydrides द्वारा मध्यस्थ/Zn परिसरों

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

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