우리는 우리의 집 기관 인정은 콜 Polytechnique 연방 공과대 학교 드 로잔 (EPFL), 그것의 관대 한 지원에 대 한. 이 프로젝트는 유럽 연합의 수평선 2020 연구에서 자금 받았다 고 혁신 프로그램 Marie Skłodowska-퀴리 아래 부여 계약 번호 665667. 저자는 XRD로 그의 도움에 대 한 파스칼 알렉산더 Schouwink 감사합니다.

주의: 읽기 신중 하 게 관련 된 화학 물질의 물질 안전 데이터 시트 (MSDS). 일부는 실험에 사용 된 화학 물질의 독성이 있다. 현재 방법은 나노 입자의 합성을 포함 한다. 따라서, 적절 한 예방 조치. 환기가 증기 두건에서 전체 합성 절차를 수행 해야 합니다.
참고: 악기, 화학 물질, MOF 영화의 합성에 관련 된 자료의 세부 정보는 표 1에 나열 됩니다.
1. 준비 금속 소금 솔루션 및 링커 솔루션의 선구자 솔에 대 한
주: ZIF-8 영화의 합성, 아연 질 산 hexahydrate [Zn (3)2.6H2O] 사용 금속 소금으로 하 고 2-methylimidazole (HmIm) 링커로 사용 된다.
<ol><li>금속 소금 솔루션에 대 한 Zn (3)2.6H2O 물 500 ml에서의 2.75 g을 분해.</li>
	<li>링커 솔루션 56.75 g HmIm의 물 500 mL에 녹이 고 명확한 해결책을 얻을 때까지 계속 저 어.</li>
</ol>2입니다. Cu 전극의 준비
<ol><li>4 x 4 cm 조각으로 (99.9% 순도, 127 µ m 두께)와 고 순도 구리 호 일을 잘라.</li>
	<li>Cu 악어 클립의 집합을 잘라 호 일 죄의 용이성을 위해 사각 호 일의 가장자리 중 하나에서 0.5 cm의 거리에서 선을 그립니다.</li>
	<li>원통형 롤러를 사용 하 여 깨끗 한 표면에 호 일을 평평 하 게.</li>
	<li>15 분, 15 분 동안 소 프로 파 놀에 목욕 쥡니다 다음 아세톤에 목욕 쥡니다, 구리 포 일을 철저 하 게 청소.</li>
	<li>깨끗 한 분위기에서 구리 포 일을 건조.</li>
</ol>3. 기판 전극 (음극)을 부착
참고: MOF 필름을 예금 하는 적절 한 기질을 선택 했다. 메서드는 AAO (Anodisc, 0.1 μ m의 기 공 직경 13 m m 직경 호스팅 모 공), polyacrylonitrile에 적용할 수 있는 (팬, 분자량 컷오프: 100 kDa), Cu 호 일 (99.9% 순도, 25 µ m 두께), 화학 증기 증 착 물질 그래 핀 필름에는 Cu 호 일11, 그리고 수 제 성공 탄소 필름 Cu 호 일12,,1314에.
<ol><li>조심 스럽게 테이프를 사용 하 여 Cu 전극의 센터에 원하는 기판 위치.</li>
	<li>기판/전극 어셈블리 소 프로 파 놀, 다음 물으로 다시 약 1 분 물으로 린스.</li>
	<li>양극에 벌 거 벗은 Cu 전극 (4 x 4 cm)를 연결 합니다. 다음에 음극 기판/전극 어셈블리를 연결 합니다.</li>
	<li>100 mL 유리 비 커 안에 1 cm 두 전극 사이의 거리를 조정 합니다.</li>
</ol>4. ZIF-8 영화에 대 한 절차를 제정
<ol><li>31.6 g 금속 전조 솔루션 및 100 mL 비 커에 ligand 솔루션의 35 g을 혼합 하 고 30에 대 한 저 어 선구자 솔을 실 온에서 s. 참고: 이러한 조건에서 ZIF-8의 유도 시간입니다 미만 60 s 고, 따라서, EPD는 지체 없이 실시 하는.</li>
	<li>전극 호스팅 선박 선구자 솔을 전송 합니다.</li>
	<li>전극에 3.5 cm 마크까지 두 전극을 담가. 참고: 우리의 실험에서 우리는 관찰 전에 솔 노화의 3 분의 다공성 기판 (AAO이 특정 경우에), 피해 야 하는 숨 구멍으로 작은 ZIF-8 핵의 침투에 리드 전기장을 적용 그. 따라서, 전기 분야 켜져 3 분 후에 핵 다소 커질 때.</li>
	<li>1 V 4 분의 증 착 전압 EPD를 실시 합니다. 현재는 2.5-3.5 mA의 범위에 있어야 합니다.</li>
	<li>EPD는의 끝에, 비 커를 천천히 낮춥니다. 약한 갓 예금 된 핵과 기판 사이의 접착으로, 기판 처리 하는 동안 최대한 배려를가지고 한다.</li>
	<li>미세한 유리 슬라이드에 말린된 기판 전송. 테이프를 사용 하 여 기판 장소에서 개최.</li>
	<li>결정 성장, 금속 소금 솔루션 및 35 g 100 mL 비 커에 링커 솔루션의 31.6 g 섞는다.</li>
	<li>전조 솔루션에 기판 함께 미세한 유리 슬라이드를 수직으로 배치와 30 ° c.에 10 h 그대로 두고</li>
	<li>최대 10 h의 결정 성장, 후 기판 30 분 물으로 린스 하 고 깨끗 한 분위기에서 건조.</li>
</ol>5. ZIF-7 영화에 대 한 절차를 제정
<ol><li>사용 하지만 다음과 같은 차이점이 ZIF-8 영화와 비슷한 방법으로 AAO 지원에 ZIF-7 영화 음성 합성.</li>
	<li>(3) Zn의 0.82 g를 혼합 후2·6H2O 30 ml에서 dimethylformamide (DMF)과 3 분, 메탄올 30 mL에 benzimidazole의 0.72 g 수행 1 분 동안 EPD.</li>
	<li>ZIF-7 핵 영화 선구자 솔 Zn (3)2·6H2O의 0.58 g, 0.3 g의 benzimidazole, 그리고 110 ° C 4 h에서 DMF의 30 mL에에서 immersing 하 여 intergrown ZIF-7 영화 음성 합성.</li>
	<li>솔루션을 냉각, 후 12 h 60 ° C에서 건조 뒤 DMF에 몸을 담글 하 여 ZIF-7/AAO 멤브레인을 씻어.</li>
</ol>6. 막 준비 및 특성화
<ol><li>
막의 준비
	<ol>
<li>실 란 트의 준비에 대 한 수 지는 경화제의 동등한 비율을 철저 하 게 혼합 하 고 1 시간에 대 한 혼합물을 두고.</li>
		<li>ZIF-8/지원 막 센터에서 5 m m 직경 구멍 24 m m 와이드 스틸 디스크에 배치 합니다.</li>
		<li>처음에 기판의 가장자리를 따라 에폭시를 적용 하 고, 그 후, 중앙에 5 m m 직경 구멍을 제외한 기판 커버.</li>
		<li>하룻밤 건조에 에폭시를 허용 합니다.</li>
		<li>스테레오 현미경을 사용 하 여 알려진된 기준 규모 함께 막 스캔.</li>
		<li>그래픽 소프트웨어를 사용 하 여 스캔 한 이미지에서 막의 노출된 영역을 계산.</li>
	</ol>
</li>
	<li>
가스 투과 테스트 참고: 우리의 실험에서 단일 구성 요소 가스 투과 테스트 실행 되었다 만든 투과 셀에서 Wicke Kallenbach 기술에 의해. 질량 유량 컨트롤러 (MKS)와 투과 설정에 사용 되는 질량 분 서 계는 5% 오차 범위 내에서 보정 했다. 질량 유량 컨트롤러 (MFC) 피드와 가스 흐름 율 통제. 아칸소 보정된 질량 분석기 (MS) permeate 가스 운반 청소 가스 permeate 농도 실시간 분석을 위해 사용 됩니다.<ol>
<li>스테인리스 스틸 투과 셀에는 막으로 강철 디스크를 놓습니다.</li>
		<li>Viton O-링 위의 배치 하 여, 강철 디스크 아래 누출 단단한 적합을 확인 하 고 나사를 고정. 제거 하려면 흡착된 물 합성 하는 동안, H2/Ar 분위기에서 130 ° C에서 막 건조 한 꾸준한 H2 permeance에 도달할 때까지.</li>
		<li>설정 오븐 안에 놓고 130 ° c 온도 설정</li>
		<li>피드 라인 preheated 청소를 확인 합니다.</li>
		<li>피드 및 30 mL/min를 청소 면에 가스 흐름 율을 설정 합니다.</li>
		<li>피드 및는 retentate에 니 들 밸브를 조정 하 여 스윕 측 및 permeate 측에서 0.1 MPa의 압력을 각각 유지 한다.</li>
		<li>일단 정상 상태 설정 되는 permeance를 계산 합니다.</li>
		<li>천천히 30 ° C를 (약 2 시간)에 오븐을 진정 하 고 안정적인 상태 설정 되 면 다시 값을 기록 합니다.</li>
	</ol>
</li>
</ol>

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저자는 공개 없다.

기존 방법15 에 관하여 ENACT 메서드의 뛰어난 기능 ENACT 메서드를 사용 하면 다양 한 다공성 및 nonporous 기판에 높은 intergrown, ultrathin MOF 영화 합성 수 이다. 이 메서드를 MOF 영화의 합성에 대 한 매우 간단 합니다 만드는 모든 기판 전처리는 피 한다. EPD 장비 핵 영화의 증 착에 사용 되는, 장비 전원, 금속 전극과 비 커, 매우 간단 하 고 액세스할 수 있는 구성 됩니다. 우리는 다양 한 ...

얇은 분자 체질 하 세포 막 분자의 분리에서 고 에너지 효율성을 제공 하 고 연료, 콜로라도2 캡처, 물 정화, 솔벤트 복구, 등1,2의 전반적인 비용을 줄일 수 있습니다. MOFs 관련된 isoreticular 합성 화학 및 결정 화 비교적 간단한3분자 체질 하 세포 막의 합성에 대 한 자료의 유망한 클래스는. 날짜, MOF 막 이루어진 ZIF-4,-7,-8의-9,-11,-67,-90,-93, UiO-66, 동아-1, 그리고 밀-53 이었다고 보고4,5을 포함 한 다양 한 결정 구조. 이러한 막 여 다공성 지원에 높은-품질 다 MOF 영화 crystallizing 합성 됩니다. 일반적으로, 높은 분리 선택도를, 그것이 다 MOF 영화 (pinholes 곡물 경계 결함 등)에 결함을 줄이기 위해 필요 합니다. 결함을 줄이기 위해 편리한 접근 두꺼운 필름을 구체화 하는 것입니다. 아니나 다를까, 몇몇 이전 보고의 MOF에 막 끝났다 매우 두꺼운 (5 µ m). 불행 하 게도, 두꺼운 필름 막 permeance 제한 긴 확산 경로를 리드. 따라서, 선택도 향상 하는 동안 permeance 희생 이다. 이 트레이드 오프를 우회, ultrathin 구체화 하는 방법을 개발 하는 것이 필수적입니다 (< 0.5 µ m 두께), 결함이 없는 MOF 영화.
ZIF-8은 가장 집중적으로 뛰어난 화학 및 열 안정성과 간단한 결정 화 화학6,7막 합성에 대 한 MOF를 공부 했다. 지금까지 보고 된 ultrathin ZIF-8 세포 막 표면 화학 또는 ZIF-8의 이기종 nucleation를 선호 하는 intergrown 다 영화에 대 한 필수적인 기본 다공성 기판의 토폴로지를 변경 하 여 실현 되고있다. 예를 들어, 첸은 외. (3-aminopropyl) triethoxysilane-수정 된 티 오2에 1 µ m 두께 ZIF-8 영화의 합성을 보고-코팅된 poly(vinylidene fluoride) (PVDF) 중공 섬유8. 그들은 높은 이기종 nucleation 밀도 관찰 하 고 표면 화학과 nanostructure의 동시 수정에 그것을 돌렸다. Peinemann 그룹은 금속 킬레이트 화, polythiosemicarbazide (PTSC) 지원9ultrathin ZIF 8 막을 보도 했다. 이 독특한 금속 킬레이트 화 능력 PTSC ZIF-8는, 연속적으로, 높은-성능 ZIF-8 세포 막의 이기종 nucleation 홍보 아연 이온 바인딩 이끌어 냈다. 일반적으로, 높은-성능 MOF 막;의 합성을 용이 하 게 기판 화학과 nanostructure 튜닝 그러나, 이러한 방법은 매우 복잡 하 고, 그리고 일반적으로 다른 매력적인 MOF 구조에서 MOF 막 합성을 다시 적용할 수 없습니다.
여기, 우리는 매우 여러 가지 결정 자료10의 intergrown 박막 형성을 다시 수 있는 간단 하 고 다재 다능 한 결정 화 접근을 사용 하 여 ZIF-8 영화 intergrown의 ultrathin, 합성을 보고 합니다. 우리는 ZIF-8와 ZIF-7 영화 준비 과정을 크게 단순화 어떤 기판 전처리 없이도 준비의 예를 보여줍니다. ZIF-8 영화는 다양 한 기판 (세라믹, 폴리머, 금속, 탄소, 그리고 그래 핀)에 준비가 되어 있습니다. 양극 알루미늄 산화물 (AAO) 지원에 500 nm 두께 ZIF-8 영화는 매력적인 분리 성능을 표시합니다. 8.3 x 10-6 mol m-2 s-1 펜 실바 니 아-1 와 7.3 (H2/CO2), 15.5 (H2/N2), 16.2 (H2/CH4), 및 2655 (H의 매력적인 이상적인 selectivities의 높은 H2 permeance 2/C3H8) 달성 된다.
위에서 언급 한 묘기를 가능 하 게 결정 화 접근 ENACT 이다. ENACT은 크리스털의 선구자 솔에서 직접 기판에 ZIF-8 핵 예금. 접근 유도 시간 (때 핵 선구자 솔에 표시 하는 시간) 직후 아주 짧은 시간 (1-4 분) 동안 EPD을 이용 한다. 충전된 MOF 핵에 전기 분야의 응용 적용된 전기장 (E), (μ), 콜 로이드의 전기 이동 성과의 농도의 강도에 비례 하는 플럭스와 전극 쪽으로 그들을 드라이브합니다 방정식 1와 2에서와 같이 핵 (Cn).
<img alt="Equation 1" src="/files/ftp_upload/58301/58301eq1.jpg"> (식 1)
<img alt="Equation 2" src="/files/ftp_upload/58301/58301eq2.jpg"> (식 2)
여기, v = 드리프트 속도 Ζ = 핵의 제타 전위 Εo = 진공의 유전율 Εr = 유 전체 상수와 Η = 선구자 솔의 점성.
따라서, 전자 및 솔루션 pH (는 ζ 결정)을 제어 하 여 핵의 패킹 조밀도 제어할 수 있습니다. 선구자 솔에 조밀 하 게 포장 하는 핵의 연속적인 성장 연구원을 매우 intergrown 다 결정 필름을 얻을 수 있습니다.

<table>
	<tbody>
		<tr>
			<td>Zinc nitrate hexahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>96482-500G</td>
			<td>98% purity</td>
		</tr>
		<tr>
			<td>2-Methylimidazole</td>
			<td>Sigma-Aldrich</td>
			<td>M50850-500G</td>
			<td>99% purity</td>
		</tr>
		<tr>
			<td>Benzimidazole</td>
			<td>TCI</td>
			<td>B0054-500G</td>
			<td>98% purity</td>
		</tr>
		<tr>
			<td>Tape</td>
			<td>DuPont</td>
			<td>KPT-1/8</td>
			<td></td>
		</tr>
		<tr>
			<td>Epoxy</td>
			<td>GC Electronics</td>
			<td>19-823</td>
			<td></td>
		</tr>
		<tr>
			<td>Copper foil</td>
			<td>Alfa Aesar</td>
			<td>13380.CV</td>
			<td>99.9% purity</td>
		</tr>
		<tr>
			<td>Power source for EPD</td>
			<td>Gamry Instruments</td>
			<td>Interface 1000E Potentiostat</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic cleaner</td>
			<td>MTI corporation</td>
			<td>VGT-1860QTD</td>
			<td></td>
		</tr>
		<tr>
			<td>AAO</td>
			<td>GE Healthcare Life Sciences&#8206;</td>
			<td>6809-7013</td>
			<td></td>
		</tr>
		<tr>
			<td>PAN</td>
			<td>Shandong MegaVision</td>
			<td></td>
			<td>The molecular weight cut-off is 100 kDa</td>
		</tr>
	</tbody>
</table>

electrophoretic crystallization of ultrathin high-performance metal-organic framework membranes

우리는 다양 한 수정 되지 않은 다공성 및 비 다공성 지원 (고분자, 세라믹, 금속, 탄소, 그리고 그래 핀)에 얇은, 고도로 intergrown 다 결정 금속-유기 프레임 워크 (MOF) 세포 막의 합성을 보고합니다. 우리 ENACT 접근 불린다 소설 결정 화 기술 개발: 전기 이동 핵 어셈블리 (ENACT) 높은 intergrown 박막의 결정 화에 대 한. 이 접근을 선택한 기판 통해 선구자 솔에서 직접 전기 이동 증 착 (EPD)에 MOFs의 이기종 nucleation의 높은 밀도 대 한 수 있습니다. 잘 포장 된 MOF 핵의 성장을 매우 intergrown 다 MOF 영화 이끌어 낸다. 우리는 간단한 이렇게 얇은, intergrown 비 석 이미 프레임 워크 (ZIF)-7와 ZIF-8 영화의 합성에 사용 될 수 있다는 것을 보여줍니다. 결과 500 nm 두께 ZIF 8 막 보여 상당히 높은 H2 permeance (10-6 mol m-2의 -1 펜 실바 니 아-1x 8.3)와 이상적인 가스 selectivities (7.3 H2/CO2, H2/N2, 15.5 H2/CH4, 및 H2/C3H82655 16.2). C3H6/C3H8 분리에 대 한 매력적인 성능 이기도 (a C3H6 permeance 9.9 x 10-8 몰 m-2 s-1 펜 실바 니 아-1 와 C3H의 달성 6/C3H8 이상적인 선택도 31.6 25 ° C에서의)입니다. 전반적으로, ENACT 과정 그것의 단순 때문 성공 결정 물자의 광범위의 intergrown 박막을 합성 하도록 확장할 수 있습니다.

수 제 EPD 설정 MOF 영화 (그림 1) 합성에 사용 되었다. 스캐닝 전자 현미경 (SEM) 이미지 및 x 선 회절 (XRD) 패턴 ZIF-8 핵 영화 (그림 2)에 대 한 수집 했다. SEM 이미지 AAO 지원, ZIF-8/AAO 멤브레인, 팬 지원, ZIF-8/팬 막, ZIF-8/그래 핀 필름, ZIF-7/AAO 멤브레인 (그림 3)의 표면 및 횡단면 형태학에 사용 되었다. ZIF-8 세포 막...

Watch this Scientific Journal Video about Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes at JoVE.com

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

Ultrathin 높은 성능 금속-유기 프레임 워크 막의 전기 이동 화

간단 하 고, 재현성, 다양 한 다공성의 수정 되지 않은 넓은 범위에 intergrown, 다 결정 금속-유기 프레임 워크 세포 막의 합성에 대 한 접근 및 비 다공성 제공 됩니다.

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and ...

electrophoretic-crystallization-ultrathin-high-performance-metal

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Chemistry

9.9K 조회수.  École Polytechnique Fédérale de Lausanne (EPFL). 간단 하 고, 재현성, 다양 한 다공성의 수정 되지 않은 넓은 범위에 intergrown, 다 결정 금속-유기 프레임 워크 세포 막의 합성에 대 한 접근 및 비 다공성 제공 됩니다.

비디오: Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

플라즈마 통해 소수성 유기 금속 프레임 워크의 제조 암모니아의 제거에 대한 퍼플 루오로 알칸의 화학 증착을 강화

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

연구

화학

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

기능화의 합성 및 특성 금속 - 유기 프레임 워크

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

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.

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

수용성 유기 금속 복합 어레이의 합성

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 Thiol Building Block for the Crystallization of a Semiconducting Gyroidal Metal-sulfur Framework

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and porous metal-dithiolene network in the highly ordered single crystalline state. Unlike the highly reactive free-standing thiols, which tend to decompose and complicate the crystallization of metal-thiolate open frameworks, the thioester reacts in situ to provide the thiol species, serving to mitigate the reaction between the mercaptan units and the metal centers, and to improve crystallization consequently. Specifically, the thioester was synthesized in a one-pot procedure: an aromatic bromide (hexabromotriphenylene) reacted with excess sodium thiomethoxide under vigorous conditions to first form the thioether intermediate product. The thioether was then demethylated by the excess thiomethoxide to provide the thiolate anion that was acylated to form the thioester product. The thioester was conveniently purified by standard column chromatography, and then used directly in the framework synthesis, wherein NaOH and ethylenediamine serve to revert in situ the thioester to the thiol linker for assembling the single-crystalline Pb(II)-dithiolene network. Compared with other methods for thiol synthesis (e.g., by cleaving alkyl thioether using sodium metal and liquid ammonia), the thioester synthesis here uses simple conditions and economical reagents. Moreover, the thioester product is stable and can be conveniently handled and stored. More importantly, in contrast to the generic difficulty in accessing crystalline metal-thiolate open frameworks, we demonstrate that using the thioester for in situ formation of the thiol linker greatly improves the crystallinity of the solid-state product. We intend to encourage broader research efforts on the technologically important metal-sulfur frameworks by disclosing the synthetic protocol for the thioester as well as the crystalline framework solid.

Here, we present a one-pot, transition-metal-free synthesis of thiols and thioesters from aromatic halides and sodium thiomethoxide, followed by the preparation of single crystals of a metal-dithiolene network using thiol species generated in situ from the more stable and tractable thioester.

반도체 Gyroidal 금속-황 프레임 워크의 결정 화에 대 한 Thiol 빌딩 블록의 합성

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and ...

Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategies do not permit to exploit the properties of the MOF already available and it is imperative to find new methods to enhance the stability of MOFs in water while keeping their properties intact. Herein, we report a novel method to enhance the water stability of MOF crystals featuring Cu2(O2C)4&#160;paddle-wheel units, such as HKUST (where HKUST stands for Hong Kong University of Science &#38; Technology), with the catechols functionalized with alkyl and fluoro-alkyl chains. By taking advantage of the unsaturated metal sites and the catalytic catecholase-like activity of CuII ions, we are able to create robust hydrophobic coatings through the oxidation and subsequent polymerization of the catechol units on the surface of the crystals under anaerobic and water-free conditions without disrupting the underlying structure of the framework. This approach not only affords the material with improved water stability but also provides control over the function of the protective coating, which enables the development of functional coatings for the adsorption and separations of volatile organic compounds. We are confident that this approach could also be extended to other unstable MOFs featuring open metal sites.

Robust functional catechol coatings were produced in one step by direct reaction of the material known as HKUST with synthetic catechols under anaerobic conditions. The formation of homogeneous coatings surrounding the entire crystal is ascribed to the biomimetic catalytic activity of Cu(II) dimers on the external surface of the crystals.

향상 된 수 분 저항 금속-유기 프레임 워크의 표면 기능화

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. ...

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids with adsorbates. Vibrational spectra provide information on the chemical nature of adsorbed species and their structure. Thus, they are very useful for obtaining molecular level understanding of surface species. The IR spectrum of the sample itself gives some direct information about the material. General conclusions can be drawn concerning hydroxyl groups, some stable surface species and impurities. However, the spectrum of the sample is &#34;blind&#34; with respect to the presence of coordinatively unsaturated ions and gives rather poor information about the acidity of surface hydroxyls, species decisive for the adsorption and catalytic properties of the materials. Furthermore, no discrimination between bulk and surface species can be made. These problems are solved by the use of probe molecules, substances that interact specifically with the surface; the alteration of some spectral features of these molecules as a result of adsorption provides valuable information about the nature, properties, location, concentration, etc., of the surface sites.
The experimental protocol for in-situ IR studies of gas/sample interaction includes preparation of a sample pellet, activation of the material, initial spectral characterization through the analysis of the background spectra, characterization by probe molecules, and study of the interaction with a particular set of gas mixtures. In this paper we investigate a zirconium terephthalate metal organic framework, Zr6O4(OH)4(BDC)6 (BDC = benzene-1,4-dicarboxylate), namely UiO-66 (UiO refers to University of Oslo). The acid sites of the UiO-66 sample are determined by using CO and CD3CN as molecular probes. Furthermore, we have demonstrated that CO2 is adsorbed on basic sites exposed on dehydroxylated UiO-66. Introduction of water to the system produces hydroxyl groups acting as additional CO2 adsorption sites. As a result, CO2 adsorption capacity of the sample is strongly enhanced.

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

The use of FTIR spectroscopy for investigation of the surface properties of polycrystalline solids is described. Preparation of sample pellets, activation procedures, characterization with probe molecules and model studies of CO2 adsorption are discussed.

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids ...

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks (MOFs)

Substrate size discrimination by the pore size and homogeneity of the chiral environment at the reaction sites are important issues in the validation of the reaction site in metal-organic framework (MOF)&#8211;based catalysts in an enantioselective catalytic reaction system. Therefore, a method of validating the reaction site of MOF-based catalysts is necessary to investigate this issue. Substrate size discrimination by pore size was accomplished by comparing the substrate size versus the reaction rate in two different types of carbonyl-ene reactions with two kinds of MOFs. The MOF catalysts were used to compare the performance of the two reaction types (Zn-mediated stoichiometric and Ti-catalyzed carbonyl-ene reactions) in two different media. Using the proposed method, it was observed that the entire MOF crystal participated in the reaction, and the interior of the crystal pore played an important role in exerting chiral control when the reaction was stoichiometric. Homogeneity of the chiral environment of MOF catalysts was established by the size control method for a particle used in the Zn-mediated stoichiometric reaction system. The protocol proposed for the catalytic reaction revealed that the reaction mainly occurred on the catalyst surface regardless of the substrate size, which reveals the actual reaction sites in MOF-based heterogeneous catalysts. This method for reaction site validation of MOF catalysts suggests various considerations for developing heterogeneous enantioselective MOF catalysts.

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs

Here, we present a protocol for active site validation of metal-organic framework catalysts by comparing stoichiometric and catalytic carbonyl-ene reactions to find out whether a reaction takes place on the inner or outer surface of metal-organic frameworks.

키랄 금속-유기 프레임워크(MOF)를 이용한 이기종 에난티오 선택적 촉매 개발

Substrate size discrimination by the pore size and homogeneity of the chiral environment at the reaction sites are important issues in the validation of ...

Synthesis of Single-Crystalline Core-Shell Metal-Organic Frameworks

Because of their designability and unprecedented synergistic effects, core-shell metal-organic frameworks (MOFs) have been actively examined recently. However, the synthesis of single-crystalline core-shell MOFs is very challenging, and thus a limited number of examples have been reported. Here, we suggest a method of synthesizing single-crystalline HKUST-1@MOF-5 core-shells, which is HKUST-1 at the center of MOF-5. Through the computational algorithm, this pair of MOFs was predicted to have the matched lattice parameters and chemical connection points at the interface. To construct the core-shell structure, we prepared the octahedral- and cubic-shaped HKUST-1 crystals as a core MOF, in which the (111) and (001) facets were mainly exposed, respectively. Via the sequential reaction, the MOF-5 shell was well-grown on the exposed surface, showing a seamless connect interface, which resulted in the successful synthesis of single-crystalline HKUST-1@MOF-5. Their pure phase formation was proved by optical microscopic images and powder X-ray diffraction (PXRD) patterns. This method presents the potential of and insights into the single-crystalline core-shell synthesis with different kinds of MOFs.

Here, we demonstrate a protocol for the two-step synthesis of single-crystalline core-shells using a non-isostructural metal-organic framework (MOF) pair, HKUST-1 and MOF-5, which have well-matched crystal lattices.

Because of their designability and unprecedented synergistic effects, core-shell metal-organic frameworks (MOFs) have been actively examined recently. ...

A Technical Guide for Performing Spectroscopic Measurements on Metal-Organic Frameworks

Metal-organic frameworks (MOFs) offer a unique platform to understand light-driven processes in solid-state materials, given their high structural tunability. However, the progression of MOF-based photochemistry has been hindered by the difficulty in spectrally characterizing these materials. Given that MOFs are typically larger than 100 nm in size, they are prone to excessive light scatter, thereby rendering data from valuable analytical tools like transient absorption and emission spectroscopy nearly uninterpretable. To gain meaningful insights of MOF-based photo-chemical and physical processes, special consideration must be taken toward properly preparing MOFs for spectroscopic measurements, as well as the experimental setups that garner higher quality data. With these considerations in mind, the present guide provides a general approach and set of guidelines for the spectroscopic investigation of MOFs. The guide addresses the following key topics: (1) sample preparation methods, (2) spectroscopic techniques/measurements with MOFs, (3) experimental setups, (3) control experiments, and (4) post-run stability characterization. With appropriate sample preparation and experimental approaches, pioneering advancements toward the fundamental understanding of light-MOF interactions are significantly more attainable.

Here, we use a polymer stabilizer to prepare metal-organic framework (MOF) suspensions that exhibit markedly decreased scatter in their ground-state and transient absorption spectra. With these MOF suspensions, the protocol provides various guidelines to characterize the MOFs spectroscopically to yield interpretable data.

금속-유기 프레임워크에 대한 분광 측정을 수행하기 위한 기술 가이드

Metal-organic frameworks (MOFs) offer a unique platform to understand light-driven processes in solid-state materials, given their high structural ...

Multitopic Phosphine Linker에서 Low-Valent MOF의 합성

Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers

Metal-organic frameworks (MOFs) are the subject of intense research focus due to their potential applications in gas storage and separation, biomedicine, energy, and catalysis. Recently, low-valent MOFs (LVMOFs) have been explored for their potential use as heterogeneous catalysts, and multitopic phosphine linkers have been shown to be a useful building block for the formation of LVMOFs. However, the synthesis of LVMOFs using phosphine linkers requires conditions that are distinct from those in the majority of the MOF synthetic literature, including the exclusion of air and water and the use of unconventional modulators and solvents, making it somewhat more challenging to access these materials. This work serves as a general tutorial for the synthesis of LVMOFs with phosphine linkers, including information on the following: 1) the judicious choice of the metal precursor, modulator, and solvent; 2) the experimental procedures, air-free techniques, and required equipment; 3) the proper storage and handling of the resultant LVMOFs; and 4) useful characterization methods for these materials. The intention of this report is to lower the barrier to this new subfield of MOF research and facilitate advancements toward novel catalytic materials.

저자 스포트라이트: Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers  

Here, we describe a protocol for the synthesis of low-valent metal-organic frameworks (LVMOFs) from low-valent metals and multitopic phosphine linkers under air-free conditions. The resulting materials have potential applications as heterogeneous catalyst mimics of low-valent metal-based homogeneous catalysts.

Multitopic Phosphine Linkers로부터 저가 금속-유기 프레임워크의 합성을 위한 실험적 접근법

Metal-organic frameworks (MOFs) are the subject of intense research focus due to their potential applications in gas storage and separation, biomedicine, ...