Gli autori ringraziano il Defense Threat Reduction Agency per il finanziamento con il numero di progetto BA07PRO104, Martin Smith, Corrine Stone e Colin Willis del Defence Science and Technology Laboratory (DSTL) per la loro esperienza nella tecnologia del plasma a bassa pressione, e Matteo Browe e Wesley Gordon di Edgewood Chemical Biological Center (ECBC) per il test microbreakthrough e misure di angolo di contatto, rispettivamente.

1. Cu-BTC sintesi e preparazione <ol><li> Mescolare 12,5 ml di acqua deionizzata e 12,5 ml di dimetilformammide in un vasetto da 100 ml a vite tappo per circa 5 min. </li><li> Aggiungere 0,87 g (3,6 mmol) di rame (II) triidrato nitrato seguita da 0,50 g (2,4 mmol) di acido trimesico alla soluzione nel vaso e agitare per circa 5 min. La soluzione diventerà di colore blu. Posizionare il vaso ricoperto in forno preriscaldato a 120 ° C per circa 24 ore. </li><li> Rimuovere il vaso dal forno. Una volta che il vaso si è raffreddato a temperatura ambiente, recuperare i cristalli Cu-BTC tramite filtrazione sotto vuoto su carta da filtro valutazione di recuperare cristalli uguali o superiori a 2,5 micron. Risciacquare i cristalli risultanti con diclorometano, infine mettendo i cristalli in una soluzione fresca di diclorometano. </li><li> Sostituire il solvente ogni 24 ore e sostituirlo con diclorometano fresco per i prossimi tre giorni per aiutare la rimozione dei solventi meno volatili dai pori della Cu-BTC. </li><li> Riscaldare i cristalli Cu-BTC a 170 ° C in un forno sotto vuoto o mediante una linea Schlenk per rimuovere eventuali molecole ospiti residui dal materiale. Completamente attivato Cu-BTC deve essere profondo blu al viola a colori. </li><li> Confermano la struttura e composizione chimica di Cu-BTC via polvere diffrazione di raggi X e trasformata di Fourier spettroscopia infrarossa, rispettivamente. </li></ol> 2. Plasma avanzata Chemical Vapor Deposition di perfluoroalcani in Cu-BTC 14 <ol><li> Prima di ogni esperimento pulire il reattore al plasma e qualsiasi vetreria da utilizzare nel trattamento del plasma con un plasma di aria a 50 W per almeno 30 min. Questo rimuove qualsiasi film perfluoroalcano che possono formarsi sulle superfici interne della camera di reazione o di vetro da esperimenti precedenti. </li><li> Mettere una quantità nota di attivazione Cu-BTC in una bottiglia 250 ml Pyrex e diffusa nel flacone su un lato per assicurare un trattamento omogeneo. Un panno permeabile deve essere collocato intornocollo della bottiglia con un elastico per minimizzare la quantità di campione che si perde su applicazione di un vuoto. </li><li> Posizionare la bottiglia nella camera di plasma. Applicare un vuoto finché la camera ha raggiunto una pressione ≤ 0,20 mbar per almeno 30 minuti per rimuovere l&#39;acqua che eventualmente adsorbita sul campione. </li><li> Collegare il gas perfluoroalcano e regolare il regolatore di pressione entro le specifiche del controllore di flusso di massa. </li><li> Regolare il controllore di flusso di massa per riempire la camera di reazione con la quantità appropriata di gas perfluoroalcano per mantenere la pressione desiderata dell&#39;esperimento. Ruotare la bottiglia all&#39;interno dell&#39;apparato PECVD per creare un trattamento più omogenea della polvere. </li><li> Accendere il plasma con un generatore di 13,56 MHz RF, e sintonizzare la frequenza radio con l&#39;unità LC corrispondenza per massimizzare la potenza riducendo al minimo la riflettanza. Risintonizzare periodicamente durante il trattamento. </li><li> Una volta che il trattamento è completo, evacuare la camera di qualsiasiperfluoroalcano gas residuo e poi sfogo alla pressione atmosferica. Rimuovere il campione dall&#39;apparecchio PECVD e recuperare il materiale trattato dai lati della bottiglia. Un dispositivo antistatico deve essere usato per recuperare la massima quantità di materiale. </li><li> Collocare il materiale trattato in stufa a 120 ° C per rimuovere eventuali gas perfluoroalcano non reagito. Poi posto il materiale trattato in un essiccatore per evitare assorbimento di acqua dall&#39;atmosfera. </li><li> Sciacquare il materiale residuo lasciato in bottiglia e filtrare di recuperare i rifiuti per il corretto smaltimento. </li><li> Caratterizzare il trattato Cu-BTC con 20 Magic Angle F filatura risonanza magnetica nucleare, trasformata di Fourier spettroscopia infrarossa, e la spettroscopia di fotoelettroni a raggi x. </li></ol> 3. Invecchiamento della Cu-BTC in condizioni di umidità <ol><li> Impostare la temperatura desiderata e umidità relativa della camera ambientale e lasciarlo equilibrare. </li><li> Stendere il campione in modo uniforme inun contenitore aperto e posto nella camera ambientale per il tempo desiderato. </li><li> Caratterizzare il campione Cu-BTC con diffrazione di raggi X e una isoterma di azoto a 77 K per determinare il grado di degrado. </li></ol> 4. Esperimenti Ammoniaca Microbreakthrough 2 <ol><li> Preparare un 14,6 L zavorra di ammoniaca a 5.000 mg / m 3 da primo iniettando una zavorra vuoto con 210 ml di ammoniaca ordinata. Quindi riempire il reattore con aria zero a una pressione di 15 psi. Collegare la zavorra in linea con l&#39;apparato microbreakthrough. </li><li> Eseguire un tubo vuoto nell&#39;apparecchio microbreakthrough per determinare il segnale di alimentazione. Impostare controllori di flusso di massa per ammoniaca e aria secca a 8 e 12 ml / min, rispettivamente, per creare un flusso di 20 ml / min di 2.000 mg / m 3 ammoniaca. Eseguire un metodo programmato per controllare il gascromatografo e fotoionizzatore per determinare il segnale di alimentazione di ammoniaca nell&#39;effluente. L&#39;umidità può essere aggiunto al sistemase desiderato eseguendo parte della corrente di diluente attraverso una cella saturatore temperatura controllata nella misura necessaria per raggiungere l&#39;umidità relativa desiderata. </li><li> Mettere una piccola quantità di lana di vetro sotto della fritta di vetro in un tubo di vetro nominale 4 mm id. Pesare circa 10-15 mg di materiale nel tubo. La massa utilizzata deve risultare in circa 55 mm 3 di volume di sorbente, risultando in un tempo di permanenza letto di circa 0,15 sec. </li><li> Flusso di aria secca attraverso il tubo di vetro come si è riscaldata a 150 ° C per 1 ora per rimuovere l&#39;acqua adsorbita. Pesare il campione dopo la rigenerazione. </li><li> Trasferire il campione in linea e fissare in posizione verticale in un bagnomaria regolato a 25 ° C. </li><li> Impostare i controllori di flusso di massa per l&#39;ammoniaca e aria secca a 8 e 12 ml / min, rispettivamente, per creare un flusso di 20 ml / min a 2000 mg / m 3 ammoniaca bypassando il campione per le linee di riempimento con il gas di alimentazione. </li><li> Flusso il flusso di ammoniaca attraverso il campione ed eseguire un programmatoMetodo per controllare il gascromatografo e fotoionizzatore per monitorare la concentrazione di ammoniaca nell&#39;effluente. </li><li> Una volta che la concentrazione dell&#39;effluente ha raggiunto la concentrazione di alimentazione, spegnere il flusso di ammoniaca e permettere al campione di off-gas di ammoniaca che non è fortemente adsorbita al campione. </li><li> Togliere il campione dal bagno d&#39;acqua per l&#39;analisi post-esposizione tramite diffrazione di raggi X e trasformata di Fourier analisi a raggi infrarossi. </li><li> Integrare il segnale gascromatografo vs dati, per determinare il carico di ammoniaca per il campione. </li></ol>

<ol>
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Gli autori dichiarano di non avere interessi finanziari in competizione.

La sintesi di Cu-BTC, come nella maggior parte MOFs, può essere fortemente dipendente dal rapporto di reagenti utilizzati e la temperatura di sintesi viene condotta a. Variando la temperatura o il solvente usato nella sintesi ha dimostrato di produrre diverse morfologie di una struttura MOF 20. Pertanto è di forte importanza di seguire la procedura prevista in letteratura per qualsiasi MOF essere sintetizzato. Inoltre, si dovrebbe considerare i reagenti, solventi e condizioni di sintesi nella scelta di un r...

Strutture in metallo-organica (MOF) sono diventati una classe leader di materiali porosi per la rimozione dei gas tossici 1-3. MOF hanno una capacità senza precedenti di personalizzare le funzionalità di interazione chimica mirata. Cu-BTC (noto anche come HKUST-1 o Cu 3 (BTC) 2) precedentemente trovato per avere un altissimo carico di ammoniaca, tuttavia, questo è un costo di stabilità strutturale del materiale 4. Ulteriori studi su Cu-BTC hanno indicato che si umidità è in grado di degradare la struttura MOF, rendendolo inefficace per molte potenziali applicazioni 5,6,21. L&#39;instabilità strutturale di alcuni contenente carbossilato MOFs in presenza di acqua liquida o elevata umidità è stato un deterrente importante da utilizzare in applicazioni commerciali o industriali 7. Sarebbe più ideale per MOFs utilizzati per la rimozione chimica per avere stabilità intrinseca in presenza di umidità. Tuttavia, molti MOFs con stabilità superiore, come UiO-66, hanno scarsa capacità di rimozione chimica, mentre molti MOFs con siti metallici aperti come MOF-74 e Cu-BTC hanno superiori capacità di rimozione chimica 2,4,8,9. Siti metallici aperto in MOF-74 e Cu-BTC aumentano l&#39;assorbimento di gas tossici quali ammoniaca, ma questi siti sono anche suscettibili di legare l&#39;acqua, avvelenare i siti attivi e in molti casi con conseguente rottura strutturale. Al fine di preservare le proprietà chimiche di acqua instabile MOF, sono stati fatti vari tentativi per migliorare la stabilità dell&#39;acqua di MOF. MOF-5 è stato mostrato un miglioramento nella resistenza di umidità in seguito al trattamento termico, creando uno strato carbonioso intorno al MOF, tuttavia, la maggiore idrofobicità è a scapito della superficie e funzionalità in definitiva 10. MOF-5 è stato anche dimostrato di avere la sua stabilità all&#39;idrolisi aumentata attraverso drogaggio con Ni 2 + ioni 11. Inoltre, 1,4-diazabiciclo [2.2.2] ottano contenuteMOFs ING (noto anche come DMOFs) sono stati utilizzati per mostrare l&#39;accordatura della stabilità dell&#39;acqua per incorporazione di vari gruppi pendenti sul 1,4-benzene dicarbossilato linker 12,13. La mancanza di stabilità all&#39;idrolisi di alcuni di MOF, in particolare quelle ad elevato assorbimento di gas tossico, ha portato all&#39;uso di plasma la deposizione di vapore chimico (PECVD) di perfluoroalcani per creare gruppi fluorurati sulle superfici del MOF per aumentare la sua idrofobicità 14. Questa tecnica offre il vantaggio unico che può essere utilizzato per modificare qualsiasi MOF contenente idrogeni aromatici, nonché altri potenziali gruppi funzionali sulle superfici interne di MOF. Tuttavia, la tecnica può essere difficile da controllare a causa della formazione di radicali altamente reattivi nel plasma. I radicali reagiscono non solo con gli atomi di idrogeno aromatici, ma anche con CF x gruppi già reagito sulle superfici MOF. Il controllo attento della procedura è necessaria per garantire blo poricompleto costituito non si verifica, rendendo il MOF inefficace. Questa tecnica è stata utilizzata da altri per alterare le proprietà bagnanti di materiali di carbonio, tuttavia, a nostra conoscenza non era mai stato precedentemente utilizzato per migliorare stabilità all&#39;idrolisi di materiale microporoso 15,16..

<table border="1">
	<tbody>
		<tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>Copper (II) Nitrate Trihydrate</td>
			<td>Sigma-Aldrich</td>
			<td>61194</td>
			<td></td>
		</tr>
		<tr>
			<td>Trimesic acid</td>
			<td>Sigma-Aldrich</td>
			<td>482749</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma-Aldrich</td>
			<td>130147</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl Formamide</td>
			<td>Sigma-Aldrich</td>
			<td>319937</td>
			<td></td>
		</tr>
		<tr>
			<td>Dichloromethane</td>
			<td>Sigma-Aldrich</td>
			<td>187332</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexafluoroethane</td>
			<td>Synquest Labs</td>
			<td>1100-2-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Femto-Plasma System</td>
			<td>Diener Electronic</td>
			<td>Basic unit type B</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasma Generator</td>
			<td>Diener Electronic</td>
			<td>Type D</td>
			<td>0-100 W at 13.56 MHz</td>
		</tr>
		<tr>
			<td>Rotary Vane Pump for Plasma System</td>
			<td>Leybold</td>
			<td>D16BCS PFPE</td>
			<td>Appropriate for corrosive gases</td>
		</tr>
		<tr>
			<td>Powder Treatment Device</td>
			<td>Diener Electronic</td>
			<td>Option 5.9</td>
			<td>Glass bottle and rotating devise within plasma system</td>
		</tr>
		<tr>
			<td>Environmental Chamber</td>
			<td>Associated Environmental Systems</td>
			<td>HD-205</td>
			<td></td>
		</tr>
		<tr>
			<td>Gas Chromatograph</td>
			<td>Hewlet Packard</td>
			<td>HP5890 Series II</td>
			<td></td>
		</tr>
		<tr>
			<td>Photoionization Detector</td>
			<td>O-I Analytical</td>
			<td>4430/5890</td>
			<td></td>
		</tr>
		<tr>
			<td>Photoionization Detector Lamp</td>
			<td>Excilitis</td>
			<td>FK-794U</td>
			<td></td>
		</tr>
		<tr>
			<td>Water bath</td>
			<td>NESLAB</td>
			<td>RTE-111</td>
			<td></td>
		</tr>
		<tr>
			<td>Fritted glass tubes</td>
			<td>CDA Analytical</td>
			<td>MX062101</td>
			<td>Dynatherm sampling tubes</td>
		</tr>
	</tbody>
</table>

preparation of hydrophobic metal-organic frameworks via plasma enhanced chemical vapor deposition of perfluoroalkanes for the removal of ammonia

Plasma maggiore deposizione di vapore chimico (PECVD) di perfluoroalcani è stata a lungo studiata per accordare le proprietà umettanti delle superfici. Per i materiali microporosi elevata area superficiale, come ad esempio strutture metallo-organici (MOF), sfide uniche si presentano per i trattamenti PECVD. Qui il protocollo per lo sviluppo di un MOF che in precedenza era instabile a condizioni di umidità è presentato. Il protocollo descrive la sintesi di Cu-BTC (noto anche come HKUST-1), il trattamento di Cu-BTC con PECVD di perfluoroalcani, l&#39;invecchiamento dei materiali in condizioni umide, e gli esperimenti successivi ammoniaca microbreakthrough sulle quantità milligrammo di materiali microporosi. Cu-BTC ha una superficie estremamente elevata (~ 1.800 m 2 / g) rispetto alla maggior parte dei materiali o superfici che sono stati precedentemente trattati con metodi PECVD. Parametri quali la pressione della camera e tempo di trattamento sono estremamente importanti per garantire il plasma perfluoroalcano penetra e reagires con le superfici interne MOF. Inoltre, il protocollo per esperimenti microbreakthrough ammoniaca stabiliti qui può essere utilizzata per una varietà di gas di prova e materiali microporosi.

<html> Entro i risultati rappresentativi autori hanno scelto di presentare le caratteristiche di un 0,50 g campione di Cu-BTC trattati con esafluoroetano (C 2 F 6) per 4 ore ad una pressione di 0,30 mbar e un plasma potenza di 50 W. MOFs trattati con una plasma perfluoroalcano in condizioni adeguate dovrebbe mostrare maggiore idrofobicità. Questo può essere dimostrato mettendo la polvere sulla cima di acqua liquida e determinare se i galleggianti esempio o misurando l&#39;angolo di contatto dell&#...

Watch this Scientific Journal Video about Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia at JoVE.com

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

Qui vengono descritte le procedure di plasma enhanced chemical vapour deposition di perfluoroalcani su materiali microporosi quali strutture metallo-organici per migliorare la loro stabilità e idrofobicità. Inoltre, prove svolta di quantità milligrammo di campioni è descritto in dettaglio.

Preparazione del idrofobi Frameworks Metal-Organic tramite Plasma avanzata Chemical Vapor Deposition del perfluoroalcani per la rimozione di ammoniaca

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

preparation-hydrophobic-metal-organic-frameworks-via-plasma-enhanced

Research

JoVE Journal

Chemistry

15.4K Views.  Science Applications International Corporation (SAIC).  Qui vengono descritte le procedure di plasma enhanced chemical vapour deposition di perfluoroalcani su materiali microporosi quali strutture metallo-organici per migliorare la loro stabilità e idrofobicità. Inoltre, prove svolta di quantità milligrammo di campioni è descritto in dettaglio. 

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

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.

Sintesi e caratterizzazione di funzionalizzato metallo-organici quadri

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

Ricerca

Chimica

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in traditional materials, including low cost and mechanical flexibility. In a similar vein, it would be advantageous to expand the use of organics into high frequency electronics and spin-based electronics. This work presents a synthetic process for the growth of thin films of the room temperature organic ferrimagnet, vanadium tetracyanoethylene (V[TCNE]x, x~2) by low temperature chemical vapor deposition (CVD). The thin film is grown at &#60;60 &#176;C, and can accommodate a wide variety of substrates including, but not limited to, silicon, glass, Teflon and flexible substrates. The conformal deposition is conducive to pre-patterned and three-dimensional structures as well. Additionally this technique can yield films with thicknesses ranging from 30 nm to several microns. Recent progress in optimization of film growth creates a film whose qualities, such as higher Curie temperature (600 K), improved magnetic homogeneity, and narrow ferromagnetic resonance line-width (1.5 G) show promise for a variety of applications in spintronics and microwave electronics.

We present the synthesis of the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x, x~2) via low temperature chemical vapor deposition (CVD). This optimized recipe yields an increase in Curie temperature from 400 K to over 600 K and a dramatic improvement in magnetic resonance properties.

Chemical Vapor Deposition di un magnete biologico, Vanadium Tetracyanoethylene

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

Crescita epitassiale di perovskite titanato di stronzio su Germanio via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

Aerosol-assisted Chemical Vapor Deposition di strutture in ossido di metallo: aste di ossido di zinco

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

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.

Funzionalizzazione superficiale di Metal-Organic Frameworks per resistenza all'umidità migliorata

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

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.

Sviluppo di catalizzatori Enantiosesehedse utilizzando Chiral Metal-Organic Frameworks (MOF)

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.

Sintesi di strutture metallo-organiche monocristalline core-shell

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.

Una guida tecnica per l'esecuzione di misure spettroscopiche su strutture metallo-organiche

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

Sintesi di MOF a basso valenza da linker fosfinici multitopici

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.

Autore in primo piano: Approcci sperimentali per la sintesi di strutture metallo-organiche a bassa valenza da linker fosfinici multitopici  

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.

Approcci sperimentali per la sintesi di strutture metallo-organiche a basso contenuto di valenti da linker multitopici di fosfina

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