Funding from the European Research Council (ERC Grant 239831) and a Humboldt Fellowship (BS) is gratefully acknowledged.

The authors have nothing to disclose.

Die gewünschte hexayne Amphiphil (3) durch die sequentielle Bromierung 52,53 und Pd-katalysierten Verlängerung 30,31 des Alkins Segment, gefolgt von einer abschließenden Schutzgruppenabspaltungsreaktion des tritylphenyl Ester (2) (1a) 29 ohne weiteres hergestellt. Die erfolgreiche Synthese wird durch das 13 C - NMR - Spektrum (Abbildung 1b) sowie die UV-Vis - Absorptionsspektrum (Figur 1c) 31,54 bestätigt. Dies ...

Zweidimensionale Kohlenstoffnanostrukturen gewinnen große Aufmerksamkeit aufgrund der berichteten hervorragenden elektrischen, thermischen sowie mechanischen Eigenschaften 1-5. Diese Materialien werden voraussichtlich 8-10 den technischen Fortschritt auf dem Gebiet der Polymer - Kompositen 6, Energiespeichereinrichtungen 7 und molekulare Elektronik weiter. Trotz intensiver Forschungsanstrengungen in den letzten Jahren jedoch, den Zugang zu größeren Mengen von gut definierten Kohlenstoff - Nanomaterialien ist noch begrenzt, die behindert ihre großtechnische Umsetzung in technologischen Anwendungen 11,12. Kohlenstoff-Nanomaterialien sind zugänglich entweder durch top-down oder bottom-up-Ansatz. Typische Ansätze wie Abblätterung Techniken 13 oder Hochenergieprozesse auf Oberflächen 14-16 bieten die Möglichkeit , Materialien mit einem hohen Grad an struktureller Perfektion und sehr gute Leistung zu erhalten. Jedoch ist die Isolierung und Reinigung von the Produkte bleibt eine Herausforderung, und die großtechnische Produktion von definierten nanostrukturierten Materialien ist schwierig , 12. Auf der anderen Seite, von unten nach oben Ansätze eingesetzt werden können , die auf die Verwendung von molekularen Vorstufen angewiesen sind , deren Anordnung in definierte Strukturen und eine nachfolgende Verkokung, die die Kohlenstoffnanostrukturen 17-23 ergibt. In diesem Fall sind die Vorläufer selbst komplexer und ihre Herstellung erfordert oft mehrere Syntheseschritte. Diese Ansätze können bieten ein hohes Maß an Kontrolle über die chemischen und physikalischen Eigenschaften der resultierenden Materialien und kann einen direkten Zugang zu maßgeschneiderten Materialien liefern. Jedoch ist die Umwandlung der Vorläufer in Kohlenstoff - Nanomaterialien typischerweise bei Temperaturen oberhalb von 800 ° C durchgeführt wird , die 24-27 zu einem Verlust der eingebetteten chemische Funktionalisierung führt. Die oben genannten Einschränkungen wurden durch den Einsatz von hochreaktiven oligoynes in unserer Gruppe gerichtet, die can in Kohlenstoff - Nanomaterialien bei Raumtemperatur 28,29 umgewandelt werden. Insbesondere Amphiphile eine hydrophile Kopfgruppe und eine hexayne Segment , das sind über eine Folge von Bromierungsreaktion und Palladium-vermittelte Negishi - Kreuzkupplungsreaktionen 30,31. Die Umwandlung dieser Vorläufermolekülen in die Zielstruktur auftritt bei oder unterhalb der Raumtemperatur bei Bestrahlung mit UV-Licht. Die hohe Reaktivität der oligoyne Amphiphile macht die Verwendung von Soft-Vorlagen, beispielsweise die Luft-Wasser-Grenzfläche oder Flüssig-Flüssig-Grenzflächen, möglich. In früheren Untersuchungen haben wir erfolgreich 28 Amphiphile Vesikeln aus Lösungen von hexayne Glykosid vorbereitet. Vernetzung dieser Vesikel wurde unter milden Bedingungen durch UV-Bestrahlung der Proben erreicht. Darüber hinaus haben wir vor kurzem selbstorganisierende Monoschichten aus hexaynes mit einem Carbonsäuremethylester- Kopfgruppe und einem hydrophoben Alkylschwanz an der Luft-Wasser-Grenzfläche in einem Langmuir-Trog vorbereitet. Das dicht Packed molekularen Vorstufen wurden dann in selbsttragenden Kohlenstoff-Nanoschichten bei Raumtemperatur durch UV-Bestrahlung ohne weiteres umgesetzt. In verwandten Ansätze molekularen Vorläufern definiert kürzlich für die Herstellung von zwei Dimensionen ausgedehnte Nanoschichten an der Luft-Wasser - Grenzfläche 32-38 verwendet. Das Ziel dieser Arbeit ist es, einen kurzen, praktischen Überblick über die Gesamtsynthese und Herstellungsschritte zu geben, die für die Herstellung von Kohlenstoff-Nanoschichten aus hexayne Amphiphile ermöglichen. Der Schwerpunkt liegt auf der experimentellen Ansatz und präparative Fragen.

<table border="0" cellpadding="0" cellspacing="0" width="1557">
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		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Methyllithium lithium bromide complex (2.2M solution in diethylether)</td>
			<td style="width:195px;">Acros</td>
			<td style="width:119px;">18129-1000</td>
			<td style="width:731px;">air-sensitive, flammable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Zinc chloride (0.7M solution in THF)</td>
			<td style="width:195px;">Acros</td>
			<td style="width:119px;">38945-1000</td>
			<td>air-sensitive, flammable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">1,1&#39;-Bis(diphenylphosphino)ferrocene] 
			dichloropalladium(II), DCM adduct&#160;</td>
			<td style="width:195px;">Boron Molecular</td>
			<td style="width:119px;">BM187</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">N-Bromosuccinimide</td>
			<td style="width:195px;">Acros</td>
			<td style="width:119px;">10745</td>
			<td>light-sensitive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Silver fluoride</td>
			<td style="width:195px;">Fluorochem</td>
			<td style="width:119px;">002862-10g</td>
			<td>light-sensitive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">n-Butyllithium (2.5M solution in hexanes)</td>
			<td style="width:195px;">Acros</td>
			<td style="width:119px;">21335-1000</td>
			<td>air-sensitive, flammable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Sodium methanolate</td>
			<td style="width:195px;">Acros</td>
			<td style="width:119px;">17312-0050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Tetrahydrofuran (unstabilized, for HPLC)</td>
			<td style="width:195px;">Fisher Chemicals</td>
			<td style="width:119px;">T/0706/PB17</td>
			<td>This solvent was dried as well as degassed using a solvent purification system (Innovative Technology, Inc, Amesbury, MA, USA)</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Toluene (for HPLC)</td>
			<td style="width:195px;">Fisher Chemicals</td>
			<td style="width:119px;">T/2306/17</td>
			<td>This solvent was dried as well as degassed using a solvent purification system (Innovative Technology, Inc, Amesbury, MA, USA)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Acetonitrile (for HPLC)</td>
			<td style="width:195px;">Fisher Chemicals</td>
			<td style="width:119px;">A/0627/17</td>
			<td>This solvent was dried as well as degassed using a solvent purification system (Innovative Technology, Inc, Amesbury, MA, USA)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Dichloromethane (Extra Dry over Molecular Sieve)</td>
			<td style="width:195px;">Acros</td>
			<td style="width:119px;">34846-0010</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Chloroforme (p.a.)</td>
			<td style="width:195px;">VWR International</td>
			<td style="width:119px;">1.02445.1000</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Pentane</td>
			<td style="width:195px;">Reactolab</td>
			<td style="width:119px;">99050</td>
			<td>Purchased as reagent grade and distilled once prior to use</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Heptane</td>
			<td style="width:195px;">Reactolab</td>
			<td style="width:119px;">99733</td>
			<td>Purchased as reagent grade and distilled once prior to use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Dichloromethane</td>
			<td style="width:195px;">Reactolab</td>
			<td style="width:119px;">99375</td>
			<td>Purchased as reagent grade and distilled once prior to use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Diethylether</td>
			<td style="width:195px;">Reactolab</td>
			<td style="width:119px;">99362</td>
			<td>Purchased as reagent grade and distilled once prior to use</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Geduran silica gel (Si 60, 40-60&#181;m)</td>
			<td style="width:195px;">Merck</td>
			<td style="width:119px;">1115671000</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Langmuir trough</td>
			<td style="width:195px;">R&#38;K, Potsdam</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thermostat&#160;</td>
			<td style="width:195px;">E1 Medingen</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hamilton syringe&#160;</td>
			<td>Model 1810 RN SYR</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Vertex 70 FT-IR spectrometer&#160;</td>
			<td style="width:195px;">Bruker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">External air/water reflection unit (XA-511)&#160;</td>
			<td style="width:195px;">Bruker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">UV lamp (250 W, Ga-doped metal halide bulb)</td>
			<td style="width:195px;">UV-Light Technology</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Brewster angle microscope (BAM1+)&#160;</td>
			<td style="width:195px;">NFT G&#246;ttingen</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Sapphire substrates</td>
			<td style="width:195px;">Stecher Ceramics</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:513px;">Quantifoil holey carbon TEM grids</td>
			<td style="width:195px;">Electron Microscopy Sciences</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Nuclear magnetic resonance spectrometer (Bruker Avance III 400)</td>
			<td style="width:195px;">Bruker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">JASCO V-670 UV/Vis spectrometer</td>
			<td style="width:195px;">JASCO</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:513px;">Scanning Electron Microscope (Zeiss Merlin FE-SEM)</td>
			<td style="width:195px;">Zeiss</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of carbon nanosheets at room temperature

Amphiphilic molecules equipped with a reactive, carbon-rich "oligoyne" segment consisting of conjugated carbon-carbon triple bonds self-assemble into defined aggregates in aqueous media and at the air-water interface. In the aggregated state, the oligoynes can then be carbonized under mild conditions while preserving the morphology and the embedded chemical functionalization. This novel approach provides direct access to functionalized carbon nanomaterials. In this article, we present a synthetic approach that allows us to prepare hexayne carboxylate amphiphiles as carbon-rich siblings of typical fatty acid esters through a series of repeated bromination and Negishi-type cross-coupling reactions. The obtained compounds are designed to self-assemble into monolayers at the air-water interface, and we show how this can be achieved in a Langmuir trough. Thus, compression of the molecules at the air-water interface triggers the film formation and leads to a densely packed layer of the molecules. The complete carbonization of the films at the air-water interface is then accomplished by cross-linking of the hexayne layer at room temperature, using UV irradiation as a mild external stimulus. The changes in the layer during this process can be monitored with the help of infrared reflection-absorption spectroscopy and Brewster angle microscopy. Moreover, a transfer of the carbonized films onto solid substrates by the Langmuir-Blodgett technique has enabled us to prove that they were carbon nanosheets with lateral dimensions on the order of centimeters.

Das 13 C - Kernspinresonanz (NMR) Spektrum des hergestellten Vorläufermolekül 3 zeigt die 12 sp -hybridisierten Kohlenstoffatome der hexayne Segment mit den entsprechenden chemischen Verschiebungen δ = 82-60 ppm (Abbildung 1b). Außerdem werden die Signale bei δ = 173 ppm und bei δ = 52 ppm zur Carbonylgruppe und Methylkohlen des Esters zugeordnet sind. Die Signale zwischen δ = 33-14 ppm an den aliphatischen Kohlenstoffatomen de...

Watch this Scientific Journal Video about Preparation of Carbon Nanosheets at Room Temperature at JoVE.com

Preparation of Carbon Nanosheets at Room Temperature

We present the synthesis of an amphiphilic hexayne and its use in the preparation of carbon nanosheets at the air-water interface from a self-assembled monolayer of these reactive, carbon-rich molecular precursors.

Herstellung von Kohlenstoff-Nanoschichten bei Raumtemperatur

Amphiphilic molecules equipped with a reactive, carbon-rich "oligoyne" segment consisting of conjugated carbon-carbon triple bonds self-assemble into ...

preparation-of-carbon-nanosheets-at-room-temperature

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Chemistry

Chemical Bonding: Basic Concepts

SCIENTISTS IN ACTION

12.0K Aufrufe.  Ecole Polytechnique Fédérale de Lausanne (EPFL). We present the synthesis of an amphiphilic hexayne and its use in the preparation of carbon nanosheets at the air-water interface from a self-assembled monolayer of these reactive, carbon-rich molecular precursors.

Serie: Preparation of Carbon Nanosheets at Room Temperature

Transport of Surface-modified Carbon Nanotubes through a Soil Column

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.

Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.

Transport von oberflächenmodifizierte Kohlenstoff-Nanoröhren durch eine Bodensäule

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, ...

Forschung

Chemie

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

Metall-Silikat-Partitionierung unter hohem Druck und Temperatur: Experimentelle Verfahren und ein Protokoll zum Unterdrücken von Hoch siderophile Element Einschlüsse

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

Facile Preparation of Internally Self-assembled Lipid Particles Stabilized by Carbon Nanotubes

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled (functionalized) CNTs are used as stabilizers to produce Pickering type oil-in-water (O/W) emulsions. Lipids namely, Dimodan U and Phytantriol are used as emulsifiers, which in excess water self-assemble into the bicontinuous cubic Pn3m phase. This highly viscous phase is fragmented into smaller particles using a probe ultrasonicator in presence of conventional surfactant stabilizers or CNTs as done here. Initially, the CNTs (powder form) are dispersed in water followed by further ultrasonication with the molten lipid to form the final emulsion. During this process the CNTs get coated with lipid molecules, which in turn are presumed to surround the lipid droplets to form a particulate emulsion that is stable for months. The average size of CNT-stabilized nanostructured lipid particles is in the submicron range, which compares well with the particles stabilized using conventional surfactants. Small angle X-ray scattering data confirms the retention of the original Pn3m cubic phase in the CNT-stabilized lipid dispersions as compared to the pure lipid phase (bulk state). Blue shift and lowering of the intensities in characteristic G and G&#39; bands of CNTs observed in Raman spectroscopy characterize the interaction between CNT surface and lipid molecules. These results suggest that the interactions between the CNTs and lipids are responsible for their mutual stabilization in aqueous solutions. As the concentrations of CNTs employed for stabilization are very low and lipid molecules are able to functionalize the CNTs, the toxicity of CNTs is expected to be insignificant while their biocompatibility is greatly enhanced. Hence the present approach finds a great potential in various biomedical applications, for instance, for developing hybrid nanocarrier systems for the delivery of multiple functional molecules as in combination therapy or polytherapy.

We report on a smart application of carbon nanotubes for kinetic stabilization of lipid particles that contain self-assembled nanostructures in their cores. The preparation of lipid particles requires rather low concentrations of carbon nanotubes permitting their use in biomedical applications such as drug delivery.

Facile Herstellung von Intern Selbstorganisierte Lipidpartikel stabilisiert durch Kohlenstoff-Nanoröhren

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled ...

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. Detailed and generalized protocols are also presented for testing the catalytic activity of such complexes in arylation and Suzuki-Miyaura cross-coupling reactions. Representative results are shown for the catalytic activity of the four complexes in arylation and Suzuki-Miyaura type reactions. For each of the reactions investigated, at least one of the four complexes successfully catalyzed the reaction, qualifying them as promising candidates for catalysis of many carbon-carbon bond-forming reactions. The protocols presented are general enough to be adapted for the synthesis, purification and catalytic activity testing of new palladium N-heterocyclic carbene complexes.

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. The complexes were tested for catalytic activity in arylation and Suzuki-Miyaura reactions. For each reaction investigated, at least one of the four complexes successfully catalyzed the reaction.

Palladium<em&gt; N.</em&gt; -Heterocyclische Carbenkomplexe: Synthese aus Benzimidazoliumsalzen und katalytische Aktivität bei Kohlenstoff-Kohlenstoff-Bindungs-bildenden Reaktionen

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Elektrochemische Impedanz Spektroskopie als Instrument zur elektrochemischen Rate Konstanten Schätzung

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables the acquisition of photoluminescence spectra covering the time regime from nanoseconds up to 0.1 s. This enables us to follow the changes in the intensity (decay) and emission of the spectra over time. Using this method, it is possible to study diverse photophysical phenomena, such as the emission of phosphorescence, and the contributions of prompt and delayed fluorescence in molecules showing thermally activated delayed fluorescence (TADF). Remarkably, all spectra and decays are obtained in a single experiment. This can be done for solids (thin film, powder, crystal) and liquid samples, where the only limitations are the spectral sensitivity of the camera and the excitation wavelength (532 nm, 355 nm, 337 nm, and 266 nm). This technique is, thus, very important when investigating the excited state dynamics in organic emitters for their application in organic light-emitting diodes and other areas where triplet harvesting is of paramount importance. Since triplet states are strongly quenched by oxygen, emitters with efficient TADF luminescence, or those showing room temperature phosphorescence (RTP), must be correctly prepared in order to remove any dissolved oxygen from solutions and films. Otherwise, no long-lived emission will be observed. The method of degassing solid samples as presented in this work is basic and simple, but the degassing of liquid samples creates additional difficulties and is particularly interesting. A method of minimizing solvent loss and changing the sample concentration, while still enabling to remove oxygen in a very efficient and a repeatable manner, is presented in this work.

Here, we present a method of the spectroscopic characterization of organic molecules by means of time-resolved photoluminescence spectroscopy on the nanosecond-to-millisecond timescale in oxygen-free conditions. Methods to efficiently remove oxygen from the samples and, thus, limit luminescence quenching are also described.

Zeitaufgelöste photophysikalischen Charakterisierung der Triplett-Ernte organische Verbindungen in einer sauerstofffreien Umgebung verwenden eine iCCD Kamera

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables ...

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule on the vibrational level of energy. Raman and IR spectroelectrochemistry can be used for advanced characterization of the structural changes in the organic electroactive compounds. Here, the step-by-step analysis by means of Raman and IR spectroelectrochemistry is shown. Raman and IR spectroelectrochemical techniques provide complementary information about structural changes occurring during an electrochemical process, i.e. allows for the investigation of redox processes and their products. The examples of IR and Raman spectroelectrochemical analysis are presented, in which the products of the redox reactions, both in solution and solid state, are identified.

A protocol of step-by-step Raman and IR spectroelectrochemical analysis is presented.

Raman und IR Spectroelectrochemical Methoden als Werkzeuge konjugierte organische Verbindungen zu analysieren

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule ...

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance (EPR) or ultraviolet-visible and near-infrared (UV-Vis-NIR) spectroscopies, we obtain useful information such as electron affinity, ionization potential, band-gap energies, the type of charge carriers, and degradation information that can be used to synthesize stable organic electronic devices. In this study, we present electrochemical and spectroelectrochemical methods to analyze the processes occurring in active layers of an organic device as well as the generated charge carriers.

In this article, we describe electrochemical, electron paramagnetic resonance, and ultraviolet-visible and near-infrared spectroelectrochemical methods to analyze organic compounds for application in organic electronics.

Mithilfe von zyklischer Voltammetrie, UV-Vis-NIR und EPR Spectroelectrochemistry organische Verbindungen analysieren

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

Oberflächeneigenschaften von synthetisierten nanoporöse Carbon und Silica-Matrizen

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...

Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid

The accurate molecular simulation prediction of vibrational spectra, and other structural, energetic and spectral characteristics, of photo-active metal-oxide surfaces in contact with light-absorbing dyes is an ongoing thorny and elusive challenge in physical chemistry. With this in mind, a molecular-dynamics (MD) simulation were performed by using optimized empirical potentials for a well-representative and prototypical dye-sensitized solar cell (DSC) solvated by a widely-studied room temperature ionic liquid (RTIL), in the guise of a [bmim]+[NTf2]- RTIL solvating an N719-sensitizing dye adsorbed onto 101 anatase-titania. In doing so, important insights were gleaned into how using a RTIL as the electrolytic hole acceptor modulates the dynamical and vibrational properties of a N719 dye, estimating the spectra for the DSC photo-active interface via Fourier transformation of mass-weighted velocity autocorrelation functions from MD. The acquired vibrational spectra were compared with the experiment spectra and those sampled from ab initio molecular dynamics (AIMD); in particular, various empirical-potential spectra generated from MD provide insight into how partial-charge charge parameterization of the ionic liquid affects vibrational spectra prediction. In any event, careful fitting of empirical force-field models has been shown to be an effective tool in handling DSC vibrational properties, when validated by AIMD and an experiment.

A dye-sensitized solar cell was solvated by RTILs; using optimized empirical potentials, a molecular dynamics simulation was applied to compute vibrational properties. The obtained vibrational spectra were compared with experiment and ab initio molecular dynamics; various empirical potential spectra show how partial-charge charge parameterization of the ionic liquid affects vibrational spectra prediction.

Vibrationsspektra einer N719-Chromophore/Titania Schnittstelle aus Empirisch-Potential-Molekulardynamik-Simulation, Solvated by a Room Temperature Ionic Liquid

Herstellung von Kohlenstoff-Nanoschichten bei Raumtemperatur

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