The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Fotios Papadimitrakopoulos - One of the best experts on this subject based on the ideXlab platform.
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handedness enantioselection of carbon nanotubes using helical assemblies of Flavin Mononucleotide
Journal of the American Chemical Society, 2012Co-Authors: Sang Yong Ju, Darlington C Abanulo, Christopher A Badalucco, Jose A Gascon, Fotios PapadimitrakopoulosAbstract:In order to truly unlock advanced applications of single-walled carbon nanotubes (SWNTs), one needs to separate them according to both chirality and handedness. Here we show that the chiral d-ribityl phosphate chain of Flavin Mononucleotide (FMN) induces a right-handed helix that enriches the left-handed SWNTs for all suspended (n,m) species. Such enantioselectivity stems from the sp3 hybridization of the N atom anchoring the sugar moiety to the Flavin ring. This produces two FMN conformations (syn and anti) analogous to DNA. Electrostatic interactions between the neighboring uracil moiety and the 2′-OH group of the side chain provide greater stability to the anti-FMN conformation that leads to a right-handed FMN helix. The right-handed twist that the FMN helix imposes to the underlying nanotube, similar to “Indian burn”, causes diameter dilation of only the left-handed SWNTs, whose improved intermolecular interactions with the overlaying FMN helix, impart enantioselection.
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selection of carbon nanotubes with specific chiralities using helical assemblies of Flavin Mononucleotide
Nature Nanotechnology, 2008Co-Authors: Sang Yong Ju, Jonathan Doll, Ity Sharma, Fotios PapadimitrakopoulosAbstract:The chirality of single-walled carbon nanotubes affects many of their physical and electronic properties. Current production methods result in nanotubes of mixed chiralities, so facile extraction of specific chiralities of single-walled carbon nanotubes is an important step in their effective utilization. Here we show that the Flavin Mononucleotide, a common redox cofactor, wraps around single-walled carbon nanotubes in a helical pattern that imparts efficient individualization and chirality selection. The cooperative hydrogen bonding between adjacent Flavin moieties results in the formation of a helical ribbon, which organizes around single-walled carbon nanotubes through concentric π–π interactions between the Flavin Mononucleotide and the underlying graphene wall. The strength of the helical Flavin Mononucleotide assembly is strongly dependent on nanotube chirality. In the presence of a surfactant, the Flavin Mononucleotide assembly is disrupted and replaced without precipitation by a surfactant micelle. The significantly higher affinity of the Flavin Mononucleotide assembly for (8,6)-single-walled carbon nanotubes results in an 85% chirality enrichment from a nanotube sample with broad diameter distribution. A small organic molecule self-assembles into helical ribbons that wrap around single-walled carbon nanotubes. The strength of the wrapping interaction depends on the chirality of each nanotube and enables mixtures to be separated.
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synthesis and redox behavior of Flavin Mononucleotide functionalized single walled carbon nanotubes
Journal of the American Chemical Society, 2008Co-Authors: Sang Yong Ju, Fotios PapadimitrakopoulosAbstract:In this contribution, we describe the synthesis and covalent attachment of an analogue of the Flavin Mononucleotide (FMN) cofactor onto carboxylic functionalities of single-walled carbon nanotubes (SWNTs). The synthesis of FMN derivative (12) was possible by coupling Flavin H-phosphonate (9) with an aliphatic alcohol, using a previously unreported N-(3-dimethylaminopropyl)-N‘-ethylcarbodiimide hydrochloride coupling. We found that the Flavin moiety of 12-SWNT shows a strong π−π interaction with the nanotube side-walls. This leads to a collapsed FMN configuration that quenches Flavin photoluminescence (PL). The treatment of 12-SWNT with sodium dodecyl sulfate (SDS) overcomes this strong nanotube/isoalloxazine interaction and restores the FMN into extended conformation that recovers its luminescence. In addition, redox cycling as well as extended sonication were proven capable to temporally restore PL as well. Cyclic voltammetry of FMN onto SWNT forests indicated profound differences for the extended and co...
Sang Yong Ju - One of the best experts on this subject based on the ideXlab platform.
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graphene nanoribbons formed by a sonochemical graphene unzipping using Flavin Mononucleotide as a template
Carbon, 2015Co-Authors: Woojin Yoon, Hongje Jang, Myungsu Jang, Seongil Im, Jiwoong Park, Sang Yong JuAbstract:Abstract When the width of a graphene nanoribbon (GNR) is only a few nanometers, it possesses semiconducting properties that enable various high-end electronic applications. In this study, we report that the dense and stable dispersion of a natural graphite formed using Flavin Mononucleotide (FMN) as a surfactant produces GNRs as small as 10 nm in width. High-resolution transmission electron microscopy reveals GNRs with various widths, along with a graphene flake containing straight-edged GNRs and cuts, depending on substrate treatments. Such nanoribbon formation originates from sonochemical graphene unzipping with a one-dimensional FMN supramolecular ribbon as a template. Raman spectroscopy demonstrates the universal intensity ratio of D over D′ bands near 4, supporting formation of continuous edge defect. Thermal annealing enhances the optical contrast and van der Waals interactions of the graphene film, resulting in increased conductivity compared to the as-prepared graphene film, which is also better than that of reduced graphene oxide.
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handedness enantioselection of carbon nanotubes using helical assemblies of Flavin Mononucleotide
Journal of the American Chemical Society, 2012Co-Authors: Sang Yong Ju, Darlington C Abanulo, Christopher A Badalucco, Jose A Gascon, Fotios PapadimitrakopoulosAbstract:In order to truly unlock advanced applications of single-walled carbon nanotubes (SWNTs), one needs to separate them according to both chirality and handedness. Here we show that the chiral d-ribityl phosphate chain of Flavin Mononucleotide (FMN) induces a right-handed helix that enriches the left-handed SWNTs for all suspended (n,m) species. Such enantioselectivity stems from the sp3 hybridization of the N atom anchoring the sugar moiety to the Flavin ring. This produces two FMN conformations (syn and anti) analogous to DNA. Electrostatic interactions between the neighboring uracil moiety and the 2′-OH group of the side chain provide greater stability to the anti-FMN conformation that leads to a right-handed FMN helix. The right-handed twist that the FMN helix imposes to the underlying nanotube, similar to “Indian burn”, causes diameter dilation of only the left-handed SWNTs, whose improved intermolecular interactions with the overlaying FMN helix, impart enantioselection.
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selection of carbon nanotubes with specific chiralities using helical assemblies of Flavin Mononucleotide
Nature Nanotechnology, 2008Co-Authors: Sang Yong Ju, Jonathan Doll, Ity Sharma, Fotios PapadimitrakopoulosAbstract:The chirality of single-walled carbon nanotubes affects many of their physical and electronic properties. Current production methods result in nanotubes of mixed chiralities, so facile extraction of specific chiralities of single-walled carbon nanotubes is an important step in their effective utilization. Here we show that the Flavin Mononucleotide, a common redox cofactor, wraps around single-walled carbon nanotubes in a helical pattern that imparts efficient individualization and chirality selection. The cooperative hydrogen bonding between adjacent Flavin moieties results in the formation of a helical ribbon, which organizes around single-walled carbon nanotubes through concentric π–π interactions between the Flavin Mononucleotide and the underlying graphene wall. The strength of the helical Flavin Mononucleotide assembly is strongly dependent on nanotube chirality. In the presence of a surfactant, the Flavin Mononucleotide assembly is disrupted and replaced without precipitation by a surfactant micelle. The significantly higher affinity of the Flavin Mononucleotide assembly for (8,6)-single-walled carbon nanotubes results in an 85% chirality enrichment from a nanotube sample with broad diameter distribution. A small organic molecule self-assembles into helical ribbons that wrap around single-walled carbon nanotubes. The strength of the wrapping interaction depends on the chirality of each nanotube and enables mixtures to be separated.
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synthesis and redox behavior of Flavin Mononucleotide functionalized single walled carbon nanotubes
Journal of the American Chemical Society, 2008Co-Authors: Sang Yong Ju, Fotios PapadimitrakopoulosAbstract:In this contribution, we describe the synthesis and covalent attachment of an analogue of the Flavin Mononucleotide (FMN) cofactor onto carboxylic functionalities of single-walled carbon nanotubes (SWNTs). The synthesis of FMN derivative (12) was possible by coupling Flavin H-phosphonate (9) with an aliphatic alcohol, using a previously unreported N-(3-dimethylaminopropyl)-N‘-ethylcarbodiimide hydrochloride coupling. We found that the Flavin moiety of 12-SWNT shows a strong π−π interaction with the nanotube side-walls. This leads to a collapsed FMN configuration that quenches Flavin photoluminescence (PL). The treatment of 12-SWNT with sodium dodecyl sulfate (SDS) overcomes this strong nanotube/isoalloxazine interaction and restores the FMN into extended conformation that recovers its luminescence. In addition, redox cycling as well as extended sonication were proven capable to temporally restore PL as well. Cyclic voltammetry of FMN onto SWNT forests indicated profound differences for the extended and co...
Hiromichi Kataura - One of the best experts on this subject based on the ideXlab platform.
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determination of enantiomeric purity of single wall carbon nanotubes using Flavin Mononucleotide
Journal of the American Chemical Society, 2017Co-Authors: Takeshi Tanaka, Takuya Hirakawa, Yohei Yomogida, Hiromichi KatauraAbstract:Although enantiomeric separation of single-wall carbon nanotubes is possible, their enantiomeric purity (EP) remains an issue due to a lack of effective evaluation methods. In this work, we report the EP of (6,5) carbon nanotube enantiomers using Flavin Mononucleotide (FMN) as an enantiomer-sensitive dispersant. The enantiomers (6,5) and (11,–5) were separated by a gel column chromatography method and dispersed in a FMN aqueous solution. In these solutions, (6,5) and (11,–5) showed E11 optical transitions at different wavelengths due to handedness-dependent interactions with the FMN molecule, which enabled us to estimate each concentration, namely, the EP. We prepared six intermediate-purity enantiomer samples by mixing the (6,5) and (11,–5) enantiomers and measured their circular dichroism (CD) spectra. The CD signal was confirmed to change linearly with the EP. Using this relationship, we can estimate the EP of any mixture of (6,5) and (11,–5) from its CD intensity.
Martina H Stenzel - One of the best experts on this subject based on the ideXlab platform.
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riboFlavin vitamin b2 and Flavin Mononucleotide as visible light photo initiators in the thiol ene polymerisation of peg based hydrogels
Polymer Chemistry, 2017Co-Authors: Rhiannon Batchelor, G Kwandou, Patrick T Spicer, Martina H StenzelAbstract:The photoinitiators used in light mediated hydrogelation have been limited due to cytotoxicity and solubility issues. Here we report the use of riboFlavin and Flavin Mononucleotide as nontoxic, naturally occurring photoinitiators for the thiol–ene hydrogelation of functionalised poly(ethylene glycol). High Resolution Magic Angle Spinning (HRMAS) NMR spectroscopy and oscillatory rheometry were used to probe the efficiency of these initiators for this hydrogel system. The gelation and reaction progression could easily be manipulated using different initiator concentrations and light intensities.
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(−)-RiboFlavin (vitamin B2) and Flavin Mononucleotide as visible light photo initiators in the thiol–ene polymerisation of PEG-based hydrogels
Polymer Chemistry, 2017Co-Authors: Rhiannon Batchelor, G Kwandou, Patrick T Spicer, Martina H StenzelAbstract:The photoinitiators used in light mediated hydrogelation have been limited due to cytotoxicity and solubility issues. Here we report the use of riboFlavin and Flavin Mononucleotide as nontoxic, naturally occurring photoinitiators for the thiol–ene hydrogelation of functionalised poly(ethylene glycol). High Resolution Magic Angle Spinning (HRMAS) NMR spectroscopy and oscillatory rheometry were used to probe the efficiency of these initiators for this hydrogel system. The gelation and reaction progression could easily be manipulated using different initiator concentrations and light intensities.
Takeshi Tanaka - One of the best experts on this subject based on the ideXlab platform.
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determination of enantiomeric purity of single wall carbon nanotubes using Flavin Mononucleotide
Journal of the American Chemical Society, 2017Co-Authors: Takeshi Tanaka, Takuya Hirakawa, Yohei Yomogida, Hiromichi KatauraAbstract:Although enantiomeric separation of single-wall carbon nanotubes is possible, their enantiomeric purity (EP) remains an issue due to a lack of effective evaluation methods. In this work, we report the EP of (6,5) carbon nanotube enantiomers using Flavin Mononucleotide (FMN) as an enantiomer-sensitive dispersant. The enantiomers (6,5) and (11,–5) were separated by a gel column chromatography method and dispersed in a FMN aqueous solution. In these solutions, (6,5) and (11,–5) showed E11 optical transitions at different wavelengths due to handedness-dependent interactions with the FMN molecule, which enabled us to estimate each concentration, namely, the EP. We prepared six intermediate-purity enantiomer samples by mixing the (6,5) and (11,–5) enantiomers and measured their circular dichroism (CD) spectra. The CD signal was confirmed to change linearly with the EP. Using this relationship, we can estimate the EP of any mixture of (6,5) and (11,–5) from its CD intensity.