Photochemical generation of bis-hexahapto chromium interconnects between the graphene surfaces of single-walled carbon nanotubes

Pekker, Áron; Chen, Mingguang; Bekyarova, Elena; Haddon, Robert C.

doi:10.1039/c4mh00192c

Cited by 13 publications

(20 citation statements)

References 33 publications

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“…This result confirms that the formation of a significant concentration of M(SWCNT) 2 or M(graphene) 2 moieties is only possible for samples with ultra low catalyst residue; however, the benefit for increased conductivity is clear [40][41][42] and therefore should prompt future research into new approaches to high purity carbon nanomaterials.…”

Section: Discussionsupporting

confidence: 69%

Catalyst Residue and Oxygen Species Inhibition of the Formation of Hexahapto-Metal Complexes of Group 6 Metals on Single-Walled Carbon Nanotubes

Wright

Barron

2017

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Abstract:The reaction of Group 6 metals with SWCNT has the potential to bridge the resistive SWCNT . . . SWCNT junctions by the formation of "Cr(SWCNT) 2 " complexes analogous to Cr(C 6 H 6 ) 2 . This study reports that the formation of such species is very sensitive to oxidation by a residual iron oxide catalyst used for the growth of the SWCNTs and adsorbed/bound oxygen functionality. The reaction of raw HiPco SWCNTs with M(CO) 6 and (C 7 H 8 )M(CO) 3 (M = Cr, W) or (C 6 H 6 )Cr(CO) 3 results in the formation of the Group 6 metal oxides. Annealing and acid treating the HiPco SWCNTs to reduce the catalyst content allows for the observation of zero valent metals by XPS, while the use of very high purity SWCNTs and graphene allows for the addition of primarily zero valent Group 6 metals, including the bis-hexahapto metal complex.

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Section: Discussionsupporting

confidence: 69%

Catalyst Residue and Oxygen Species Inhibition of the Formation of Hexahapto-Metal Complexes of Group 6 Metals on Single-Walled Carbon Nanotubes

Wright

Barron

2017

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“…Metal complexes on CNT walls with higher hapticity were reported for Cr(0) complexes . The interconnected η 6 ‐(SWNT) 2 Cr complex substantially increased conductivity, proving that interconnectivity is a viable strategy to alter the electronic properties of CNTs . Electrostatic interactions are also exploited to engage functional molecules close to CNTs (Figure c).…”

Section: Typical Noncovalent Interactions On the Surface Of Cntsmentioning

confidence: 96%

“…[24] The interconnected h 6 -(SWNT) 2 Cr complex substantially increased conductivity, proving that interconnectivity is a viable strategy to alter the electronic properties of CNTs. [25] Electrostatic interactions are also exploited to engage functional molecules close to CNTs (Figure 1c). Oxidized CNTs bearing carbox- ylate groups form ion pairs with outer cationic species.…”

Section: Typical Noncovalent Interactions On the Surface Of Cntsmentioning

confidence: 99%

Strategic Immobilization of Molecular Catalysts onto Carbon Nanotubes via Noncovalent Interaction for Catalytic Organic Transformations

Kumagai

Shibasaki

2016

Israel Journal of Chemistry

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Since their discovery, carbon nanotubes (CNTs) continue to attract growing interest from scientists in a wide range of fields, likely due to their fascinating nanoarchitecture as well as their electronic and physical properties. From the viewpoint of synthetic chemistry, the chemical and physical stability, high surface area, and π‐stacking nature of CNTs are attractive features for their application as solid supports for molecular catalysts. The chemical functionalization of CNTs has been explored for various applications, including covalent and noncovalent grafting of molecular catalysts. Although noncovalent grafting provides less stable immobilized catalysts compared with covalently grafted hybrid molecular catalysts and CNTs, the preparation protocol is expeditious and repetitive use of the catalysts is well demonstrated, confirming their potential broad utility in synthetic organic chemistry.

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“…Also, a photochemical method could effectively organometallic-functionalize carbon materials ( e . g ., single-walled carbon nanotubes) . Three-dimensional cross-linked graphene nanoplatelets (GNPs) are synthesized under irradiation of UV light in which bis-hexahapto bonds work as bridges to interconnect GNPs and electrical conductivity is enhanced correspondingly .…”

Section: The Chemical Mechanismmentioning

confidence: 99%

“…33 Also, a photochemical method could effectively organometallic-functionalize carbon materials (e.g., single-walled carbon nanotubes). 34 Three-dimensional crosslinked graphene nanoplatelets (GNPs) are synthesized under irradiation of UV light in which bis-hexahapto bonds work as bridges to interconnect GNPs and electrical conductivity is enhanced correspondingly. 35 The same photoactivated reactions are also performed on single-layer graphene to synthesize a (η 6 -graphene)CrL [L = C 6 H 6 , (CO) 3 )] complex, leading to enhanced conductivity.…”

mentioning

confidence: 99%

Photo-organometallic, Nanoparticle Nucleation on Graphene for Cascaded Doping

2019

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Controlling the doping levels in graphene by modifying the electric potential of interfaced nanostructures is important to understand “cascaded-doping”-based applications of graphene. However, graphene does not have active sites for nanoparticle attachment, and covalently adding functional groups on graphene disrupts its planar sp2-hybridization, affecting its cascaded doping. Here we show a hexahepto (η6) photo-organometallic chemistry to interface nanoparticles on graphene while retaining the sp2-hybridized state of carbon atoms. For testing cascaded doping with ethanol interaction, transition metal oxide nanoparticles (TMONs) (Cr2O3/CrO3, MoO3, and WO3) are attached on graphene. Here, the transition metal forms six σ-bonds and π-back-bonds with the benzenoid rings of graphene, while its opposite face binds to three carbonyl groups, which enable nucleation and growth of TMONs. With a radius size ranging from 50 to 100 nm, the TMONs downshift the Fermi level of graphene (−250 mV; p-doping) via interfacial charge transfer. This is consistent with the blue shift of graphene’s G and 2D Raman modes with a hole density of 3.78 × 1012 cm–2. With susceptibility to ethanol, Cr x O3 nanoparticles on graphene enable cascaded doping from ethanol that adsorbs on Cr x O3, leading to doping of graphene to increase the electrical resistance of the TMONs–graphene hybrid. This nanoparticle-on-graphene construct can have several applications in gas/vapor sensing, electrochemical catalysis, and high-energy-density supercapacitors.

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Photochemical generation of bis-hexahapto chromium interconnects between the graphene surfaces of single-walled carbon nanotubes

Abstract: The linkage of single-walled carbon nanotube junctions by the photochemistry of organometallic chromium reagents produces dramatic increases in network conductivity.

Cited by 13 publications

References 33 publications

Catalyst Residue and Oxygen Species Inhibition of the Formation of Hexahapto-Metal Complexes of Group 6 Metals on Single-Walled Carbon Nanotubes

Catalyst Residue and Oxygen Species Inhibition of the Formation of Hexahapto-Metal Complexes of Group 6 Metals on Single-Walled Carbon Nanotubes

Strategic Immobilization of Molecular Catalysts onto Carbon Nanotubes via Noncovalent Interaction for Catalytic Organic Transformations

Photo-organometallic, Nanoparticle Nucleation on Graphene for Cascaded Doping

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