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C–H functionalization of undecahalogenated carborane anions, [HCB 11 X 11 − ] (X = Cl, Br, I), is performed with Cs 2 CO 3 in acetonitrile. We show that the requisite Cl, Br and I carborane dianions can all be efficiently accessed with Cs 2 CO 3 . The utilization of Cs 2 CO 3 eliminates the complications associated with competing E2 elimination reactions providing an efficient, more functional group tolerant, and broader scope than previously reported. The ensuing functionalized cages provide potential synthons for constructing advanced materials and other molecular architectures for various applications.
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Covalent adsorption of functional groups on N-carbophenes
Abstract Starting from the planar molecule 1,3,5-trihydroxybenzene, Duet al.reported synthesizing one of a couple of possible 2D materials: graphenylene or 3-carbophene.[1] 3-carbophene is a member of a novel class of two-dimensional covalent organic framework, [N]-carbophenes (carbophenes). Using a high throughput method, we computed the formation energies and conduction properties of 3-, 4-, 5-, and 6-carbophenes with hydroxyl (OH), carbonyl (CO), nitro (NO2), amine (NH2), carboxyl (COOH) functional groups replacing hydrogen terminating agents. Five hundred and nine structures with randomly picked motifs, with functionalizations from a single functional group per cell to fully functionalized were studied. Our results demonstrate a negatively sloped linear relationship between the degree of functionalization and formation energy when the type of functional group and type of carbophene are held constant. The decrease in formation energy with functionalization makes Du’s synthesis of functionalized 3-carbophene more creditable. The type of carbophene, type of functional group, and the degree of functionalization all play a role in the band structure of the materials. For example, CO functional groups may lead to a mid- gap state pinned to the Fermi level, whereas the other functional groups studied keep the semiconducting nature of pristine carbophene. Thus, because carbonyl functional groups are often present in defected carbon systems, care should be taken to limit the amount of oxygen in carbophene devices where the band gap is important. Thus, this work strengthens the hypothesis of Junkermeier et al.’s hypothesis thatDu et al.synthesized 3-carbophene and not graphenylene.[2]
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- PAR ID:
- 10361885
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Materials Research Express
- ISSN:
- 2053-1591
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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