Nanotemplated growth of graphene nanoribbons (GNRs) inside carbon nanotubes is a promising mean to fabricate ultrathin ribbons with desired side edge configuration. We report the optical properties of the GNRs formed in single-wall carbon nanotubes. When coronene is used as the precursor, extended GNRs are grown via a high-temperature annealing at 700 °C. Their optical responses are probed through the diazonium-based side-wall functionalization, which effectively suppresses the excitonic absorption peaks of the nanotubes without damaging the inner GNRs. Differential absorption spectra clearly show two distinct peaks around 1.5 and 3.4 eV. These peaks are assigned to the optical transitions between the van Hove singularities in the density of state of the GNRs in qualitative agreement with the first-principles calculations. Resonance Raman spectra and transmission electron microscope observations also support the formation of long GNRs.
The self‐assembly of an amide‐functionalized dithienyldiketopyrrolopyrrole (DPP) dye in aqueous media was achieved through seed‐initiated supramolecular polymerization. Temperature‐ and time‐dependent studies showed that the spontaneous polymerization of the DPP derivative was temporally delayed upon cooling the monomer solution in a methanol/water mixture. Theoretical calculations revealed that an amide‐functionalized DPP derivative adopts an energetically favorable folded conformation in the presence of water molecules due to hydration. This conformational change is most likely responsible for the trapping of monomers in the initial stage of the cooperative supramolecular polymerization in aqueous media. However, the monomeric species can selectively interact with externally added fragmented aggregates as seeds through concerted π‐stacking and hydrogen‐bonding interactions. Consequently, the time course of the supramolecular polymerization and the morphology of the aggregated state can be controlled, and one‐dimensional fibers that exhibit a J‐aggregate‐like bathochromically shifted absorption band can be obtained.
The low quality of education in MAS Al-Hikmah Soe shows that teachers are still lacking in the ability to develop teaching materials due to lack of training. Therefore, this program aims to develop teaching materials based on the local wisdom of the Timorese. In this community service, using a dialogical method that is carried out with training directly to the teachers and students. The result is (1) the teacher's response in this activity has a strong effect on their ability to develop teaching materials based on local wisdom, because they did not realize and know that the values of local wisdom can be used as material to develop teaching materials, but after participating in training they realize that teaching material is not difficult, because there are many around us that can be used as teaching material. (2) The teacher's paradigm for smartphones has changed after attending this training, because they consider smartphones to be dangerous to students, but after attending this training they realize that smartphones are the future of human civilization that cannot be resisted, precisely the applications in them can be used as online learning media.
Hydroboration of alkenes is a classical reaction in organic synthesis, in which alkenes react with boranes to give alkylboranes, with subsequent oxidation resulting in alcohols. The double bond (π-bond) of alkenes can be readily reacted with boranes owing to its high reactivity. However, the single bond (σ-bond) of alkanes has never been reacted. To pursue the development of σ-bond cleavage, we selected cyclopropanes as model substrates since they present a relatively weak σ-bond. Herein, we describe an iridium-catalyzed hydroboration of cyclopropanes, resulting in β-methyl alkylboronates. These unusually branched boronates can be derivatized by oxidation or cross-coupling chemistry, accessing "designer" products that are desired by practitioners of natural product synthesis and medicinal chemistry. Furthermore, mechanistic investigations and theoretical studies revealed the enabling role of the catalyst. Recently, several chemists including our group reported an iridium-catalyzed C-H borylation of cyclopropanes [19-21]. In one report, cyclopropanes were reacted with iridium complexes with a nitrogen bidentate ligand, 3,4,7,8-tetramethylphenanthroline (3,4,7,8-tetraMephen), which engendered a cyclopropane carbonhydrogen activation to afford borylated cyclopropanes (Fig. 1B). With the aim of achieving cyclopropane carbon-carbon activation, we forged a blueprint for selective bond activation. If an appropriate ligand were used, it might be possible to perform a "chemoselectivity switch" from C-H (intermediate A) to CC (intermediate B) bond activation in which the selectivity of CC activation could be achieved by reaction of the catalyst with the sterically less hindered Cb-Cg bond [22-24]. With these goals in mind, we conducted an extensive screening of ligands, and by using 2-[4-(1,1-dimethylethyl)-4,5-dihydro-2-oxazolyl]quinoline (t-Bu-Quinox), we achieved the first iridium-catalyzed σ-bond hydroboration of cyclopropanes (Fig. 1C). We initiated our study by finding a suitable ligand for the target reaction, consisting of N-cyclopropylpivalamide (1a) as a model mono-substituted cyclopropane. 1a was reacted with pinacolborane (H-Bpin: 1.5 equiv) in the presence of Ir dimer [Ir(OMe)(cod)]2 (5 mol%) and ligands (5 mol%) in THF at 80 ºC under nitrogen atmosphere. After an extensive screening of ligands (see Supplementary Materials), it was found that t-BuQuinox (L1) effects the cleavage of the σ-bond and forms hydroboration product 2a in 62% yield
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