Atomic-number (
            <i>Z</i>
            )-correlated atomic sizes for deciphering electron microscopic molecular images

Xing, Junfei; Takeuchi, Keishi; Kamei, Ko; Nakamuro, Takayuki; Harano, Koji; Nakamura, Eiichi

doi:10.1073/pnas.2114432119

Cited by 18 publications

(11 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The formation of TPB−TFB COF is further confirmed by high-resolution transmission electron microscopy (HR-TEM). Figure 1e shows a TEM image of the periodic hexagonal patterns for an exfoliated TPB−TFB COF thin film, where the obtained contrast matches well with an image for the simulated AA-stacking TPB−TFB COF 42 (Figure S3a). Figure S3b visualizes a stacked-layer structure with an interlayer distance of 3.6 Å (Figure S3c), in good agreement with the PXRD data.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Outstanding Charge Mobility by Band Transport in Two-Dimensional Semiconducting Covalent Organic Frameworks

Jin

Hanayama

et al. 2022

J. Am. Chem. Soc.

View full text Add to dashboard Cite

Two-dimensional covalent organic frameworks (2D COFs) represent a family of crystalline porous polymers with a long-range order and well-defined open nanochannels that hold great promise for electronics, catalysis, sensing, and energy storage. To date, the development of highly conductive 2D COFs has remained challenging due to the finite π-conjugation along the 2D lattice and charge localization at grain boundaries. Furthermore, the charge transport mechanism within the crystalline framework remains elusive. Here, time- and frequency-resolved terahertz spectroscopy reveals intrinsically Drude-type band transport of charge carriers in semiconducting 2D COF thin films condensed by 1,3,5-tris(4-aminophenyl)benzene (TPB) and 1,3,5-triformylbenzene (TFB). The TPB–TFB COF thin films demonstrate high photoconductivity with a long charge scattering time exceeding 70 fs at room temperature which resembles crystalline inorganic materials. This corresponds to a record charge carrier mobility of 165 ± 10 cm 2 V –1 s –1 , vastly outperforming that of the state-of-the-art conductive COFs. These results reveal TPB–TFB COF thin films as promising candidates for organic electronics and catalysis and provide insights into the rational design of highly crystalline porous materials for efficient and long-range charge transport.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Outstanding Charge Mobility by Band Transport in Two-Dimensional Semiconducting Covalent Organic Frameworks

Jin

Hanayama

et al. 2022

J. Am. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…This difference implies that the image contrast of the alkyl chains within Hx is relatively weak and is obscured by the background signal arising from the support film. 77 Consequently, only the aromatic and barbituric acid sections appear discernible in the TEM image. In contrast, the Hc fiber, which presents the π-plane of the 1 6 rosettes oriented nearly parallel to the substrate, does not exhibit significant image contrast between the aromatic and alkyl chain domains.…”

Section: ■ Resultsmentioning

confidence: 99%

Supramolecular Polymer Polymorphism: Spontaneous Helix–Helicoid Transition through Dislocation of Hydrogen-Bonded π-Rosettes

Otsuka,

Takahashi,

Isobe

et al. 2023

J. Am. Chem. Soc.

Self Cite

View full text Add to dashboard Cite

Polymorphism, a phenomenon whereby disparate self-assembled products can be formed from identical molecules, has incited interest in the field of supramolecular polymers. Conventionally, the monomers that constitute supramolecular polymers are engineered to facilitate one-dimensional aggregation and, consequently, their polymorphism surfaces primarily when the states of assembly differ significantly. This engenders polymorphs of divergent dimensionalities such as one- and two-dimensional aggregates. Notwithstanding, realizing supramolecular polymer polymorphism, wherein polymorphs maintain one-dimensional aggregation, persists as a daunting challenge. In this work, we expound upon the manifestation of two supramolecular polymer polymorphs formed from a large discotic supramolecular monomer (rosette), which consists of six hydrogen-bonded molecules with an extended π-conjugated core. These polymorphs are generated in mixtures of chloroform and methylcyclohexane, attributable to distinctly different disc stacking arrangements. The face-to-face (minimal displacement) and offset (large displacement) stacking arrangements can be predicated on their distinctive photophysical properties. The face-to-face stacking results in a twisted helix structure. Conversely, the offset stacking induces inherent curvature in the supramolecular fiber, thereby culminating in a hollow helical coil (helicoid). While both polymorphs exhibit bistability in nonpolar solvent compositions, the face-to-face stacking attains stability purely in a kinetic sense within a polar solvent composition and undergoes conversion into offset stacking through a dislocation of stacked rosettes. This occurs without the dissociation and nucleation of monomers, leading to unprecedented helicoidal folding of supramolecular polymers. Our findings augment our understanding of supramolecular polymer polymorphism, but they also highlight a distinctive method for achieving helicoidal folding in supramolecular polymers.

show abstract

“…It should be noted that the sizes of the atomic images are approximately proportional to Z 2/3 ( Z = atomic number), and we can see using TEM only the heavy atoms, Br ( Z = 35), Cs (55), and Pb (82) atoms, but not C, N, and H atoms. A Z -correlated (ZC) model is shown in Figure k …”

Section: Resultsmentioning

confidence: 99%

“…A Z-correlated (ZC) model is shown in Figure 5k. 51 Figure 5f−j show a series of 20 ms video frames (50 fps) of 2 partially exposed to vacuum. It is partially buried in an electronrich and conductive CNT substrate (≈10 3 more conductive than aC) that protects the specimen from radiolysis.…”

Section: Carboxylic Acid-enabled Shape Control Of Perovskitementioning

confidence: 99%

Precision Synthesis and Atomistic Analysis of Deep-Blue Cubic Quantum Dots Made via Self-Organization

et al. 2022

Self Cite

View full text Add to dashboard Cite

As a crystal approaches a few nanometers in size, atoms become nonequivalent, bonds vibrate, and quantum effects emerge. To study quantum dots (QDs) with structural control common in molecular science, we need atomic precision synthesis and analysis. We describe here the synthesis of lead bromide perovskite magic-sized nanoclusters via self-organization of a lead malate chelate complex and PbBr3 – under ambient conditions. Millisecond and angstrom resolution electron microscopic analysis revealed the structure and the dynamic behavior of individual QDsstructurally uniform cubes made of 64 lead atoms, where eight malate molecules are located on the eight corners of the cubes, and oleylammonium cations lipophilize and stabilize the edges and faces. Lacking translational symmetry, the cube is to be viewed as a molecule rather than a nanocrystal. The QD exhibits quantitative photoluminescence and stable electroluminescence at ≈460 nm with a narrow half-maximum linewidth below 15 nm, reflecting minimum structural defects. This controlled synthesis and precise analysis demonstrate the potential of cinematic chemistry for the characterization of nanomaterials beyond the conventional limit.

show abstract

Atomic-number ( Z )-correlated atomic sizes for deciphering electron microscopic molecular images

Cited by 18 publications

References 51 publications

Outstanding Charge Mobility by Band Transport in Two-Dimensional Semiconducting Covalent Organic Frameworks

Outstanding Charge Mobility by Band Transport in Two-Dimensional Semiconducting Covalent Organic Frameworks

Supramolecular Polymer Polymorphism: Spontaneous Helix–Helicoid Transition through Dislocation of Hydrogen-Bonded π-Rosettes

Precision Synthesis and Atomistic Analysis of Deep-Blue Cubic Quantum Dots Made via Self-Organization

Contact Info

Product

Resources

About