Liquid Phase Exfoliation of Rubrene Single Crystals into Nanorods and Nanobelts

Abstract

Liquid phase exfoliation (LPE) is a popular method to create dispersions of two-dimensional nanosheets from layered inorganic van der Waals crystals. Here, it is applied to orthorhombic and triclinic single crystals of the organic semiconductor rubrene with only noncovalent interactions (mainly π–π) between the molecules. Distinct nanorods and nanobelts of rubrene are formed, stabilized against aggregation in aqueous sodium cholate solution, and isolated by liquid cascade centrifugation. Selected-area electron diffraction and Raman spectroscopy confirm the crystallinity of the rubrene nanorods and nanobelts while the optical properties (absorbance, photoluminescence) of the dispersions are similar to rubrene solutions due to their randomized orientations. The formation of these stable crystalline rubrene nanostructures with only a few molecular layers by LPE confirms that noncovalent interactions in molecular crystals can be strong enough to enable mechanical exfoliation similar to inorganic layered materials.

π‐Sticked Metal‒Organic Monolayers for Single‐Metal‐Site Dependent CO2 Photoreduction and Hydrogen Evolution Reaction

“…DFT theoretical calculations revealed the π···π interaction energies for two independent dimers (A…B or C…D) and one trimer (A…B and C…D) in Fe‐πMOL and Co‐πMOL. [ 41 ] The interaction energies of A…B fashion (‒58.16 and ‒55.65 kJ mol −1 for Fe‐πMOL and Co‐πMOL, respectively) are smaller than those of the C…D fashion (‒43.93 and ‒43.10 kJ mol −1 ) (Figures S2 and S3, Supporting Information), which is indicative of the stronger packing effect due to smaller dihedral angle. The total π···π interaction energies in the trimer are calculated to be ‒110.46 and ‒108.37kJ mol −1 for Fe‐πMOL and Co‐πMOL (Figure 1c,d), respectively, which are comparable to those of other exfoliated monolayers.…”

Electrochemical Intercalation and Exfoliation of CrSBr into Ferromagnetic Fibers and Nanoribbons

“…The exfoliation protocol was significantly faster than previously reported performances for various 2D materials exfoliation processes. [16][17][18][19][20][21][22][23] In this case, a period of 1 h was sufficient, since the crystal started to swiftly expand forming visible fiber-shape structures of intercalated CrSBr, which led to eventual crystal breakdown and exfoliation (Figure 1A).…”

“…[13,14] On the other hand, liquid phase exfoliation (LPE) has been proven to be an efficient way to produce high-quality 2D nanosheets in large quantities. This top-down approach has been applied to exfoliate inorganic van der Waals crystals such as graphite, [15] h-BN, [16] transition metals dichalcogenides (MoS 2 , WS 2 , MoSe 2 ), [17,18] MXenes, [19] pnictogens [20,21] as well as organic semiconductors, [22] and layered polymers. [23] Among the exfoliation methods, electrochemical exfoliation is a promising approach to preparing uniform nanosheets under mild conditions.…”

Interface‐Confined Assembly of Layered Molecular Crystal Arrays Toward Wearable UV‐Radiation Monitor

“…[10][11][12][13] Semiconducting organic small molecules are typically composed of a rigid 𝜋-conjugated skeleton and flexible solubilizing side chains. [14] As a result of their anisotropic intermolecular interactions, these molecules tend to crystallize at the phase interface with diversified crystallographic morphology, including 1D structures (like wire and rod), [15][16][17][18] 2D structures (like sheet and disk), [19][20][21][22][23] and 3D structures (like cube and sphere). [24,25] For wearable electronics, it is required to assemble these organic molecules with different crystallization behaviors into single crystal structures, then achieve ordered molecule packing and decreased grain boundaries to boost exciton dissociation and charge carrier transport.…”