Heterogeneous nucleation of organic crystals mediated by single-molecule templates

Abstract

Fundamental understanding of how crystals of organic molecules nucleate on a surface remains limited because of the difficulty of probing rare events at the molecular scale. Here we show that single-molecule templates on the surface of carbon nanohorns can nucleate the crystallization of two organic compounds from a supersaturated solution by mediating the formation of disordered and mobile molecular nanoclusters on the templates. Single-molecule real-time transmission electron microscopy indicates that each nanocluster consists of a maximum of approximately 15 molecules, that there are fewer nanoclusters than crystals in solution, and that in the absence of templates physisorption, but not crystal formation, occurs. Our findings suggest that template-induced heterogeneous nucleation mechanistically resembles two-step homogeneous nucleation.

Direct quantitative measurement of the C═O⋅⋅⋅H–C bond by atomic force microscopy

“…Recent improvements in scanning transmission electron microscopy (STEM), namely, aberration correction ( 1 ), allow us to see individual atoms in thin films, and even hydrogen atoms in the crystalline solid YH 2 can be resolved by annular bright-field imaging ( 2 ). However, for molecules, electron irradiation with high energy strongly limits the resolution, with only rare examples of the observation of small molecular clusters ( 3 ). Thus, the observation of hydrogen atoms in a single molecule via STEM has yet to be achieved.…”

Nucleus in a droplet

“…Direct imaging of crystal nuclei in molecular systems is difficult owing to the rarity and brevity of nucleation events (because of the free-energy barrier to nucleation, local fluctuations that lead to the formation of nuclei are few in number, occur at random locations and exist for a short time). Now, Harano and colleagues report in Nature Materials that the nucleation of organic molecules in solution can also follow a twostep process 9 . To image molecular clusters, the researchers chose a combination of ingenious strategies.…”

“…This suggests that the nanohorn-mounted tribromide-Y molecules Figure 1 | Schematic of the two-step mechanism of nucleation of crystals of tribromide-Y on single-molecule hooks 9 . Each hook consists of a tribromide-Y molecule (blue) attached to a carbon nanohorn through an amide bond (red).…”

Filme molekularer Bewegungen und Reaktionen: Einzelmolekültransmissionselektronenmikroskopie in Echtzeit

“…[14] Da wir uns der Rigidität der Benzolamidbindung bewusst waren, synthetisierten wir ein Dibromben-zolamid auf einem Kohlenstoffnanohorn (CNH, 5), [15] der konischen Variante einer einwandigen CNT (Abbildung 7). [14] Da wir uns der Rigidität der Benzolamidbindung bewusst waren, synthetisierten wir ein Dibromben-zolamid auf einem Kohlenstoffnanohorn (CNH, 5), [15] der konischen Variante einer einwandigen CNT (Abbildung 7).…”

“…[14] In der erwähnten Studie benutzten wir das Dibromphenylbenzamid-Molekül auf einem CNH (5) SMRT-TEM decylcarborans 2, das sich schnell zuerst nach oben und dann nach unten bewegt (es sei angemerkt, dass sich die "oben/ unten"-Notation lediglich auf die Bilderpräsentation bezieht, ohne jegliche physikalische Bedeutung). Dieser Vorteil wird am besten durch die Strukturbestimmung an Van-der-Waals-Clustern verdeutlicht, die keine strukturelle Periodizität aufweisen und nur als Clustermischung unterschiedlicher molekularer Zusammensetzung erhalten werden kçnnen.…”