Two-Dimensional Nanocrystals of Molecular Janus Particles

Abstract

This paper describes a rational strategy to obtain self-assembled two-dimensional (2D) nanocrystals with definite and uniform thickness from a series of molecular Janus particles based on molecular nanoparticles (MNPs). MNPs are 3D framework with rigid shapes. Three different types of MNPs based on derivatives of polyhedral oligomeric silsesquioxane (POSS), [60]fullerene (C60), and Lindqvist-type polyoxometalate (POM) are used as building blocks to construct these amphiphilic molecular Janus particles by covalently connecting hydrophobic crystalline BPOSS with a charged hydrophilic MNP. The formation of 2D nanocrystals with an exact thickness of double layers of molecules is driven by directional crystallization of the BPOSS MNP and controlled by various factors such as solvent polarity, number of counterions, and sizes of the MNPs. Strong solvating interactions of the ionic MNPs in polar solvents (e.g., acetonitrile and dimethylformamide) are crucial to provide repulsive interactions between the charged outlying ionic MNPs and suppress further aggregation along the layer normal direction. The number of counterions per molecule plays a major role in determining the self-assembled morphologies. Size matching of the hydrophobic and ionic MNPs is another critical factor in the formation of 2D nanocrystals. Self-assembly of rationally designed molecular Janus particles provides a unique "bottom-up" strategy to engineer 2D nanostructures.

Manipulation of Self-Assembled Nanostructure Dimensions in Molecular Janus Particles

“…S10), confirming the insensitivity to solvent polarity of this self-assembled structure. 70 In analogy to previously reported MJPs, 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 21 building blocks could be potentially useful in applications related to the POM clusters, which range from catalysis, 73 electrochemistry 74 , photochromism 75 , magnetism 76 , to medicine...…”

Structure-Determining Step in the Hierarchical Assembly of Peptoid Nanosheets

“…The direct synthesis of organic 2D nanomaterials from solution overcomes some of these limitations, and several elegant approaches have been recently reported. 4,8,[12][13][14] This approach typically uses rigid, symmetric, small-molecule building blocks bearing multiple reactive groups that can combine to form 2D periodic networks bound covalently or non-covalently. This provides a flexible route to surface-functionalized 2D nanomaterials.…”

Synthetische kovalente und nichtkovalente zweidimensionale Materialien

“…[107] Bei der genannten Studie hatten die Januspartikel eine amphiphile Struktur aus einem hydrophilen ionischen molekularen Nanopartikel und einem hydrophoben kristallinen molekularen Nanopartikel, mit dem Ziel, dass elektrostatische Abstoßung die Entstehung von 2D-Nanokristallen gegenüber 3D-Strukturen begünsti-gen sollte. [108] Um dies zu erreichen, wurden vier Sätze von Januspartikeln synthetisiert:B POSS-Lind, BPOSS-APOSS, BPOSS-AC 60 und DiBPOSS-AC 60 (POSS = polyedrisches oligomeres Silsesquioxan;A bbildung 8a). Die Synthese der Januspartikel erfolgte durch verschiedene Kupplungsreaktionen, um die beiden molekularen Nanopartikel miteinander zu verbinden.…”