A Tale of Tails: Alkyl Chain Directed Formation of 2D Porous Networks Reveals Odd–Even Effects and Unexpected Bicomponent Phase Behavior

Abstract

Supramolecular self-assembly of suitably functionalized building blocks on surfaces can serve as an excellent test-bed to gain understanding and control over multicomponent self-assembly in more complex matter. Here we employ a powerful combination of scanning tunnelling microscopy (STM) and molecular modeling to uncover two-dimensional (2D) crystallization and mixing behavior of a series of alkylated building blocks based on dehydrobenzo[12]annulene, forming arrays of nanowells. Thorough STM investigation employing high-resolution spatial imaging, use of specially designed marker molecules, statistical analysis and thermal stability measurements revealed rich and complex supramolecular chemistry, highlighting the impact of odd-even effects on the phase behavior. The methodology and analysis presented in this work can be easily adapted to the self-assembly of other alkylated building blocks.

Reversing the Handedness of Self‐Assembled Porous Molecular Networks through the Number of Identical Chiral Centres

“…The handedness of the monolayer formed by achiral DBA molecules is domain specific and overall the surface remains globally achiral . In contrast, the chirality of the DBA networks is controlled for cDBAs that comprise stereogenic centres at the 2‐positions of all alkyl chains.…”

Reversing the Handedness of Self‐Assembled Porous Molecular Networks through the Number of Identical Chiral Centres

“…[12] Unit cell parameters of the CCW honeycomb structure of cDBAOC12(S)OC12 are a = b = 4.5 AE 0.1 nm, g = 60 AE 28 8 (Figure 3b). [8] Unit cell parameters of the CW honeycomb structure of cDBAOC12(S)OC13 are a = b = 4.5 AE 0.1 nm, g = 60 AE 18 8 (Figure 3d). [8] Unit cell parameters of the CW honeycomb structure of cDBAOC12(S)OC13 are a = b = 4.5 AE 0.1 nm, g = 60 AE 18 8 (Figure 3d).…”

“…[6] First, we summarize some key features of relevance to this study.D BAsf orm chiral honeycomb type porous monolayer structures through van der Waals interactions of the interdigitated alkyl chains.T he chirality of the DBAh oneycomb networks is expressed at different structural levels.The mode of interaction of two adjacent molecules can be classified as "+ + type" or "À type", depending on the relative position of the four interdigitated alkyl chains ( Figure 1b). [8] In contrast, the chirality of the DBA networks is controlled for cDBAs that comprise stereogenic centres at the 2-positions of all alkyl chains.N amely, cDBAOC12(S) or cDBAOC13(R) having six chiral OC12(S) or OC13(R)c hains exclusively form CW or CCW pores because of steric interactions of the methyl groups attached to the stereogenic centres in the interdigitation pattern (Figure 1a). Consistent À type interdigitations lead to so-called clockwise (CW) pores,w hile + + type interdigitations produce counterclockwise (CCW) pores ( Figure 1c).…”

Imine‐Based Architectures at Surfaces and Interfaces: From Self‐Assembly to Dynamic Covalent Chemistry in 2D

“…This variable range of parameters allows one to designa nd create compounds that can adjust to their environment. Beyond the mere imagining of the physisorbed monolayers, [54,55] recent studies have demonstrated that STM is the most powerful toolt os tudy physical and chemical properties of nanostructures by meanso f, for example,m olecule manipulation, [56][57][58][59][60] monitoring of molecular dynamics, [43,61] surface chirality, [62] and so forth. [11] In particular,D CC includes the chemistry of disulfides, [12,13] acetals, [14,15] esters, [16,17] oxime, [18] boroxine, [19,20] alkynes, [21] and imines [22][23][24][25][26][27][28][29] to allow the generation of new covalents tructures.…”