The self-assembly of a pair of low-symmetry tetracarboxylic acid molecules and their co-assembly with bridging molecules at the liquid–solid interface

Abstract

The supramolecular self-assembly behavior of a pair of low symmetric tetracarboxylic acid molecules (H4OBDB and H4ADDI) and their co-assembly behaviors with TMA bridging molecule were studied at the liquid–solid interface....

F···Br and F···S Heterohalogen-Bond-Directed 2D Self-Assemblies of a Benzothiadiazole Derivative

“…Besides, one dodecyl side chain is attached to the thiophene ring on each side. From the top-view and side-view images of the 3D ESP maps in Figure b and c, a positively charged σ-hole on top of the Br atom at the end of the C–Br bond can be recognized (shown in red), accompanied by the negatively charged surroundings (shown in blue). , However, the F atom shows no feature with a σ-hole, which will act as a donor in XBs when connecting with exceedingly strong electron-withdrawing groups. ,, Therefore, F···Br and Br···S XBs might be formed via the interaction between the electron-deficient σ-hole on Br and the electron-rich S/F atom.…”

“…15,38 However, the F atom shows no feature with a σ-hole, which will act as a donor in XBs when connecting with exceedingly strong electronwithdrawing groups. 3,26,39 Therefore, F•••Br and Br•••S XBs might be formed via the interaction between the electrondeficient σ-hole on Br and the electron-rich S/F atom.…”

“…The adsorption tendency arising from the multiple methylene groups in n- tridecane and n -tetradecane provides additional solvent–substrate interaction to stabilize the ladder-like, linear I, and linear II patterns. The coabsorbed solvents diversify the molecular nanostructures because of intermolecular interactions and the number of coabsorbed solvents. , Besides the van der Waals interactions, the intermolecular XBs and HBs between conjugated cores (F···Br, F···S, Br···Br, Br···S, and H···S) also play important roles during self-assembly. ,, Therefore, we think that the interactions are in competition and cooperation. However, their contributing fractions are hard to determine.…”

“…Generally, the energy per unit area will be used to compare the energies of varied patterns because it can eliminate the different numbers of adsorbed molecules in each unit cell on monolayers. , In Table , the energy per unit area for the frame-like (−0.491 kcal mol –1 Å –2 ), bamboo-like (−0.559 kcal mol –1 Å –2 ), and wave-like (−1.048 kcal mol –1 Å –2 ) patterns shows that the energies of frame-like and bamboo-like patterns are about equal, while the energy of the wave-like pattern is lower than them. However, the results of the consecutive in situ STM scans in these areas show that no phase transition occurs in the areas containing the frame-like, bamboo-like, and wave-like patterns (Figure S11, SI) in heptanoic acid, suggesting that these assemblies are all stable.…”

“…Though the XB was identified as a kind of noncovalent interaction by the International Union of Pure and Applied Chemistry in 2013, the 2D self-assemblies constructed by homo- or hetero-XBs, − where halogen atoms or other types of Lewis bases (e.g., N, O, S) act as electron donors for the σ-holes of building blocks, have already drawn a great amount of attention in the past two decades. − Lately, even the construction of 2D assemblies by integrating XBs and other intermolecular interactions such as hydrogen bonding (HB), , metal–ligand coordination, − and host–guest encapsulation ,− has attracted a great amount of interest, considering the feasibility of achieving more abundant and well-defined 2D assembly patterns on the surface and at the interface. For example, Silly et al.…”