Self-Assembly of Alkyl-Substituted Oligothiophenes on MoS₂: A Joint Experimental/Theoretical Study

Abstract

The molecular arrangements of two different alkylsubstituted oligothiophenes, α,α′-dihexylquaterthiophene (DH4T) and α,α′-dioctylterthiophene (DOTT), in monolayers on molybdenum disulfide (MoS 2 ) were studied with a joint theoretical/experimental approach. Scanning tunneling microscopy was used both at the liquid/ solid interface and in dry conditions to investigate the ordering of the conjugated oligomers in two-dimensional layers. DH4T and DOTT form well-ordered monolayers at large scales with interdigitated packing on MoS 2 . In addition, DOTT exhibits an arrangement in which a dimer-type stacking of the conjugated backbone with an interlocking of the alkyl side chains is formed. Molecular modeling simulations have been used to provide insights into the microscopic morphology and to assess the stability of the different assemblies of DOTT and DH4T on MoS 2 .

Host–guest chemistry in two-dimensional supramolecular networks

“…A typical example where van der Waals forces have been used as potent directional intermolecular interactions is the porous networks of triangular phenylene-ethynylene macrocycles, commonly known as DBAs. These building blocks consist of a rigid triangular or rhombic dehydrobenzo [12]annulene core substituted with alkoxy or alkyl chains. The peripheral chains stabilize the self-assembled network not only via van der Waals interactions with the surface, but they also function as highly directional intermolecular linkages by forming a characteristic binding pattern commonly known as interdigitation.…”

“…The research on DBA derivatives has been at the forefront of multicomponent host-guest systems. A large polycyclic aromatic hydrocarbon nicknamed 'nanographene' (NG) was used as a guest for DBA derivatives with different chain lengths (n = 8,12,14,16,18). Depending on the cavity size offered by the DBA host network, one or up to six triangular NG guests could be immobilized.…”

“…Highly oriented pyrolytic graphite (HOPG) and Au (111) are most commonly used, however MoS 2 has also been used for self-assembly experiments under ambient conditions. 12,13 Although the solution-solid interface provides a 'real-life' view of the assembly process, the UHV environment has unique attributes such as ultra-clean environment and choice of variety of surfaces. Deposition of molecules is typically carried out using organic molecular beam epitaxy (OMBE) technique.…”

Structure of van der Waals bound hybrids of organic semiconductors and transition metal dichalcogenides: the case of acene films on MoS2

“…In a previous AFM study of pentacene films on MoS 2 several coexisting adlayer morphologies (snowflake‐like and granular) were reported so that the intrinsic film growth remains unclear. Interestingly, even before the discovery of 2D materials several surface science studies have been devoted to molecular adsorbates on the basal plane of MoS 2 which was essentially used as inert and flat substrate like graphite. However, these studies were mostly limited to films of monolayer thickness, while the structure of thicker films had not been studied systematically.…”

Beyond “decorative” 2D supramolecular self-assembly: strategies towards functional surfaces for nanotechnology

“…The possibility to use as substrates, beside graphene, other 2D materials such as hexagonal boron nitride (h-BN), [107][108] or transition metal dichalcogenides (e.g. MoS 2 ), 109 should also offer novel opportunities to create functional structures by alternating 2D materials and organic adlayers. Moreover, in relation to the processing of these materials for device applications, working at liquid-solid interface must be favoured in order to be compatible with techniques such as printed organic electronics.…”