Coronene guest molecule selectivity in host templates formed by hydrogen bonding and van der Waals forces at liquid/solid interfaces

COR guest molecules are selectively adsorbed in the hexagonal cavities in both H6PDB and H6PAB self-assembled systems and preferentially adsorbed in the H6PAB host template in the H6PAB/HPB system.

TiO x /Pt3Ti(111) surface-directed formation of electronically responsive supramolecular assemblies of tungsten oxide clusters

Highly ordered titanium oxide films grown on a Pt₃Ti(111) alloy surface were utilized for the controlled immobilization and tip-induced electric field-triggered electronic manipulation of nanoscopic W₃O₉ clusters. Depending on the operating conditions, two different stable oxide phases, z'-TiO _x and w'-TiO _x , were produced. These phases show a strong effect on the adsorption characteristics and reactivity of W₃O₉ clusters, which are formed as a result of thermal evaporation of WO₃ powder on the complex TiO _x /Pt₃Ti(111) surfaces under ultra-high vacuum conditions. The physisorbed tritungsten nano-oxides were found as isolated single units located on the metallic attraction points or as supramolecular self-assemblies with a W₃O₉-capped hexagonal scaffold of W₃O₉ units. By applying scanning tunneling microscopy to the W₃O₉-(W₃O₉)₆ structures, individual units underwent a tip-induced reduction to W₃O₈. At elevated temperatures, agglomeration and growth of large WO₃ islands, which thickness is strongly limited to a maximum of two unit cells, were observed. The findings boost progress toward template-directed nucleation, growth, networking, and charge state manipulation of functional molecular nanostructures on surfaces using operando techniques.

Synthesis and photophysics of new pyridyl end-capped 3D-dithia[3.3]paracyclophane-based Janus tectons: surface-confined self-assembly of their model pedestal on HOPG

Once synthesized, these new tectons demonstrated both ionic and coordination bonding. Surprisingly, P forms a quasi-square self-assembly independently of the underlying HOPG lattice.

Dichotomy between frustrated local spins and conjugated electrons in a two-dimensional metal-organic framework

Dichotomy between local spins and conjugated electrons spawns various exotic physical phenomena, however, it has mostly been reported in three-dimensional (3D) inorganic systems. We show, for the first time, that a rare 2D metal-organic framework exhibits intriguing dichotomy behavior, which can be directly identified through scanning tunneling microscopy/spectroscopy (STM/STS). In a newly synthesized Cu-hexaiminobenzene [Cu3(HAB)2], on the one hand, the Cu2+ ions form an ideal S - 1/2 antiferromagnetic (AFM) kagome lattice; on the other hand, the conjugated-electrons from the organic ligands produce a frustrated πx,y model on a honeycomb lattice, giving rise to completely dispersionless energy bands around the Fermi level that favour the ferromagnetic (FM) state. Remarkably, the frustrated local spins and conjugated electrons interact through a strong FM Hund's coupling, giving rise to a wide range of intriguing quantum phases. Furthermore, we propose that this dichotomy can be directly characterized through STM/STS measurements due to its special 2D nature, which provides a unique exciting platform to investigate the dichotomy of frustrated spins and electrons in a single lattice.

Supramolecular Assemblies on Surfaces: Nanopatterning, Functionality, and Reactivity

Understanding how molecules interact to form large-scale hierarchical structures on surfaces holds promise for building designer nanoscale constructs with defined chemical and physical properties. Here, we describe early advances in this field and highlight upcoming opportunities and challenges. Both direct intermolecular interactions and those that are mediated by coordinated metal centers or substrates are discussed. These interactions can be additive, but they can also interfere with each other, leading to new assemblies in which electrical potentials vary at distances much larger than those of typical chemical interactions. Earlier spectroscopic and surface measurements have provided partial information on such interfacial effects. In the interim, scanning probe microscopies have assumed defining roles in the field of molecular organization on surfaces, delivering deeper understanding of interactions, structures, and local potentials. Self-assembly is a key strategy to form extended structures on surfaces, advancing nanolithography into the chemical dimension and providing simultaneous control at multiple scales. In parallel, the emergence of graphene and the resulting impetus to explore 2D materials have broadened the field, as surface-confined reactions of molecular building blocks provide access to such materials as 2D polymers and graphene nanoribbons. In this Review, we describe recent advances and point out promising directions that will lead to even greater and more robust capabilities to exploit designer surfaces.

Solution phase post-modification of a trimesic acid network on Au(111) with Zn2+ ions

Post-modification of a TMA network of crown-like hexamers with Zn²⁺ ions transforms it into a metal–organic network of TMA–Zn²⁺ coordinated chevron-pairs.

Molecular self-assembly at nanometer scale modulated surfaces: trimesic acid on Ag(111), Cu(111) and Ag/Cu(111)

A modulated substrate strongly influences the self-assembly of trimesic acid: from disorder at room temperature to perfect order upon annealing.

Tunable two-dimensional binary molecular networks

A novel approach to constructing tunable and robust 2D binary molecular nanostructures on an inert graphite surface is presented. The guest molecules are embedded into a host molecular matrix and constrained via the formation of multiple intermolecular hydrogen bonds. By varying the binary molecular ratio and the molecular geometry, various molecular arrays with tunable intermolecular distances are fabricated. The results suggest a promising route for the fabrication of ordered and stable molecular nanostructure arrays for molecular sensors, molecular spintronic devices, and molecular p-n nanojunctions.

Directing two-dimensional molecular crystallization using guest templates

The use of a coronene guest template directs the formation of a 2D Kagomé network in preference to alternative close packed and parallel hydrogen-bonded structures of tetracarboxylic acid tectons self-assembled from solution on a graphite surface.

Function follows form: exploring two-dimensional supramolecular assembly at surfaces

Two-dimensional surface structures formed by organic self-assembly offer an efficient route to bottom-up assembly of tailored nanostructures. Organic building blocks are especially interesting because of the wide variety of structures and properties that can be "built-in" at the synthesis stage. Well-controlled studies of these systems under ultrahigh vacuum conditions allow a careful look at the fundamental properties and relevant kinetic growth limitations. Further work will develop our understanding of the functionality of the systems and their potential use in technological applications.