An optimized alkyl chain-based binding motif for 2D self-assembly: a comprehensive crystallographic approach

Highly Ordered Co-Assembly of Bisurea Functionalized Molecular Switches at the Solid-Liquid Interface

Immobilization of stimulus-responsive systems on solid surfaces is beneficial for controlled signal transmission and adaptive behavior while allowing the characterization of the functional interface with high sensitivity and high spatial resolution. Positioning of the stimuli-responsive units with nanometer-scale precision across the adaptive surface remains one of the bottlenecks in the extraction of cooperative function. Nanoscale organization, cooperativity, and amplification remain key challenges in bridging the molecular and the macroscopic worlds. Here we report on the design, synthesis, and scanning tunneling microscopy (STM) characterization of overcrowded alkene photoswitches merged in self-assembled networks physisorbed at the solid-liquid interface. A detailed anchoring strategy that ensures appropriate orientation of the switches with respect to the solid surface through the use of bis-urea groups is presented. We implement a co-assembly strategy that enables the merging of the photoswitches within physisorbed monolayers of structurally similar 'spacer' molecules. The self-assembly of the individual components and the co-assemblies was examined in detail using (sub)molecular resolution STM which confirms the robust immobilization and controlled orientation of the photoswitches within the spacer monolayers. The experimental STM data is supported by detailed molecular mechanics (MM) simulations. Different designs of the switches and the spacers were investigated which allowed us to formulate guidelines that enable the precise organization of the photoswitches in crystalline physisorbed self-assembled molecular networks.

Effects of Alkyl Chain Length on the Cold Crystallization of Schiff-Base Nickel(II) Complexes

"Cold crystallization" is the exothermic phenomenon occurring during the heating process of a supercooled liquid. Molecules that exhibit cold crystallization can be used as heat storage materials. Schiff-base nickel(II) complexes...

Assignment of the Absolute-Handedness Chirality of Single-Walled Carbon Nanotubes Using Organic Molecule Supramolecular Structures

Supramolecular structures of organic molecules on planar nanocarbon surfaces, such as highly oriented pyrolytic graphite (HOPG), have been extensively studied and the factors that control them are generally well-established. In contrast, the properties of supramolecular structures on curved nanocarbon surfaces like carbon nanotubes remain challenging to predict and/or to understand. This paper reports an investigation into the first study of the supramolecular structures of 5,15-bisdodecylporphyrin (C12P) on chiral, concentrated single-walled carbon nanotubes (SWNTs; with right-handed helix P- and left-handed helix M-) surfaces using STM. Furthermore, the study is the first of its kind to experimentally assign the absolute-handedness chirality of SWNTs, as well as to understand their effect on the supramolecular structures of organic molecules on their surfaces. Interestingly, these SWNT enantiomers resulted in supramolecular structures of opposite chirality based on the handedness chirality. With molecular modelling, we predicted the absolute-handedness chirality of SWNTs, before demonstrating this experimentally.

Synthesis of new dithia[3.3]parapara- and metapara-cyclophane based tectons: toward an universal surface-confined 2D/3D molecular binding motif

A series of new paraphenylene-based 2D and 3D tectons has been designed for supramolecular self-assembly on both HOPG and Au. Several versatile chemical strategies have been developed to reach the target tectons, bearing either metaparacyclophane or paraparacyclophane cores, functionalized or not, allowing the obtention soon of more complex 3D tectons bearing functional unit such as chromophores. Moreover, preliminary STM results show that these compounds can successfully self-assemble both on HOPG and Au(111) substrates at liquid-solid interface, encouraging us in finding an universal surface-confined 2D/3D molecular binding motif. This feature combined with the preliminary results of the self-assembly on the plasmonic substrate Au(111) open-up opportunities in the field of Nanoscience.

Nanotemplate-directed DNA segmental thermal motion

Nanotemplate directed DNA segmental thermal motion on molecular nanotemplates on graphite was directly observed and characterized using AFM in a liquid.