1. Programmable Hierarchical Three-Component 2D Assembly at a Liquid-Solid Interface: Recognition, Selection and Transformation Shengbin Lei 1 , Mathieu Surin 2 , Kazukuni Tahara 3 , Jinne Adisoejoso 1 , Roberto Lazzaroni 2 , Yoshito Tobe 3 , Steven De Feyter 1 1 Afdeling Moleculaire en Nanomaterialen, Departement Chemie, Katholieke Universiteit Leuven, B-3001, Heverlee, Belgium ² Service de Chimiee des Matériaux Nouveaux, Université de Mons-Hainaut, 20, Place du Parc, B-7000 Mons, Belgium 3 Division of Frontier Materials Science, Graduate school of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan Lei et al., Nano. Lett ., 2008, 8, 8 , 2541 - 2546 Recognition and selection are of fundamental importance for the hierarchical assembly of supramolecular systems. Coronene induces the formation of a hydrogen-bonded isophthalic acid supramolecular macrocycle, and this well-defined heterocluster forces, in its turn, DBA1 to form a van der Waals stabilized honeycomb lattice, leading to a three-component 2D crystal containing nine molecules in the unit cell. The recognition and selection events enable efficient error correction and healing in redundant mixtures. Building Blocks To summarize, with the aid of a molecular template (COR) ISA was forced to self-assemble into a supramolecular macrocycle of well-defined size, composition and symmetry. The DBA host matrix could specifically recognize and select these heteromolecular clusters, i.e. the template containing macrocycles, even in presence of other structurally similar, strong interacting molecules comparable with ISA . The efficient self-recognition and self-selection processes allow for a programmable fabrication of highly complex hierarchical architectures and paves the way for using the nanoporous DBA networks as nanoreactors to create oligomers with well-defined size, symmetry and composition. Though maybe not very practical, DBA1 networks could act as molecular sieves, i.e. to ‘purify’ a solution by retaining ISA . Introduction Experimental Conclusions Recognition and Selection Dynamics and Healing I x z y HOPG solution monolayer tip I = Tunneling current (10 -10 to 10 -9 Å) V = Voltage Φ = Effective tunneling barrier (effective barrier height) s = Spacing (typically few 10 -10 m) Scanning Tunneling Microscopy Coronene (COR) Isophthalic Acid (ISA) Trimesic Acid (TMA) DBA1, R=C10H21 DBA2, R=C12H25 Two Components Three Components Monocomponent supramolecular assembly: ISA ISA assembles into a zig-zag chain by Hydrogen bond interaction Bicomponent supramolecular assembly: ISA – COR COR transforms ISA into a cyclic hexamer which surrounds COR Three-component supramolecular assembly: ISA – COR – DBA1 ISA and COR induce a structural transformation of DBA1. COR 1 -ISA 6 clusters fill the honeycomb cavity Chirality of the three-component system Due to the offset between the alkyl chains of interdigitating molecules the pore is chiral. Recognition and selection: ISA – COR – DBA2 Majority of cavities appear fuzzy and featureless. Only DBA1 supports the uptake and stabilization of the COR 1 -ISA 6 clusters in its cavities Recognition and Selection: ISA – COR – TMA - DBA1 In absence of DBA1, TMA-ISA-COR forms heteroclusters where TMA hosts COR. In presence of DBA1 however, only COR 1 -ISA 6 cluster are present in the honeycomb voids. Dynamics in ISA – COR – TMA In time, the ISA guest in the TMA network is replaced by COR Healing upon adding DBA1 to the ISA – COR – TMA mixture The presence of DBA1 ‘cleans’ ISA guest molecules from the TMA network Large scale images of the ternary mixture TMA-ISA-COR (left), addition of DBA1 releases ISA from the TMA network (middle) and DBA1 networks filled with COR 1 -ISA 6 clusters are observed at TMA domain boundaries