Beyond molecular chemistry, supramolecular chemistry focuses on constructing highly complicated and functional systems from chemical species held together by intermolecular non-covalent interactions. Metal-ligand coordinative interaction plays an important role in construction of supramolecules; 2,2':6',2"-terpyridine (tpy) is one ligand that has been widely used in this arena. Bis(terpyridine) ligands with suitable geometry are able to form cyclic structures upon complexation with metal ions. Either by a stepwise procedure or by a self-assembled process, a series of metallomacrocyles containing tpy-M-tpy units (M = metal) has been constructed and isolated.
Self-assembly using the labile tpy-CdII-tpy connectivity provides access in quantitative yields to hexacadmium macrocycles that were characterized by traveling wave ion mobility mass spectrometry (TWIM-MS), which enhances the resolving power of electrospray ionization mass spectrometry by adding shape-dependent dispersion and completely deconvolutes the isotope patterns of different charge states, as well as avoids isomer superposition. The self-assembly of a series of CdII metallomacrocycles with different sizes and architectures has been achieved by controlling the stoichiometry and shapes of the building blocks.
Novel approaches to the development of artificial multivalent carbohydrate conjugate objects remain an important area of research due to their strong and specific interactions with receptors. Integrating carbohydrates with metallomacrocycles, linear or branched sugar-functionalized 3,5-di(terpyridinyl)arenes have been synthesized and shown to self-assemble using FeII into hexameric and pentameric macrocycles. The self-assembled nanofibers of both macrocycles were generated by slowly diffusing the non-polar solvent hexane into a homogeneous solution of the complexes in CHCl3/MeOH/MeCN.
In order to fabricate nanometer-sized materials from predesigned building blocks, a bottom-up approach has been used to incorporate Au nanorods (NRs) into multi-component structures containing tpy-FeII-tpy connectivity. This was the first example of Au NR assembly to afford predominately end-to-end linear and branched nanoarchitectures using metal complexes, which can be disassembled under mild conditions.