| Recently, there has been a huge push to elucidate the rules that dictate the organization of monomeric units into self-assembled materials. Our lab has developed bis-urea macrocycles that predictably self-assembled into porous materials by urea-urea hydrogen bonding interactions. We are now exploring macrocycles that combine ureas and a second functional group (pyridine) to potentially give two modes of assembly or upon columnar assembly afford functionalized pores. This talk will focus on the one pot synthesis of three symmetrical macrocyclic pyridyl urea hosts. X-ray crystal structures show the conformational difference between the free host and the host*guest complexes. These solid-state studies also revealed the interactions that are important for binding cations. The host*guest complexation was also studied in solution via NMR titrations and diffusion NMR studies.;This talk will also focus on the self-assembly of pyridyl bis -urea building into columns. Individual columns are closely packed into highly dense structures without any cavities. This seemingly nonporous structure is surprisingly altered in presence of polar guests. Solid-state characterization methods suggest that these guests are incorporated in between the layers. Our results suggest that in the presence of external guests the organic solid-state may be dynamic in nature. |
