Content area
Abstract
Squaramides (3,4-diaminocyclobutene-1,2-diones) are known to be strong hydrogen bond donors, and recently have been demonstrated to show unusual responses to anions and the potential to adopt secondary structures. In the first part of the project, a small molecule version of a fluorene-based poly(squaramide) was synthesized to gain insights into the mechanism of the “turn-on” fluorescence response of the polymer in the presence of mono-basic phosphate anions. In the second part, mono and dipyridyl squaramides are examined. Pyridyl squaramides were discovered to form strong intramolecular hydrogen bonds, making the folding process more favorable than their urea counterparts. They are particularly interesting as their urea analogues are capable of taking up helical conformations when folded. The folding properties of these pyridyl squaramides in a range of solvents, and the influence of added anions on the folding process, are described herein.