Gelation-driven selection in dynamic covalent C[double bond, length as m-dash]C/C[double bond, length as m-dash]N exchange

Knoevenagel barbiturate derivatives bearing long alkyl chains were proven to form organogels in suitable solvents based on supramolecular interactions. Their reaction with imines allows for component exchange through C[double bond, length as m-dash]C/C[double bond, length as m-dash]N recombination. The effect of various parameters (solvents, chain length, and temperature) on the C[double bond, length as m-dash]C/C[double bond, length as m-dash]N exchange reaction has been studied. Mixing Knoevenagel compound K and imine I-16 in a 1 : 1 ratio generated a constitutional dynamic library containing the four constituents K, I-16, K′-16, and I′. The reversible exchange reaction was monitored by (1)H-NMR, showing marked changes in the fractions of the four constituents on sol–gel interconversion as a function of temperature. The library composition changed from statistical distribution of the four constituents in the sol state to selective amplification of the gel forming K′-16 constituent together with that of its agonist I′. The process amounts to self-organization driven component selection in a constitutional dynamic organogel system undergoing gelation. This process displays up-regulation of the gel-forming constituent by component redistribution through reversible covalent connections.