Metric engineering of soft molecular host frameworks

The self-assembly and solid-state structures of host-guest inclusion compou nds with lamellar architectures based on a common building block, a resilie nt hydrogen-bonded sheet consisting of guanidinium ions and sulfonate moiet ies of organodisulfonate "pillars", are described. The pillars connect adja cent sheets to generate galleries with molecular-scale cavities occupied by guest molecules. The size, shape, and physicochemical character of the inc lusion cavities can be systematically adjusted by interchanging framework c omponents while maintaining the lamellar architecture, enabling prediction and control of crystal lattice metrics with a precision that is unusual for "crystal engineering". The reliability of the lamellar architecture is a d irect consequence of conformational flexibility exhibited by these hosts th at, unlike rigid systems, enables them to achieve optimal packing with gues t molecules. The adaptability of these hosts is further reflected by an arc hitectural isomerism that is driven by guest templating during assembly of the inclusion compounds. Host frameworks constructed with various pillars d isplay metric interdependences among specific structural features that reve al a common mechanism by which these soft frameworks adapt to different gue sts. This unique feature facilitates structure prediction and provides guid ance for the design of inclusion compounds based on these hosts.