Hosted by: Mircea Cotlet

Lamellar inclusion compounds synthesized by directed assembly of guanidinium organomonosulfonates (GMS) and disulfonates (GDS) display a variety of framework architectures that are characterized by nanoscale pores bounded by organic walls and a common two-dimensional (2D) network of complementary guanidinium ions (G) and sulfonate moieties (S) assembly through charge-assisted hydrogen bonds. The structural robustness of this network and the versatility of organic synthesis provides an avenue to frameworks with well-defined pores with sizes, shapes and physicochemical characteristics that can be tuned systematically without loss of generic architectural features, representing a rare example of true "crystal engineering." These pores can be occupied by functional guest molecules with retention of framework architecture, illustrating a materials design strategy wherein function and solid-state structure are regulated independently. Furthermore, guest molecules serve as templates for the cooperative assembly of a number of compositionally identical framework isomers, not unlike templating strategies employed for zeolite synthesis. Notably, the framework architecture often can be predicted based on simple steric principles that account for the relative sizes of the guest and the organosulfonate substituent. This capability has permitted the development of protocols for inclusion-based separations, design of non-linear optical materials, new prospects for lasing materials, unusual "endo-inclusion" compounds, and structural engineering that can afford unusual cylindrical and cubic zeolite-like frameworks, all with a reasonable degree of predictability that is rare in the design of crystalline organic materials. More recently, these frameworks have been used to encapsulate complex molecules with multiple chiral centers, promising a new route to solving crystal structures that otherwise can be challenging.