A team of researchers at the University of Minnesota in Minneapolis has devised a crystal engineering technique that promises to enable the design of organic structures at the lattice level. The group already has demonstrated the growth of a crystal that exhibits polarity and second-harmonic generation, which it reported in the Nov. 30 issue of Science.The researchers begin their work with accordionlike sheets of guanidinium and sulfonate. They infiltrate these layers with banana-shaped pillar molecules and inclusion compounds that pucker the host framework into the desired shape.