World's Lowest Density Crystals - 1 gram = 4500 square meters (1 acre)

Reticular chemistry deals with the ability to construct chemical structures from molecular building blocks to create new classes of materials of exceptional variety.

A team of chemists from the Center for Reticular Chemistry at UCLA's California NanoSystems Institute and the departments of chemistry and biochemistry at UCLA, led by Omar Yaghi, professor of chemistry and biochemistry, has developed a class of materials in which components can be changed nearly at will.

Named COF-108, the latest development in reticular chemistry looks like crystal sponges and has a high surface area, with more than 4,500 meters per gram. One gram, unraveled, could cover the surface area of approximately 30 tennis courts.

COFs (pronounced coffs), covalent organic frameworks, are the first crystalline porous organic networks, and by using organic building blocks, these structures can be easily arranged to suit a particular applications.

They have nanoscale-size openings, or pores, in which gases like hydrogen and methane - that are generally difficult to transport - can be stored. "These are the first materials ever made in which the organic building blocks are linked by strong bonds to make covalent organic frameworks," Yaghi said. "The key is that COFs are composed of light elements, such as boron, carbon and oxygen, which provide thermal stability and great functionality. I have long been interested in making materials in a rational way. At the beginning of my career, I always thought it should be possible to create a predetermined chemical structure by linking together well-defined molecules as building blocks, just as an architect creates a blueprint prior to construction on buildings."

The research could lead to various applications like hydrogen fuel that powers not only cars but also laptops, cellular phones, digital cameras and other electronic devices for the alternative energy industry.

Such crystals could also develop greenhouse gas emissions, by capturing and storing carbon dioxide from power plant smoke before it reaches the atmosphere.