Fluorine-functionalized metal–organic frameworks and porous coordination polymers

Fluorine, the element with the highest electronegativity and low electric polarizability, can produce a variety of characteristics, including specific adsorption sites for molecules as well as flexibility to the host materials. In this review, we will introduce fluorine-functionalized metal–organic frameworks/porous coordination polymers that show unique and unprecedented structures, structural transformations, and gas and vapor adsorption/separation properties derived from the fluorine characteristics. Adding chemistry's most electronegative atom to porous polymer networks may lead to gas-specific filters capable of flexible 'breathing'. The tunable activity of metal–organic frameworks towards specific guest molecules, such as drugs or pollutants, has led to a flurry of recent research reports. Shin–ichiro Noro and Takayoshi Nakamura from Hokkaido University in Japan review these findings to show the potential of fluorinated building blocks in porous polymers. The hydrophobic nature and strong bond polarity of organic–fluorine units induce preferential adsorption sites and hydrophobic character useful for oil spill clean-ups. Alternatively, combining inorganic fluorine anions with neutral molecules produces weaker network bonds that easily slip and deform in certain directions. Framework flexibilities and other properties including luminescent emission for sensors are adjustable through appropriate organic or inorganic fluorine units. Fluorine, the element with the highest electronegativity and low electric polarizability, can produce a variety of characteristics, including specific adsorption sites for molecules as well as flexibility to the host materials. In this review, we will introduce fluorine-functionalized metal–organic frameworks/porous coordination polymers that show unique and unprecedented structures, structural transformations, and gas and vapor adsorption/separation properties derived from the fluorine characteristics.