Fabrication of bilayer tetrathiafulvalene integrated surface covalent organic frameworks

A bilayer covalent organic framework (COF) of TTF-based building blocks was obtained by imine reaction between tetrathiafulvalene tetraaldehyde (4ATTF) and p-phenylenediamine (PPDA). Direct evidence for the eclipsed stacking of bilayer structure via π-π interaction between TTF units is provided by high resolution scanning tunneling microscopy.