Deciphering anion-π-acceptor interactions and detecting fluoride using a naphthalenediimide-based Pd(II) coordination polymer

Unequivocal structural evidence of noncovalent interactions between pi-acidic naphthalenediimides (NDIs) and anions has been elicited by X-ray crystallographic analysis of a zigzag coordination polymer involving Pd(II) ions and linear N,N'-di(4-pyridyl)NDI (DPNDI) ligands. Electrochemical studies show that the DPNDI/TfO- interactions suppress DPNDI's pi-acidity, whereas Pd(II)-coordination of DPNDI enhances its pi-acidity. The ability of DPNDI to participate in F--induced electron transfer leading to colorimetric sensing of F- remains intact in the [Pd(II)/DPNDI](n) coordination polymer.