Design and Synthesis of Luminescent Bis(isocyanoborato) Rhenate(I) Complexes as a Selective Sensor for Cyanide Anion

A series of luminescent bis(isocyanoborato) rhenate(I) phenanthroline complexes with the general formula of cis,trans-[Re(CO)₂(CNBR₃)₂(phen)]K (R = C₆F₅ and C₆H₅) have been designed and synthesized. The solutions of these complexes exhibit MLCT phosphorescence. Detailed anion titration study showed that the emission intensity of bis(isocyanotriphenylborato) complex in CH₃CN/H₂O solution would be significantly decreased in the presence of cyanide anion, while such a change would not be observed in the presence of other anions including F^-, Cl^-, Br^-, I^-, OH^-, AcO^-, N₃ ^- ClO₄ ^-, H₂PO₄ ^-, HSO₄ ^-, NO₃ ^-, NO₂ ^-, IO₃ ^-, and SCN^-. This provides a new strategy for developing highly selective cyanide luminescent sensors based on isocyanoborato transition metal complexes.