Selective Sensing of Phosphates by a New Bis-heteroleptic RuIIComplex through Halogen Bonding: A Superior Sensor over Its Hydrogen-Bonding Analogue.
The selective phosphate-sensing property of a bis-heteroleptic RuIIcomplex, 1[PF6]2, which has a halogen-bonding iodotriazole unit, is demonstrated and is shown to be superior to its hydrogen-bonding analogue, 2[PF6]2. Complex 1[PF6]2, exploiting halogen-bonding interactions, shows enhanced phosphate recognition in both acetonitrile and aqueous acetonitrile compared with its hydrogen-bonding analogue, owing to considerable amplification of the RuII-center-based metal-to-ligand charge transfer (MLCT) emission response and luminescence lifetime. Detailed solution-state studies reveal a higher association constant, lower limit of detection, and greater change in lifetime for complex 1 in the presence of phosphates compared with its hydrogen-bonding analogue, complex 2. The1H NMR titration study with H2PO4-ascertains that the binding of H2PO4-occurs exclusively through halogen-bonding or hydrogen-bonding interactions in complexes 1[PF6]2and 2[PF6]2, respectively. Importantly, the single-crystal X-ray structure confirms the first ever report on metal-assisted second-sphere recognition of H2PO4-and H2P2O72-with 1 through a solitary C-I⋅⋅⋅anion halogen-bonding interaction.
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A&2B Raja S. C. Mullick Road, Kolkata, 700032, India.
Bijit
B
Chowdhury
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A&2B Raja S. C. Mullick Road, Kolkata, 700032, India.
Sanghamitra
S
Sinha
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A&2B Raja S. C. Mullick Road, Kolkata, 700032, India.
Pradyut
P
Ghosh
C−H⋅⋅⋅anion interaction; X-ray diffraction; halogen bonding; phosphates; ruthenium