文摘
Hydrogen bonding interaction plays an essential role in the early phases of molecular recognition and colorimetric sensing of various anions in aprotic media. In this work, the host鈥揼uest interaction between fac-[Re(CO)3Cl(L)] with L = 4-([2,2鈥?bipyridin]-4-yl)phenol and fluoride ions is investigated for the hydrogen bond dynamics and the changing local coordination environment. The stoichiometric studies using 1H NMR and ESI-MS spectroscopies have shown that proton transfer in the H-bonded phenol鈥揻luoride complex activates the dissociation of the CO ligand in the Re(I) center. The phenol-to-phenolate conversion during formation of HF2鈥?/sup> ion induces nucleophilic lability of the CO ligand which is probed by intraligand charge transfer (ILCT) and ligand-to-metal charge transfer (LMCT) transitions in transient absorption spectroscopy. After photoexcitation, phenol鈥損henoxide conversion rapidly equilibrates in 280 fs time scale and the ensuing excited state [ReII(bpy鈥?sup>鈥?/sup>鈥攑henolate炉) (CO)3Cl]* undergoes CO dissociation in the ultrafast time scale of 鈭? ps. A concerted mechanism of hydrogen cleavage and coordination change is established in anion sensing studies of the rhenium complex.