TDDFT studies on electronic structures, chiroptical properties and solvent effect on the CD spectra of diphosphonate-functionalized polyoxomolybdates

Abstract

The ultraviolet–visible and electronic circular dichroism (UV–vis/ECD) spectra of diphosphonate-functionalized asymmetric cantilever-type chiral polyoxomolybdate (POM) enantiomer R-{Mo2O5[(Mo2O6)NH3CH2CH2CH2C(O)(PO3)2]2}6− (R) were systematically investigated using time-dependent density functional theory (TDDFT) method. From the view of molecular structure and relative energy, we inferred that there is likely a structural conversion from enantiomers R to S-{Mo2O5[(Mo2O6)NH3CH2CH2CH2C(O)(PO3)2]2}6− (S) via the intermediate configuration (IN). The ECD spectra of the enantiomer R were produced over the range of 3.0–6.3eV. The UV–vis and ECD spectra of enantiomer R in the gas phase and different solvents were calculated. The results reveal that the UV–vis and ECD spectra of the chiral POM in gas phase, polar solvent, or non-polar solvent are different. The calculated electron density difference maps (EDDMs) display that the POM cluster is a chiroptical chromophore in studied compound.