Figure 5.

Q UV-vis absorption spectrum and TD-DFT calculated spectra and predicted rR enhancement of Q models. (A) Experimental absorption spectrum for intermediate Q. Inset: expanded scale for low energy region. Adapted from reference 16. (B) TD-DFT spectrum (calculated using CAM-B3LYP, downshifted by 3,000 cm⁻¹ based on calibration in Figure S14), left, of bis(μO)-H₂O-6 as representative of the bis(μO)-L (L = OH⁻, H₂O, or vacant site) models. A qualitative description of transition 2 is shown on the right, along with the LCT for transition 2 calculated for modes ν₁, ν₂, and ν₃ (Figure 4 top). (C) TD-DFT calculated spectrum (left) of OC10 as a representative spectrum of the OC -OH/-OH models. A qualitative depiction of transition 1 is given on the right, along with the LCTs for transition 1 along modes ν₁, ν₂, and ν₄ (Figure 4, middle). (D) TD-DFT spectrum (left) of OC26 as representative of the OC -OH/=O models. Transition 1 is schematically given on the right, along with LCTs for transition 1 for modes ν₂, ν₃, and ν₄ (Figure 4, bottom).