The left side HOMOs and LUMO represent the molecule in a nonpolar solvent, and the right side represent the HOMOs and LUMO in a polar solvent, such as water. You can see the change in the energy of the HOMOs and LUMO when the polar solvent interacts with the electrons in the ? an n orbitals. Study the figure and choose which of the following statements are true or false about why a red shift occurs.
Select all that are True.
[1] the interaction between the polar solvent and the polar ketone is so strong that the energy gain would add to any incoming photon, through a process called quantum tunneling, and thus require a less energetic photon
[2] the polar solvent forms an H-bond with the polar nonbonding electrons in the n MO and lowers the energy of the n MO much more than the ?* MO is lowered; this lower energy means lower photon energy, and thus the red shift
[3] since the gap between the ? and ?* MOs is smaller in the polar solvent the photon needed to excite the electron will be lower in energy, causing the red shift
[4] a nonpolar solvent would have an extensive interaction with the ? bonding electrons and lower the energy of the ? HOMO more than the ?* LUMO
[5] the polar solvent interacts more with the ?* LUMO than with the ? MO because the ?* LUMO is slightly more polar than the ? HOMO