Under the action of incident light with specific frequency, there is almost no distinction in αiso(λ) of different M + @C18 in , and the variation of γ||(λ) with the complexed metal ion is also subtle. This is because the charges of all M + are close to +1 e, so the polarizabilities of them are small, and the polarization properties of C18 unit are similar due to its electronic structure is almost unaffected by complextion.