Cis–trans isomerization and spin multiplicity dependences on the static first hyperpolarizability for the two-alkali-metal-doped saddle[4]pyrrole compounds

Abstract

Doping two alkali-metal atoms (Li and Na) into the saddle-shaped saddle[4]pyrrole forms four new two-alkali-metal-doped compounds with alkalide or electride characteristic. They are cis-LiNa(saddle[4]pyrrole) isomers 1(singlet) and 2(triplet), and trans-Li(saddle[4]pyrrole)Na isomers 3(singlet) and 4(triplet). The four structures with all-real frequencies are obtained at the density functional theory (DFT) B3LYP/6-311+G(d) level. All calculations of electric properties have been carried out at the second order Moller–Plesset perturbation theory (MP2) level. The order of the β 0 values is 3.54 × 103 for trans-4(triplet) <1.51 × 104 for cis-1(singlet) <3.57 × 104 for cis-2(triplet) <2.34 × 105 a.u. for trans-3(singlet). The static first hyperpolarizability (β 0) depends on the cis–trans isomerization and spin multiplicity. The result demonstrates that the cis–trans isomerization and spin multiplicity controls of the second-order NLO response are possible.