First hyperpolarizability of new sulfonamide amphiphiles by calculation, and hyper-Rayleigh scattering

Abstract

The first hyperpolarizability β of the 4-(4′-N-methyl-N-alkylaminophenylazo)-N-(thiazol-2-yl)benzenesulfonamides (1) and 4-(4′-N-methyl-N-alkylaminophenylazo)-N-(pyrimidin-2-yl)benzenesulfonamides (2) was evaluated by ab initio (GAUSSIAN and GAMESS), and semiempirical (INDO1/S) calculations for isolated molecule and in DMF solution (SCRF option). The values of β (static) of the amphiphiles having a dodecyl chain were of the same range and were: 215.6 and 212.4 (GAMESS), and 203.1 and 189.4 (GAUSSIAN), all in 10 ^–40 m ⁴ V ^–1 , for 1 and 2, respectively. The SCRF option used in calculations resulted in increase of β by ca. 55-65%. Direct determination of β by hyper-Rayleigh scattering measurement in DMF solution gave the values equal to: 763 and 775 (at λ=1319 nm), and 1625 and 1722 (at λ=1064 nm), for 1 and 2, respectively (units as above). On a relative scale, referred to p-nitroaniline (PNA) as an external standard, the first hyperpolarizability values of the amphiphiles were in the range of 6.3-9.7 times that of PNA, depending on the method of evaluation. Based on the results of the quantum chemical calculations, the role of the molecular structure fragments on β was discussed.