Non-linear optical properties of novel fluorenyl derivatives - ab initio quantum chemical calculations

We report accurate ab initio studies of the first static hyperpolarizabilities (beta) of fluorenyl derivatives in which electron donating (D) and electron accepting (A) groups were introduced either side of the fluorenyl ring system. Geometries of all molecules were optimized at the Hartree-Fock level in a series of steps, first with the STO-3G minimal basis set, then with the 3-21G split valence basis set and finally with the 6-31G basis set. The first static hyperpolarizabilities of these molecules were calculated using Hartree-Fock level using 6-31G basis set using GAUSSIAN98W. The calculated hyperpolarizabilities of these molecules were compared with biphenyl derivatives and other available data in the literature. To understand this phenomenon in the context of molecular orbital picture, we examined the molecular HOMOs and molecular LUMOs generated via GAUSSIAN98W. The study reveals that the fluorenyl derivatives have large beta values hence in general may have potential applications in the development of non-linear optical materials. (C) 2002 Elsevier Science B.V. All rights reserved.