Molecular Structure, Optical Properties and Frontier Molecular Orbitals for Some of the 4-Substituted Cinnolines: Ab initio Calculations

In this paper, quantum chemical calculations were performed on urea, cinnoline, and some cinnoline derivatives (1-8) at ab initio/HF/6-311G (d, p) level of theory using Gaussian09 and Gussview05 programs. Calculated optimized molecular structure, dipole moment (μ), polarizability (α), molecular electrostatic potential (MEP), and the first order hyperpolarizability (β) for hetero-aromatics 1 to 8, and urea (as a standard molecule) in three phases (gas phase, in presence of water and ethanol) were calculated. The effects of water and ethanol as solvents were taken into account with the aid of the polarizable continuum model (IEF-PCM). The optical properties of studied molecules are increasing in presence of solvents and their values have a direct relationship with the electric constants of solvents. There is a relationship between optical property and energy of the frontier molecular orbitals (FMOs), so these orbitals and the HOMO-LUMO energy gap (ΔE) were investigated. The nonlinear optical (NLO) materials are applied in optical devices, so they are very important. Since experimentally measurement of NLO property is hard, theoretical chemistry is useful in designing new NLO materials.