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This study spotlights the fundamental insights about the structure and static first hyperpolarizability ( β) of a series of 2,4-dinitrophenol derivatives (1-5), which are designed by novel bridging core modifications. The central bridging core modifications show noteworthy effects to modulate the optical and nonlinear optical properties in these derivatives. The derivative systems show significantly large amplitudes of first hyperpolarizability as compared to parent system 1, which are 4, 46, 66, and 90% larger for systems 2, 3, 4, and 5, respectively, at Moller-Plesset (MP2)/6-31G* level of theory. The static first hyperpolarizability and frequency dependent coupled-perturbed Kohn-Sham first hyperpolarizability are calculated by means of MP2 and density functional theory methods and compared with respective experimental values wherever possible. Using two-level model with full-set of parameters dependence of transition energy (Δ Ε), transition dipole moment ( μ0) as well as change in dipole moment from ground to excited state (Δ μ), the origin of increase in β amplitudes is traced from the change in dipole moment from ground to excited state. The causes of change in dipole moments are further discovered through sum of Mulliken atomic charges and intermolecular charge transfer spotted in frontier molecular orbitals analysis. Additionally, analysis of conformational isomers and UV-Visible spectra has been also performed for all designed derivatives. Thus, our present investigation provides novel and explanatory insights on the chemical nature and origin of intrinsic nonlinear optical (NLO) properties of 2,4-dinitrophenol derivatives. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The structural, electro-optical and charge-transport properties of compound trans -3-(3,4-dimethoxyphenyl)-2-(4-nitrophenyl)prop-2-enenitrile (DMNPN) were studied using quantum chemical methods. The neutral, cation and anion molecular geometries were optimized in the ground state using density functional theory (DFT) at the restricted and unrestricted B3LYP/6-31G** level of theory. The excited state geometries were optimized by applying time-dependent DFT at the TD-B3LYP/6-31G** level of theory. The absorption and fluorescence wavelengths were calculated at the TD-CAM-B3LYP/6-31G** and TD-LC-BLYP/6-31G** levels of theory. The distribution pattern of the charge densities on the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) are discussed. Intramolecular charge transfer was observed from the dimethoxyphenyl to (nitrophenyl)prop-2-enenitrile moieties. The detailed charge-transport behavior of the DMNPN molecule is investigated based on its ionization potential, electron affinity, hole and electron reorganization energies, hole and electron-transfer integrals, and hole and electron intrinsic mobilities. The total/partial densities of states and structure–property relationship are discussed in detail. The higher computed hole intrinsic mobility than electron intrinsic mobility reveals that DMNPN is an efficient hole-transport material. [ABSTRACT FROM AUTHOR]