The DFT Study On Redox-switchable Second-order NLO Properties Of The O-carborane Derivatives

Nonlinear optical (NLO) processes are being theoretically and experimentally explored in a variety of optoelectronic modulators for optical telecommunication and photonic applications such as optical data-manipulations, storage, and transmission. Icosahedral carboranes and metallacarboranes with the transition elements, owing to their generally robust character, high solubility in organic solvents, afford special opportunities for investigating the electronic properties of well-defined organometallic systems. Thus some theoretical studies on the NLO properties of carborane and metallacarboranes have been motivated.We evaluate second-order NLO properties of 12-vertex fluorocarborane molecules and ruthenacarorane half-sandwich complexes employing density functional theory (DFT), it includes the following results:(1) The structure and NLO properties of tetrafluocarborane and its derivatives were calculated using DFT method. The results showed that substituents conjugated of the upper portion of fluorocarborane or carborane cage at the lower portion of the introduction of a strong electron withdrawing group, make carborane cage expansion or contraction. Substituents volume size and conjugate are the main factors that affect susceptibility values. The greater dipole moment to its electron acceptor, the stronger the carborane cage substituent, such as the introduction of strong electron-withdrawing group in the tetranitrocarborane increases dipole moment. The charge transfer of carborane cage to benzene having good conjugation increased the second NLO response.(2) A series of 12-vertex ruthenacarborane half-sandwich complexes with the substituted 2,2-bipyridyl and I ion ligands have been investigated by density functional theory (DFT). The calculated first hyperpolarizabilities (?tot) of the neutral complexes increase with replacing the -CO unite with electron donor 2,2'-bipyridyl and I ion. Furthermore, the enhanced ?tot values of the substituted systems are dominated by the intraligand charge transfer, ligand-to-metal charge transfer, metal-to-ligand charge transfer, and d-d transitions of Ru ion. The redox processes of complex 3 significantly reduce ?tot value. The oxidation process of complex 4 also reduce ?tot value, while the reduced process enhance ?tot value. Therefore, it can be concluded that different substituents and redox processes significantly influence the second-order NLO responses.