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Recently, graphene-based materials have become well-known nonlinear optical materials for the potential application of laser protection. Two new graphene oxide-platinum  complex (GO-Pt) hybrid materials (GO-Pt-1, GO-Pt-2) have been fabricated through covalent modification and electrostatic adsorption of different Pt complexes with GO. The structural and photophysical properties of the resultant hybrid materials were studied. The nonlinear optical properties and optical power limiting (OPL) performance of Pt complexes, GO, and GO-Pt hybrid materials were investigated by using Z-scan measurements at 532 nm. At the same transmittance, the results illustrate that functionalization of GO makes GO-Pt hybrid materials possess better nonlinear optical properties and OPL performance than individual Pt complexes and GO due to a combination of nonlinear scattering, nonlinear absorption, and photoinduced electron and energy transfer between GO and Pt complex moieties. Furthermore, the nonlinear optics and OPL performance of GO-Pt-2 are better than those of GO-Pt-1, due to not only the excellent optical limiting of Pt-2 and more molecules per area of GO but also the way of combination of Pt-2 and GO.

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A family of novel bis-tridentate Ir­(III) complexes (Ir1–Ir5) incorporating both functional N∧C∧N-type ligands (L1–L5) and N∧N∧C-type ligand (L0) were synthesized attentively and characterized scientifically. The crystalline structures of Ir1, Ir3 and Ir4 were resoundingly confirmed by XRD. With the aid of experimental and theoretical methods, their photophysical properties at transient and steady states were scientifically investigated. The broadband charge-transfer absorption for these aforementioned Ir­(III) complexes is up to 600 nm as shown in the UV–visible absorption spectrum. The emission lifetimes of their excited states are good. Between the visible and near-infrared regions, Ir1–Ir5 possessed powerful excited-state absorption. Hence, a remarkably robust reverse saturable absorption (RSA) process can occur once the complexes are irradiated by a 532 nm laser. The RSA effect follows the descending order: Ir3 > Ir5 > Ir4 ≈ Ir1 > Ir2. To sum up, modifying electron-donating units (−OCH3) and large π-conjugated units to the pyridyl N∧C∧N-type ligands is a systematic way to markedly raise the RSA effect. Therefore, these octahedral bis-tridentate Ir­(III) complexes are potentially state-of-the-art optical limiting (OPL) materials.

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