Nonlinear optical characterization of multinuclear iridium compounds containing tricycloquinazoline.

Nonlinear optical properties were characterized for a series of multinuclear iridium compounds of the form TCQ[Ir(ppz)], where n=1, 2, or 3, TCQ is tricycloquinazoline, and ppz is 1-phenylpyrazole. Transient absorption (TA) spectroscopy indicated that the triplet metal-to-ligand charge transfer excited state was formed on a subpicosecond time scale and decayed back to the ground state on a microsecond time scale, consistent with precedents in the literature. TA bands were observed for all three compounds from 475 to 900 nm, implying the potential for reverse-saturable absorption (RSA) at those wavelengths.

Fluence-induced reversal of saturable absorption in a ruthenium-based porphyrin.

Experimental nonlinear absorption data obtained using the open-aperture Z-scan technique are presented for 2, 3, 7, 8, 12, 17, 18-octaethyl-21H, 23H-porphine ruthenium (II) carbonyl in tetrahydrofuran. These data show saturation of nonlinear absorption dominating at low fluence but being overcome by induced absorption (reverse saturable absorption) at high fluence. Large-angle scattering measurements demonstrate that the induced absorption is real and not merely the result of scattering of light outside of the collection aperture of the detector by scattering centers induced at high fluence.

Strong triplet excited-state absorption in a phenanthrolinyl iridium(III) complex with benzothiazolylfluorenyl-substituted ligands.

Femtosecond transient difference absorption (fs TA) measurements, together with a series of open-aperture Z scans at picosecond and nanosecond pulse widths and a variety of pulse energies, were performed on a 1,10-phenanthrolinyl iridium(III) complex bearing ligands containing a benzothiazolylfluorenyl motif. An analysis of decay data from the fs TA experiment yields a value of 1.24±0.

Excited-state absorption of a bipyridyl platinum(II) complex with alkynyl-benzothiazolylfluorene units.

The singlet excited-state lifetime of a bipyridyl platinum(II) complex containing two alkynyl-benzothiazolylfluorene units was determined to be 145+/-105 ps by fitting femtosecond transient difference absorption data, and the triplet quantum yield was measured to be 0.14. A ground-state absorption cross section of 6.

Excited-state absorption in a terpyridyl platinum(II) pentynyl complex.

The singlet excited-state lifetime of a terpyridyl platinum(II) pentynyl complex was determined to be 268+/-87 ps by fitting femtosecond transient absorption data, the triplet excited-state lifetime was found to be 62 ns by fitting nanosecond transient absorption decay data, and the triplet quantum yield was measured to be 0.16. A ground-state absorption cross section of 2.