A robust macrocyclic tetraamide complex of Th(IV) binds phosphate diesters and promotes cleavage of RNA and phosphate diesters at 37 °C in the pH range 5.00-7.90.
Pentaazadentate metal complexes are a macrocyclic ligand containing 22 ir-electrons,which coordinate with numerous metal ions to form near coplanar configurations with excellent thermal and light stabilities. A more extended optical window between Soret (420 nm) and Q (760 nm) band in visible region provides a condition for requiring high transmttances at low incident light intensity and they are of also large third-order nonlinear optical susceptibilities comparing with porphyrin's and phthalocyanine's metal complexes. The third-order optical susceptibilities are determined at 647 nm in methanol by pump-probed procedure and the molecular second hyperpolarizabilities I 1 1 which are of I esu are also obtained.Optical limiting based on reverse saturable absorption are observed for ns pulses laser. The optical limiting behaviors may be alternated by introduce different substituents onto the benzene ring or/and different metal ion into the centre of macrocyclic ligand. The limiting threshold at T/T0 0.5 is I 3 1 mJ/cm2 for complex [(PL-N02)CdJCI , the corresponding clamped energy is 34 mi/cm2 . The optical limiting performance may be influenced by solution concentrations.Keywords: pentaazadentate metal complexes, second-order molecular hyperpolarizabilities, reverse saturable absorption, limiting threshold, clamped energy, substituent effect, metal ion effect, concentration effect.
The relaxation of optically excited carrier in c 7 0 thin film fabricated by physical jet deposition was investigated by femtosecond pumpprobe measurements. A transient decrease in transmission was observed indicating induced absorption. In comparison to C ~O thin film the initial response of c 7 0 film is laser pulse limited and the long lived component has smaller magnitude. The third order optical nonlinear susceptibility of c 7 0 thin film was determined to be x(3) = 3.3 x esu by femtosecond time-resolved optical Kerr effect. n o m the primarily pulse limited response the dephasing time of c 7 0 thin film has been proved to be shorter than the laser pulse width.
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