Related Experiment Video
Updated: Mar 26, 2026
Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Two photon absorption properties of four coordinated transition metal complexes of tetraarylazadipyrromethene
E Akhüseyin1, O Türkmen2, B Küçüköz1
1Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Beşevler, Ankara, Turkey. yoglu@eng.ankara.edu.tr.
Abstract:
New tetraarylazadipyrromethene metal complexes with four coordinate metals (cobalt(ii), nickel(ii), copper(ii) and zinc(ii)) and with three moieties (4-methylphenyl,4-methoxyphenyl and 1-naphthyl) were designed and synthesized targeting applications utilizing two photon absorption. The effects of metals with filled or unfilled d orbitals and substituents with various electron donor properties on the charge transfer mechanism and two photon absorption properties of tetraarylazadipyrromethene compounds were investigated by ultrafast pump-probe spectroscopy and open aperture Z-scan experiments as well as density functional theory (DFT) calculations. Ultrafast transient absorption spectra provide evidence of an efficient photoinduced intramolecular charge transfer between the ligand and metals which is independent of filled or unfilled d orbitals of metals. Although zinc has filled d orbitals, its complexes possess an absorption maximum including a shoulder which is attributed to partial ligand to metal L(π) → M(d*) charge transfer character (LMCT). Due to the charge transfer mechanism, metal complexes of tetraarylazadipyrromethene compounds exhibited two photon absorption properties in the femtosecond regime at 800 nm wavelength. The greatest two photon absorption cross section value was measured as 2690 GM for Zn(L(2))2 and 2374 GM for Co(L(3))2 complexes.
Related Concept Videos
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
02:42Valence Bond Theory
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
01:11Aryldiazonium Salts to Azo Dyes: Diazo Coupling
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:58Properties of Transition Metals