Related Experiment Video
Updated: Jan 6, 2026
Low-energy Cathodoluminescence for OxyNitride Phosphors
Published on: November 15, 2016
The Role of Rigidity in Augmentation of Fluorescence and Room-Temperature Phosphorescence in Multinuclear Zn2+-Schiff
Arkaprava Chowdhury1, Souradip Dasgupta1, Mirza Nasib Begg1
1Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
None:
The effect of incorporating an additional metal ion in Zn2+-Schiff base complexes has been investigated using two model compounds: the binuclear Znsalpr and trinuclear Znsalbn, using time-resolved emission spectroscopy. Fluorescence of the trinuclear complex is twice as strong as that of the binuclear one. This is ascribed to a greater extent of rigidity of the trinuclear complex and consequent hindrance offered to nonradiative relaxation involving movement of molecules. Both the complexes exhibit long-lived green afterglow at 77 K, indicating the promotion of intersystem crossing brought about by complexation. Room-temperature phosphorescence is obtained from the complexes in PMMA matrix, thus making them potential candidates for optoelectronic applications.
Related Concept Videos
01:26Variables Affecting Phosphorescence and Fluorescence
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...
01:14Photoluminescence: Applications
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...
02:42Valence 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,...