Related Experiment Video
Updated: May 14, 2026

Modeling Ligands into Maps Derived from Electron Cryomicroscopy
Published on: July 19, 2024
Ligand Design with [CNSbF5]-: An Ultrastrong π-Accepting Ancillary Ligand for Blue-Shifted MLCT Emission in Re(I)
Yu Fan1, Shun-Cheung Cheng1, Shing-Lun Chan1
1Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, P. R. China.
Abstract:
A new class of tricarbonyl Re(I) phenanthroline complexes with the highly π-accepting isocyanopentafluoroantimonate ligand [CNSbF5]- has been synthesized and characterized. These complexes exhibit 3MLCT phosphorescence. Their photophysical and electrochemical properties have been investigated and compared against structurally related Re(I) analogues containing [CNB(C6F5)3]- and [NCPF5]- ancillary ligands for a direct comparison of ligand π-accepting properties across this series. Detailed photophysical and electrochemical investigations establish [CNSbF5]- as the strongest π-accepting ligand among this series, which results in pronounced stabilization of dπ(Re) orbital and significant blue-shifts of the MLCT emission relative to cyanide complex analogues. However, the inductive electron-withdrawing effect of the SbF5 fragment also stabilizes the diimine-based LUMO, partly attenuating the extent of the blue shift and illustrating the balance between π-backbonding and inductive effects. These isocyanoantimonate ligands thus provide a versatile anionic platform for transforming cationic MLCT emitters into charge-neutral phosphors while retaining high emission energies and quantum efficiencies, and for fine-tuning redox potentials and excited-state energies. The present findings offer a clear experimental support for the rational design of new phosphorescent materials, photosensitizers, and photocatalysts based on strongly π-accepting ancillary ligands.
More Related Videos
Related Concept Videos
Crystal 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...
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Colors 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 eye.
Valence Bond Theory
Complexation Equilibria: The Chelate Effect
Complexation Equilibria: Factors Influencing Stability of Complexes

