Special Issue "Fluorescent Metal-Ligand Complexes"

Guest Editor
Dr. Grzegorz Piszczek
Biophysics Facility Head, Biochemistry and Biophysics Center, NHLBI/NIH, 50 South Dr, Rm. 2341, MSC-8012 Bethesda, MD 20892-8012, USA
E-Mail:

Dear Colleagues,

Fluorescence spectroscopy is the most popular optical spectroscopy method in research and analytical measurements. The wide range of research applications includes studies of structure, conformation dynamics and stability of biomolecules. Fluorescence is applied to study interactions and structure-function relationships of proteins and nucleic acids. In analytical applications it is used in trace element detection and DNA sequencing. In clinical laboratories fluorescence immunoassays are successfully replacing radioimmunoassay techniques. New applications of fluorescence usually require fluorescent probes with specific properties and while there are numerous organic fluorophores available, most of them display fluorescence lifetimes in the 1 ns to 10 ns range. Discovery of a long-lifetime polarized emission of Metal-Ligand Complexes opened a new window into the dynamic information content of fluorescence. It also allowed the MLCs fluorescence to be applied in gated detection and immunoassays. An important advantage of MLCs fluorophores is their high chemical and photochemical stability under physiological conditions. Various MLC based probes were successfully applied to measure protein-protein interactions and to obtain molecular dynamics information about proteins, DNA and lipid bilayers systems. Fluorescent MLCs remain the only class of fluorescent probes with a number of favorable properties; they have fluorescence lifetimes in the 10 ns to 1000 ns range, polarized emission, large Stocks shifts, and their absorption coefficients are high enough to allow an efficient direct excitation.

The source of MLCs fluorescence is the metal-to-ligand charge-transfer state and a careful selection of metal and ligands can generate MLCs with favorable spectroscopic and physical properties. Many laboratories continue to work on the development of new MLC based probes. Newly synthesized probes often have higher quantum efficiency, increased emission anisotropy and their properties are tailored to specific applications in biological and medical research. In this issue we explore the current progress in synthesis, characterization and applications of fluorescent Metal-Ligand Complexes.

Dr. Grzegorz Piszczek
Guest Editor

Submission

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• metal-ligand complex
• metal-ligand probes
• long lifetime probes
• fluorescence
• polarization
• anisotropy

Type of Paper: Review
Title: Quinoline-Derived Small Molecular Probes for Detecting and Imaging Metal Ions
Authors: Lin Xue and Hua Jiang
Affiliation: Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; E-Mail: hjiang@iccas.ac.cn
Abstract: The detection and monitoring metal ions in vitro and in vivo are of paramount interest owing to their essential roles in life activities. Small fluorescent molecules with high sensitivity and selectivity offer the effective pathway of probing specific metal ions spatially and temporally and have been widely investigated following the development of coordination chemistry and biochemistry. Quinoline derivatives, as versatile ligands, can form unique complexes and have been designed as fluorescent probes to monitor metal ions for more than twenty years. This brief review presents recent applications of quinoline derivatives for fluorescence detecting and imaging metal ions.

Type of Paper: Article
Title: Spectroscopic Characterization of Symmetric to Asymmetric Metal Tetra-Phenyl Porphyrines
Authors: Julien Duboisset ¹, Mikael Lindgren ¹, Boris Minaev ², Hung-Shiun Lee ³, Yann Bretonniere ⁴ and Chantal Andraud ⁴
Affiliations: ¹ Department of Physics, NTNU, Trondheim, Norway; E-mail: mikael.lindgren@ntnu.no (M.K)
² Computational Chemistry, KTH-Stockholm, Sweden
³ Linköping University, Linköping, Sweden
⁴ ENS-Lyon, France
Abstract: A series of asymmetrically substituted free-base tetraphenylporphyrins and Zn-tetraphenyl-porphyrins were synthesized and studied by infrared, electronic absorption spectra, as well as fluorescense emission spectroscopy, along with theoretical simulations of the electronic and vibration structures. The synthesis afforded trans-A2B2 porphyrins without scrambling, where the AA and BB were taken as donor- and acceptor-substituted phenyl groups. The combined results point to minor differences in fluorescence properties from symmetrically substituted TPPs, however, differences were observed in the vibration spectra and fluorescence from the associated vibration sublevels.
Keywords: tetraphenyl porphyrin; asymmetric substitution; electronic structure; DFT; FTIR; fluorescence