Photophysical Properties Of Metal Complexes Research Articles

Synthesis and photophysical properties of metal complexes of curcumin dyes: Solvatochromism, acidochromism, and photoactivity

Curcumin and its dyes have attracted attention due to their environment-sensitivity and optical properties. However, the free molecule has low photoactivity, which is a limitation for use in photodynamic therapy. To overcome this limitation, we proposed the chelation of a D-π-A-π-D curcumin dye (1) with the metals Cu (II) and Pd (II). The photophysical properties of the curcumin dyes were investigated in different solvents, using UV–vis spectroscopy and time-resolved/steady-state fluorescence techniques. In our results, all curcumin dyes exhibited a positive solvatochromism from non-polar to polar solvents, with the Stokes’ shift in the range of 1895–4970 cm−1. The acidochromism studies were performed in chloroform solution and TLC plates using trifluoroacetic acid (TFA). The results exhibited a negative acidochromism and fluorescence quenching upon gradual addition of TFA, demonstrating reversibility upon addition of triethylamine (TEA). The main mechanism which influences the solvatochromism/acidochromism is the ICT system and fluorescence lifetime decays exhibited mono-exponential fit for aprotic solvents and bi-exponential fit for protic solvents (EtOH and MeOH). Compared to the curcumin ligand (1), the metal complexes (1a-b) exhibited higher singlet oxygen quantum yields (ΦΔ = 0.36 and 0.54, respectively). The in vitro antimicrobial photoactivity of the compounds was evaluated against six different microorganisms. The results showed that the metal complexes (1a-b) exhibited both antileishmanial (MIC = 2.29 μM against Leishmania amazonensis promastigotes) and antifungal (IC50 = 10 μM against Sporothrix brasiliensis yeasts) activities, while the ligand showed no activity, suggesting the chelation with the metals Cu (II) and Pd (II) may improve its photoactivity.

Photophysics of metal complexes

This review summarises the literature reported in 2011 on the photophysical properties of metal complexes and their polynuclear supramolecular assemblies.

Photophysical properties of metal complexes

Photophysical properties of metal complexes

Metal-containing triarylboron compounds for optoelectronic applications

Triarylboranes have recently emerged as a powerful new class of electron acceptors with great potential as optoelectronic materials. The empty p(z) orbital on the boron centre promotes strong charge-transfer transitions, leading to highly luminescent compounds with colors spanning the entire visible spectrum. Due to intense research efforts over the past decade, many examples now exist of organic molecules based on this structural motif. Only recently, however, have transition metal-containing triarylboranes been closely investigated. These compounds are capable of bright luminescence from a triplet excited state, and have been developed as efficient emissive materials for organic light-emitting diodes (OLEDs) as a result. In addition, their long-lived phosphorescence gives these materials potential as highly selective chemical sensors for small anions using time-gated detection, eliminating interference from background fluorescence. The research of the past several years has now led to a better understanding of the impact of the triarylboron group on the photophysical properties of metal complexes, which we expect will provide many opportunities for research into this class of functional phosphorescent materials.

Photophysical properties of metal complexes

This review summarises the literature reported in 2010 on the photophysical properties of metal complexes and their polynuclear supramolecular assemblies.

Photophysical properties of metal complexes

Photophysical properties of metal complexes

Photophysical properties of metal complexes

This review summarises developments in the photophysical properties of metal complexes and their polynuclear assemblies reported in the literature for 2007.

Photophysical properties of metal complexes

Photophysical properties of metal complexes

The photophysical properties of metal complexes of fluorescein–porphyrin dyads

Zn, Cu and Ni complexes of fluorescein–porphyrin dyads were synthesized and characterized by ESI-MS and their photophysical properties were studied. Each of the complexes possessed Q band degeneration in their absorption spectra. The Zn complex displayed a blue shifted fluorescence emission and shorter fluorescence lifetime compared with the parent fluorescein–porphyrin dyads, whilst the Cu and Ni complexes were not fluorescent. These findings imply that different electron transfer processes are occurring in the complexes.

Photophysical properties of metal complexes

This review summarises developments in the photophysical properties of molecular metal complexes and their polynuclear and supramolecular assemblies for 2005. The huge increase in the popularity of this field (291 references included this year, compared to 145 last year) means that only the major high-impact journals have been covered. Particular highlights for the year (in the author’s opinion) include the following: single-molecule luminescence studies on very large multi-porphyrin oligomers containing up to 96 chromophores; achievement of exceptionally long near-IR luminescence lifetimes for lanthanide complexes using two quite different strategies; the demonstration of simultaneous multi-colour luminescence from metal complexes or complex assemblies using three different strategies; the detection of a picosecond-scale luminescence component from a simple [Ru(bpy)3]2+ derivative arising from a non-thermalised excited state; and generation of long-lived charge-separated states of up to 1 second in a donor-chromophore-acceptor triad. Areas of particularly strong interest have been the generation and evaluation of new dyes for solar cells, and intensely phosphorescent complexes [usually of Ir(III) and Pt(II)] for use in OLEDs.

Photophysical Properties of Metal Complexes with Bis-(8-hydroxyquinoline) Open Chain Crown Ether

Photophysical Properties of Metal Complexes with Bis-(8-hydroxyquinoline) Open Chain Crown Ether

Polypyridyl ruthenium complexes binding with nucleic acids

The binding mechanism and interactions between the octahedral polypyridyl ruthenium(II) complexes and DNA are reviewed. The influence of ligands including the intercalative ligand and the ancillary ligands on DNA-binding behavior, enantioselectivity, the nonradioactive nucleic acids probes and DNA molecular light switches are discussed, respectively. Focus on the modification of the ligands resulting in the photophysical properties of metal complexes and the DNA-binding properties emphasized.