Pyrazolo[4,3-h]quinoline Ligand-Based Iridium(III) Complexes for Electrochemiluminescence.

Electrochemiluminescence (ECL) based on [Ru(bpy)3 ]2+ systems is widely utilized for immunoassays. In order to extend the promising potential of ECL-based applications, IrIII complexes have recently attracted attention as probes because of their excellent luminescent properties and tunable emission wavelength. Here we describe a series of Ir complexes using a large π-conjugated ligand and different ancillary chelates. The complexes synthesized have been chemically and spectroscopically characterized and used for ECL measurements with annihilation and co-reactant methods. One of the IrIII complexes investigated exhibits the brightest, ever reported, ECL efficiency in acetonitrile employing the benzoyl peroxide (BPO) co-reactant method.

Chiral Amplification by Self-Assembly of Neutral Luminescent Platinum(II) Complexes.

Two novel enantiomerically pure chiral ligands and the corresponding neutral PtII complexes have been synthetized and characterized. The self-assembly properties of the complexes have been investigated using different morphological and photophysical techniques. The two enantiomeric complexes, 4 a and 4 b, show high tendency to self-assemble into chiral supramolecular aggregates with right (P) and left-handed (M) helical configurations, respectively, as proven by SEM and absorption circular dichroism. The formation of such organized structures is driven by the formation of metallophilic and π-π interactions between spatially close Pt complexes with an enhancement of the chiro-optical properties in the solid state.

Photoisomerization of azobenzene derivatives in nanostructured silica.

A series of derivatized azobenzene molecules are synthesized such that one of the phenyl groups can be chemically bonded to mesostructured silica and the other, derivatized with dendrons, is free to undergo large-amplitude light-driven motion. The silica frameworks on which the motion takes place are either 150 nm thick films containing ordered hexagonal arrays of tubes (inner diameter about 2 nm) containing the bonded azobenzenes, or particles (about 500 nm in diameter) containing the same ordered arrays of functionalized tubes. The photoisomerization yields and the rate constants for the thermal cis to trans back-reaction of the azobenzenes in the tubes are measured and compared to those of the molecules in solution. The rate constants decrease with increasing size of the dendrons. Fluorescence spectra of the cis and trans isomers in the pores show that the photoisomerization in the nanostructured materials is selectively driven by specific wavelengths of light and is reversible.