Kalen N. Swanick

Bright electrochemiluminescence of iridium(III) complexes

Electrochemiluminescence (ECL) of four bright iridium(III) complexes containing aryltriazole cyclometallated ligands is reported. The ECL mechanisms, spectra and high efficiencies via annihilation and coreactant paths have been investigated.

Self-Enhanced Electrochemiluminescence of an Iridium(III) Complex: Mechanistic Insight**

Improved luminophore: The electrochemiluminescence (ECL) of an iridium complex self-enhanced up to 16 times is reported. Three excited states were observed in the emission spectra (see picture). The ECL efficiency of this complex is the highest reported for an iridium complex.

Highly Efficient Dual-Color Electrochemiluminescence from BODIPY-Capped PbS Nanocrystals

Electrochemiluminescence (ECL) of a hybrid system consisting of PbS nanocrystals (NCs) and a BODIPY dye (BDY) capping ligand was discovered to produce highly efficient dual emissions with tri-n-propylamine as a coreactant. By means of spooling ECL spectroscopy, the strong dual ECL emission peaks of 984 and 680 nm were attributed to the PbS and BDY moieties, respectively, and found to be simultaneous during the light evolution and devolution. The ECL of the PbS was enhanced via NC collisions with the electrode and reached an efficiency of 96% relative to that of Ru(bpy)3(2+), which is the highest among the semiconductor NCs.

Enhanced Electrochemiluminescence from a Stoichiometric Ruthenium(II)–Iridium(III) Complex Soft Salt

Electrochemiluminescence (ECL) and electrochemistry are reported for a heterometallic soft salt, [Ru(dtbubpy)3 ][Ir(ppy)2 (CN)2 ]2 ([Ir][Ru][Ir]), consisting of a 2:1 ratio of complementary charged Ru and Ir complexes possessing two different emission colors. The [Ru](2+) and [Ir](-) moieties in the [Ir][Ru][Ir] greatly reduce the energy required to produce ECL. Though ECL intensity in the annihilation path was enhanced 18× relative to that of [Ru(bpy)3 ](2+) , ECL in the co-reactant path with tri-n-propylamine was enhanced a further 4×. Spooling spectroscopy gives insight into ECL mechanisms: the unique light emission at 634 nm is due to the [Ru](2+) * excited state and no [Ir](-) * was generated in either route. Overall, the soft salt system is anticipated to be attractive and suitable for the development of efficient and low-energy-cost ECL detection systems.

A multi-channel sensor based on 8-hydroxyquinoline ferrocenoate for probing Hg(II) ion

A new sensing molecule 8-hydroxyquinoline ferrocenoate (Fc-Q) which combines ferrocene and 8-hydroxyquinoline moieties was synthesized and applied as a multi-channel sensor for the detection of Hg(2+) ion. Fc-Q can coordinate with Hg(2+) to give colorimetric, fluorescent and electrochemical responses. Upon complexation with Hg(2+) ion, the characteristic absorption peak is red-shifted (Δλ=45 nm), the fluorescent intensity is quenched at 303 nm, and the oxidation peak is cathodic shifted (ΔE(1/2)=-149 mV). Quantitatively analyzed Hg(2+) ions at the range of ppb level could be achieved by electrochemical response. For the practical application of sensing Hg(2+) in real world water, Fc-Q modified screen-printed carbon electrodes were obtained for facile, sensitive, and on-site analysis of Hg(2+).

Correlating electronic structures to electrochemiluminescence of cationic Ir complexes

Electrochemiluminescence (ECL) of heteroleptic cationic iridium complexes is correlated to their structures in order to get insight into tuning their emission wavelength and intensity. While the installation of fluorine and tert-butyl substituents on the ligands increases the electrochemical gap and promotes blue shifts in ECL emission, it reduces ECL efficiencies.

Synthesis, Structure, Electrochemistry, and Electrochemiluminescence of Thienyltriazoles

Four blue-emitting thienyltriazoles with desired N and O coordination atoms were prepared in high yield via click chemistry for potential incorporation into metal complexes. Three of their crystal structures were determined by X-ray crystallography. The electrochemical properties, electronic structures of these thienyltriazoles, 1-4, and their correlations were studied using cyclic voltammetry and differential pulse voltammetry techniques along with density function theory (DFT) calculations. All of the compounds underwent irreversible redox reactions, leading to unstable electrogenerated radical cations and anions. Electrochemical gaps determined from the differences between first formal reduction and oxidation reactions were correlated to HOMO-LUMO energy gaps obtained from UV-vis spectroscopy and the DFT calculations as well as energies of excited states measured from photoluminescence spectroscopy. We observed weak electrochemiluminescence (ECL) from annihilation of these thienyltriazole radicals in acetonitrile containing 0.1 M tetra-n-butylammonium perchlorate as electrolyte. An enhancement in ECL efficiency ranging from 0.16 to 0.50% was observed upon addition of benzoyl peroxide as a coreactant in the above electrolyte solutions. The generation of excimers in solutions of 1-4 was observed as seen by the red-shift in ECL maxima relative to their corresponding photoluminescence peak wavelengths. Our work is of importance for the development of efficient blue-emitting fluorophores via click chemistry that could be potential luminophores in metal complexes.