Aggregation induced emission of gold(i) complexes in water or water mixtures

Abstract

Gold(i) complexes are an expanding area of investigation due to the possibility of giving rise to supramolecular aggregates with particular morphologies that can be modulated together with their luminescent properties. A detailed study has been carried out for gold(i) complexes that self-assemble in aqueous media (in pure water or in mixtures of water and organic solvents in different proportions). The majority of the examples reported until now were found in mixtures of water and DMSO, acetone, DMF or acetonitrile. The addition of cations to a solution of gold(i) complexes has been observed to show a direct impact on the resulting process of aggregation. The use of perhalogenated ligands together with isocyanide moieties should be highlighted to promote the resulting self-organization. Nevertheless, other ligands like alkynyls or carbenes also promote self-assembly. A careful analysis of the data shows that aurophilic interactions have a key role in the formation of the resulting aggregates and in the enhancement of luminescence (aggregation induced emission, AIE).

Luminescent Tetranuclear Gold(I) Dibenzo[g,p]chrysene Derivatives: Effect of the Environment on Photophysical Properties

“…This was compatible with excimer emission, which could be ascribed to the higher polarity of the PMMA matrix and the highly apolar character of the gold complexes, allowing them to self-assemble in this medium. The larger affected changes in 3 and 4 with respect to 1 supported the involvement of the Au(I) atom in the Au···Au or Au···π excimeric aggregates [7,24,25]. The presence of alkynyl and aromatic moieties in the studied complexes led us to the possibility of obtaining heterometallic complexes containing not only Au(I), but also another heavy metal atom, such as Ag(I), able to coordinate to these groups.…”

“…This was compatible with excimer emission, which could be ascribed to the higher polarity of the PMMA matrix and the highly apolar character of the gold complexes, allowing them to self-assemble in this medium. The larger affected changes in 3 and 4 with respect to 1 supported the involvement of the Au(I) atom in the Au···Au or Au···π excimeric aggregates [7,24,25].…”

Excimer‐ und Exciplex‐Bildung in durch aurophile Wechselwirkungen präkonditionierten Gold(I)‐ Komplexen

“…Für einkernige Gold(I)‐Komplexe sind ähnliche Phänomene in Lösung selten, da die schwachen aurophilen Wechselwirkungen durch effiziente Solvatisierung der einkernigen Einheiten leicht aufgehoben werden können. Bei hohen Konzentrationen der Komplexe und bei niedrigen Temperaturen erhöht sich die Zahl der Aurophilie‐basierten Dimere oder Oligomere allerdings, und die Assoziation kann über verschiedene analytische Techniken nachgewiesen werden, insbesondere durch Verfolgung der UV/Vis‐Absorptions‐ und ‐Emissionseigenschaften . In allen Diskussionen muss daran erinnert werden, dass Au⋅⋅⋅Au‐Wechselwirkungen – als schwache Kräfte – fast immer nur kleine Beiträge zur Gesamtenergie eines gegebenen Systems liefern, und dass nur eine sorgfältige Evaluierung aller Parameter ein konsistentes Bild des tatsächlichen Beitrags vergleichbarer chemischer und physikalischer Phänomene ergibt.…”

“…Die Prototypen der aurophilen Bindung wurden in der Einleitung vorgestellt ( A – F ) . In allen Fällen werden die Goldatome auf Sub‐van‐der‐Waals‐Abstände aneinander geführt, sobald die sterischen Voraussetzungen des Systems eine derartige Annäherung erlauben.…”

pH-Responsive Au(i)-disulfide nanoparticles with tunable aggregation-induced emission for monitoring intragastric acidity

“…As a family of luminescent probes with excellent biocompatibility, gold-based luminescent materials have been widely applied in biological systems, [12][13][14] Of particular interest are aggregation-induced emission (AIE)-featuring Au(I) complexes. [15][16][17] The AIE characteristics enable Au(I) materials to overcome the difficulties of the ACQ effect, making them serving as superior probes to monitor physiological changes in biological systems, by virtue of their excellent sensitivity, large Stokes shi, high signal-to noise ratio and high photostability. [18][19][20][21][22] However, scarcely any of AIE-featuring Au(I) complexes are applied in living systems, since most of them showed poor stability in water, large size, and a strong tendency to precipitate from water, making them difficult to survive in physiological environments.…”