Aggregation-Induced Emission with Alkynylcoumarin Dinuclear Gold(I) Complexes: Photophysical, Dynamic Light Scattering, and Time-Dependent Density Functional Theory Studies

Abstract

Aggregation-induced emission (AIE) has gained a remarkable amount of interest in the past 20 years, but the majority of the studies are based on organic structures. Herein, three dinuclear gold(I) complexes, with the general formula [PPh 2 XPPh 2 -Au 2 -Coum 2 ], where the Au(I) atom is linked to three different diphosphanes [PPh 2 XPPh 2 ; DPPM for X = CH 2 (1.1), DPPP for X = (CH 2 ) 3 (1.2), and DPPA for X = CC (1.3)] and the propynyloxycoumarin precursor (1, 4-methyl-substituted coumarin), have been synthesized. The compounds present AIE characteristics, AIEgens, with high luminescence quantum yields in the solid state when they are compared to dilute solutions. Photophysical studies (steady-state and time-resolved fluorescence) were obtained, with AIE being observed with the three gold(I) complexes in acetonitrile/water mixtures. This was further corroborated with dynamic light scattering measurements. Time-dependent density functional theory (TDDFT) electronic calculations show that the compounds have different syn and anti conformations (relative to the coumarin core) with 1.1 syn and 1.2 and 1.3 both anti. From time-resolved fluorescence experiments, the augment in the contribution of the longer decay component is found to be associated with the emission of the aggregate (AIE effect) and its nature (involving a dimer) rationalized from TDDFT electronic calculations.

Mono‐ and Dinuclear Gold(I) Coumarin Complexes: Luminescence Studies and Singlet Oxygen Production

“…This can be due to the stronger intersystem crossing effect produced to the same coumarin chromophore in comparison with the other compounds where one atom is close coordinated to one chromophore. These values agree with previous data of singlet oxygen production with gold(I) complexes containing coumarin as chromophore [13,14] . Previous ϕ Δ values obtained with gold(I) coumarin compounds were in the order of ca.…”

“…Taking the interest of both gold(I) systems and coumarins, we have previously studied in our group some luminescent gold(I) coumarin complexes whose luminescence is mainly governed by the coumarin moiety. The photophysical properties of this type of compounds deserve more investigation due to the limited number of examples reported in the literature where the photophysics has been carefully analysed [13,14,27,28,34,35] . For this reason, in this work, we have designed and synthesized a new coumarin ligand containing a thiol terminal group suitable to be coordinated to a gold(I) atom.…”

Toward Near-Infrared Emission in Pt(II)-Cyclometallated Compounds: From Excimers’ Formation to Aggregation-Induced Emission

“…An interesting tangent in the field is the modulation of the chemical structures and assemblies to shift the emission to the red since, for example, OLEDs and materials that emit in the infrared (IR) or near-infrared (NIR) region represent a challenging target due to the favored deactivation processes in low-energy emissive populated states . IR and NIR emission is of vital importance in several relevant applications such as full-color displays, remote sensing of environmental conditions, night-vision displays, bio-chemosensors, in vivo imaging, light-fidelity (Li-Fi) communication, or security authentication devices, and it is mostly explored with pure organic molecules. − Different strategies can be followed to modulate the final emission of the complexes to red, with excimers’ formation and aggregation-induced emission (AIE) being popular design methodologies. ,,,− …”

“… 21 − 25 Different strategies can be followed to modulate the final emission of the complexes to red, with excimers’ formation and aggregation-induced emission (AIE) being popular design methodologies. 10 , 20 , 22 , 26 − 30 …”

The role of solvents and concentrations in the properties of oxime bearing A2B corroles

“…Frequency analyses of each compound were also computed and no imaginary frequencies were observed, thus indicating that the structure of each molecule corresponds to, at least, a local minimum on the potential energy surface. 39 The nature of the different absorption spectrum profile will be, therefore, rationalized in the following paragraphs and essentially involves the influence the oxime moiety of the corrole at the meso -position, the solvent-dependent and the formation of different species: neutral forms (tautomers), anionic form (deprotonated) and aggregates (a homoconjugated dimeric complex).…”