The synthesis of five novel cyclometalated platinum(II) compounds containing five different alkynyl-chromophores was achieved by the reaction of the previously synthesized Pt−Cl cyclometalated compound (1) with the corresponding RCCH by a Sonogashira reaction. It was observed that the spectral and photophysical characteristics of the cyclometalated platinum(II) complexes (Pt−Ar) are essentially associated with the platinum-cyclometalated unit. Room-temperature emission of the Pt−Ar complexes was attributed to phosphorescence in agreement with DFT calculations. Broad nanosecond (ns)-transient absorption spectra were observed with decays approximately identical to those obtained from the emission of the triplet state. From the femtosecond-transient absorption (fs-TA) data, two main excitedstate decay components were identified: one in the order of a few picoseconds was assigned to fast intersystem crossing to populate the triplet excited-state and the second (hundreds of ns) was associated with the decay of the transient triplet state. In general, efficient singlet oxygen photosensitization quantum yields were observed from the triplet state of these complexes.

Six gold(I) complexes (R 3 P-Au-Coum) containing three different alkynylcoumarin chromophores (Coum) with different electron-donating and electron-withdrawing characteristics and two different water-soluble phosphanes (PR 3 = PTA (a) and DAPTA (b)) have been synthesized (1a,b, unsubstituted coumarin; 2a,b, 4-methyl substituted coumarin; 3a,b, 3-chloro and 4-methyl substituted coumarin). A comprehensive study of the photophysical properties of the R 3 P-Au-Coum, together with their propynyloxycoumarin precursors 1−3, was performed in solution at room and low temperatures. Spectral and photophysical characteristics of the R 3 P-Au-Coum essentially depend on the electronic characteristics of the propynyloxycoumarin ligand. The presence of the Au(I) atom was found to be responsible for an increase of the intersystem crossing, with triplet state quantum yield values, ϕ T , ranging from ∼0.05 to 0.35 and high coumarin phosphorescence quantum yield values for derivatives 1 and 2; fluorescence dominates the deactivation in derivatives 3. Efficient singlet oxygen photosensitization was observed for the new compounds 3a,b. From TDDFT calculations, the relevant HOMO and LUMO of the compounds, i.e., those involved in the transitions, are dominated by the frontier orbitals associated with the coumarin core. The Au(I)-phosphane structure introduces a new transition assigned to an intraligand transition involving the phosphane ligand, and π(CC) system, to the p orbitals of phosphorus and gold atoms.

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.

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Diphenyldibenzofulvene derivatives consisting of an aromatic tertbutyl-substituted fluorene stator and different rotors consisting of nonsubstituted phenyl groups (3,6-dtb-DPBF) and monomethyl-substituted (3,6-dtb-DPBFMe) and dimethyl-substituted [3,6-dtb-DPBF(Me) 2 ] forms have been synthesized and found to display aggregation-induced emission (AIE). The incremental number of substituents from 3,6-dtb-DPBF to the 3,6-dtb-DPBFMe and 3,6-dtb-DPBF-(Me) 2 derivatives promotes significant changes, from a good solvent (acetonitrile, MeCN), where it is very poorly emissive, to thin films or aggregates, in MeCN/ water mixtures, and a huge increment in fluorescence emission, which is found to be dependent on the water fraction, f w . The characteristics (size and distribution) of the aggregates were further corroborated with dynamic light scattering measurements. From time-resolved fluorescence experiments (TCSPC and FLIM), the increase in the contribution of the longer decay component is linked to the emission of the aggregate (AIE effect). To assist in the elucidation of the aggregation process at a molecular level, the data were complemented with computational studies [time-dependent density functional theory (TDDFT) and molecular dynamics (MD) simulations]. From MD, the octamer properly addresses the properties of the aggregate. As determined by the X-ray data, the crystal structure of a two-unit special disposition is identical to the geometry of the most stable structure obtained from MD and TDDFT calculations.