Effect of Gold(I) on the Room‐Temperature Phosphorescence of Ethynylphenanthrene

Abstract

The synthesis of two series of gold(I) complexes with the general formulae PR3‐Au‐C≡C‐phenanthrene (PR3=PPh3 (1 a/2 a), PMe3 (1 b/2 b), PNaph3 (1 c/2 c)) or (diphos)(Au‐C≡C‐phenanthrene)2 (diphos=1,1‐bis(diphenylphosphino)methane, dppm (1 d/2 d), 1,4‐bis(diphenylphosphino)butane, dppb (1 e/2 e)) has been realized. The two series differ in the position of the alkynyl substituent on the phenanthrene chromophore, being at the 9‐position (9‐ethynylphenanthrene) for the L1 series and at the 2‐position (2‐ethynylphenanthrene) for the L2 series. The compounds have been fully characterized by 1H, 31P NMR, and IR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction resolution in the case of compounds 1 a, 1 e, 2 a, and 2 c. The emissive properties of the uncoordinated ligands and corresponding complexes have been studied in solution and within organic matrixes of different polarity (polymethylmethacrylate and Zeonex). Room‐temperature phosphorescence (RTP) is observed for all gold(I) complexes whereas only fluorescence can be detected for the pure organic chromophore. In particular, the L2 series presents better luminescent properties regarding the intensity of emission, quantum yields, and RTP effect. Additionally, although the inclusion of all the compounds in organic matrixes induces an enhancement of the observed RTP owing to the decrease in non‐radiative deactivation, only the L2 series completely suppresses the fluorescence, giving rise to pure phosphorescent materials.

Aggregation versus Biological Activity in Gold(I) Complexes. An Unexplored Concept

“…All complexes present a linear coordination around the gold­(I) center, with the P–Au–C angles ranging between 169.2(4) and 177.6(1)° (Table ). The P–Au and Au–C bond distances are in good agreement with those previously reported for gold­(I) complexes with the general structure phosphane–gold alkynyl. ,− The three complexes display near-linear geometry of the P–Au–CC–C units and N–H···C sp and C–H···π interactions in the 3D crystal packing, both previously reported in the literature, ,,,− together with aurophilic contacts in both 1a and 1b .…”

Gold(i)-doped films: new routes for efficient room temperature phosphorescent materials

“…These parameters fit well with those expected, in comparison with previous reported data for similar structures. 16,21,[33][34][35][36][37][38][39][40] Scheme 2. Experimental synthetic method and resulting structure of complex 3.…”

“…These values are much larger for deoxygenated samples (N2-saturated) and are ca 1.5-2-fold compared to the corresponding compounds where the phenanthrene is coordinated to the gold(I) atom through an alkynyl moiety, which evidences of the effect of the proximity of the chromophore to the heavy atom. 38 Room temperature phosphorescence is expected to be enhanced by increasing the rigidity of the medium, where the Au(I) atoms may be closer to each other and strengthen a cooperative heavy atom effect and thus, triplet population. This can be achieved by including the luminophores in organic matrixes; PMMA and Zeonex were chosen due to their different polarity (Figure 6).…”

Driving Forces and Routes for Aggregation-Induced Emission-Based Highly Luminescent Metal Nanocluster Assembly

“…Among them, organometallic AIEgens with d-block heavy metals as one of the key components are attractive because of the prospect of making hybrid aggregates through metal–metal bonds (so-called metallophilic interaction) . In contrast to the traditional organic AIEgens, which are primarily excited singlet (S 1 )-state emitters, heavy metal-based AIEgens preferably decay from the excited triplet state (T 1 ), resulting in room-temperature phosphorescence (RTP). − The red emission of several Au­(I)­(5d 10 )-complexes containing phosphine and thiolate ligands or the blue emission of a few Au­(I)–carbene complexes are a few examples of RTP under ambient conditions. , The remarkable features of these complexes render the study of organometallic AIEgens even more meaningful, as the size and morphology of their corresponding aggregates and their luminescence properties can be modulated by the unique metallophilic interactions.…”