Correlation between Photophysical Parameters and Gold–Gold Distances in Gold(I) (4-Pyridyl)ethynyl Complexes

Abstract

The systematic analysis of the luminescence of a series of alkynyl gold derivatives with general formulas [(diphos)(AuC≡Cpy)(2)] (diphosphane =2,2'-bis(diphenylphosphanyl)propane or dppip (1), bis(diphenylphosphanyl)acetylene or dppa (2), 1,2-bis(diphenylphosphanyl)ethane or dppe (3) and 1,4-bis(diphenylphosphanyl)butane or dppb, (4), has shown a straightforward correlation between the Au(I)···Au(I) distance and the emission quantum yields and decaytimes. The analysis of the decaytimes, quantum yields and thus, the corresponding calculated rate constants demonstrated the existence of a correlation between Au(I)···Au(I) distance and the radiative rate constant for the deactivation of the emissive triplet states. It was concluded that the increased emission of these compounds results from the increase in spin-orbit coupling that favors the spin forbidden transition to the singlet ground state.

Tuning supramolecular aurophilic structures: the effect of counterion, positive charge and solvent

“…265-300 assigned to intraligand (IL) π-π* (C≡Cpy) transitions based on literature. 11,15,16,42,43 This transition exhibits some broadening (not completely vibronically resolved) which is indicative of an aggregation process where the Au-C≡Cpy moiety is directly involved. 15 Thus,  stacking together with aurophilic interactions are expected to be present in solution and should be responsible for the formation of the rod-like structures.…”

“…A lower intensity broad band or tail above 300 nm can be assigned to a σ* Au···Au -π* transition according to theoretical studies carried out recently for analogous neutral complexes. 42,44 The intraligand absorption band of 2-6 is about 20 nm red-shifted and without vibronical resolution. In the case of 2, 3, 5 and 6, this is due to the methylated pyridyl group.…”

“…50,51 The recorded yellow emission is also in agreement with this assignment and with the fact that approximation of Au centers increases the emission in this region of the spectrum. 42 An XLCT origin should be ruled out since it is also observed for triflate derivatives and also for aged solutions where the XLCT absorption band disappears. …”

Light-Activated Metal-Coordinated Supramolecular Complexes with Charge-Directed Self-Assembly

“…There are literature reports showing fluorescence lifetime of gold nanoclusters to be around a few hundred nanoseconds, which is comparable with our observation. [42][43][44][45] The mechanism of such emission is still under investigation but it is believed to be related to the charge transfer from ligand. 39,42 For example, Wu and Jin reported that the Au25SG18 -cluster has decay times of 246 nsec and 1200 nsec, where SG denotes for glutathione.…”

Exploiting Metallophilicity for the Assembly of Inorganic Nanocrystals and Conjugated Organic Molecules

“…As depicted in Figure 3, the SPR band is more red-shifted and broader at neutral and slightly basic media (pH 7-8), evidencing a clear enhancement of interparticle interactions. Interestingly, in the UV-Vis spectra of water solutions of free complex 1 at pH 7-8 (see Figure S7) there is a notable intensification of the broad and weak band at 300 nm, assigned to the aurophilic interactions, 29 indicating a better capacity of complex 1 to create Au(I)-Au(I) bonds at this pH. Indeed, for the NCP sample, the ratio of absorption intensities at 300 nm and 260 nm (A300/A260) is maximum at pH 7-8, confirming the higher degree of aurophilic interactions under these specific conditions ( Figure S8).…”