It remains challenging to control the single-, two-, and three-photon excited fluorescence of metal nanoclusters. In this work, the control over the nonlinear optics of metal nanoclusters as single-, two-, and three-photon excited fluorescence has been accomplished via exploiting the solvent effect. An emissive nanocluster, Au 9 Ag 6 (SPh t OMe) 4 (DPPOE) 3 Cl 3 , was synthesized and structurally determined. The solvent effect can not only control the fluorescence of this nanocluster, but more significantly, it can also regulate the photoluminescence nature of the cluster as single-, two-, and three-photon excited fluorescence. We concluded that the increased solution polarity, improved dipole moment, enlarged HOMO-LUMO energy gap, and reduced solution viscosity of the cluster in solutions endow them with excellent high-order multiphoton excited fluorescence. The results provide an intriguing cluster template that enables us to manipulate the linear and nonlinear optics at the atomic level.
Although several approaches have been exploited to trigger the structural transformation of metal nanoclusters, most cases are assigned to the unidirectional conversion, while the reversible conversion of nanoclusters remains challenging....
The structure/composition of nanoclusters has a decisive influence on their physicochemical properties. In this work, we obtained two different Au–Ag nanoclusters, [Au9Ag12(SAdm)4(dppm)6Cl6]3+ and Au11Ag6(dppm)4(SAdm)4(CN)4, via controlling the Au/Ag molar ratios by a one-pot synthetic approach. The structure of nanoclusters was confirmed and testified by single-crystal x-ray diffraction, electrospray ionization time-of-flight mass spectrometry, XPS, powder x-ray diffraction, and electron paramagnetic resonance. The Au11Ag6 nanocluster possessed a M13 core caped by four Au atoms and four dppm and four AdmS ligands. Interestingly, four CN are observed to locate at the equator of the M13 core. Both nanoclusters contain a similar icosahedral M13 core, whereas their surface structures are totally different. However, the Au11Ag6 nanocluster exhibits good stability and strong red photoluminescence in solution.
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