Role of Ligand on Photophysical Properties of Nanoclusters with fcc Kernel: A Case Study of Ag₁₄(SC₆H₄X)₁₂(PPh₃)₈ (X = F, Cl, Br)

Abstract

The structure–property correlation of a series of silver nanoclusters (NCs) is essential to understand the origin of photophysical properties. Here, we report a series of face-centered cubic (fcc)-based silver NCs by varying the halogen atom in the thiolate ligand to investigate the influence of the halide atoms on the electronic structure. These are {Ag14(FBT)12(PPh3)8·(solvent) x } (NC-1), Ag14(CBT)12(PPh3)8 (NC-2), and Ag14(BBT)12(PPh3)8 (NC-3), where 4-fluorothiophenol (FBT), 4-chlorothiophenol (CBT), and 4-bromothiophenol (BBT) have been utilized as thiolate ligands, respectively. Interestingly, the optical and electrochemical bandgap values of these NCs nicely correlated with the electronic effect of the halides, which is governed by the intracluster and interclusters π–π interactions. These clusters are emissive at room temperature and the luminescence intensity increases with the lowering of temperature. The short lifetime data suggest that the emission is predominantly originating due to the interband relaxation (d → sp) of the Ag cores. Femtosecond transient absorption (TA) spectra revealed similar types of decay profiles for NC-2 and NC-3 and longer decay time for NC-2. The relaxation dominates the decay profile to the surface states and most of the excited-state energy dissipates via this process. This supports the molecular-like dynamics of these series of NCs with an fcc core. This overview shed light on an in-depth understanding of ligand’s role in luminescence and transient absorption spectra.

Platonic and Archimedean solids in discrete metal-containing clusters

“…59). [518][519][520][521][522][523][524][525][526][527][528][529][530][531] In 2013, Zheng and co-workers reported the preparation of a thiolate and phosphine co-protected Ag 14 cluster containing two zero-valent Ag atoms, [Ag 14 (3,4-SPhF 2 ) 12 (PPh 3 ) 8 ] (Ag 14 , 3,4-SPhF 2 = 3,4-difluorothiophenol, Fig. 59a), exhibiting excellent yellow luminescence.…”

“…Thereafter, a series of similar Ag 14 (Ag 6 @Ag 8 with octahedron@cube) superatomic clusters was prepared. [519][520][521][522][523][524] In 2018, utilizing a common mixed-ligand strategy, Zhu and co-workers synthesized a unique pair of new cube-shaped superatomic nanoclusters, [Ag 40 (2,4-SPh(CH 3 ) 2 ) 24 (PPh 3 ) 8 ] (Ag 40 , 2,4-SPh(CH 3 ) 2 = 2,4-dimethylbenzenethiolate, Fig. 59b) and [Ag 46 (2,5-SPh(CH 3 ) 2 ) 24 (PPh 3 ) 8 ] 2+ (Ag 46 , 2,5-SPh(CH 3 ) 2 = 2,5dimethylbenzenethiolate, Fig.…”

“…Thereafter, a series of similar Ag 14 (Ag 6 @Ag 8 with octahedron@cube) superatomic clusters was prepared. 519–524…”

The New Ag–S Cluster [Ag50S13(StBu)20][CF3COO]4 with a Unique hcp Ag14 Kernel and Ag36 Keplerian-Shell-Based Structural Architecture and Its Photoresponsivity

“…Over the past few years, the face-centered cubic ( fcc ) core of silver NCs has also attracted deep interest, as it correlates with the macroscopic fcc bulk silver metals. Indeed, several fcc -type kernel structure based NCs have been reported, including Ag 14 , − Ag 15 , Ag 23 , Ag 38 , Ag 46 , , Ag 62 , Ag 63 , Ag 67 , and Ag 100 . However, another type of cubic closed packing, i.e., hexagonal close-packed ( hcp ), is not known to our knowledge.…”

Unraveling the Effect of Single Atom Doping on the Carrier Relaxation Dynamics of MAg24n– Nanoclusters

“…Because of the strong structure–property correlation, monolayer-protected metal nanoclusters (NCs) have emerged for photonic materials. − Quantum effect originates in NCs as the size approaches the Fermi wavelength of electrons, introducing discrete electronic transitions. − The emergence of significant Stokes shift, tunable photoluminescence (PL), and long excited-state lifetime differentiate them from the larger counterpart, i.e., plasmonic metallic NPs. − The directional movement of electrons within the well-separated energy levels of NCs is of paramount interest for light–energy conversion. − The deactivation of the photoexcited state of NCs is generally dominated by the molecular-like relaxation pathways. Time-resolved spectroscopic techniques such as nanosecond time-correlated single-photon counting, femtosecond fluorescence upconversion, pump–probe transient absorption, and 2D electronic spectroscopic studies have been employed to unravel the complex relaxation processes. ,− The relaxation pathway of magic sized Au 25 NCs consists of three processes; (a) cooling to lower excited states via internal conversion (<1 ps), (b) charge transfer (few picoseconds), and (c) electron–hole recombination (nanoseconds to microseconds) . The pump-power-dependent dynamics of Au NCs reveal the appearance of metallic behavior with increasing core size, attributed to the electron–phonon coupling. − The shape and structure of NCs can control the distribution of valence electron wave function, which eventually influences the carrier relaxation even though they possess identical sizes.…”