Hollow polyhedral structures and properties of Ag2n-1Sn- (n = 2-11) clusters: A theoretical study

CONTEXT

The structures of Ag_2n-1S_n^- (n = 2-11) clusters are obtained by the combination of genetic algorithm (GA) and density functional theory (DFT). All the global minimum structures prefer hollow polyhedral structures, in which S-Ag-S element, triangular Ag₃S₃ and tetragonal Ag₄S₄ units present to stabilize the structures. The S atoms in the structures appear in μ₃-S or μ₄-S form. Adiabatic and vertical electron affinities of the clusters have been obtained, which reveals that they increases as cluster size. Stability analysis shows that Ag₉S₅^- and Ag₁₉S₁₀^- have special stability. The HOMO, LUMO orbitals of the clusters are obtained and the orbital components of them are calculated. The HOMO orbitals are mainly from the p orbitals of S atoms, whereas the s, p and d orbitals of Ag atoms contribute much bigger than the p orbitals of S atoms for LUMO orbitals. The orbital delocalization indexes (ODI) of the HOMOs and LUMOs are calculated, and the small ODIs of the HOMOs and LUMOs for n = 4-10 reveal that these orbitals are highly delocalized. By studying the projected density of states and molecular orbitals of Ag₉S₅^- and Ag₁₉S₁₀^- clusters, it is found that their molecular orbitals have superatomic properties. Superatomic properties play an important role in stabilizing clusters.

METHODS

This work used combined genetic algorithm and density functional theory (GA-DFT), and PBE0/Lanl2tz(Ag)/6-311G(d,p)(S) method to optimize the structures. Gaussian 16 program, Gauss view 6.0.16 program and Multiwfn 3.8 code are the softwares used.

N-Heterocyclic Thione-Protected Ag4 Tetrahedra and Ag8 Cubes Cocrystallized in a Single Crystal

Polynuclear silver clusters have attracted intensive attention in the academic community owing to their rich physicochemical properties. The development of thione-protected silver clusters has been lagging behind the well-explored thiolate-protected silver-sulfide clusters. Herein, we report two N-heterocyclic thione-protected silver clusters: [Ag₄(2-TBI)₆(SO₄)₃]^2- (Ag₄) and [Br@Ag₈(2-TBI)₁₂(SO₄)₂]³⁺ (Ag₈) (2-TBI = 2-thiobenzimidazol), which cocrystallize to form cluster-based molecular crystals with a CaF₂-type structure. The cocrystal shows high thermal stability in air. Notably, the two cluster-based layers are alternately assembled to exhibit a unique k-vector-differential crystallographic arrangement. This work may lay a foundation for synthesis of atomically precise and stable silver clusters using readily available N-heterocyclic thione ligands.

Solvent-Controlled Condensation of [Mo2 O5 (PTC4A)2 ]6- Metalloligand in Stepwise Assembly of Hexagonal and Rectangular Ag18 Nanoclusters

Stepwise assembly starting from a preassembled metalloligand is a promising approach to obtain otherwise unattainable silver nanoclusters, but hard to be intrinsically identified due to the lack of convincing evidence to justify such a process. Herein, hexagonal and rectangular Ag₁₈ nanoclusters are constructed from the [Mo₂ O₅ (PTC4A)₂ ]^6- (H₄ PTC4A=p-phenyl-thiacalix[4]arene) metalloligand through stepwise assembly. The formation of the metalloligand is confirmed by electrospray ionization mass spectrometry, then assembled with silver ions to form two geometrically different Ag₁₈ nanoclusters in different solvents. The cyclization from the metalloligand to [(Mo₂ O₅ PTC4A)₆ ]^12- can be realized without alcohols and otherwise blocked by them. The installation of this metalloligand not only provides comprehensive understanding of how the solvents regulate the silver nanocluster structures, but also brings new insights for the controllable ligand metallization and subsequent condensation.

Molecular surface modification of silver chalcogenolate clusters

This study presents a molecular surface modification approach to synthesizing a family of silver chalcogenolate clusters (SCCs) containing the same [Ag12S6] core and different surface-bonded organic ligands (DMAc or pyridines;...

The mystery of Ph3PS revealed in magic-size Ag–S cluster nucleation

PPh3S was employed to direct the regulation of {Ag32S3} cluster by slowing down the kinetic process of nucleation. The process that Agn(CCBut)m and traces of water induces breakage of PS from [Ag2(Ph3PS)4]2+ to generate {Ag32S3} was established.

Structural rearrangement of Ag60 nanocluster endowing different luminescence performances

It is well known that structure determines property, but obtaining a pair of silver nanoclusters with comparable structures to understand the structure-property relationship is a very challenging task. A new 60-nuclei silver nanocluster (SD/Ag60a) protected by a mixed-ligand shell of ^tBuS^- and o-CH₃OPhCOO^- was obtained and characterized. Single crystal x-ray diffraction reveals that SD/Ag60a has an identical metal nuclearity and core-shell structural type to SD/Ag1 previously reported by our group, whereas the compositions of the core and shell have undergone a rearrangement from an Ag₁₂ cuboctahedron core and an Ag₄₈ rhombicuboctahedron shell in SD/Ag1 to an Ag₁₄ rhombic dodecahedron core and an oval Ag₄₆ shell in SD/Ag60a. The core enlargement from Ag₁₂ to Ag₁₄ originates from the replacement of two S^2- in Ag₁₂S₁₅ by two Ag⁺, which gives a new Ag₁₄S₁₃ core. This result indicates that the metal frameworks of silver nanoclusters have some extent flexibility despite the same nuclearity, which can be influenced by ligands, solvents, anion templates, and others in the embryonic stage of the assembly. Interestingly, different core-shell architectures of Ag₆₀ nanoclusters also significantly endow the different optical absorption bands, photocurrent-generating properties, and luminesecent behaviors. This work not only realizes the regulation of the core-shell structure of silver nanoclusters with the same nuclearity but also provides a comparable model for investigating the relationship of structure-photoelectric properties.

Unusual structural transformation and luminescence response of magic-size silver(I) chalcogenide clusters via ligand-exchange

Structural transformations of nanoclusters provide a platform to tune their properties and understand the fundamental science due to their intimate structure-property correlation. Here, we present an alkynyl ligand-exchange induced growth of atomically precise silver(I) clusters, which are particularly of interest because of their luminescence response at room temperature. SCXRD and UV-vis map out the growth steps of the cluster from [Ag₃₂S₃(CCBu^t)₂₃]³⁺ featuring a pseudo-D_3h concave Ag₃₂S₃ to [Ag₄₅S₆(CCPhBr)₃₂]⁺ with a pseudo-O_h core-shell Ag₉S₆@Ag₂₄@Ag₁₂, which is driven by a thermodynamic route under the disruption of ligands. To our knowledge, the findings in this work establish the first example of ligand-exchange as a versatile tool for tuning the size and luminescence of semiconductor silver(I) clusters.

A comparative study of [Ag11(iPrS)9(dppb)3]2+ and [Ag15S(sBuS)12(dppb)3]+: templating effect on structure and photoluminescence

Atomically precise silver clusters with tunable photoluminescence (PL) properties have attracted extensive attention due to their great value for basic science and future applications. Here, we report that the addition of a sulfido template into a triangular thiolated silver cluster [Ag11(iPrS)9(dppb)3]·2CF3SO3·CH3OH (Ag11, dppb = 1,4-bis(diphenylphosphino)butane), which is emissive at 660 nm under ambient conditions, produced another silver cluster [S@Ag15(sBuS)12(dppb)3]·CF3SO3·H2O (Ag15) that displays 716 nm emission with a 56 nm redshift aided by the ligand sec-butyl mercaptan. The sulfido template, which affects the geometrical and electronic structures, results in a redshift of Ag11 room-temperature PL as a result of opening up the template-to-metal charge transfer (TMCT) and disturbing the electronic transition between the metal core and ligands at the periphery.

tert-Butyl thiol and pyridine ligand co-protected 50-nuclei clusters: the effect of pyridines on Ag-SR bonds

Constructing silver(i)-thiolate clusters from simple building blocks usually involves elusive self-assembly processes and remains a long-standing challenge. In this work, we report 6 silver(i)-thiolate clusters protected by pyridines, namely, [Ag3(tBuS)2(Py)(NO3)]n (Py = pyridine) (1), [Ag10(tBuS)6(Py)6(CF3CO2)4]·3Py (2), [Ag12(iPrS)6(Py)8(NO3)6]·2H2O (3), Ag12(iPrS)6(Py)8(CF3CO2)6 (4), Ag12(iPrS)6(4-ap)6(NO3)6 (4-ap = 4-aminopyridine) (5), and [Ag50S13(tBuS)20(Py)12]·4BF4·4Py·4CH3OH·2H2O (6). Single-crystal X-ray crystallography analysis reveals that six clusters are constructed by four types of structural blocks, including the PyAg(tBuS)2 monomer, Py2Ag2(tBuS)2 dimer, Py3Ag3(tBuS)3 trimer and (4-ap)6Ag6(iPrS)6 hexamer. Notably, cluster 6 consists of a rhombic dodecahedron S@Ag14 kernel with 12 interstitial S2- atoms encapsulated by 8 μ4-tBuS- ligands, as well as six unique butterfly-like (Py)2Ag6(tBuS)2 staple motifs composed of a Py2Ag2(tBuS)2 dimer and four silver ions. Moreover, it is found that pyridine ligands have important influence on the construction of silver thiolate clusters and their Ag-SR bond lengths.

A stably discrete 31-nuclearity silver(i) thiolate nanocluster luminescent thermometer supported by DMF auxiliary ligands

The stably discrete [Ag₃₁S₃(S^tBu)₁₇(CF₃COO)₇(CO₃)_0.5(CF₃COOH)_0.5(DMF)₄] nanocluster in Ag31S20-DMF (1) shaped in a turtle-like structure exhibits temperature-sensitive luminescence properties.