Theory Study of the Adsorption of Hydrocyanic Acid onto Small Silver Clusters

Density functional theory calculations have been performed to study the interaction of small silver clusters, Ag2-Ag9, with HCN. The adsorption of HCN on-top site of the silver cluster, among various possible sites, is energetically preferred. The adsorption energies of HCN on the silver clusters reach a local maximum at n = 4, which is only about 0.450 eV, indicating that the adsorbed HCN molecule is weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.

Exploring the Interactions of Atomic Oxygen on Silver Clusters with Hydrogen

The interactions between AgnO- （n=1-8） and H2 （or D2） were explored by combination of the mass spectroscopy experiments and density function theory （DFT） calculations. The experiments found that all oxygen atoms in AgnO- （n--1-8） are inert in the interactions with H2 or D2 at the low temperature of 150 K, which is in contrast to their high reactivity with CO under the same condition. These observations are parallel with the preferential oxidation （PROX） of CO in excess hydrogen catalyzed by dispersed silver species in the condensed phase. Possible reaction paths between AgnO- （n=1-8） and H2 were explored using DFT calculations. The results indicated that adsorption of H2 on any site of AgnO- （n=1-8） is extremely weak, and oxidation of H2 by any kind of oxygen in AgnO- （n=1-8） has an apparent barrier strongly dependent on the adsorption style of the ＂O＂. These experiments and theoretical results about cluster reactions provided molecule-level insights into the activity of atomic oxygen on real silver catalysts.

Dipole (hyper)polarizabilities of neutral silver clusters

At the Douglas-Kroll-Hess （DKI4） level, the B3PW91 functional along with the all-eleclron relativistic basis sets of valence triple and quadruple zeta qualities are used to determine the structure, stability, and electronic properties of the small silver clusters （Agn, n ≤ 7）. The results presented in this study are in good agreement with the experimental data and theoretical values obtained at a higher level of theory from the literature. Static polarizability and hyperpolarizability are also reported. It is verified that the mean dipole polarizability per atom exhibits an odd-even oscillation and that the polarizability anisotropy is directly related to the cluster shape. In this article, the first study of hyperpolarizabilities of small silver clusters is presented. Except for the monomer, the second hyperpolarizabilities of the silver clusters are significantly larger than those of the copper clusters.

Synthesis,Structure and Luminescence Properties of Dumbbell-like Silver Clusters

In this work,three stable dumbbell-shaped silver clusters 1~3,formed by a novel bifunctional ligand Ph2P-C6H4-3-C=CH,are presented.All three complexes have cage structures constructed with thirty-six silver atoms,which are templated by chloride anions.During the self-assembly process of silver acetylides,argentophilic interactions and Ag(I)-ethynide interactions are important for the formation of silver cores to yield a diversity of silver clusters.Weak molecular interactions(π-π,C-H…π,C-H…F,C-H…O)are also found in these complexes,which are crucial to stabilizing these silver clusters.Compared with simple alkynyl ligands(RC≡C-),the introduction of phosphine groups into alkynyl ligand can effectively control the undesired infinite growth of silver acetylides.The photophysical behaviors of complexes 1~3 are studied,showing intense orange roomtemperature luminescence in the solid state upon the exposure to UV light.The luminescence mainly arises from ligand-to-metal charge transfer(LMCT)and metal-cluster-centered transitions(MC)within the silver clusters.

GAG-containing nucleotides as mediators of DNA-silver clusters and iron-DNA interplay

New types of fluorescence DNA-based silver nanoclusters（DNAn-Ag NCs, n = 1, 2, 3c, 4c, 5c） were synthesized by C3T-rich nucleotides as templates. It is found that the assembly of DNAn-Ag NCs with nucleotides containing GAG sequences produce silver clusters with an enhanced red emission. Results indicate that GAG is the good enhancer of DNAn-Ag NCs constructed by C3T-rich nucleotides. The fluorescence titration reveals that enhanced red emission is sensitive to Fe（Ⅲ/Ⅱ） ions with the formation of non-emission nanoclusters. Thus, the GAG-containing nucleotide can be an enhancer for the emission of silver clusters with C3T-rich nucleotide and a mediator of the iron-cluster interplay.

Structure and Luminescence Property of a Hexanuclear Silver(Ⅰ) Cluster Containing Benzaldehyde Thiosemicarbazone

A new hexanuclear silver （I） compound 2 containing thiosemicarbazone with the group of benzene was synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis and fluorescence spectrum. The title compound crystallizes in triclinic, space group P with a = 11.611（3）, b = 15.610（5）, c = 15.624（7） , α = 113.942（6）, β = 104.520（6）, γ = 104.230（4）°, V = 2304.1（14） 3, C60H77Ag6N22O4.5S6, Mr = 2018.02, Dc = 1.454 g/cm3, μ（MoKα） = 1.435 mm-1, F（000） = 1005, Z = 1, the final R = 0.0468 and wR = 0.1474 for 6608 observed reflections （I 2σ（I））. In the structure, the S atom of the ligand L2 （L2 = benzaldehyde thiosemicarbazone） served as a triply bridged chelator to connect the six silver atoms into a Ag6L26 cluster. The luminescence property of compound 2 was investigated at room temperature.

Engineering intelligent chiral silver cluster-assembled materials for temperature-triggered dynamic circularly polarized luminescence

The development of stimuli-responsive circularly polarized luminescence(CPL)materials is quite attractive but challenging.Here,a pair of atomically precise enan-tiomers R/S-Ag20 nanoclusters has been synthesized using chiral acid ligands.And then,stimuli-responsive CPL materials were developed by assembling the chiral silver nanoclusters with an achiral bridging ligand.The atomically precise silver cluster-assembled materials produce CPL with a dissymmetry factor(|glum|)of 1×10-3,through the high-efficiency chiral induction process.More interestingly,the single CPL band at room temperature could quickly transform into highly separated dual CPL emissions at low temperature.This study provides a new strategy for the rational functionalization of chiral silver clusters in preparing cluster-based CPL emitters and enriches the types of stimuli-responsive CPL materials.

Macrocyclic-ligand Induced Synthesis of Aryl Ethynides with Divergent Silver（I） Clusters

Two structurally characterized metal-cluster-centered supramolecular architectures named [Ag8（1,2-（C= C）2-C6H4）（Py[6]）（CF3CO2）6]·2.5MeOH （1） and [Ag12（1,2,4,5-（C=C）aC6H2）（Py[6]）2（CF3SO3）s]·4MeOH·3H2O （2） are synthesized through the interaction with a bowl-shaped macrocyclic ligand PyI61. Particularly, two dissimilar silver（I） clusters are resulted in 2 within the structure under the influence of the macrocyclic ligand Py[6]. Such dissimilarity of the silver（1） cluster is also reflected on the structural and photophysical differences between 1 and 2.

Luminescence Regulation of Silver-Thiolate Clusters Protected by 1,2-Dithiolate-o-carborane

Engineering the surface of the metal clusters with the core structure maintained and tuning their luminescence in a wide range is still a challenge in the nanomaterial research.We modified six mono-pyridyl ligands with different electronic effects(conjugation effect or induction effect)on a superatomic silver cluster[Ag_(14)(C_(2)B_(10)H_(10)S_(2))_(6)(CH_(3)CN)_(8)](denoted as Ag_(14))through in situ site-specific surface engineering.

Anion-templated Self-assembly for the Preparation of Silver-t-butylthiolate Clusters

Silver thiolate polymers are intercepted to form different structural fragments when reacting with variant solubilizing reagents,which usually serve as the starting point for the preparation of clusters.However,such a process is still far from clear.Herein,we report the controlled synthesis of silver-t-butylthiolate clusters from reactions of polymeric[Ag^(t)BuS]n and suitable templates in the presence of solubilizing reagents to offer a detailed look at the mechanism of cluster’s formation.As the provided solubilizing reagents have weak coordina-tion ability,such as O-or N-donating ligands,the obtained polymeric compound retains the linear structure pat-tern that S and Ag atoms are arranged alternately.When extra templates NO_(3)^(−)and CO_(3)^(2−)are applied,the disk-like clusters Ag_(19)and Ag_(20)are constructed with the same[Ag^(t)BuS]_(5)circles that may directly cyclize from the linear[Ag^(t)BuS]_(n)fragments.In contrast,(EtO)_(2)PS_(2)^(−)and(iPrO)_(2)PS_(2)^(−)anions have large size and strong coordination abil-ity rendering the structure of the polymer completely fragmented.Thus extremely short[Ag^(t)BuS]n pieces with silver ions and solubilizing ligands assemble around the templates V_(2)O_(7)^(4−)and W_(2)O_(9)^(4−),leading to the formation of clusters Ag_(22)and Ag_(24).

A novel 58-nuclei silver nanowheel encapsulating a subvalent Ag64+ kernel

The combination of CrO4^2-anion and N,N′-dimethylformamide(DMF)-containing solvent helps to stabilize an atom-precise ultrasmall Ag6 kernel into a 52-nuclei silver shell,giving a core-shell Ag6@Ag52 wheel-like structure(SD/Ag58b).The solution behavior and photocurrent response property were investigated in details.

In Situ Capture of a Ternary Supramolecular Cluster in a 58-Nuclei Silver Supertetrahedron

Although inorganic anion templates are highly appreciated in the synthesis of nanosized silver clusters,supramolecular clusters used as templates to mold silver nanoclusters remain as-yet-unknown due to their existence as volatile forms in solution.Here,we report the synthesis of a novel silver-thiolate nanocluster(SD/Ag58a),comprising an outer tetrahedral cage of 58 silver atoms and a central supramolecular cluster[CH_(3)OH@(SO_(4))_(4)(H_(2)O)6]8−(hereafter abbreviated as CS_(4)H_(6)).Ternary CS_(4)H_(6) cluster was constructed from an(SO_(4))_(4) tetrahedron encaging one CH_(3)OH molecule inside and six water molecules sitting between paired SO_(4)^(2−)ions to form the[SO_(4)…H_(2)O…SO_(4)]hydrogen bonds(H-bonds).Also,the CS4H6 could coordinate to the inner wall of the Ag58 cage by forming Ag-O bonds,exerting templating effect on the formation of SD/Ag58a.Moreover,SD/Ag58a showed a photocurrent response upon visible light irradiation and emitted luminescence in the near-infrared(NIR)region at a cryogenic temperature.This work exemplifies the ternary supramolecule templating effect in the construction of silver nanocluster and facilitates understanding of the structure of complex solvated anion cluster in atomic precision.

Evolution of all-carboxylate-protected superatomic Ag clusters confined in Ti-organic cages

In this study,the size of the titanium organic cage was controlled to achieve the restricted growth from a single Ag(I)atom(Ag@Ti_(5))to rare all-carboxylate-protected superatomic Ag cluster(Ag6@Ti_(6)).The classical octahedral Ag_(6)^(4+) cluster with two delocalized electrons(2e)has been encapsulated in a Ti6 organic cage,which shows high stability in air and dimethyformamide(DMF).Furthermore,larger 2e nested double-tetrahedra Ag clusters(Ag_(8)^(6+) and Ag_(9)^(7+))protected using a tetrahedral hollow metalloligand framework(Ag_(8)@Ti_(4) and Ag_(9)@Ti_(4))were obtained.Electrospray ionization mass spectrometry(ESI-MS)and density functional theory(DFT)calculations confirmed that there are two delocalized electrons on these small Ag clusters.This study provides a new form of protection for superatomic Ag clusters and provides a feasible strategy for the development of stable Ag clusters.

Anionic passivation layer-assisted trapping of an icosahedral Ag_(13)kernel in a truncated tetrahedral Ag_(89)nanocluster

Isolating reductive silver kernel from shell is a challenging task but is quite important to understand the embryonic form during the formation of silver nanoclusters.The intercalation of suitable anionic species may be of benefit for passivating then capturing such highly active kernel.Herein,we successfully isolated a novel silver thiolate nanocluster[Ag_(13)@Ag_(76)S_(16)(Cyh S)_(42)(p-NH_(2)-Ph As O_(3))_(4)]^(3+)(SD/Ag89 a,Cyh SH=cyclohexanethiol)that contains a well-isolated icosahedral Ag_(13) kernel passivated by four Ag S_(4)^(7-) tetrahedra and four p-NH_(2) Ph As O_(3)^(2-) piercing from outer Ag_(72) shell.Of note,this Ag_(13) kernel is the largest isolable subvalent silver kernel beneath the silver shell with extremely legible core-shell boundary ever before and represents a precise embryonic model formed in the reducing Ag(I)to Ag(0)followed by aggregating to large silver nanoparticles.The reductive role of DMF and the introduction of anionic passivation layer(APL)synergistically modulate the reduction kinetics,facilitating the capture of ultrasmall subvalent silver kernel.SD/Ag89 a emits in near infrared(NIR)region(λ_(em)=800 nm)at low temperature.The synthetic strategy shown in this work opens up new opportunities for precisely capturing and recognizing diverse reductive silver kernels in different systems.