Crystal structure determination has revolutionized modern science in biology, chemistry, and physics. However, the difficulty in obtaining periodic crystal lattices which are needed for X-ray crystal analysis has hindered the determination of atomic structure in nanomaterials, known as the "nanostructure problem". Here, by using rigid and bulky ligands, we have overcome this limitation and successfully solved the X-ray crystallographic structure of the largest reported thiolated gold nanomolecule, Au133S52. The total composition, Au133(SPh-tBu)52, was verified using high resolution electrospray ionization mass spectrometry (ESI-MS). The experimental and simulated optical spectra show an emergent surface plasmon resonance that is more pronounced than in the slightly larger Au144(SCH2CH2Ph)60. Theoretical analysis indicates that the presence of rigid and bulky ligands is the key to the successful crystal formation.

We report the discovery of an unprecedentedly large, 2.2 nm diameter, thiolate protected gold nanocrystal characterized by single crystal X-ray crystallography (sc-XRD), Au(SPh-tBu) named Faradaurate-279 (F-279) in honor of Michael Faraday's (1857) pioneering work on nanoparticles. F-279 nanocrystal has a core-shell structure containing a truncated octahedral core with bulk face-centered cubic-like arrangement, yet a nanomolecule with a precise number of metal atoms and thiolate ligands. The AuS geometry was established from a low-temperature 120 K sc-XRD study at 0.90 Å resolution. The atom counts in core-shell structure of Au follows the mathematical formula for magic number shells: Au@Au@Au@Au@Au, which is further protected by a final shell of Au. Au core is protected by three types of staple motifs, namely: 30 bridging, 18 monomeric, and 6 dimeric staple motifs. Despite the presence of such diverse staple motifs, AuS structure has a chiral pseudo-D symmetry. The core-shell structure can be viewed as nested, concentric polyhedra, containing a total of five forms of Archimedean solids. A comparison between the Au and Au cuboctahedral superatom model in shell-wise growth is illustrated. F-279 can be synthesized and isolated in high purity in milligram quantities using size exclusion chromatography, as evidenced by mass spectrometry. Electrospray ionization-mass spectrometry independently verifies the X-ray diffraction study based heavy atoms formula, AuS, and establishes the molecular formula with the complete ligands, namely, Au(SPh-tBu). It is also the smallest gold nanocrystal to exhibit metallic behavior, with a surface plasmon resonance band around 510 nm.

Ultrastable gold nanomolecule Au144(SCH2CH2Ph)60 upon etching with excess tert-butylbenzenethiol undergoes a core-size conversion and compositional change to form an entirely new core of Au133(SPh-tBu)52. This conversion was studied using high-resolution electrospray mass spectrometry which shows that the core size conversion is initiated after 22 ligand exchanges, suggesting a relatively high stability of the Au144(SCH2CH2Ph)38(SPh-tBu)22 intermediate. The Au144 → Au133 core size conversion is surprisingly different from the Au144 → Au99 core conversion reported in the case of thiophenol, -SPh. Theoretical analysis and ab initio molecular dynamics simulations show that rigid p-tBu groups play a crucial role by reducing the cluster structural freedom, and protecting the cluster from adsorption of exogenous and reactive species, thus rationalizing the kinetic factors that stabilize the Au133 core size. This 144-atom to 133-atom nanomolecule's compositional change is reflected in optical spectroscopy and electrochemistry.

The direct depletion of lactate accumulated in the tumor microenvironment holds promise for cancer therapybut remains challenging.H erein, we report ao ne-pot synthesis of openwork@ dendritic mesoporous silica nanoparticles (ODMSNs) to address this problem. ODMSNs self-assembled through atime-resolved lamellar growth mechanism feature an openworked core and ad endritic shell, both constructed by silica nanosheets of % 3nm. With alarge pore size, high surface area and pore volume,O DMSNs exhibited ah igh loading capacity (> 0.7 gg À1)o fl actate oxidase (LOX) and enabled intratumoral lactate depletion by > 99.9 %, leading to antiangiogenesis,d own-regulation of vascular endothelial growth factor,and increased tumor hypoxia. The latter event facilitates the activation of ac o-delivered prodrug for enhancing antitumor and anti-metastasis efficacy.T his study provides an innovative nano-delivery system and demonstrates the first example of direct lactate-depletion-enabled chemotherapy.

Here, we report the synthesis and experimental and theoretical characterizations of Au 36−x Ag x (SPh-tBu) 24 alloy nanomolecule to atomic precision. By changing the incoming gold-to-silver metal ratio during the synthesis of crude mixture, up to eight silver atoms can be incorporated into Au 36 (SPh-tBu) 24 , as theoretically confirmed and rationalized in terms of its core and staple structure. Tuning of optical response by Ag doping is strongly affected by aromatic conjugation and qualitatively different with respect to the aliphatic case, with a strikingly nonmonotonic behavior of absorption intensity in the low-and high-energy regions, in fair agreement with theoretical predictions, as rationalized via an original analysis tool: independent component mapping of oscillatory strength plots.