A calibrated B3LYP/6-311++G(2df,2p)//B3LYP/6-31+G(d) method was found to be able to predict the gas-phase adiabatic ionization potentials of 160 structurally unrelated organic molecules with a precision of 0.14 eV. A PCM solvation model was benchmarked that could predict the pK(a)'s of 15 organic acids in acetonitrile with a precision of 1.0 pK(a) unit. Combining the above two methods, we developed a generally applicable protocol that could successfully predict the standard redox potentials of 270 structurally unrelated organic molecules in acetonitrile. The standard deviation of the predictions was 0.17 V. The study demonstrated that computational electrochemistry could become a powerful tool for the organic chemical community. It also confirmed that the continuum solvation theory could correctly predict the solvation energies of organic radicals. Finally, with the help of the newly developed protocol we were able to establish a scale of standard redox potentials for diverse types of organic free radicals for the first time. Knowledge about these redox potentials should be of great value for understanding the numerous electron-transfer reactions in organic and bioorganic chemistry.

Small size molybdenum disulfide (MoS2) quantum dots (QDs) with desired optical properties were controllably synthesized by using tetrabutylammonium-assisted ultrasonication of multilayered MoS2 powder via OH-mediated chain-like Mo-S bond cleavage mode. The tunable up-bottom approach of precise fabrication of MoS2 QDs finally enables detailed experimental investigations of their optical properties. The synthesized MoS2 QDs present good down-conversion photoluminescence behaviors and exhibit remarkable up-conversion photoluminescence for bioimaging. The mechanism of the emerging photoluminescence was investigated. Furthermore, superior (1)O2 production ability of MoS2 QDs to commercial photosensitizer PpIX was demonstrated, which has great potential application for photodynamic therapy. These early affording results of tunable synthesis of MoS2 QDs with desired photo properties can lead to application in fields of biomedical and optoelectronics.

The concept of aggregation-induced emission (AIE) has been exploited to render non-luminescent Cu(I) SR complexes strongly luminescent. The Cu(I) SR complexes underwent controlled aggregation with Au(0) . Unlike previous AIE methods, our strategy does not require insoluble solutions or cations. X-ray crystallography validated the structure of this highly fluorescent nanocluster: Six thiolated Cu atoms are aggregated by two Au atoms (Au2 Cu6 nanoclusters). The quantum yield of this nanocluster is 11.7 %. DFT calculations imply that the fluorescence originates from ligand (aryl groups on the phosphine) to metal (Cu(I) ) charge transfer (LMCT). Furthermore, the aggregation is affected by the restriction of intramolecular rotation (RIR), and the high rigidity of the outer ligands enhances the fluorescence of the Au2 Cu6 nanoclusters. This study thus presents a novel strategy for enhancing the luminescence of metal nanoclusters (by the aggregation of active metal complexes with inert metal atoms), and also provides fundamental insights into the controllable synthesis of highly luminescent metal nanoclusters.

The ligand-dependent selectivities in Ullmann-type reactions of amino alcohols with iodobenzene by β-diketone- and 1,10-phenanthroline-ligated Cu(I) complexes were recently explained by the single-electron transfer and iodine atom transfer mechanisms (Jones, G. O., Liu, P., Houk, K. N., and Buchwald, S. L. J. Am. Chem. Soc. 2010, 132, 6205.). The present study shows that an alternative, oxidative addition/reductive elimination mechanism may also explain the selectivities. Calculations indicate that a Cu(I) complex with a negatively charged β-diketone ligand is electronically neutral, so that oxidative addition of ArI to a β-diketone-ligated Cu(I) prefers to occur (and occur readily) in the absence of the amino alcohol. Thus, coordination of the amino alcohol in its neutral form can only occur at the Cu(III) stage where N-coordination is favored over O-coordination. The coordination step is the rate-limiting step and the outcome is that N-arylation is favored with the β-diketone ligand. On the other hand, a Cu(I) complex with a neutral 1,10-phenanthroline ligand is positively charged, so that oxidative addition of ArI to a 1,10-phenanthroline-ligated Cu(I) has to get assistance from a deprotonated amino alcohol substrate. This causes oxidative addition to become the rate-limiting step in the 1,10-phenanthroline-mediated reaction. The immediate product of the oxidative addition step is found to undergo facile reductive elimination to provide the arylation product. Because O-coordination of a deprotonated amino alcohol is favored over N-coordination in the oxidative addition transition state, O-arylation is favored with the 1,10-phenanthroline ligand.

In this study, we successfully synthesized the rod-like [Au 25 (PPh 3 ) 10 (SePh) 5 Cl 2 ] q (q = +1 or +2) nanoclusters through kinetic control. The single crystal X-ray crystallography determined their formulas to be [Au 25 (PPh 3 ) 10 (SePh) 5 Cl 2 ]-(SbF 6 ) and [Au 25 (PPh 3 ) 10 (SePh) 5 Cl 2 ](SbF 6 )(BPh 4 ), respectively. Compared to the previously reported Au 25 coprotected by phosphine and thiolate ligands (i.e., [Au 25 (PPh 3 ) 10 (SR) 5 Cl 2 ] 2+ ), the two new rod-like Au 25 nanoclusters show some interesting structural differences. Nonetheless, each of these three nanoclusters possesses two icosahedral Au 13 units (sharing a vertex gold atom) and the bridging "Au−Se(S)−Au" motifs. The compositions of the two new nanoclusters were characterized with ESI-MS and TGA. The optical properties, electrochemistry, and magnetism were studied by EPR, NMR, and SQUID. All these results demonstrate that the valence character significantly affects the properties of the "non-superatom" Au 25 nanoclusters, and the changes are different from the previously reported "superatom" Au 25 nanoclusters. Theoretical calculations indicate that the extra electron results in the half occupation of the highest occupied molecular orbitals in the rod-like Au 25 + nanoclusters and, thus, significantly affects the electronic structure of the "non-superatom" Au 25 nanoclusters. This work offers new insights into the relationship between the properties and the valence of the "non-superatom" gold nanoclusters.

Ultrasmall nanoclusters (e.g., Au(SR)) are crucial in not only real applications such as bioapplication but also in understanding the structure transition from gold complexes to gold nanoclusters. However, the determination of these transition-sized gold nanoclusters has long been a major challenge. In this work, two new nanoclusters in the transition regime, including the thus far smallest thiolated alloy nanocluster CdAu(S tBu) and the homogold nanocluster Au(S-Adm), are obtained and their atomic structures are fully determined by single crystal X-ray diffraction. Moreover, based on the structures of CdAu(SR) and Au(SR), we perform DFT calculations to predict the structure of the "transformation" nanocluster, Au (Au(SR) and Au(SR)). Overall, this work bridges the gaps between gold complexes and nanoclusters.

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A new method termed "in situ two-phase ligand exchange" was developed to obtain alloy nanoclusters. With this approach, a series of alloy nanoclusters were obtained for the first time, including AuAg(SR), AuAg(SR) (x = 4-8), AuCu(SR) (x = 0, 1), and AuCu(SR) (x = 2-5) (R = tert-butyl). Interestingly, single-crystal X-ray crystallography (SC-XRD) shows that their frameworks are all alike except for AuCu(SR) (x = 2-5), indicating that more Cu dopants alter the structure. AuCu(SR) (x = 2-5) exhibits a significantly different configuration. The optical absorption spectra of these bimetal nanoclusters (NCs) show distinct characteristic peaks, indicating that the metal-doping remarkably affects the electronic structure of NCs. The DFT calculations were also employed for determination of NC 1-3 frameworks and understanding their optical properties.