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A new strategy was developed by using a polymer ligand, poly(isophthalic acid)(ethylene oxide), to modulate the growth of metal–organic polyhedra (MOP) crystals. This macromolecular modulator can effectively control the crystal habit of several different Cu24L24 (L = isophthalic acid derivatives) MOPs. The polymer also directed the formation of MOP structures under reaction conditions that only produce metal–organic frameworks in the absence of modulator. Moreover, the polymer also enabled the deposition of MOP crystals on glass surfaces. This macromolecular modulator strategy provides an innovative approach to control the morphology and assembly of MOP particles.

An entirely new type of chalcogenide cluster and a new structural mechanism for the formation of large semiconducting tetrahedral clusters have been revealed as a result of crystallization of a templated indium sulfide consisting of an unprecedented cluster, In(38)S(65), which is the largest supertetrahedral cluster based on trivalent metal ions. At the core of this cluster is In(10)S(13), which can be considered as a fragment of the NaCl-type lattice. The In(10)S(13) cluster is coupled to four In(4)S(10) supertetrahedral T2 clusters and four In(3)S(3) hexagonal rings to give In(38)S(65), which is also the largest inorganic chalcogenide supertetrahedral cluster, superseding a supertetrahedral T5 cluster with only 35 metal sites.

Supertetrahedral Tn clusters are exact fragments of cubic ZnS-type lattice and are often formed in situ as building units for the construction of 3-D open-framework chalcogenide materials. Small Tn clusters can also be synthesized in discrete forms, allowing them to exist as soluble species in solution. In addition to their tunable electronic and optical properties, these soluble clusters can be used as precursors for the synthesis of porous semiconducting and optical materials. However, the synthesis of large Tn clusters is a significant challenge, and for several decades prior to this work, the size of the discrete Tn cluster remained at T3, with only 10 metal sites (e.g., [Cd(10)S(4)(SPh)(16)](4-) and [M(5)Sn(5)S(20)](10-), M = Zn, Co). Here we report a family of discrete chalcogenide T4 clusters ([M(x)Ga(18-x)Sn(2)Q(35)](12-), x = 2 or 4; M = Mn, Cu, Zn; Q = S, Se) whose discovery resulted from an unusual phase transformation from a 3-D T4 covalent framework into 0-D T4 molecular clusters. The driving force for such a transformation is the perfect match in both charge density and geometry between chalcogenide clusters and protonated amine, leading to the higher stability of isolated clusters. The perfect match is achieved by using complex quaternary compositions to maximize charge tunability of the cluster. These T4 clusters are the largest molecular Tn clusters known to date and can be made in various compositions showing tunable band structures in both solution and solid state.

We report a simple and yet effective method to introduce Mn(2+) ions into semiconducting nanoclusters with atomically precise control. Our method utilizes one type of micrometer-sized crystals, composed of well-defined isolated supertetrahedral chalcogenide nanoclusters (∼2 nm, [Cd6In28S52(SH)4]) whose core metal site is unoccupied in as-synthesized pristine form. This unique model structure with vacant core site makes it possible to achieve ordered distribution of Mn(2+) dopants, and at the same time effectively preclude the formation of Mn(2+) clusters in the host matrix. A two-step synthesis strategy is applied to realize an atomically precise doping of Mn(2+) ion into the core site of the nanoclusters, and to achieve uniform distribution of Mn(2+) dopants in the crystal lattice. The PL, X-ray photoelectron (XPS), as well as the electron paramagnetic resonance (EPR) spectra reveal the successful incorporation of Mn(2+) ion into the core site of the nanocluster. Different from the pristine host material with weak green emission (∼490 nm), the Mn(2+)-doped material shows a strong red emission (630 nm at room temperature and 654 nm at 30 K), which is significantly red-shifted relative to the orange emission (∼585 nm) observed in traditional Mn(2+)-doped II-VI semiconductors. Various experiments including extensive synthetic variations and PL dynamics have been performed to probe the mechanistic aspects of synthesis process and resultant unusual structural and PL properties. The quaternary semiconductor material reported here extends the emission window of Mn(2+)-doped II-VI semiconductor from yellow-orange to red, opening up new opportunities in applications involving photonic devices and bioimaging.

We apply a two-step strategy to realize ordered distribution of multiple components in one nanocluster (NC) with a crystallographically ordered core/shell structure. A coreless supertetrahedral chalcogenide Cd-In-S cluster is prepared, and then a copper ion is inserted at its void core site through a diffusion process to form a Cu-Cd-In-S quaternary NC. This intriguing molecular cluster with mono-copper core and Cd-In shell exhibits enhanced visible-light-responsive optical and photoelectric properties compared to the parent NC.

Supertetrahedral Tn clusters are exact fragments of a cubic ZnS type lattice. Thus far, Tn clusters up to T4 with 20 metal sites can be synthesized in a discrete molecular form. Yet, synthesis of larger discrete supertetrahedral clusters still remains a great challenge, likely due to the rapidly increasing negative charge on the cluster as the size goes up. By using organic superbases (DBN and DBU) to help stabilize the negative charge, a family of discrete supertetrahedral chalcogenide clusters with sizes spanning from T3 (10 metal sites) to T5 (35 metal sites) have been made. The T5 cluster represents the largest molecular supertetrahedral Tn cluster known to date.

Through a facile one-step combustion method, partially reduced TiO(2) has been synthesized. Electron paramagnetic resonance (EPR) spectra confirm the presence of Ti(3+) in the bulk of an as-prepared sample. The UV-vis spectra show that the Ti(3+) here extends the photoresponse of TiO(2) from the UV to the visible light region, which leads to high visible-light photocatalytic activity for the generation of hydrogen gas from water. It is worth noting that the Ti(3+) sites in the sample are highly stable in air or water under irradiation and the photocatalyst can be repeatedly used without degradation in the activity.

Cytochrome bc(1) complex (EC 1.10.2.2, bc(1)), an essential component of the cellular respiratory chain and the photosynthetic apparatus in photosynthetic bacteria, has been identified as a promising target for new drugs and agricultural fungicides. X-ray diffraction structures of the free bc(1) complex and its complexes with various inhibitors revealed that the phenyl group of Phe274 in the binding pocket exhibited significant conformational flexibility upon different inhibitors binding to optimize respective pi-pi interactions, whereas the side chains of other hydrophobic residues showed conformational stability. Therefore, in the present study, a strategy of optimizing the pi-pi interaction with conformationally flexible residues was proposed to design and discover new bc(1) inhibitors with a higher potency. Eight new compounds were designed and synthesized, among which compound 5c, with a K(i) value of 570 pM, was identified as the most promising drug or fungicide candidate, significantly more potent than the commercially available bc(1) inhibitors, including azoxystrobin (AZ), kresoxim-methyl (KM), and pyraclostrobin (PY). To our knowledge, this is the first bc(1) inhibitor discovered from structure-based design with a potency of subnanomolar K(i) value. For all of the compounds synthesized and assayed, the calculated binding free energies correlated reasonably well with the binding free energies derived from the experimental K(i) values, with a correlation coefficient of r(2) = 0.89. The further inhibitory kinetics studies revealed that 5c is a noncompetitive inhibitor with respect to substrate cytochrome c, but it is a competitive inhibitor with respect to substrate ubiquinol. Due to its subnanomolar K(i) potency and slow dissociation rate constant (k(-0) = 0.00358 s(-1)), 5c could be used as a specific probe for further elucidation of the mechanism of bc(1) function and as a new lead compound for future drug discovery.