Pseudotetrahedral Organotin-Capped Chalcogenidometalate Supermolecules with Optical Limiting Performance.

The rational design of crystalline clusters with adjustable compositions and dimensions is highly sought after but quite challenging as it is important to understand their structural evolution processes and to systematically establish structure-property relationships. Herein, a family of organotin-based sulfidometalate supertetrahedral clusters has been prepared via mixed metal and organotin strategies at low temperatures (60-120 °C). By engineering the metal composition, we can effectively control the size of the clusters, which ranges from 8 to 35, accompanied by variable configurations: P1-[(RSn)4M4S13], T3-[(RSn)4In4M2S16] (R = nbutyl-Bu and phenyl-Ph; M = Cd, Zn, and Mn), T4-[(BuSn)4In13Cu3S31], truncated P2, viz. TP2-[(BuSn)6In10Cu6S31], and even T5-[(BuSn)4In22Zn6Cu3S52], all of which are the largest organometallic supertetrahedral clusters known to date. Of note, the arylstannane approach plays a critical role in regulating the peripheral ligands and further enriching geometric structures of the supertetrahedral clusters. This is demonstrated by the formation of tin-oxysulfide clusters, such as T3-[(RSn)4Sn6O4S16] (R = Bu, Ph, and benzyl = Be) and its variants, truncated T3, viz., TT3-[(BuSn)6Sn3O4S13] and augmented T3, viz., T3-[(Bu3SnS)4Sn6O4S16]. Especially, two extraordinary truncated clusters break the tetrahedral symmetry observed in typical supertetrahedral clusters, further substantiating the advantages offered by the arylstannane approach in expanding cluster chemistry. These organometallic supertetrahedral clusters are highly soluble and stable in common solvents. Additionally, they have tunable third-order nonlinear optical behaviors by controlling the size, heterometallic combination, organic modification, and intercluster interaction.

Multilevel-Regulated Metal-Organic Framework Platform Integrating Pore Space Partition and Open-Metal Sites for Enhanced CO2 Photoreduction to CO with Nearly 100% Selectivity.

Rational design and regulation of atomically precise photocatalysts are essential for constructing efficient photocatalytic systems tunable at both the atomic and molecular levels. Herein, we propose a platform-based strategy capable of integrating both pore space partition (PSP) and open-metal sites (OMSs) as foundational features for constructing high-performance photocatalysts. We demonstrate the first structural prototype obtained from this strategy: pore-partitioned NiTCPE-pstp (TCPE = 1,1,2,2-tetra(4-carboxylphenyl)ethylene, pstp = partitioned stp topology). Nonpartitioned NiTCPE-stp is constructed from six-connected [Ni3(µ3-OH)(COO)6] trimer and TCPE linker to form 1D hexagonal channels with six coplanar OMSs directed at channel centers. After introducing triangular pore-partitioning ligands, half of the OMSs were retained, while the other half were used for PSP, leading to unprecedented microenvironment regulation of the pore structure. The resulting material integrates multiple advanced properties, including robustness, wider absorption range, enhanced electronic conductivity, and high CO2 adsorption, all of which are highly desirable for photocatalytic applications. Remarkably, NiTCPE-pstp exhibits excellent CO2 photoreduction activity with a high CO generation rate of 3353.6 µmol g-1 h-1 and nearly 100% selectivity. Theoretical and experimental studies show that the introduction of partitioning ligands not only optimizes the electronic structure to promote the separation and transfer of photogenerated carriers but also reduces the energy barrier for the formation of *COOH intermediates while promoting CO2 activation and CO desorption. This work is believed to be the first example to integrate PSP strategies and OMSs within metal-organic framework (MOF) photocatalysts, which provides new insight as well as new structural prototype for the design and performance optimization of MOF-based photocatalysts.

Superhydrophobic Pseudosupertetrahedral Sulfido Metalate Clusters for Constructing Liquid Marbles.

One pseudopentasupertetrahedral chalcogenidometalate cluster, [(BuSn)3SnCd4S13(OH)]·6(H+DMP) (PPS-1; H+DMP = protonated 3,5-dimethylpiperidine), has been isolated by use of an organotin precursor. They are arranged to generate two types of tetrahedrally patterned cages, which further interconnect to form a diamond network. Owing to the covalent attachment of abundant alkyl groups, PPS-1 exhibits excellent hydrophobicity and could be used as an assembly substance for building liquid marbles.

Energy Band Alignment and Redox-Active Sites in Metalloporphyrin-Spaced Metal-Catechol Frameworks for Enhanced CO2 Photoreduction.

Two new chemically stable metalloporphyrin-bridged metal-catechol frameworks, InTCP-Co and FeTCP-Co, were constructed to achieve artificial photosynthesis without additional sacrificial agents and photosensitizers. The CO2 photoreduction rate over FeTCP-Co considerably exceeds that obtained over InTCP-Co, and the incorporation of uncoordinated hydroxyl groups, associated with catechol, into the network further promotes the photocatalytic activity. The iron-oxo coordination chain assists energy band alignment and provides a redox-active site, and the uncoordinated hydroxyl group contributes to the visible-light absorptance, charge-carrier transfer, and CO2 -scaffold affinity. With a formic acid selectivity of 97.8 %, FeTCP-OH-Co affords CO2 photoconversion with a reaction rate 4.3 and 15.7 times higher than those of FeTCP- Co and InTCP-Co, respectively. These findings are also consistent with the spectroscopic study and DFT calculation.

Construction of Titanium-Based Metal-Organic Frameworks Based on the Ti/Cu Heteronuclear Cluster.

Presented here are two titanium-based metal-organic frameworks (Ti-MOFs) based on well-defined [Ti6Cu6(µ3-O)2(µ2-O)9(HSO4)2(SO4)6], which can be easily obtained from a cheap Ti source and CuSO4 and exhibited interesting magnetic properties. Furthermore, this clusters can be isolated in pure phase. Numerous uncoordinated sites of SO4 and labile ligands on the Ti and Cu centers of this cluster make it a good candidate as a secondary building unit to construct various Ti-MOFs in the future.

Photochemical In Situ Exfoliation of Metal-Organic Frameworks for Enhanced Visible-Light-Driven CO2 Reduction.

Two novel two-dimensional metal-organic frameworks (2D MOFs), 2D-M2 TCPE (M=Co or Ni, TCPE=1,1,2,2-tetra(4-carboxylphenyl)ethylene), which are composed of staggered (4,4)-grid layers based on paddlewheel-shaped dimers, serve as heterogeneous photocatalysts for efficient reduction of CO2 to CO. During the visible-light-driven catalysis, these structures undergo in situ exfoliation to form nanosheets, which exhibit excellent stability and improved catalytic activity. The exfoliated 2D-M2 TCPE nanosheets display a high CO evolution rate of 4174 µmol g-1 h-1 and high selectivity of 97.3 % for M=Co and Ni, and thus are superior to most reported MOFs. The performance differences and photocatalytic mechanisms have been studied with theoretical calculations and photoelectric experiments. This study provides new insight for the controllable synthesis of effective crystalline photocatalysts based on structural and morphological coregulation.

Robust Porphyrin-Spaced Zirconium Pyrogallate Frameworks with High Proton Conduction.

An isoreticular family of zirconium polyphenolate networks (ZrPP- n, n = 1 and 2), bridged by porphyrinic macrocycles in an eclipsed arrangement, have excellent stability toward water, especially strong basic media of saturated NaOH aqueous solution. Endowed with spatial alignment of protic sites, viz., partially protonated phenols of acidity enhanced by coordination to Zr4+, along with guest dimethylamine cations, the newly synthesized ZrPP- n reveal exceptional conductivity (8.0 × 10-3 and 4.2 × 10-3 S cm-1, for n = 1 and 2, respectively, pelleted sample, under 98% relative humidity at 25 °C).

Charge- and Size-Complementary Multimetal-Induced Morphology and Phase Control in Zeolite-Type Metal Chalcogenides.

Zeolite-type chalcogenides are desirable due to their integration between porosity and semiconductivity. CPM-120, with super-sodalite topology (Zeolite Structure Code: RWY), is among the few zeolite-type chalcogenides with permanent porosity, and is the only chalcogenide with a zeolite code. Importantly, the RWY-type has evolved into a platform for studying properties of porous chalcogenides. Yet so far, few studies have been made to probe the effects of synthetic parameters and framework compositions on this platform. Here, we probe the effects of the third metal type (Ga3+ , In3+ , Cd2+ , and Sn4+ ) on the Zn2+ /Ge4+ /S2- platform. We find that charge-complementary and size-compatible Ga3+ leads to the synthesis of CPM-120-ZnGaGeS which is the first trimetallic zeolite-type chalcogenide, with improved crystal morphology and reproducibility. We also find that charge-compatible and size-complementary cations (Cd2+ or Sn4+ ) can induce an abrupt phase transition from super-sodalite to super-diamond, also with unprecedented trimetallic T2 clusters. For In3+ , which is dual-complementary (charge and size), a gradual phase transition is observed with increasing In3+ amount. Furthermore, by controlling the cluster composition, tunable band gaps can be realized. These materials show promising properties such as high CO2 uptake (4.32 mmol cm-3 , 298 K, 1 bar) and high photocatalytic activity.

Water-Soluble and Ultrastable Ti4L6 Tetrahedron with Coordination Assembly Function.

We have successfully constructed a tetrahedral Ti4L6 cage with calixarene-like coordination-active vertices. It further features high solubility and stability in H2O and DMF/H2O solution, affording an interesting stepwise assembly function with other metal ions. Through trapping of different amounts of Co or Ln ions, the Ti4L6 tetrahedra can be organized into various dimensional architectures, including a Ti4L6-Co3 cage, a Ti4L6-Ln2 cage, a Ti4L6-Ln2 chain, and a three-dimensional Ti4L6-Ln framework. An unusual mixed-valence phenomenon was observed in the Ti4L6 cage, whose Ti3+/4+ compositions were adequately identified by electron spin resonance and X-ray photoelectron spectroscopy analyses. More remarkably, the calixarene-like oxygen vertices of the Ti4L6 cage can also be used for the recognition of C3-symmetric dye molecules through N-H···O hydrogen bonding. Accordingly, driven by visible light, selective and efficient homogeneous photodecomposition of acid blue 93 and alkali blue 4B were successfully achieved. Therefore, this work not only represents a milestone in constructing symmetric Ti-based cages with interesting coordination assembly function but also provides a new method for preparing technologically important soluble photoactive cages.

Selective Ion Exchange and Photocatalysis by Zeolite-Like Semiconducting Chalcogenide.

The development of novel photocatalysts usually centers on features such as band structures, various nano-, micro-, or macro-forms, and composites in efforts to tune their light absorption and charge separation efficiency. In comparison, the selectivity of photocatalysts with respect to features of reactants such as size and charge has received much less attention, in part due to the difficulty in designing semiconducting photocatalysts with uniform pore size. Here, we use crystalline porous chalcogenides as a platform to probe reactant selectivity in photocatalytic processes. The 3-in-1 integration of high surface area, uniform porosity, and favorable band structures in such chalcogenides makes them excellent candidates for efficient and selective photocatalytic processes. We show that their photocatalytic activity and selectivity are closely related to their differing affinity and selectivity for different guest species. In particular, unlike common solid-state photocatalysts with neutral framework, the anionic nature of the porous chalcogenide framework used here endows them with a high degree of selectivity for cationic species in both guest exchange and closely coupled photocatalytic transformation of such guests. Another interesting discovery is the observation of an unusual ion exchange process involving a transient state of over-saturation of exchanged ions, which can be explained by a transition from an initially kinetically controlled process to a subsequent thermodynamically controlled one. This work is part of ongoing efforts to contribute to the development of a new generation of crystalline porous photocatalysts with custom-designed selectivity for various reactants or products.

Integrating Zeolite-Type Chalcogenide with Titanium Dioxide Nanowires for Enhanced Photoelectrochemical Activity.

Developing photoanodes with efficient visible-light harvesting and excellent charge separation still remains a key challenge in photoelectrochemical water splitting. Here zeolite-type chalcogenide CPM-121 is integrated with TiO2 nanowires to form a heterostructured photoanode, in which crystalline CPM-121 particles serve as a visible light absorber and TiO2 nanowires serve as an electron conductor. Owing to the small band gap of chalcogenides, the hybrid electrode demonstrates obvious absorption in visible-light range. Electrochemical impedance spectroscopy (EIS) shows that electron transport in the hybrid electrode has been significantly facilitated due to the heterojunction formation. A >3-fold increase in photocurrent is observed on the hybrid electrode under visible-light illumination when it is used as a photoanode in a neutral electrolyte without sacrificial agents. This study opens up a new avenue to explore the potential applications of crystalline porous chalcogenide materials for solar-energy conversion in photoelectrochemistry.

Framework Cationization by Preemptive Coordination of Open Metal Sites for Anion-Exchange Encapsulation of Nucleotides and Coenzymes.

Cationic frameworks can selectively trap anions through ion exchange, and have applications in ion chromatography and drug delivery. However, cationic frameworks are much rarer than anionic or neutral ones. Herein, we propose a concept, preemptive coordination (PC), for targeting positively charged metal-organic frameworks (P-MOFs). PC refers to proactive blocking of metal coordination sites to preclude their occupation by neutralizing ligands such as OH(-) . We use 20 MOFs to show that this PC concept is an effective approach for developing P-MOFs whose high stability, porosity, and anion-exchange capability allow immobilization of anionic nucleotides and coenzymes, in addition to charge- and size-selective capture or separation of organic dyes. The CO2 and C2 H2 uptake capacity of 117.9 cm(3) g(-1) and 148.5 cm(3) g(-1) , respectively, at 273 K and 1 atm, is exceptionally high among cationic framework materials.

Mimicking high-silica zeolites: highly stable germanium- and tin-rich zeolite-type chalcogenides.

High-silica zeolites, as exemplified by ZSM-5, with excellent chemical and thermal stability, have generated a revolution in industrial catalysis. In contrast, prior to this work, high-silica-zeolite-like chalcogenides based on germanium/tin remained unknown, even after decades of research. Here six crystalline high-germanium or high-tin zeolite-type sulfides and selenides with four different topologies are reported. Their unprecedented framework compositions give these materials much improved thermal and chemical stability with high surface area (Langmuir surface area of 782 m(2)/g(-1)) comparable to or better than zeolites. Among them, highly stable CPM-120-ZnGeS allows for ion exchange with diverse metal or complex cations, resulting in fine-tuning in porosity, fast ion conductivity, and photoelectric response. Being among the most porous crystalline chalcogenides, CPM-120-ZnGeS (exchanged with Cs(+) ions) also shows reversible adsorption with high capacity and affinity for CO2 (98 and 73 cm(3) g(-1) at 273 and 298 K, respectively, isosteric heat of adsorption = 40.05 kJ mol(-1)). Moreover, CPM-120-ZnGeS could also function as a robust photocatalyst for water reduction to generate H2. The overall activity of H2 production from water, in the presence of Na2S-Na2SO3 as a hole scavenger, was 200 µmol h(-1)/(0.10 g). Such catalytic activity remained undiminished under illumination by UV light for as long as measured (200 h), demonstrating excellent resistance to photocorrosion even under intense UV radiation.

New heterometallic zirconium metalloporphyrin frameworks and their heteroatom-activated high-surface-area carbon derivatives.

Four cubic zirconium-porphyrin frameworks, CPM-99(H2, Zn, Co, Fe), were synthesized by a molecular-configuration-guided strategy. Augmentation of meso-substituted side arms (with double-torsional biphenyl rings) of tetratopic porphyrin linkers leads to a successful implementation of zirconium-carboxylate frameworks with cubic 2.5 nm cage. The hard-templating effect of Zr6-polyoxo-cluster and uniformly embedded (metallo)porphyrin centers endow CPM-99 with highly desirable properties as precursors for oxygen reduction reaction (ORR) catalysts. The pyrolytic products not only retain the microcubic morphology of the parent CPM-99 but also possess porphyrinic active sites, hierarchical porosity, and highly conducting networks. CPM-99Fe-derived material, denoted CPM-99Fe/C, exhibits the best ORR activity, comparable to benchmark 20% Pt/C in alkaline and acidic media, but CPM-99Fe/C is more durable and methanol-tolerant. This work demonstrates a new route for the development of nonprecious metal ORR catalysts from stable metalloporphyrinic MOFs.

Cooperative Crystallization of Heterometallic Indium-Chromium Metal-Organic Polyhedra and Their Fast Proton Conductivity.

Metal-organic polyhedra (MOPs) or frameworks (MOFs) based on Cr(3+) are notoriously difficult to synthesize, especially as crystals large enough to be suitable for characterization of the structure or properties. It is now shown that the co-existence of In(3+) and Cr(3+) induces a rapid crystal growth of large single crystals of heterometallic In-Cr-MOPs with the [M8L12] (M=In/Cr, L=dinegative 4,5-imidazole-dicarboxylate) cubane-like structure. With a high concentration of protons from 12 carboxyl groups decorating every edge of the cube and an extensive H-bonded network between cubes and surrounding H2O molecules, the newly synthesized In-Cr-MOPs exhibit an exceptionally high proton conductivity (up to 5.8×10(-2) S cm(-1) at 22.5 °C and 98% relative humidity, single crystal).

Visible-light-driven, tunable, photoelectrochemical performance of a series of metal-chelate, dye-organized, crystalline, CdS nanoclusters.

CdS nanoclusters of four different sizes were integrated with ruthenium-complex dyes. The cluster-dye crystalline composites, [Cd(4)(SPh)(10)][Ru(bpy)(3)], [Cd(8)S(SPh)(16)][Ru(bpy)(3)], [Cd(8)S(SPh)(13) ⋅Cl⋅(CH(3)OCS(2))(2)][Ru(phen)(3)], [Cd(17)S(4)(SPh)(28)][Ru(bpy)(3)], and [Cd(32)S(14)(SPh)(40)][Ru(phen)(3)](2) (phen=1,10-phenanthroline and bpy=bipyridine), show intense absorption in the visible-light region. They also exhibit size-dependent photocurrent responses under the illumination of visible light. The photocurrent increases with increased cluster size. The dyes also have significant influence on the photocurrent generation of the composite.

Polymorphic graphene-like cuprous germanosulfides with a high Cu-to-Ge ratio and low band gap.

Metal chalcogenides based on heterometallic Ge-Cu-S offer dual attractive features of lattice stabilization by high-valent Ge(4+) and band gap engineering into solar region by low-valent Cu(+). Herein via cationic amine intercalation, we present three new copper-rich materials with the Cu-to-Ge ratio as high as 3. Two different patterns of Cu-Ge-S distribution could be achieved within each honeycomb sheet. The decoration of such honeycomb sheet by -Cu-S- chain or self-coupling between two honeycomb sheets leads to two layer configurations with different thickness and band gaps. The band gap of these new phases (2.06-2.30 eV), tuned by the layer thickness and the Cu/Ge ratio, represents a significant red shift over known Cu-Ge-S phases with lower Cu/Ge ratios.

Zeolitic metal-organic frameworks based on amino acid.

Two enantiomorphic metal-organic frameworks with zeotype SOD topology have been successfully synthesized from enantiopure L-alanine and D-alanine, respectively, which demonstrates the feasibility of fabricating MOFs that integrate the 4-connected zeotype topologies and homochiral nature by the employment of enantiopure amino acids.

Regulating electron transfer and orbital interaction within metalloporphyrin-MOFs for highly sensitive NO2 sensing.

The understanding of electron transfer pathways and orbital interactions between analytes and adsorption sites in gas-sensitive studies, especially at the atomic level, is currently limited. Herein, we have designed eight isoreticular catechol-metalloporphyrin scaffolds, FeTCP-M and InTCP-M (TCP = 5,10,15,20-tetrakis-catechol-porphyrin, M = Fe, Co, Ni and Zn) with adjustable charge transfer schemes in the coordination microenvironment and precise tuning of orbital interactions between analytes and adsorption sites, which can be used as models for exploring the influence of these factors on gas sensing. Our experimental findings indicate that the sensitivity and selectivity can be modulated using the type of metals in the metal-catechol chains (which regulate the electron transfer routes) and the metalloporphyrin rings (which fine-tune the orbital interactions between analytes and adsorption sites). Among the isostructures, InTCP-Co demonstrates the highest response and selectivity to NO2 under visible light irradiation, which could be attributed to the more favorable transfer pathway of charge carriers in the coordination microenvironment under visible light illumination, as well as the better electron spin state compatibility, higher orbital overlap and orbital symmetry matching between the N-2s2pz hybrid orbital of NO2 and the Co-3dz2 orbital of InTCP-Co.

Thiophenol-spaced 2D coordination polymers with extraordinary alkali resistance and efficient photothermal conversion.

Coordination polymers (CPs) based on metal-sulfur bonds are rare; we herein realize a series of thiol-functionalized linker-based CPs (thiol-CPs), MTBT (M = Fe, Co and Zn; TBT = dehydrated 4,4'-thiobisbenzenethiol), which feature an anionic two-dimensional (2D) network, [M(TBT)2]n2n-, with the tetrahedral coordination unit {MS4} serving as a node. These compounds exhibit excellent hydrolytic stability, especially in alkaline solution (20M NaOH for five days), which is the highest value reported for CPs so far. In addition, among them, CoTBT displays favorable photo-thermal conversion effectiveness under an energy power of 0.5 W cm-2 808 nm laser irradiation for 15 s, with the temperature rising rapidly from room temperature to 135.2 °C.