Metal-organic Clusters Research Articles

Induced aggregation and synergistic coordination strategy in metal oxo clusters and their organic frameworks

The new class of materials of metal cluster organic framework (MCOFs) derive from metal organic framework (MOFs) and metal oxo clusters (MOCs). In recent years, MCOFs has attracted considerable attention for their combination of metal oxo clusters and porous characteristics. We herein summarize the progress of lanthanide cluster organic framework (LnCOFs), and point out the induced aggregation and synergetic coordination strategy. This strategy is suitable for making MCOFs and MOCs.

Synthesis, characterization and DFT studies of water stable Cd(II) metal–organic clusters with better adsorption property towards the organic pollutant in waste water

In this report, two water stable Cd(II) metal–organic clusters using slow evaporation method are designed and synthesized in order to explore for functional applications. The complexes are formulated as [Cd2(pda)2(H2O)6].(H2pda)2 (1) and [Cd4(Hpda)4(µ2-OH)2(Cl)2(H2O)6].2H2O (2) where H2pda = 2,6-pyridine dicarboxylic acid. The synthesized complexes show unusual hepta-coordinated geometry around the central metal ion. 1 is dinuclear while 2 is a tetranuclear discrete complex. The tetranuclear complex is the very first example of cadmium with H2pda ligand. The two complexes were characterized by various spectroscopic studies and with the help of single crystal technique the, structures of 1 and 2 was elucidated. Various non covalent interactions such as π-π and CH…π consolidate the network against water solubility. The metal–organic clusters exhibit various non-covalent interactions which were further verified by Hirshfeld surface analysis. The DFT calculations were also performed on both the complex which corroborate the electronic and spectral aspects of complexes. The stability of 1 and 2 was checked using the PXRD pattern of 1 and 2 after 10 hrs in water and it shows the identical pattern even after the 24 hrs. Further, the metal–organic clusters were checked for their adsorption property towards the cationic dye such as Rhodamine B. Out of the two complexes, only 2 shows better adsorption property due to its better stability in water. The mechanism of dye adsorption is also explored.

Development of Nickel-Based Negative Tone Metal Oxide Cluster Resists for Sub-10 nm Electron Beam and Helium Ion Beam Lithography.

Hybrid metal-organic cluster resist materials, also termed as organo-inorganics, demonstrate their potential for use in next-generation lithography owing to their ability for patterning down to ∼10 nm or below. High-resolution resist patterning is integrally associated with the compatibility of the resist and irradiation of the exposure source. Helium ion beam lithography (HIBL) is an emerging approach for the realization of sub-10 nm patterns at considerably lower line edge/width roughness (LER/LWR) and higher sensitivity as compared to electron beam lithography (EBL). Here, for the first time, a negative tone resist incorporating nickel (Ni)-based metal-organic clusters (Ni-MOCs) was synthesized and patterned using HIBL and EBL at 30 keV. This resist comprises a nickel-based metal building unit covalently linked with the organic ligand: m-toluic acid (C8H8O2). Dynamic light scattering confirmed a narrow size distribution of ∼2 nm for metal-organic cluster (MOC) formulations. High-resolution ∼9 nm HIBL line patterns were well developed at a sensitivity of 22 μC/cm2 and at a significantly low LER and LWR of 1.81 ± 0.06 and 2.90 ± 0.06 nm, respectively. Analogous high-resolution patterns were also observed in EBL with a sensitivity of 473 μC/cm2. Hence, the Ni-MOC-based resist investigated using HIBL and EBL elucidates the ability of its potential for the sub-10 nm technology node, under standard processing conditions.

Metal Organic Cluster Photoresists for EUV Lithography

Metal Organic Cluster Photoresists for EUV Lithography

Functionalized dipyridyl-methanol ligand for a targeted synthesis of Mn cubane and double-cubane aggregates

Trisubstituted methanol derivative 2-(hydroxy(bipyridin-2-yl)methyl)phenol (H2L) was designed as a specific generator for cubane-like metal-organic clusters. Initial attempts of this ligand with manganese ions produced [MnII3MnIV(L)3(μ3-OCH3)(Cl)3·(CH3OH)2.25] and [MnII3MnIII(L)3(μ3-OH)(N3)2]2 compounds. Both clusters contain similar [Mn4O4] cubane core. Magnetic studies revealed predominant antiferromagnetic interactions in both cases.

Progress in metal organic cluster EUV photoresists

Most advanced microelectronic devices are made by using 193 nm immersion lithography systems, but it is difficult to follow the rapid development of semiconductors due to their approaching physical limits. Extreme ultraviolet (EUV) lithography which uses a shorter wavelength (i.e., 13.5 nm) light source can offer a way to print features under a 20 nm HP. EUV lithography requires photoresists that utilize EUV photons because photons generated by EUV exposure are fewer than photons generated by 193 nm light exposure. In this paper, our recent progress in metal oxide photoresist research will be discussed.

Metal–Organic Framework-Inspired Metal-Containing Clusters for High-Resolution Patterning

We report the preparation of discrete nanometer-scale zinc-based clusters and use them to form sub-15 nm structures by means of extreme ultraviolet lithography. By taking advantage of a metal-containing building unit derived by a metal–organic framework—MOF-2, we found the 3-methyl-phenyl-modified Zn-mTA cluster that formed is well-defined with controlled size and structure and demonstrates extremely high solubility. Progress in recent years in metal–organic frameworks has created a rich variety of metal-containing structures that are useful for numerous applications. Substitution of the bridging ligands with monovalent ligands produces a discrete metal–organic cluster that strongly interacts with soft X-rays at a wavelength of 13 nm. Here we describe the design, preparation, computational modeling, and physical characterization of these new materials. Such metal-containing structures may form the basis of photoresists that enable the next generation of microelectronic devices.

Anionic cobalt-platinum-ethynyl (CoPt\u2013C2H) metal-organic subnanoparticles: a DFT modeling study

Anionic CoPt-ethynyl metal-organic clusters have been investigated comprehensively. The lowest energetic of anionic ConPtm(ethynyl) clusters have been generally found as 3D structure but with low symmetrical point groups. Our results indicate that the most preferred dissociation channel of the studied clusters is Co atom ejection and the favorable dissociation channel is independent of cluster size. The anionic Pt5C2H cluster shows the highest chemical stability according to the HOMO-LUMO Gap analysis. The C2H generally prefers to bind on a bridge site with a few exceptions. The Co4−5 nanoparticles have a lengthening effect on the C≡C bond of the ethynyl molecule, which may be valuable for C≡C bond activation. In addition, the lowest and the highest vibrational frequencies are reported to guide further experimental studies.

Multivariable Modular Design of Pore Space Partition.

Pore space partition, especially the one using C3-symmetric 2,4,6-tri(4-pyridyl)-1,3,5-triazine as pore-partition agent in MIL-88 type (the acs net), has been shown to dramatically enhance CO2 uptake to near-record values. The continued advance in property engineering via pore space partition would depend on intelligent design of both framework components and pore-partition agent. Here, we report a new advance in the design of pore-partition agent by demonstrating a symmetry-guided pathway to develop a large variety of di- and trinuclear 1,2,4-triazolate-based clusters for use as pore-partition agent. The use of metal-organic clusters (instead of organic ligands) as pore-partition agent gives rise to many new pore-partitioned materials with huge compositional variety. The full assembly involves the simultaneous formation of two separate coordination architectures (i.e., the 3-D acs framework and 0-D triazolate clusters) and the eventual welding between the acs framework and triazolate clusters. The wide range of new compositions and structures provides a high degree of tunability in gas sorption properties.

Chiral Porous Metacrystals: Employing Liquid-Phase Epitaxy to Assemble Enantiopure Metal-Organic Nanoclusters into Molecular Framework Pores.

We describe the fabrication of hybrid yet well-ordered porous nanoparticle (NP) arrays with full three-dimensional periodicity by embedding nanometer-sized metal-organic clusters (MOCs) into metal-organic frameworks (MOFs). Although conventional NP@MOF encapsulation procedures failed for these fairly large (1.66 nm diameter) NPs, we achieved maximum loading efficiency (one NP per pore) by using a modified liquid phase epitaxy (LPE) layer-by-layer approach to grow and load the MOF. The preformed NPs, homochiral Ti4(OH)4(R/S-BINOL)6 clusters (Ti-MOC, BINOL = 1,1'-bi-2-naphthol), formed a regular lattice inside the pores of an achiral HKUST-1 (or Cu3(BTC)2, BTC = 1,3,5-benzenetricarboxylate) MOF thin film. Exposure to the different enantiomers of methyl lactate revealed that the NP@MOF metacrystal is quite efficient regarding enantiomer recognition and separation. The approach presented here is also suited for other MOF types and expected to provide a substantial stimulus for the fabrication of metacrystals, crystalline solids made from nanoparticles instead of atoms.

First UHF Implementation of the Incremental Scheme for Open-Shell Systems.

The incremental scheme makes it possible to compute CCSD(T) correlation energies to high accuracy for large systems. We present the first extension of this fully automated black-box approach to open-shell systems using an Unrestricted Hartree-Fock (UHF) wave function, extending the efficient domain-specific basis set approach to handle open-shell references. We test our approach on a set of organic and metal organic structures and molecular clusters and demonstrate standard deviations from canonical CCSD(T) values of only 1.35 kJ/mol using a triple ζ basis set. We find that the incremental scheme is significantly more cost-effective than the canonical implementation even for relatively small systems and that the ease of parallelization makes it possible to perform high-level calculations on large systems in a few hours on inexpensive computers. We show that the approximations that make our approach widely applicable are significantly smaller than both the basis set incompleteness error and the intrinsic error of the CCSD(T) method, and we further demonstrate that incremental energies can be reliably used in extrapolation schemes to obtain near complete basis set limit CCSD(T) reaction energies for large systems.

Controllable Scission and Seamless Stitching of Metal-Organic Clusters by STM Manipulation.

Scanning tunneling microscopy (STM) manipulation techniques have proven to be a powerful method for advanced nanofabrication of artificial molecular architectures on surfaces. With increasing complexity of the studied systems, STM manipulations are then extended to more complicated structural motifs. Previously, the dissociation and construction of various motifs have been achieved, but only in a single direction. In this report, the controllable scission and seamless stitching of metal-organic clusters have been successfully achieved through STM manipulations. The system presented here includes two sorts of hierarchical interactions where coordination bonds hold the metal-organic elementary motifs while hydrogen bonds among elementary motifs are directly involved in bond breakage and re-formation. The key to making this reversible switching successful is the hydrogen bonding, which is comparatively facile to be broken for controllable scission, and, on the other hand, the directional characteristic of hydrogen bonding makes precise stitching feasible.

Controllable Scission and Seamless Stitching of Metal–Organic Clusters by STM Manipulation

AbstractScanning tunneling microscopy (STM) manipulation techniques have proven to be a powerful method for advanced nanofabrication of artificial molecular architectures on surfaces. With increasing complexity of the studied systems, STM manipulations are then extended to more complicated structural motifs. Previously, the dissociation and construction of various motifs have been achieved, but only in a single direction. In this report, the controllable scission and seamless stitching of metal–organic clusters have been successfully achieved through STM manipulations. The system presented here includes two sorts of hierarchical interactions where coordination bonds hold the metal–organic elementary motifs while hydrogen bonds among elementary motifs are directly involved in bond breakage and re‐formation. The key to making this reversible switching successful is the hydrogen bonding, which is comparatively facile to be broken for controllable scission, and, on the other hand, the directional characteristic of hydrogen bonding makes precise stitching feasible.

On-surface self-organization of a robust metal-organic cluster based on copper(I) with chloride and organosulphur ligands.

Direct sublimation of a Cu4Cl4 metal-organic cluster on Cu(110) under ultra-high vacuum allows the formation of ultra-large well-organized metal-organic supramolecular wires. Our results show that the large monomers assemble with each other by π-π interactions connecting dipyrimidine units and are stabilized by the surface.

Group 13 Metal Carboxylates: Using Molecular Clusters As Hybrid Building Units in a MIL-53 Type Framework

Systematic investigation of the reactions of the system AlCl3·6H2O/pyridine-2,4,6-tricarboxylic acid (H3PTC)/pyridine in water yielded two new compounds, both containing the dimeric {AlPTC(μ-OH)(H2O)}22– unit. With long reaction times, the framework compound [Al(μ-OH){AlPTC(μ-OH)(H2O)}2]·2H2O (CAU-16, compound 1) is obtained, the first example of a framework compound with a metal–organic cluster linker, and bearing the MIL-53 network. Although the compound does not breathe, as other MIL-53 compounds do, it has a maximum uptake of CO2 of 1.76(2) mmol g–1 at 196 K. With shorter reaction times, the molecular compound {Al(HPTC)(μ-OH)(H2O)}2 (2) was prepared, leading to the proposal of a crystallization scheme for the Al3+-pyridine-2,4,6,-tricarboxylic acid system. To determine whether further framework compounds bearing hybrid metal cluster linkers could be prepared, systematic high-throughput investigations of pyridine-2,4,6-tricarboxylic acid in water with Ga3+ and In3+ were undertaken. These yielded two chain-type compounds, GaPTC(H2O)2 (3) and InPTC(H2O)2 (4), with different coordination chemistries. Optimized syntheses for compounds 1, 2, and 4 are reported.

A Cationic Metal–Organic Solid Solution Based on Co(II) and Zn(II) for Chromate Trapping

We report the synthesis and characterization of a solid solution series of cationic metal–organic materials with full compositional range from pure Co(II) to Zn(II) end-members. The materials consist of [ZnxCo1–x(H2O)4(4,4′-bipy)2]2+ metal–organic clusters that π–π stack into 2-D positively charged layers, with the metal ratio tunable by molar ratio under hydrothermal conditions. The interlamellar α,ω-alkanedisulfonate serves as an anionic template and noncovalently interacts with the cationic layers. The weak interaction allows anion exchange for toxic oxometal anions, such as chromate, CrO42–. The highest chromate adsorption capacity was 68.5 mg/g (0.43 mol/mol) for the as-synthesized 50 mol % Co(II)-incorporated material. Our cationic material can also selectively trap these toxic oxo-anions when nontoxic anions (e.g., nitrate, sulfate) were present in an over 50-fold excess concentration.

Conformational control of ligands to create a finite metal–organic cluster and an extended metal–organic framework

While a twofold interpenetrated 3-D metal–organic framework, [Cu3(L1)2(H2O)3]·14DMF·16H2O (1) (where, L1 is 4,4′,4′′-[1,3,5-benzenetriyltris(carbonylimino)]trisbenzoate and DMF is N,N′-dimethylformamide), with a (3,4)-connected pto net topology was prepared using a tricarboxylic acid linked via secondary benzamide as an extended 3-connected node and a Cu paddle-wheel secondary building unit as a planar 4-connected node, another tricarboxylic acid with methylated tertiary benzamide linkage in a folded geometry completely converted its role from diverging to chelating ligand and resulted in a finite Ni14 metal–organic cluster, [Ni14(μ3-OH)8(L2)6(formate)2(DMF)10(H2O)2]·28DMF·14H2O (2) (where L2 is N,N′,N′′-methyl-4,4′,4′′-[1,3,5-benzenetriyltris(carbonylimino)]trisbenzoate).

Assembly of super-supertetrahedral metal–organic clusters into a hierarchical porous cubic framework

A porous framework comprising a super-supertetrahedral metal-organic cluster building block has been synthesized. Its cubic framework represents a multi-level hierarchical architecture and also possesses an interesting magnetic property.

Poly[(μ4-benzene-1,3,5-tricarboxylato)bis(dimethyl sulfoxide-κO)neodymium(III)

The asymmetric unit of the title compound, [Nd(C9H3O6)(C2H6OS)2]n, contains one Nd3+ ion, one benzene-1,3,5-tricarb­oxy­lic ligand and two coordinating dimethyl sulfoxide mol­ecules. The Nd3+ ion is coordinated by six O atoms from four carboxyl­ate groups of the benzene-1,3,5-tricarboxyl­ate ligands and two O atoms from two dimethyl sulfoxide mol­ecules. The metal-organic cluster formed upon symmetry expansion of the asymmetric unit consists of two metal atoms and four benzene-1,3,5-tricarboxyl­ate groups, creating a paddle-wheel-type building block arrangement. The remaining coordination sites are occupied by additional benzene-1,3,5-tricarboxyl­ate groups and dimethyl sulfoxide mol­ecules, forming a three-dimensional polymeric rare earth metal-organic framework structure.

A density functional theory study on the interaction of hydrogen molecule with MOF-177

The binding energies of H2 molecule with metal-organic framework MOF-177 clusters at various possible interaction sites have been calculated using density functional theory. The binding energy of adsorbed H2 molecule in MOF-177 was investigated, with the consideration of the favourable adsorption sites and the orientations at the inorganic cluster Zn4O and organic linker (1,3,5-benzenetribenzoate) in order to evaluate the role of these two principal components in MOF for H2 adsorption. Our results showed that both the inorganic connector and the organic linker play an important role in the H2 adsorption. The binding energy calculated for the inorganic cluster is 2.96–4.50 kJ mol− 1 and for the organic linker is 2.6–3.8 kJ mol− 1.