Inorganic Organic Hybrid Framework Research Articles

Synthesis of Layered Rare-Earth Hydroxide Intercalated with Benzoate Ions

We report a new family of lanthanide-based inorganic-organic hybrid frameworks Y1.9Eu0.1(OH)(5)[C6H5COO] center dot 2H(2)O synthesized by homogeneous precipitation. The crystal structure obtained from powder X-ray diffraction data revealed that this material comprises two-dimensional cationic lanthanide hydroxide {[Ln(2)(OH)(5)(H2O)](+)}(infinity) layers, which are cross-linked by benzoate ligands into a three-dimensional pillared framework. The single layered nanosheets were obtained in n-butanol after the supersonic treatment. The morphologies of the nanosheets were a hexagonal structure about 800 nm in size as determined by transmission electron microscopy, and the thickness of the nanosheets was about 1.8 nm measured by atomic force microscopy. The fluorescence intensity of the D-5(0)-F-7(2) transition increased nearly 3.8 times. The lifetime of the material increased to 0.43 ms compared with the lifetime of Eu3+ in an aqueous medium of 0.1 ms.

Two Magnetic 2D Inorganic–Organic Hybrid Framework Materials Constructed by Phosphotungstates

Two magnetic 2D inorganic–organic hybrid phosphotungstates, K2(H2dap)4[Cu(dap)2]{Cu(A-α-PW9O34)2[Cu(dap)]2}·6H2O (1) and [Cu(dap)2]H2{Cu[Cu(dap)Cu(dap)2(A-α-PW9O34)]2[Cu(dap)]2}·4H2O (2) (dap = 1,3-diaminopropane) have been synthesized and well-characterized. Both 1 and 2 show a 2D layer-like framework with the (4, 4)-connected topological network based on 1D sinusoidal chain-like structure. The studies of magnetic properties indicate that 1 and 2 are indicative of a typical antiferromagnetic coupling between Cu2+ cations.

Biodegradable and biocompatible monodispersed hollow mesoporous organosilica with large pores for delivering biomacromolecules.

The construction of large pore-sized hollow mesoporous organosilica nanoparticles (HMONs) with a concurrent small particle size is of great challenge for the delivery of large biomacromolecules. In this work, we report, for the first time, on the construction of monodispersed and biodegradable HMONs with a unique large mesopore size, hollow interior, a small particle size and a molecularly organic-inorganic hybrid framework. The incorporation of thioether groups into the framework of large pore-sized HMONs (LHMONs) leads to the fast biodegradation of the nanocarriers with specific responsibility and acceleration to the reducing microenvironment. Systematic in vivo biocompatibility assays of LHMONs demonstrate their high biosafety for potential clinical translation. Based on their large mesopore and high pore volume, these LHMONs show high drug-loading capacity for large biomolecular proteins (RNase A), efficient intracellular uptake and a high therapeutic outcome against cancer cells as compared to free protein drugs because of their unique structural features. This first demonstration of the construction of molecularly organic-inorganic hybrid HMONs with a unique large mesopore size, a small particle size and tumor microenvironment-responsive biodegradability promises the intracellular delivery of biomacromolecules for various therapeutic applications, especially for combating cancer.

Hydrogen bonding: a mechanism for tuning electronic and optical properties of hybrid organic–inorganic frameworks

AbstractThe field of hybrid inorganic–organic framework materials is one of the fastest growing fields in materials science because their enormous structural and chemical diversity presents great opportunities for creating many technologically relevant properties. One of the most important issues is controlling and tuning the structural, optical, thermal, mechanical and electronic properties of these complex materials by varying their chemistry, fabrication techniques and preparation conditions. Here we demonstrate that significant progress in this area may be achieved by introducing structural elements that form hydrogen bonds with the environment. Considering hybrid framework materials with different structural ordering containing protonated sulfonium cation H3S+and electronegative halogen anions (I−, Br−, Cl−and F−), we found that hydrogen bonding increases the structural stability of the material and may be used for tuning electronic states near the bandgap. We suggest that such a behaviour has a universal character and should be observed in hybrid inorganic–organic framework materials containing protonated cations. This effect may serve as a viable route for optoelectronic and photovoltaic applications.

Giant Hollow Heterometallic Polyoxoniobates with Sodalite‐Type Lanthanide–Tungsten–Oxide Cages: Discrete Nanoclusters and Extended Frameworks

AbstractThe first series of niobium–tungsten–lanthanide (Nb‐W‐Ln) heterometallic polyoxometalates {Ln12W12O36(H2O)24(Nb6O19)12} (Ln=Y, La, Sm, Eu, Yb) have been obtained, which are comprised of giant cluster‐in‐cluster‐like ({Ln12W12}‐in‐{Nb72}) structures built from 12 hexaniobate {Nb6O19} clusters gathered together by a rare 24‐nuclearity sodalite‐type heterometal–oxide cage {Ln12W12O36(H2O)24}. The Nb‐W‐Ln clusters present the largest multi‐metal polyoxoniobates and a series of rare high‐nuclearity 4d‐5d‐4f multicomponent clusters. Furthermore, the giant Nb‐W‐Ln clusters may be isolated as discrete inorganic alkali salts and can be used as building blocks to form high‐dimensional inorganic–organic hybrid frameworks.

Giant Hollow Heterometallic Polyoxoniobates with Sodalite‐Type Lanthanide–Tungsten–Oxide Cages: Discrete Nanoclusters and Extended Frameworks

The first series of niobium-tungsten-lanthanide (Nb-W-Ln) heterometallic polyoxometalates {Ln12 W12 O36 (H2 O)24 (Nb6 O19 )12 } (Ln=Y, La, Sm, Eu, Yb) have been obtained, which are comprised of giant cluster-in-cluster-like ({Ln12 W12 }-in-{Nb72 }) structures built from 12 hexaniobate {Nb6 O19 } clusters gathered together by a rare 24-nuclearity sodalite-type heterometal-oxide cage {Ln12 W12 O36 (H2 O)24 }. The Nb-W-Ln clusters present the largest multi-metal polyoxoniobates and a series of rare high-nuclearity 4d-5d-4f multicomponent clusters. Furthermore, the giant Nb-W-Ln clusters may be isolated as discrete inorganic alkali salts and can be used as building blocks to form high-dimensional inorganic-organic hybrid frameworks.

Hydrogen Bonding and Stability of Hybrid Organic-Inorganic Perovskites.

In the past few years, the efficiency of solar cells based on hybrid organic-inorganic perovskites has exceeded the level needed for commercialization. However, existing perovskites solar cells (PSCs) suffer from several intrinsic instabilities, which prevent them from reaching industrial maturity, and stabilizing PSCs has become a critically important problem. Here we propose to stabilize PSCs chemically by strengthening the interactions between the organic cation and inorganic anion of the perovskite framework. In particular, we show that replacing the methylammonium cation with alternative protonated cations allows an increase in the stability of the perovskite by forming strong hydrogen bonds with the halide anions. This interaction also provides opportunities for tuning the electronic states near the bandgap. These mechanisms should have a universal character in different hybrid organic-inorganic framework materials that are widely used.

Porous Materials as a Platform for Highly Uniform Single-Atom Catalysts: Tuning the Electronic Structure for the Low-Temperature Oxidation of Carbon Monoxide

The selective oxidation of carbon monoxide (CO) remains a challenge in many research areas. Here we propose using porous hybrid organic–inorganic frameworks as tunable single-metal site catalysts which can be utilized for the oxidation reaction. Low-valent zinc ions were embedded on ZSM-5 zeolite and metal organic framework (MOF) supports to be used as nonprecious metal catalysts. Unlike the case with ionic compensation between the metal and zeolite, linker-functionalized MOFs exhibit a delocalized electron of the metal residing on both the organic linker and the metal atom. This electron delocalization plays a crucial role in the catalytic activity by assisting charge transfer of the metal site to break the O–O bond. By adding electron-donating groups to the linker, we found the activation energy to be dramatically decreased to ∼4 kcal/mol compared with 18 kcal/mol for the zeolite. This is essential for oxidation at low temperature. Moreover, the donating groups result in a more stable Zn active site on ...

A NOVEL ACENTRIC CHAR SULFATE INORGANIC-ORGANIC HYBRID FRAMEWORK: PHOTOLUMINESCENT, NLO AND SEMICONDUCTOR PROPERTIES

A novel acentric char sulfate compound, [Cd(S 2 O 7 )(4,4’-bipyridine)(H 2 O) 2 ] n ( 1 ), has been solvothermally synthesized and characterized by single-crystal X-ray diffraction method. Compound 1 is characterized by a three-dimensional (3-D) inorganic-organic hybrid framework structure. Solid-state photoluminescent spectra indicate that compound 1 displays a strong violet emission. The second-order nonlinear optical measurements reveal that compound 1 has modest powder SHG efficiency of about 0.02 times than that produced by a potassium dihydrogen phosphate (KDP) powder. Optical absorption spectrum discovers that the presence of an optical gap of 3.41 eV, suggesting that compound 1 is a wide bandgap semiconductor.

Construction of three new metal-organic frameworks with distinct SBUs: trinuclear {Cd3(COO)6} clusters, inorganic -Cd-O-Cd- chains, and heterometallic trinuclear {Cd2Ba(COO)4} clusters

Three metal-organic frameworks (MOFs), [Cd3(OABDC)2(e-urea)4]n (1), [Cd3(OABDC)2(H2O)5)]n (2) and [Cd2Ba(OABDC)2(H2O)7]n (3) (H3OABDC = 5-oxyacetate isophthalic acid, e-urea = 2-imidazolidinone), were prepared using H3OABDC and metal salts. Single-crystal X-ray diffraction analyses reveal that 1 features a 2-D layered structure constructed from trinuclear {Cd3(COO)6} SBUs and represents a (3,6)-connected kgd topology. Compounds 2 and 3 are 3-D inorganic–organic hybrid frameworks; 2 employs infinite inorganic –Cd–O–Cd– chains as SBUs, whereas (3,6)-connected ant-type 3 employs heterometallic trinuclear {Cd2Ba(COO)4} clusters as SBUs. The structures of these three compounds indicate that the SBUs play an important role in the construction of MOFs. Moreover, the thermal stabilities and solid-state photoluminescent properties of these three compounds have also been investigated.

Two novel molybdenum-oxide-based organic-inorganic hybrid frameworks exhibiting twofold interpenetrated hms networks

Two novel polyoxometalate (POM)-based organic–inorganic hybrids, namely, [(CH3)2NH2][Co(tpba)(Mo2O7)]·2H2O (1) and [(CH3)2NH2][Ni(tpba)(Mo2O7)]·2H2O (2) (tpba=4-([4,2′:6′,4′′-terpyridin]-4′-yl)benzoic acid), have been synthesized and characterized by elemental analyses, IR spectra, TG analyses and single-crystal X-ray diffraction. Compounds 1 and 2 are isostructural and feature microporous interpenetrated frameworks, which are constructed from metal–organic layers pillared by the [Mo2O7]2− anions. Topologically, the overall structures of 1 and 2 can be classified as a rare (3,5)-connected twofold interpenetrated hms net, which has never been observed in POM-based hybrid materials prior to this work. Furthermore, the magnetic property of compound 1 are discussed.

A novel 3D framework indium phosphite-oxalate based on a pcu-type topology

A new inorganic–organic hybrid indium phosphite-oxalate, formulated as H[In5(HPO3)6(H2PO3)2(C2O4)2]·(C4N2H11)2·H2O 1 has been hydrothermally synthesized in the presence of piperazine acting as a structure directing agent (SDA). The single crystal X-ray diffraction reveals that compound 1 shows three-dimensional open-framework with intersecting 12-ring channels along the [010] and [001] directions, which is constructed from strictly alternating double 6-ring units (D6Rs), [C2O4]2− groups and [H2PO3]− pseudo-pyramids. It is noted that the classical D6R SBU is firstly reported in main metal phosphite/phosphite-oxalate. By regarding D6R as the 6-connected nodes, the inorganic–organic hybrid framework is based on a pcu-type topology. The as-synthesized product was characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), ICP-AES and elemental analyses.

A Facile Multi-interface Transformation Approach to Monodisperse Multiple-Shelled Periodic Mesoporous Organosilica Hollow Spheres.

The synthesis of well-defined and complex hollow structures via a simple method is still a major challenge. In this work, a facile and controllable "multi-interface transformation" approach for preparation of monodisperse multi-shelled periodic mesoporous organosilica (PMO) hollow spheres has been established by a one-step hydrothermal treatment of successively grown organosilica particles. The multi-shelled PMO hollow spheres have inorganic-organic hybrid frameworks, controllable number (1-4) of shells, high surface area (∼805 m(2)/g), accessible ordered mesochannels (∼3.2 nm), large pore volume (1.0 cm(3)/g), and uniform and tunable diameter (300-550 nm), chamber size (4-54 nm), and shell thickness (10-30 nm). In addition, various organic groups (alkyl, aromatic, and heteroelement fragments) are successfully incorporated into the multi-shelled PMO hollow spheres by successively adding different bridged organosilica precursors. Notably, the distribution of different kinds of organic groups in the multi-shelled PMO hollow spheres can be precisely controlled, showing great potential for future applications. We propose that the formation of the multi-shelled PMO hollow structures is ascribed to the creation of multiple highly cross-linked organosilica interfaces, providing a new and interesting fundamental principle for PMO materials. Due to their unique structure and frameworks, triple-shelled ethane-bridged PMO hollow spheres were successfully loaded with an anti-cancer drug doxorubicin and perfluoropentane gas, which present excellent effects in the killing of cancer cells and ultrasound imaging. It is expected that the multi-interface transformation strategy provides a simple, controllable, versatile, and template-free method for preparation of various multifunctional PMOs for different applications.

A New 3D Pb(II) Inorganic–Organic Hybrid Framework Based on Terephthalate Acid with the Inorganic Pb–O–Pb Connectivity

Solvothermal reaction of Pb(NO3)2 with terephthalate acid afforded one new inorganic–organic hybrid framework, [Pb(PBDC)]n (1) (H2PBDC = terephthalic acid). X-ray analysis shows that compound 1 crystallizes in orthorhombic space group Pbca and the two carboxy group of terephthalate acid adopt rare coordination modes. A noticeable point in this paper that compound 1 exhibits preferable catalytic property on degradation of Rhodamine B. The phase purity of the as-synthesized sample was confirmed by powder X-ray diffraction. Moreover, satisfactory elemental analysis, IR spectra, and thermogravimetric analysis were obtained.

Multiarylpolycarboxylate-Mediated Hybrid Cobalt Phosphate Frameworks with Supramolecular Zeolitic Topology and Unusual I2O2 Connectivity

Two novel organic-inorganic hybrid frameworks containing multiarylpolycarboxylate linkers and cobalt phosphate layers, [H2DABCO]·[Co(HPO4)(bpdc)] (1) and [H2DABCO]3·[Co10(npa)3(PO4)6Cl2] (2), where bpdc = 4,4'-biphenyldicarboxylate, npa = 2,6-naphthalenedicarboxylate, and DABCO = 1,4-diazabicyclo[2.2.2]octane, have been solvothermally synthesized. Compound 1 features a 3D zeolite-like supramolecular network with ABW topology, and compound 2 is a 3D framework structure with unusual I(2)O(2) connectivity.

Fabrication of Porous Covalent Organic Cages Using Cyclodextrin Metal-Organic Frameworks as Template

Up to now, transformation from metal-organic frameworks (MOFs) to covalent-organic-framework cages (COF-Cages) has never been reported. In this report, we demonstrated an organic cage crystal by transformation from a cyclodextrin MOF, via boronate ester formation reaction of the hydroxy groups of gamma-CD inside the MOF, followed by removing of the potassium ions. First, CD-MOF was prepared by reacting gamma-CD with potassium hydroxide in aqueous solution, followed by vapor diffusion of methanol into the solution according to a previously reported method. The freshly prepared CD-MOF was first washed with ethanol three times to remove the unreacted reactants, and then added to an ethanol saturated solution of benzene-1,4-diboronic acid (BDBA) in a screw top vial, and kept it at 65 degrees C for three days. Finally, the covalent cross-linked CD-MOF (CL-CD-MOF) was obtained by forming boronic esters between the uncoordinated C(2) and C(3) hydroxy groups of contiguous gamma-CD sides in the CD-MOF pores and two boronic acid groups of BDBA. Structure and physical properties of Z-Cages were fully characterized by thermogravimetric analysis (TGA), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), solid-state C-13 and B-11 cross polarization/magic angle spining nuclear magnetic resonance (CP/MAS/NMR) spectroscopy and nitrogen adsorption. The obtained zeolite-type organic cage (Z-cage) displayed a targeted sodalite-type crystalline structure and permanent porosity with the surface area of 862 m(2).g(-1). A control experiment, the cross-linked polymers (CL-polymer) formed by coupling of gamma-CD and BDBA was done by solvothermal method. The CL-polymer was synthesized by the heating of a 4 : 1 stoichiometric mixture of BDBA and gamma-CD at 90 degrees C for three days in dimethylformamide (DMF). PXRD pattern shows the CL-polymer are crystalline, but totally different with Z-cage. This transformation from crystalline inorganic-organic hybrid framework of MOF to crystalline organic framework provides an opportunity for crystal-to-crystal in porous crystalline materials.

Fluoremetric determination of amoxicillin drug in aqueous medium using hybrid framework of organic–inorganic nanoparticles

A dipodal naphthalimide based receptor 1 was synthesized, characterized and processed into organic nanoparticles (N1) using single step re-precipitation technique. These organic nanoparticles were further used as a platform for the development of hybrid organic–inorganic framework (H1). Hybrid nanoparticles thus formed were evaluated for their photo-physical behavior and their interaction with various available drugs using fluorescence spectroscopic technique and found it selective in determination of amoxicillin in aqueous medium. Competitive binding studies further confirmed the selectivity of H1 for amoxicillin, as no interference was perceived with any other drug in determination of amoxicillin. H1 was able to determine amoxicillin quite efficiently in commercially available tablets of the drug with a lowest detection limit of 236nM.

A New (4,8)-Connected scu-Type Heterometallic-Organic Framework: Synthesis, Structure and Luminescent Property

Presented here is a new heterometallic coordination polymer, namely [ZnCa(btec)(H2O)2]n (1 H4btec = 1,2,4,5-benzenetetracarboxylic acid), which was successfully synthesized via the hydrothermal reactions of H4btec, Zn(NO3)2 and CaCl2. Single crystal X-ray structural analysis reveals that compound 1 features a 3D inorganic–organic hybrid framework, which can be simplified into a (4,8)-connected scu topological network by viewing Zn(II) ions, Ca(II) ions, btec4− ligands as 4-, 4-, and 8-connected nodes, respectively. Moreover, the luminescent properties of compound 1 and the desolvated samples were also investigated at room temperature.

Synthesis of periodic mesoporous organosilicas functionalized with different amine-organoalkoxysilanes via direct co-condensation

A series of amine-functionalized periodic mesoporous organosilicas (PMOs) were synthesized from bis(triethoxysilyl)ethane via surfactant-templating using supramolecular assemblies of hexadecyltrimethylammonium chloride under basic conditions. Functionalization of the PMO materials was performed via direct co-condensation in the presence of mono-, di- or tri-amine-organoalkoxysilanes. The effect of the type and concentration of the added organosilanes on the physicochemical properties of the functionalized PMOs were investigated. Thermogravimetric/differential thermal analysis (TG/DTA) and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of the inorganic–organic hybrid framework functionalized with the amine groups. The total nitrogen content of the functionalized PMOs ranged from 0.26 to 1.27 mmol/g. The materials possessed a hexagonal lattice with the highly ordered mesostructure being preserved after the amine-functionalization as evidenced by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The N2 adsorption–desorption measurement revealed that the materials had high specific surface areas (963–1252 m2/g) and a relatively high total pore volume (0.52–0.85 cm3/g). The mesopore size and wall thickness of these materials varied in relation with the molecular size and the loading of the organosilanes. Moreover, the morphology of the PMO materials was increasingly transformed from irregular shaped particles to spheres with increasing amounts of amine-functional groups or with organo-functional groups with several amine units.

Hydrothermal syntheses, structures and properties of two 3-D organic–inorganic hybrid mixed-valent polyoxovanadates [Ni(en)2][VIV4VV2O14] and [Cu(en)2][VIV2VV3O12.5

Two 3-D organic–inorganic hybrid mixed-valent polyoxovanadates [Ni(en)2][VIV4VV2O14] (1) and [Cu(en)2][VIV2VV3O12.5] (2) (en=ethylenediamine) have been hydrothermally synthesized and characterized by elemental analyses, IR spectra, X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. The common feature of 1 and 2 is that both exhibit the 3-D organic–inorganic hybrid framework. It should be pointed out that the 3-D hybrid architecture of 1 is constructed from planar 2-D vanadium(IV/V)–oxygen layers through [Ni(en)2]2+ bridges, whereas the 3D hybrid framework of 2 is built by wavy 2-D vanadium(IV/V)–oxygen layers via [Cu(en)2]2+ connectors. The magnetic properties of 1 have been investigated and 1 behaves as the dominant antiferromagnetic interactions within VIV centers.