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Two model porphyrin metal-organic frameworks were used for the incorporation of Rh(i) species by a post-synthetic metallation under mild conditions. As a result, new rhodium MOFs (Rh/MOFs), Rh/PCN-222 and Rh/NU-1102, were synthesized and structurally characterized. To illustrate the potential of this catalytic platform, we use Rh/MOFs as phosphine-free heterogeneous catalysts in the hydrogenation of unsaturated hydrocarbons under mild reaction conditions (30 °C and 1 atm H2). We found that for our Rh/MOFs an activation step is required during the first run of the catalytic process. The presence of Rh-CO moieties allowed us to monitor the activation pathway of the catalyst under a H2 atmosphere, by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). After activation, the catalyst remains highly active during the subsequent catalytic cycles. This simple post-synthetic modification approach presents new possibilities for the utilization of Rh-based catalytic systems with robust porphyrin-based MOFs as supports.

A hybrid nanocarbon receptor consisting of a calix[4]arene and a bent oligophenylene loop ("molecular squid"), was obtained in an efficient, scalable synthesis. The system contains an electron-rich cavity with an adaptable shape, which can serve as a host for electron deficient guests, such as diquat, 10-methylacridinium, and anthraquinone. The new receptor forms inclusion complexes in the solid state and in solution, showing a dependence of the observed binding strength on the shape of the guest species and its charge. The interaction with the methylacridinium cation in solution was interpreted in terms of a 2:1 binding model, with K11 = 5.92(7) × 103 M-1. The solid receptor is porous to gases and vapors, yielding an uptake of ca. 4 mmol/g for methanol at 293 K. In solution, the receptor shows cyan fluorescence (λmaxem = 485 nm, ΦF = 33%), which is partly quenched upon binding of guests. Methylacridinium and anthraquinone adducts show red-shifted emission in the solid state, attributable to the charge-transfer character of these inclusion complexes.

Recent developments in porous coordination polymers make them attractive candidates for various potential applications including systems for controlled drug administration. Drug delivery systems based on metal–organic frameworks (MOF) are usually constructed either by non-covalent adsorption of drug molecules inside the pores of the material or by covalent modification of organic linkers. Herein, we propose alternative method for incorporation of drug molecules inside MOFs by binding them to the metal node using Solvent-Assisted Ligand Incorporation (SALI). We tested NU-1000 platform which contains 8-connecting Zr6-nodes, which can bind up to 4 carboxylate-based ligands. Using SALI technique we successfully anchored three model drug molecules containing carboxylate groups: ketoprofen, nalidixic acid and levofloxacin with drug loadings reaching 30 wt% yielding guest@NU-1000 materials. Our study shows that NU-1000 is stable in phosphate concentrations present in blood plasma, whereas drug molecules can be released from guest@NU-1000 under these conditions without decomposition of the MOF framework. We also observed that the drug release kinetics strongly depends on the size of the guest molecules.

The conversion of 2,4,6-tris(4′-bromophenyl)-1,3,5-triazine to the respective triboronic acid was successfully accomplished by a simple triple Br/Li exchange followed by boronation. Further dehydrative condensation reactions with 2,3,6,7,10,11-hexahydroxytriphenylene or 2,3,6,7-tetrahydroxy-9,10-dilalkylanthracenes (R = Me, Et) resulted in materials featuring good porosity and sorption properties with the nitrogen uptake exceeding 500 cm3/g (STP) and SBET up to 1267 m2/g (T = 77.2 K). In addition, simple dehydration of this compound was employed for the preparation of a hybrid 2D COF composed of triazine, boroxine, and benzene rings. The formation of materials was confirmed by the IR analysis and NMR studies on water-decomposed samples. All obtained COFs exhibit high thermal stability with decomposition temperatures in the range of 400–600 °C. They also show quite different morphology ranging from regular 0.5–4 μm spherical and ellipsoidal clusters to 5–12 μm bent rodlike particles. The PXRD studies suppo...

The efficient capture and storage of radioactive iodine (129I or 131I), which can be formed during nuclear energy generation or nuclear waste storage, is of paramount importance. Herein, we present highly efficient aerogels for reversible iodine capture, namely, porous silsesquioxane–imine frameworks (PSIFs), constructed by condensation of octa(3-aminopropyl)silsesquioxane cage compound and selected multitopic aldehydes. The resulting PSIFs are permanently porous (Brunauer–Emmet–Teller surface areas up to 574 m2/g), thermally stable, and present a combination of micro-, meso-, and macropores in their structures. The presence of a large number of imine functional groups in combination with silsesquioxane cores results in extremely high I2 affinity with uptake capacities up to 485 wt %, which is the highest reported to date. Porous properties can be controlled by the strut length and rigidity of linkers. In addition, PSIF-1a could be recycled at least four times while maintaining 94% I2 uptake capacity. Kin...

Solvent-assisted ligand incorporation (SALI) is useful for functionalizing the channels of metal-organic framework (MOF) materials such as NU-1000 that offer substitutionally labile zirconium(IV) coordination sites for nonbridging ligands. Each of the 30 or so previous examples relied upon coordination of a carboxylate ligand to achieve incorporation. Here we show that, with appropriate attention to ligand/node stoichiometry, SALI can also be achieved with phosphonate-terminated ligands. Consistent with stronger M(IV) coordination of phosphonates versus carboxylates, this change extends the pH range for retention of incorporated ligands. The difference in coordination strength can be exploited to achieve stepwise incorporation of pairs of ligands-specifically, phosphonates species followed by carboxylate species-without danger of displacement of the first ligand type by the second. Diffuse reflectance infrared Fourier-transform spectroscopy suggests that the phosphonate ligands are connected to the MOF node as RPO2(OH)¯ species in a moiety that leaves a base-accessible -OH moiety on each bound phosphonate.

A novel organozinc initiator with a clear mechanistic signature for organic radical reactions has been developed., This paper reports a series of comparative experiments on the activity of carbon- and oxygen-centred radical species in a model reaction of the radical addition of THF to imines mediated by a series of zinc alkyl/air reaction systems. The study strongly contradicts the notion that generally R˙ radicals are the initiating species in organic reactions mediated by RnM/air systems, and simultaneously demonstrates that oxygen-centred radical species are the key intermediates responsible for the initiation process. In addition, a new efficient RZn(L)/air initiating system for radical organic reactions exampled by a model reaction of radical addition of THF to imines is developed. Moreover, the isolation and structural characterization of the first zinc alkylperoxide supported by a carboxylate ligand, [Zn4(μ3-OOtBu)3(μ4-O)(O2CEt)3]2, as well as the novel octanuclear zinc oxo(alkoxide) aggregate with entrapped O–THF species, [Zn4(μ4-O)(μ3-2-O–THF)(O2CEt)5]2, provide clear mechanistic signatures for the mode of function of the RZn(O2CR′)/air system.

A uniform and crack-free metalorganic framework (MOF) thin film composed of free-standing acicular nanorods was grown on a transparent conducting glass substrate. The MOF thin film exhibits electrochromic switching between yellow and deep blue by means of a one-electron redox reaction at its pyrene-based linkers. The rigid MOF stabilizes the radical cations of the pyrene linkers at positive applied potential, resulting in the reversible color change of the MOF film. The regular and uniform channels of the MOF allow ions to migrate through the entire film. The MOF thin film thus exhibits a remarkable color change and rapid switching rate.

A new functionalization technique, solvent-assisted ligand incorporation (SALI), was developed to efficiently incorporate carboxylate-based functionalities in the Zr-based metal-organic framework, NU-1000. Unlike previous metal node functionalization strategies, which utilize dative bonding to coordinatively unsaturated metal sites, SALI introduces functional groups as charge compensating and strongly bound moieties to the Zr6 node. Utilizing SALI, we have efficiently attached perfluoroalkane carboxylates of various chain lengths (C1-C9) on the Zr6 nodes of NU-1000. These fluoroalkane-functionalized mesoporous MOFs, termed herein SALI-n, were studied experimentally and theoretically as potential CO2 capture materials.

Control over catenation in a pillared paddlewheel metal–organic framework was achieved via solvent-assisted linker exchange. The linker exchange was demonstrated on the noncatenated structure of DO-MOF, by using 4,4′-bipyridine (L4) and 4,4′-azobis(pyridine) (L5) as linkers, leading to noncatenated materials SALEM-3 and SALEM-4. The de novo synthesized analogues of SALEM-3 and SALEM-4 can only be obtained as 2-fold interpenetrated frameworks. The reaction progress of the linker exchange was monitored by NMR spectroscopy, and structure and framework catenation were characterized by powder X-ray diffraction and thermogravimetric methods.

The octet-compliant group 13 organometallics with highly polarized bonds in the metal coordination sphere exhibit a significant tendency to maximize their coordination number through the formation of adducts with a wide range of neutral donor ligands or by self-association to give aggregates containing tetrahedral and higher coordinated aluminium centres, and even in some cases molecular complexes equilibrate with ionic species of different coordination numbers of the metal centre. This work provides a comprehensive overview of the structural chemistry landscape of the group 13 carboxylates. Aside from a more systematic approach to the general structural chemistry of the title compounds, the structure investigations of [R2M(μ-O2CPh)]2-type benzoate complexes (where M = B, Al and Ga) and their Lewis acid–base adducts [(R2M)(μ-O2CPh)(py-Me)] are reported. DFT calculations were also performed to obtain a more in-depth understanding of both the changes in the bonding of group 13 organometallic carboxylate adducts with a pyridine ligand.

A zeolitic imidazolate framework material of SOD topology possessing primarily unsubstituted imidazolate (im) linkers has been synthesized via solvent-assisted linker exchange (SALE) of ZIF-8. The structure of the new material, SALEM-2, has been confirmed through (1)H NMR and powder and single-crystal X-ray diffraction. SALEM-2 is the first example of a porous Zn(im)(2) ZIF possessing a truly zeolitic topology that can be obtained in bulk quantities. Upon treatment with n-butyllithium, the open analogue exhibits Brønsted base catalysis that cannot be accomplished by the parent material ZIF-8. Additionally, it displays a different size cutoff for uptake and release of molecular guests than does ZIF-8.

An atom-efficient and mild synthesis of a series of oxozinc carboxylates [Zn(4)(μ(4)-O)(O(2)CR)(6)] [where R = Ph (2a), p-PhC(6)H(4) (2b), p-MeC(6)H(4) (2c), and p-MeSC(6)H(4) (2d)] from well-defined alkylzinc precursors and H(2)O is described. The molecular and crystal structures of the resulting complexes have been determined by single-crystal X-ray diffraction. A closer examination of their crystal structure provides a direct picture of the effect of the nature of substituents on the molecular self-assembly of the octahedral oxozinc through noncovalent interactions. It was revealed that these discrete oxozinc clusters can form diverse types of noncovalent assemblies ranging from structures representing zeolitic topologies in the case of 2a to soft porous materials with gated voids or open channels for the remaining molecular clusters.

Thin films of the metal-organic framework (MOF) NU-1000 were grown on conducting glass substrates. The films uniformly cover the conducting glass substrates and are composed of free-standing sub-micrometer rods. Subsequently, atomic layer deposition (ALD) was utilized to deposit Co(2+) ions throughout the entire MOF film via self-limiting surface-mediated reaction chemistry. The Co ions bind at aqua and hydroxo sites lining the channels of NU-1000, resulting in three-dimensional arrays of separated Co ions in the MOF thin film. The Co-modified MOF thin films demonstrate promising electrocatalytic activity for water oxidation.

"Breathing" metal-organic frameworks (MOFs) are an emerging class of soft porous crystals (SPCs) with potential for high working capacity for gas storage applications. However, most breathing MOFs have low stability and/or low surface area. Here we report a water-stable, high surface area, breathing MOF of ftw topology, NU-1105. While Zr6-oxo clusters as nodes introduce water stability in NU-1105, its high surface area and breathing character stem from its pyrene-based tetracarboxylate (Py-FP) linkers, in which the fluorene units (F) in the FP "arms" play a key role in promoting breathing behavior. During gas sorption studies, the "closed pore" (cp) ↔ "open pore" (op) transition of NU-1105 occurs at a propane pressure of ∼3 bar. At 1 bar, NU-1105 is in its cp form and adsorbs less propane than it would in its op form, highlighting improved working capacity. In situ powder X-ray diffraction during propane sorption was used to track the cp ↔ op transition, and molecular modeling was used to elucidate the structure of the op and cp forms of NU-1105. According to TD-DFT calculations, the proposed conformations of the Py-FP linkers in the op and cp forms are consistent with the measured excitation and emission spectra of the op and cp forms of NU-1105. Similar structural transitions are also observed in the porphyrinic MOF NU-1104 depending on the identity of the porphyrin core; we observed breathing behavior if the constituent Por-PTP linker is nonmetalated.

The installation of ferrocene molecules within the wide-channel metal-organic framework (MOF) compound, NU-1000, and subsequent configuration of the modified MOF as thin-film coatings on electrodes renders the MOF electroactive in the vicinity of the ferrocenium/ferrocene (Fc(+)/Fc) redox potential due to redox hopping between anchored Fc(+/0) species. The observation of effective site-to-site redox hopping points to the potential usefulness of the installed species as a redox shuttle in photoelectrochemical or electrocatalytic systems. At low supporting electrolyte concentration, we observe bias-tunable ionic permselectivity; films are blocking toward solution cations when the MOF is in the ferrocenium form but permeable when in the ferrocene form. Additionally, with ferrocene-functionalized films, we observe that the MOF's pyrene-based linkers, which are otherwise reversibly electroactive, are now redox-silent. Linker electroactivity is fully recovered, however, when the electrolyte concentration is increased 10-fold, that is, to a concentration similar to or exceeding that of an anchored shuttle molecule. The findings have clear implications for the design and use of MOF-based sensors, electrocatalysts, and photoelectrochemical devices.

Organozinc hydroxides ,R ZnOH, possessing the proton-reactiv ea lkylzinc group and the CO2-reactive Zn¢OH group, represent an intriguing group of organometallic pre- cursors for the synthesis of novel zinc carbonates .C ompre- hensive experimental and computational investigations on 1) solution an ds olid-stat eb ehavior of tBuZnOH (1 )s pecies in the presence of Lewis bases, namely ,T HF and 4-methyl- pyridine ;2 )s tep-by-step sequence of the reactio nb etween 1 and CO2 ;a nd 3) the effect of ad onor ligand and/or an excess of tBu2Zn as an external proto na cceptor on the reac- tion course are reported. DFT calculations for the insertion of carbon dioxide into the dinuclea ra lkylzinc hydroxide 12 are fully consisten tw ith 1 HN MR spectroscopy studies and indi- cate that this process is am ultistep reaction, in which the in- sertion of CO2 seems to be the rate-determining step. More- over ,D FT studies show that the mechanism of the rearrange- ment between key intermediates, that is, the primary alkyl- zinc bicarbonate with ap roximal position of hydrogen and the secondary alkylzinc bicarbonate with ad istal positio no f hydrogen, most likely proceeds through internal rotatio no f the dinuclear bicarbonate.

Crystallization of Me3In from hexane solution at ambient temperature allows for the isolation of a new phase that cannot be obtained by classical sublimation routes. The crystal structure analysis revealed that this new polymorph of Me3In crystallizes in the rhombohedral space group R3 h. The primary structural effect of the In-CH3‚‚‚In intermolecular interactions results in the formation of cyclic hexamers with 12-membered (InC)6 rings of an extended-chair conformation. The shortest intermolecular In‚‚‚C contact is 3.028(4) A with In‚‚‚H distances between 2.74 and 2.79 A. The hexamers are further linked by longer In-CH3‚‚‚In bridges into the 3D network. In addition, the tetragonal form of Me3In was redetermined at 100 K. The presented results demonstrate that the impact of both crystallization conditions and the character of intermolecular forces on clustering events is evident. Finally, the network topology of a family of the group 13 trimethyls is analyzed and correlated.

The reaction of (t)Bu(2)Zn with water was investigated which led to isolation of the novel hexameric tert-butylzinc hydroxide. The resulting zinc hydroxide cluster appears to be an ideal predesigned single-source precursor which decomposes smoothly in one step at only ca. 120 °C into ZnO nanoparticles.

Alkylzinc alkoxides, (RZnOR')4 ,h ave received much attention as efficient precursors of ZnO nanocrystals (NCs), and their "Zn4O4 "h eterocubane core has been regarded as a" preorganized ZnO". Ac omprehensive investigation of the synthesis and characterization of an ew family of tert-butyl- (tert-butoxy)zinc hydroxides, ((tBu)4Zn4(m3-OtBu)x(m3-OH)4¢x ), as model single-source precursors of ZnO NC si sr eported. The direct reaction between well-defined (tBuZnOH)6 (16) and (tBuZnOtBu)4 (24 )i nv arious molar ratios allows the isola- tion of new mixed cubane aggregates as crystalline solids in ah igh yield :( ( tBu)4Zn4(m3-OtBu)3(m3-OH)) (3), ((tBu)4Zn4(m3- OtBu)2(m3-OH)2 )( 4), ((tBu)4Zn4(m3-OtBu)(m3-OH)3 )( 5). The re- sulting products were characterize di ns olution by 1 HN MR and IR spectroscopy ,a nd in the soli ds tate by single-crystal X-ray diffraction .T he thermal transformations of 2-5 were monitored by in situ variable-temperature powder X-ray dif- fraction and thermogravimetric measurements. The investi- gation showe dt hat the Zn¢ OH groups appeared to be ad e- sirable feature for the solid-state synthesis of ZnO NCs that significantly decreased the decomposition temperature of crystalline precursors 3-5.

We designed, synthesized, and characterized a new Zr-based metal-organic framework material, NU-1100, with a pore volume of 1.53 ccg(-1) and Brunauer-Emmett-Teller (BET) surface area of 4020 m(2) g(-1) ; to our knowledge, currently the highest published for Zr-based MOFs. CH4 /CO2 /H2 adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predictions. The total hydrogen adsorption at 65 bar and 77 K is 0.092 g g(-1) , which corresponds to 43 g L(-1) . The volumetric and gravimetric methane-storage capacities at 65 bar and 298 K are approximately 180 vSTP /v and 0.27 g g(-1) , respectively.

Dichloroaluminum benzoate and its adducts with Lewis bases show a large structural variety from molecular complexes to ionic species as indicated by X-ray diffraction, spectroscopic studies, and quantum-chemical calculations.

We have authenticated the molecular and crystal structure of ZntBu2 and constructed the unprecedented 2D fabric structure using the tert-butylzinc molecules and 1,2-bis(4-pyridyl)ethane as building blocks. The X-ray crystal structure analysis revealed that the inorganic−organic polymeric chains were weaving to form the fabric structure by the concerted C−H···π interactions involving the pyridine rings. Subtle factors governing self-assembly processes leading to a fabric structure are discussed.

Two unique adducts of an oxozinc carboxylate cluster with H(2)O and THF were isolated and structurally characterized, [Zn(4)(μ(4)-O)(O(2)CR)(6)(H(2)O)(THF)]·2(THF) and [Zn(4)(μ(4)-O)(O(2)CR')(6)(THF)(3)] (where R = benzoate and R' = 9-antracenecarboxylate anion). The study shows that the zinc centers of the Zn(4)O core can easily form unique coordination environments without breaking of the Zn-O(carboxylate) bonds.

A series of dichloroaluminum carboxylates [Cl(2)Al(O(2)CR)](2) (were R = Ph (1a), (t)Bu (1b), CHCH(2) (1c) and C(11)H(23) (1d)) were prepared and extended investigations on their structure and reactivity toward various Lewis bases and H(2)O performed. Compounds [Cl(2)Al(O(2)CR)](2) and their adducts with Lewis bases show a large structural variety, featuring both molecular and ionic forms with different coordination numbers of the metal center and various coordination modes of the carboxylate ligand. Upon addition of a Lewis base of moderate strength the molecular form [Cl(2)Al(O(2)CR)](2) equilibrates with new ionic forms. In the presences of 4-methylpyridine the six-coordinate Lewis acid-base adducts [Cl(2)Al(λ(2)-O(2)CR)(py-Me)(2)] [R = Ph (3a), (t)Bu (3b)] with a chelating carboxylate ligand were formed. The reactions of 1a, 1b, and 1d with 0.33 equiv of H(2)O in THF-toluene solution lead to oxo carboxylates [(Al(3)O)(O(2)CR)(6)(THF)(3)] [AlCl(4)] [where R = Ph (4a(THF)), (t)Bu (4b(THF)), and C(11)H(23) (4d(THF))] in high yield. The similar reaction of 1c in tetrahydrofuran (THF) afforded the chloro(hydroxo)aluminum acrylate [(ClAl)(2)(OH)(O(2)CC(2)H(3))(2) (THF)(4)][AlCl(4)] (5), while the hydrolysis of 1b in MeCN lead to the hydroxoaluminum carboxylate [Al(2)(OH)(O(2)C(t)Bu)(2)(MeCN)(6)][AlCl(4))(3)] (6). All compounds were characterized by elemental analysis, (1)H, (27)Al NMR, and IR spectroscopy, and the molecular structure of 1a, 3a, 3b, 4a(THF), 4b(THF), 4b(py-Me'), 5, and 6 were determined by single-crystal X-ray diffraction. The study provides a platform for testing transformations of secondary building units in Al-Metal-Organic Frameworks toward H(2)O and neutral donor ligands.

Solvent-assisted ligand incorporation (SALI) was utilized to efficiently insert various carboxylate-derived functionalities into the Zr-based metal-organic framework NU-1000 as charge compensating moieties strongly bound to the Zr6 nodes. SALI-derived functionalities are accessible for further chemical reactions such as click chemistry, imine condensation and pyridine quaternization.

We report on the activation of CO2 by the well-defined alkylzinc hydroxide (tBuZnOH)6 in the absence and presence of tBu2Zn as an external proton acceptor. The slight modifications in reaction systems involving organozinc precursors enable control of the reaction products with high selectivity leading to the isolation of the mesoporous solid based on ZnCO3 nanoparticles or an unprecedented discrete alkylzinc carbonate [(tBuZn)2(μ5-CO3)]6 cluster with the Zn-C bond intact, respectively.