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Metal-coordinated frameworks derived from small peptidic ligands have received much attention thanks to peptides' vast structural and functional diversity. Various peptides with partial conformational preferences have been used to build metal-peptide frameworks, however, the use of conformationally constrained β-peptide foldamers has not been explored yet. Herein we report the first metal-coordination-mediated assembly of β-peptide foldamers with 12-helical folding propensity. The coordination of Ag+ to the terminal pyridyl moieties afforded a set of metal-peptide frameworks with unique entangled topologies. Interestingly, formation of the network structures was accompanied by notable conformational distortions of the foldamer ligands. As the first demonstration of new metal-peptide frameworks built from modular β-peptide foldamers, we anticipate that this work will be an important benchmark for further structural evolution and mechanistic investigation.

The tunable growth of metal-organic materials has implications for engineering particles and surfaces for diverse applications. Specifically, controlling the self-assembly of metal-phenolic networks (MPNs), an emerging class of metal-organic materials, is challenging, as previous studies suggest that growth often terminates through kinetic trapping. Herein, kinetic strategies were used to temporally and spatially control MPN growth by promoting self-correction of the coordinating building blocks through oxidation-mediated MPN assembly. The formation and growth mechanisms were investigated and used to engineer films with microporous structures and continuous gradients. Moreover, reactive oxygen species generated by ultrasonication expedite oxidation and result in faster (ca. 30 times) film growth than that achieved by other MPN assembly methods. This study expands our understanding of metal-phenolic chemistry towards engineering metal-phenolic materials for various applications.

Reversible single-crystal-to-single-crystal photocyclization–cycloreversion reaction of a stilbene-based coordination network exhibits a conspicuous fluorescence change. The controllable fluorescence and high fatigue resistance feature of this bistable material make it a single-crystalline device for applications in rewritable optical memory storage systems.

The first 4,2′:6′,4′′-terpyridine (4,2′:6′,4′′-tpy) containing coordination polymer was reported over 20 years ago and in the last decade, there has been increased interest in the use of ditopic 4,2′:6′,4′′-tpy ligands as linkers in coordination polymers and 2D-networks. Functionalization in the 4′-position of 4,2′:6′,4′′-tpy is synthetically straightforward, giving access to a large suite of building blocks. Less well explored is the coordination chemistry of 3,2′:6′,3′′-tpy ligands which exhibit greater conformational flexibility than 4,2′:6′,4′′-tpy. One approach to making the transition from 2D- to 3D-networks is to utilize tetratopic bis(4,2′:6′,4′′-tpy) and bis(3,2′:6′,3′′-tpy) ligands which act as 4-connecting nodes. In this highlight, we survey recent progress towards a better understanding of the design principles associated with the use of ditopic and tetratopic 4,2′:6′,4′′-tpy and 3,2′:6′,3′′-tpy containing ligands and their roles both as linkers and nodes in coordination assemblies.

peer-reviewed We report a 2-fold interpenetrated primitive cubic (pcu) network X-pcu-5-Zn, [Zn2(DMTDC)2(dpe)] (H2DMTDC = 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, dpe = 1,2-di(4-pyridyl)ethylene), that exhibits reversible switching between an as-synthesized “open” phase, X-pcu-5-Zn-α, and two nonporous or “closed” polymorphs, X-pcu-5-Zn-β and X-pcu-5-Zn-γ. There are two unusual features of X-pcu-5-Zn. The first relates to its sorption properties, which reveal that the α form exhibits high CO2 uptake (ca. 255 cm3/g at 195 K) via reversible closed-to-open switching (type F-IV isotherm) of the type desirable for gas and vapor storage; there are only three other reports of porous materials that combine these two features. Second, we could only isolate the β form by activation of the CO2 loaded α form and it persists through multiple CO2 adsorption/desorption cycles. We are unaware of a new polymorph having been isolated in such a manner. That the observed phase changes of X-pcu-5-Zn-α occur in single-crystal-to-single-crystal fashion enabled structural characterization of the three forms; γ is a coordination isomer of α and β, both of which are based upon “paddlewheel” clusters. The full text of this article will not be available in ULIR until the embargo expires on the 05/11/2019

The multistate redox-active/multi-interactive ligand 5,5',8,8'-tetra(4-pyridyl)-2,2'-(1,4-phenylene)bis-1H-perimidine (H2 TPP) was designed and synthesized. H2 TPP undergoes four one-electron oxidation steps, and was used for the preparation of a multistate redox-active coordination network in a solid-liquid interface reaction using molten Cd2+ salts. The multiple redox states of H2 TPP were confirmed spectroscopically by stepwise four-electron oxidation. Spectroscopic analysis indicated that the mixed-valence states of the ligand are class II on the UV/Vis/NIR timescale and borderline class II/class III on the ESR timescale.

The design of redox-active metal-organic frameworks and coordination networks (CNs), which exhibit metal- and/or ligand-centered redox activity, has recently received increased attention. In this study, the redox-active metalloligand (RML) [Me4N]3fac-[CrIII(mp)3] (1) (mp = 2-mercaptophenolato) was synthesized and characterized by single-crystal X-ray diffraction analysis, before its reversible ligand-centered one-electron oxidation was examined by cyclic voltammetry and spectroelectrochemical measurements. As complex 1 contains OS coordination sites in three directions, complexation with K+ ions led to the formation of a two-dimensional honeycomb sheet-structured [K3fac-{CrIII(mp)3}(H2O)6]n (2·6H2O), which is the first example of a redox-active CN constructed from a RML with o-disubstituted benzene ligands. Herein, we unambiguously demonstrate the ligand-centered redox activity of the RML, which is incorporated in the redox-active CN 2·6H2O in the solid state.

The single-crystal to single-crystal (SC–SC) transformation from a 1D coordination chain to a 3D coordination network, which is triggered by both solvent and anion exchanges, has been revealed to suffer from a tandem mechanism as proved by isolation of the intermediate state. The resulting porous crystalline material shows a high efficiency for the capture of dichromates (207 mg g−1) via the SC–SC anion-exchange.

peer-reviewed Coordination networks that reversibly switch between closed and open phases are of topical interest since their stepped isotherms can offer higher working capacities for gas‐storage applications than the related rigid porous coordination networks. To be of practical utility, the pressures at which switching occurs, the gate‐opening and gate‐closing pressures, must lie between the storage and delivery pressures. Here we study the effect of linker substitution to fine‐tune gate‐opening and gate‐closing pressure. Specifically, three variants of a previously reported pcu‐topology MOF, X‐pcu‐5‐Zn, have been prepared: X‐pcu‐6‐Zn, 6=1,2‐bis(4‐pyridyl)ethane (bpe), X‐pcu‐7‐Zn, 7=1,2‐bis(4‐pyridyl)acetylene (bpa), and X‐pcu‐8‐Zn, 8=4,4′‐azopyridine (apy). Each exhibited switching isotherms but at different gate‐opening pressures. The N2, CO2, C2H2, and C2H4 adsorption isotherms consistently indicated that the most flexible dipyridyl organic linker, 6, afforded lower gate‐opening and gate‐closing pressures. This simple design principle enables a rational control of the switching behavior in adsorbent materials.

In the two dimensional network [Fe(ebbtr)2(CH3CN)2](ClO4)2·4CH3CN a sequence of LS → HS → LS → HS transitions occurs as the exclusive result of the change in temperature. This property results from the extraordinary flexibility/elasticity manifested in the hierarchical arrangement of structural events involving the reorientation of coordinated/noncoordinated molecules as well as with the deformation and the mutual shift of the polymeric units.

Although the cyclo-P6 complex [(Cp*Mo)2(μ,η6:η6-P6)] (1) was reported 30 years ago, little is known about its chemistry. Herein, we report a high-yielding synthesis of 1, the complex 2, which contains an unprecedented cyclo-P10 ligand, and the reactivity of 1 towards the “naked” cations Cu+, Ag+, and Tl+. Besides the formation of the single oxidation products 3 a,b which have a bisallylic distorted cyclo-P6 middle deck, the [M(1)2]+ complexes are described which show distorted square-planar (M=Cu(4 a), Ag(4 b)) or distorted tetrahedral coordinated (M=Cu(5)) M+ cations. The choice of solvent enabled control over the reaction outcome for Cu+, as proved by powder XRD and supported by DFT calculations. The reaction with Tl+ affords a layered two-dimensional coordination network in the solid state.

A chiral-at-metal Ir(III) organometallic metallatecton was synthesised as a racemic mixture and as enantiopure complexes and combined with Cu(II) to afford a heterobimetallic (Ir,Cu) grid-type 2D coordination network.

A coordination network composed of a mannose-based organic ligand and a sodium ion, 'sugar sponge', was synthesized for the crystalline sponge analysis of hydrophilic compounds. Owing to multiple hydrogen-bonding interactions, hydrophilic guests are firmly trapped in the 1-dimensional channel. The sugar sponge was utilized to analyze the structures of flexible alcohol and absolute configurations of chiral epoxides.

Lone pair-π interaction-induced charge-transfer was successfully used for switching the conductance of a coordination network, through variation of the degree of charge transfer caused by external photostimulation. The underlying mechanism is attributed to the changes in efficient charge-carriers by photoinduced strong charge transfer, which was investigated by in situ UV-Vis absorption, ESR, and computational studies.

A Zn-based porphyrin containing metal–organic material (porphMOM-1) was transformed into a novel Cu-based porphyrin-encapsulating metal–organic material (porph@HKUST-1-β) via a one-pot post-synthetic modification (PSM) process involving both metal ion exchange and linker installation of trimesic acid. HKUST-1-β is the first example of yao topology and is to our knowledge the first supramolecular isomer of the archetypal coordination network HKUST-1.

A net gain: A kinetically assembled, but thermally stable network is obtained using the labile metal species [Cu4 I4 (PPh3 )4 ]. The network uniquely adsorbs I2 by chemisorption through I3 (-) formation. The chemisorbed I2 readily desorbs above 380 K owing to the dynamic motion of the framework. A thermodynamically assembled network physisorbs I2 , which is an exact fit for the channel.

Different combinations of three building blocks, namely the coordination moiety [copper(II)- 4 , 4 ′- bpy ], a carboxylato co-ligand (formato or acetato) and an anion (ClO 4 − , NO 3 − or PF 6 − ), lead to the formation of the three compounds, namely {[Cu 3 ( 4 , 4 ′- bpy ) 3 (μ-OOCH) 4 (H 2 O) 2 ](ClO 4 ) 2 (H 2 O) 6 } n ( 1 ), {[Cu( 4 , 4 ′- bpy )(μ-OOCH)(NO 3 )]} n ( 2 ) and {[Cu 2 ( 4 , 4 ′- bpy ) 2 (μ-OOCCH 3 ) 3 ](PF 6 )(H 2 O)} n ( 3 ). The molecular structures determined by single-crystal X-ray diffraction reveal notable (4,4) topology, regardless of the different monocarboxylato groups (formato for 1 and 2 and acetato for 3 ) and anions. Compound 1 , synthesized from Cu(II), 4 , 4 ′- bpy , ClO 4 − and formate as co-ligand, exhibits a 2D coordination network based on trinuclear chain secondary building units. With coordinating NO 3 − anions (instead of non-coordinating ClO 4 − ), a distinct structural motif, i.e. a 2D framework assembled from dinuclear chain secondary building units, is obtained (compound 2 ). The replacement of the formate ligands by acetate units in compound 3 , gives rise to a 2D framework which is assembled from tetranuclear chain secondary building units. The three new coordination compounds have been characterized and tested for their catalytic properties. All compounds show catalytic activities for the selective cyanosilylation of aldehydes.

Thermal or chemical treatment of crystalline 4,4-bipyridinium salts of [MCl4]2- (M=Co, Zn, Fe, or Pt) leads to HCl loss and formation of coordination network solids [{MCl2(4,4-bipy)}n]. For M=Co, Zn, and Fe, these solids can also be prepared by mechanochemical means. Their exposure to HCl vapor or the mechanochemical reaction of metal dichlorides with [4,4-H2bipy]Cl2 gives [4,4-H2bipy]2+ salts of [CoCl4]2-, [ZnCl4]2-, and, for the first time, [FeCl4]2-.

The structure of a glass obtained by the melt quenching of a two-dimensional (2D) coordination network was examined. X-ray analyses disclosed a 2D-to-0D structural transformation before and after glass formation. The mechanism is unique to coordination compounds, as it is characterized by labile and flexible coordination bonds.

The use of divergent, V-shaped, 4,2':6',4''-terpyridine building blocks that self-assemble into hydrogen-bonded domains and upon addition of copper atoms undergo metallation with concomitant transformation into a coordination network is described; multiple energetically similar structural motifs are observed in both hydrogen-bonded and adatom-coordinated networks.

International audience; An unprecedented two-dimensional honeycomb network based on fused triacontanuclear heterometallic wheels of 3.4 nm, {[Co2(Mn3O (N3)2(pic)6(NO3)]-}6 (Hpic = picolinic acid), has been assembled. The hexagonal {Co12Mn18} wheel motif is composed of six oxo-centered {Mn3} trinuclear and six {Co2} dinuclear moieties acting as nodes and linkers, respectively. The paramagnetic properties of this compound observed down to 1.8 K result from the competition of Mn...Mn, Mn...Co and Co...Co interactions in combination with spin–orbit coupling and single-ion behavior of the Co(II) centers.

We have designed and synthesized two new metal–organic-frameworks (MOFs) using the novel N-(2-tetrazolethyl)-4′-glycine spacer (TeGly)2−. We report the in situ formation of cadmium- and zinc-based MOFs using hydrothermal routes. The cadmium-based MOF shows a bi-dimensional network with luminescence emission while the zinc-based MOF exhibits a three-dimensional structure with gismondine topology and intense blue-greenish photoluminescence emission at room temperature in the solid state. In addition, the porosity of the Zn-based MOF has been fully characterized using a combination of computational methods and experimental techniques., This work was supported by the MEC of Spain (Project CTQ2011-24478) and the Junta de Andalucía (FQM-1484). D. F.-J. thanks the Royal Society for a University Research Fellowship.

Kneading them in: A versatile porous material based on the 1D coordination network [CuCl2(dace)]... (dace = trans-1,4-diaminocyclohexane) can be inexpensively prepd. by a mechanochem. reaction followed by mild thermal treatment. The system is able to reversibly absorb mols. from soln. or by simple kneading, while guest desorption from the product invariably leads back to the unsolvated form.

Neutral tetrakis-monodentate tectons 1 and 2, based on the pentaerythritol skeleton and bearing four nicotinoyl or isonicotinoyl groups respectively as coordination sites, have been prepared and their ability to generate coordination networks was studied in the presence of HgCl2 or CoCl2 behaving as metallatectons offering either a “V” or a square type geometry respectively. Whereas in the case of the tecton 1 offering four coordination sites in the same plane (square type geometry) a 1-D coordination network was observed in the presence of neutral HgCl2, in the presence of CoCl2 metallatecton presenting four available coordination sites occupying the corners of a square, a 2-D neutral coordination network was obtained. For tecton 2, possessing also four coordinating sites but occupying the apices of a pseudo tetrahedron, a 2-D network was obtained with HgCl2, whereas in the presence of CoCl2 a 3-D network was observed. In the latter case, a two-fold homo interpenetrating architecture was observed.

Defect engineering in metal-organic frameworks (MOFs) is an exciting concept for tailoring material properties, which opens up novel opportunities not only in sorption and catalysis, but also in controlling more challenging physical characteristics such as band gap as well as magnetic and electrical/conductive properties. It is challenging to structurally characterize the inherent or intentionally created defects of various types, and there have so far been few efforts to comprehensively discuss these issues. Based on selected reports spanning the last decades, this Review closes that gap by providing both a concise overview of defects in MOFs, or more broadly coordination network compounds (CNCs), including their classification and characterization, together with the (potential) applications of defective CNCs/MOFs. Moreover, we will highlight important aspects of "defect-engineering" concepts applied for CNCs, also in comparison with relevant solid materials such as zeolites or COFs. Finally, we discuss the future potential of defect-engineered CNCs. ispartof: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION vol:54 issue:25 pages:7234-7254 ispartof: location:Germany status: published

The Shockley surface state on Cu(111) reacts sensitively to the perturbation by molecular adsorbates on the surface. In the porous structure of a metal-coordinated molecular network on Cu(111), the surface state is confined to a series of discrete states. Energy and momentum of eigenstates in the pores are related to both the energy dispersion of the free surface state and the geometric and energetic details of the confining barrier formed by the molecular network. The penetration of the confined state into the barrier is found to be sensitive to the constituting architectural elements.

A surface-supported open metal-organic nanomesh featuring a 24 nm(2) cavity size and extending to mum domains was fabricated by Co-directed assembly of para-hexaphenyl-dicarbonitrile linker molecules in two dimensions. The metallosupramolecular lattice is thermally robust and resides fully commensurate on the employed Ag(111) substrate as directly verified by high-resolution scanning tunneling microscopy observations.

The first uninodal 10-connected metal-organic framework, based on pentanuclear cadmium cluster building blocks, exhibits an unprecedented gamma-Pu topology, which adds a new member to the series of metal-organic analogues which have a natural materials topology.

Independent one-, two-, and even three-dimensional nets interpenetrate each other in many solid-state structures of polymeric, hydrogen-bonded nets and coordination polymers. For example, the interpenetration of the adamantane units of two diamondlike nets is shown on the right. A detailed and systematic examination of many interpenetrating nets of this kind is made, and implications for crystal engineering are discussed.

International audience; Nanorods of the photomagnetic coordination network Mo(CN)8Cu2 coated with polyvinylpyrrolidone were prepared and exhibit an enhanced effect upon irradiation when compared to the bulk...

A novel two-dimensional complex, [Cu(bbdc)(phen)]·(H2O)(bbdc = 2-bromo-1,4-benzenedicarboxylate dianion; phen = 1,10-phenanthroline), has been synthesized and structurally characterized by single crystal X-ray analysis. The crystal structure consists of infinite chains of [Cu2(μ4-bbdc)]2+ units connected by bis-monodentate bbdc ligands, the coordination mode of which [μ4-bbdc] is very rare in the phenyldicarboxylate complexes. The substituent group of bbdc is believed to be the growth key of this coordination network.

A new type of coordination network polymer involving the redox-active polyanion, PV(2)Mo(10)O(40)(5)(-), and bridging -Cu(II)(OH(2))(4)- units, [[(Cu(II)(OH(2))(4))(3)(OH)]PV(2)Mo(10)O(40)](n)() (1), has been characterized by X-ray crystallography and several other methods. It is the first efficient heterogeneous (insoluble) catalyst for selective and rapid sulfoxidation using only the ambient environment (air at room temperature). Catalytic activity is enhanced by soluble nitrate in nontoxic perfluoropolyether (PFPE) media.

We elucidated the specific adsorption property of CO(2) for a densely interpenetrated coordination polymer which was a nonporous structure and observed gas separation properties of CO(2) over CH(4), C(2)H(4), and C(2)H(6), studied under both equilibrium and kinetic conditions of gases at ambient temperature and pressure.

In the covalently linked 2D coordination network {[Fe(bbtr)(3)](BF(4))(2)}(∞), bbtr = 1,4-di(1,2,3-triazol-1-yl)butane, the iron(II) centers stay in the high-spin (HS) state down to 10 K. They can, however, be quantitatively converted to the low-spin (LS) state by irradiating into the near-IR spin allowed (5)dd band and back again by irradiating into the visible (1)dd band. The compound shows true light-induced bistability below 100 K, thus, having the potential for persistent bidirectional optical switching at elevated temperatures.

We describe a white emitting coordination network solid that can be conveniently applied as a thin film onto a commercial UV-LED lamp for practical white lighting applications. The solid state material was discovered in an exercise of exploring molecular building blocks equipped with secondary groups for fine-tuning the structures and properties of coordination nets. Specifically, CH(3)SCH(2)CH(2)S- and (S)-CH(3)(OH)CHCH(2)S- (2-hydroxylpropyl) were each attached as secondary groups to the 2,5- positions of 1,4-benzenedicarboxylic acid (bdc), and the resultant molecules (L1 and L2, respectively) were crystallized with Pb(II) into the topologically similar 3D nets of PbL1 and PbL2, both consisting of interlinked Pb-carboxyl chains. While the CH(3)S- groups in PbL1 are not bonded to the Pb(II) centers, the hydroxy groups in PbL2 participate in coordinating to Pb(II) and thus modify the bonding features around the Pb(II), but only to a slight and subtle degree (e.g., Pb-O distances 2.941-3.116 Å). Interestingly, the subtle change in structure significantly impacts the properties, i.e., while the photoluminescence of PbL1 is yellowish green, PbL2 features bright white emission. Also, the homochiral side group in PbL2 imparts significant second harmonic generation, in spite of its seemingly weak association with the main framework (the NLO-phore). In a broad perspective, this work showcases the idea of secondary group participation (SGP) in the construction of coordination networks, an idea that parallels that of hemilabile ligands in organometallics and points to an effective strategy in developing advanced functions in solid state framework materials.

Two silver(I) coordination polymers have been synthesised and single-crystal structural analysis shows that 1 is the first coordination network containing discrete silver clusters and organic N,N′-spacers. It displays an intense blue photoluminescence with three emission maxima.

Negatively charged nanocrystals of the magnetic coordination network CsNiCr(CN)(6) were prepared in water through a seed-mediated growth with a few atomic layers accuracy and final sizes tailored from 6 to 30 nm. A lower limit of the magnetic single-domain critical size was determined to be around 15 nm possessing a blocking temperature above 20 K.

An unprecedented 2-D Cu-S network is constructed by self-assembly coordination between Cu(I) and 4-hydroxythiophenol and its structure was determined by using powder X-ray diffraction data. The self-assembled coordination network displays ionic behavior with a bulk electrical conductivity value of 120 S cm(-1).

International audience; Isolated nanometric objects of the nickel–iron cyanide-bridged coordination network are obtained by a sequential growth on “molecular seeds” anchored on Si(100) surfaces. Control of the density and the size of the nano-objects is achieved by imposing a growth process without side nucleation.

The combination of silver nitrate with a thiacalix[4]arene derivative bearing at the lower rim four benzonitrile groups leads in the crystalline phase to the formation of a 3-D coordination network in which the organic tectons are connected by decanuclear silver nanoclusters.