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The synthesis and structural characterization of an electron poor Au(III) trication bearing 2 imidazole and 2 acetonitrile ligands is described. The new complex is capable of aryl C-H metalation with the formation of a monomesitylene complex and also demonstrated to be highly oxidizing in the rapid room temperature conversion of cyclohexene to benzene.

A series of nine luminescent iridium(III) complexes with pH-responsive imidazole and benzimidazole ligands have been prepared and characterized. The first series of complexes were of the form [Ir(ppy) 2 (N^N)] + or [Ir(ppy) 2 (C^N)] + (where ppy is 2-phenylpyridine and N^N is 2-(2-pyridyl)imidazole or 2-(2-pyridyl)benzimidazole and C^N represents a pyridyl-triazolylidene-based N-heterocyclic carbene ligand). For these complexes, the benzimidazole group was either unsubstituted or substituted with electron-withdrawing (Cl) or electron-donating (Me) groups. The second series of complexes were of the form [Ir(phbim) 2 (N^N)] + or [Ir(phbim) 2 (C^N)] + (where phbim is 2-phenylbenzimidazole and N^N is either 2,2'-bipyridine or 1,10-phenanthroline and C^N is either a pyridyl-imidazolylidene or pyridyl-triazolylidene N-heterocyclic carbene ligand). UV-visible and photoluminescence pH titration studies showed that changing the protonation state of these complexes results in significant changes in the photoluminescence emission properties. The p K a values of prepared complexes were estimated from the spectroscopic pH titration data and these values show that the nature of the pH-sensitive ligands (either main or ancillary ligands) resulted in a significant capacity to modulate the p K a values for these compounds with values ranging from 5.19-11.22. Theoretical investigations into the nature of the electronic transitions for the different protonation states of compounds were performed and the results were consistent with the experimental results.

Synthesis and crystallographic characterization of NO 2 -C 6 H 4 -I(NTf 2 ) 2 (NTf 2 = bistriflimide) is reported. Experimental results find that this compound can perform oxidation reactions that ArI(OTf) 2 is unable to and theoretical analysis indicates Ar-I(NTf 2 ) 2 is the most oxidizing in the ArIL 2 class of compounds known and may also be the most oxidizing compound in the class practically possible.

The recently discovered I(III) reagent NO 2 -C 6 H 4 -I(OTf) 2 is found to rapidly react with hydride sources, including HSiEt 3 and relatively hydridic C-H precursors. These represent the first distinct reactions involving direct hydride abstraction by I(III) under ambient conditions. Direct C-F abstraction is also demonstrated, as well as oxidation of cyclic alkenes to aromatic rings, all representing new reactions for I(III) demonstrating the very high reactivity of NO 2 -C 6 H 4 -I(OTf) 2 .

The structure of Stang's reagent [PhI(CN)][OTf] is confirmed by X-ray crystallography and is determined to be best described as an ion-pair in organic solution. It is found to be a strong Lewis acid, but reaction with pyridine ligands gives [Pyr-CN][OTf] salts via oxidation of pyridine giving a new derivative of the CDAP reagent widely used as an activation agent for polysaccharides.

Both mixed λ 3 -iodoarenes and λ 3 -iodoarenes possessing -OTf ligands are coveted for their enhanced reactivities. Here we describe the synthesis, reactivity, and comprehensive characterisation of two new ArI(OTf)(X) species, a class of compound that were previously only invoked as reactive intermediates where X = Cl, F and their divergent reactivity with aryl substrates. A new catalytic system for electrophilic chlorination of deactivated arenes using Cl 2 as the chlorine source and ArI/HOTf as the catalyst is also described.

The looming threat of a "post-antibiotic era" has been caused by a rapid rise in antibacterial resistance and subsequent depletion of effective antibiotic agents in the clinic. An efficient strategy to address this shortfall lies in the reengineering of pre-existing and commercially available antibiotic drugs. This is exemplified by dimerization, a design concept in which two pharmacophores are covalently linked to form a new chemical entity. The cage hydrocarbons cubane (1), bicyclo[2.2.2]octane (BCO) (2), adamantane (3), and bicyclo[1.1.1]pentane (BCP) (4) present themselves as an attractive family of linkers in this regard. In this report, all four hydrocarbon cages were employed as linkers in a series of dimers based on the commercially available antibiotics trimethoprim and tedizolid. A detailed synthetic roadmap for the protection and deprotection of each pharmacophore is outlined. Several members of the trimethoprim series showed activity on par with that of their trimethoprim progenitor, although this was not the case for the tedizolid series. The design strategy outlined herein highlights the utility of the group as a platform for the rapid and modular construction of future novel antibiotics., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A remarkably flexible, multifunctional, 2D coordination polymer exhibiting an unprecedented mode of reversible mechanical motion, enabling pores to open and close, is reported. Such multifunctional materials are highly sought after, owing to the potential to exploit coexisting electronic and mechanical functionalities that underpin useful technological applications such as actuators and ultrasensitive detectors. The coordination polymer, of composition Mn(F 4 TCNQ)(py) 2 (F 4 TCNQ = 2,3,5,6-tetrafluoro-7,7,8,8-tetracycanoquinodimethane; py = pyridine), consists of Mn(II) centers bridged by F 4 TCNQ dianions and coordinated by py molecules that extend above and below the 2D network. Exposure of Mn(F 4 TCNQ)(py) 2 , in its collapsed state, to carbon dioxide results in a pore-opening process at a threshold pressure for a given temperature. In addition to carbon dioxide, a variety of volatile guests may be incorporated into the pores, which are lined with electron-rich F 4 TCNQ dianions. The inclusion of electron-deficient guests such as 1,4-benzoquinone, nitrobenzene, maleic anhydride, and iodine into the pores is accompanied by a striking color change associated with a new host-guest charge-transfer interaction and an improvement in the semiconductor behavior, with the iodine adduct showing an increase in conductivity of almost 5 orders of magnitude. Experimental and density functional theory calculations on this remarkable multifunctional material demonstrate a reduction in the optical band gap with increasing electron affinity of the guest.

As part of an educational exercise designed to introduce school students to the technique of single-crystal X-ray diffraction and enhance their understanding of primary and secondary bonding, a group of nine secondary school students was given the opportunity to prepare new compounds and to solve and refine data collected on the crystalline materials they had prepared. Their investigation of the alkali metal salts of 4-hydroxybenzoic acid (H 2 hba) yielded nine new compounds and their structures are described in this article. Whilst the salts might be expected to have similar atomic arrangements, there are significant differences in their structures. Although H 2 hba is a relatively simple organic molecule, it displays remarkable coordinative flexibility, forming ionic solids containing the uncharged molecule, the monoanion Hhba - or the dianion hba 2- . A common feature of the structures is their layered arrangement: alternating hydrophilic layers made up of closely packed metal-oxygen polyhedra separated by the hydrophobic component of the hydroxybenzoate linking units. Close packing of these units seems to be a dominant influence in determining the overall structure. The hydroxybenzoate units are usually both parallel and antiparallel with their immediate neighbours, with packing that can be edge-to-face, face-to-face or a mixture of the two. Hydrogen bonding plays a key role in the structure of most compounds and a short strong hydrogen bond (SSHB) is observed in two of the networks. The compounds of 4-hydroxybenzoic acid, C 7 H 6 O 3 , described here are: poly[di-μ-aqua-μ-4-oxidobenzoato-dilithium], [Li 2 (C 7 H 4 O 3 )(H 2 O) 2 ] n , 1, poly[triaqua-μ-4-oxidobenzoato-dilithium], [Li 2 (C 7 H 4 O 3 )(H 2 O) 3 ] n , 2, poly[μ-4-hydroxybenzoato-lithium], [Li(C 7 H 5 O 3 )] n , 3, catena-poly[4-hydroxybenzoate [[diaquasodium]-di-μ-aqua]], {[Na(H 2 O) 4 ](C 7 H 5 O 3 )} n , 4, poly[di-μ-aqua-aqua-μ-4-hydroxybenzoato-potassium], [K(C 7 H 5 O 3 )(H 2 O) 3 ] n , 5, poly[μ-aqua-μ-4-hydroxybenzoato-potassium], [K(C 7 H 5 O 3 )(H 2 O)] n , 6, poly[aqua-μ-4-hydroxybenzoato-rubidium], [Rb(C 7 H 5 O 3 )(H 2 O)] n , 7, poly[aqua-μ-4-hydroxybenzoato-caesium], [Cs(C 7 H 5 O 3 )(H 2 O)] n , 8, poly[[μ-aqua-aqua(μ-4-hydroxybenzoato)(4-hydroxybenzoic acid)sodium] monohydrate], {[Na(C 7 H 5 O 3 )(C 7 H 6 O 3 )(H 2 O) 2 ]·H 2 O} n , 9, poly[[(μ-4-hydroxybenzoato)(μ-4-hydroxybenzoic acid)rubidium] monohydrate], {[K(C 7 H 5 O 3 )(C 7 H 6 O 3 )]·H 2 O} n , 10, and poly[[(μ-4-hydroxybenzoato)(μ-4-hydroxybenzoic acid)rubidium] monohydrate], {[Rb(C 7 H 5 O 3 )(C 7 H 6 O 3 )]·H 2 O} n , 11., (open access.)

An investigation of the adsorption properties of two structurally related, 3D coordination polymers of composition Zn(2-Mehba) and Zn(2,6-Me 2 hba) (2-Mehba = the dianion of 2-methyl-4-hydroxybenzoic acid and 2,6-Me 2 hba = the dianion of 2,6-dimethyl-4-hydroxybenzoic acid) is presented. A common feature of these structures are parallel channels that are able to accommodate appropriately sized guest molecules. The structures differ with respect to the steric congestion within the channels arising from methyl groups appended to the bridging ligands of the network. The host network, Zn(2-Mehba), is able to take up appreciable quantities of H 2 (77 K) and CO 2 and CH 4 (298 K) in a reversible manner. In regard to the adsorption of N 2 by Zn(2-Mehba), there appears to be an unusual temperature dependence for the uptake of the gas such that when the temperature is increased from 77 to 298 K the uptake of N 2 increases. The relatively narrow channels of Zn(2,6-Me 2 hba) are too small to allow the uptake of N 2 and CH 4 , but H 2 molecules can be adsorbed. A pronounced step at elevated pressures in CO 2 and N 2 O isotherms for Zn(2,6-Me 2 hba) is noted. Calculations indicate that rotation of phenolate rings leads to a change in the available intraframework space during CO 2 dosing.

A chiral, octahedral M 12 L 12 cage, which is charge neutral and contains an internal void of about 2000 Å 3 , is reported. The cage was synthesised as an enantiopure complex by virtue of amino-acid-based dicarboxylate ligands, which assemble around copper paddlewheels at the vertices of the octahedron. The cage persists in solution with retention of the fluorescence properties of the parent acid. The solid-state structure contains large pores both within and between the cages, and displays permanent porosity for the sorption of gases with retention of crystallinity. Initial tests show some enantioselectivity of the cage towards guests in solution., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reaction of the chloranilate dianion with Y(NO 3 ) 3 in the presence of Et 4 N + in the appropriate proportions results in the formation of (Et 4 N)[Y(can) 2 ], which consists of anionic square-grid coordination polymer sheets with interleaved layers of counter-cations. These counter-cations, which serve as squat pillars between [Y(can) 2 ] sheets, lead to alignment of the square grid sheets and the subsequent generation of square channels running perpendicular to the sheets. The crystals are found to be porous and retain crystallinity following cycles of adsorption and desorption. This compound exhibits a high affinity for volatile guest molecules, which could be identified within the framework by crystallographic methods. In situ neutron powder diffraction indicates a size-shape complementarity leading to a strong interaction between host and guest for CO 2 and CH 4 . Single-crystal X-ray diffraction experiments indicate significant interactions between the host framework and discrete I 2 or Br 2 molecules. A series of isostructural compounds (cat)[M III (X-an) 2 ] with M=Sc, Gd, Tb, Dy, Ho, Er, Yb, Lu, Bi or In, cat=Et 4 N, Me 4 N and X-an=chloranilate, bromanilate or cyanochloranilate bridging ligands have been generated. The magnetic properties of representative examples (Et 4 N)[Gd(can) 2 ] and (Et 4 N)[Dy(can) 2 ] are reported with normal DC susceptibility but unusual AC susceptibility data noted for (Et 4 N)[Gd(can) 2 ]., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The need for effective CO 2 capture systems remains high, and due to their tunability, metallosupramolecular architectures are an attractive option for gas sorption. While the use of extended metal organic frameworks for gas adsorption has been extensively explored, the exploitation of discrete metallocage architectures to bind gases remains in its infancy. Herein the solid state gas adsorption properties of a series of [Pd 2 (L) 4 ] 4+ lantern shaped coordination cages (L = variants of 2,6-bis(pyridin-3-ylethynyl)pyridine), which had solvent accessible internal cavities suitable for gas binding, have been investigated. The cages showed little interaction with dinitrogen gas but were able to take up CO 2 . The best performing cage reversibly sorbed 1.4 mol CO 2 per mol cage at 298 K, and 2.3 mol CO 2 per mol cage at 258 K (1 bar). The enthalpy of binding was calculated to be 25-35 kJ mol -1 , across the number of equivalents bound, while DFT calculations on the CO 2 binding in the cage gave ΔE for the cage-CO 2 interaction of 23-28 kJ mol -1 , across the same range. DFT modelling suggested that the binding mode is a hydrogen bond between the carbonyl oxygen of CO 2 and the internally directed hydrogen atoms of the cage., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A Zn II complex of the dianionic tetradentate ligand formed by deprotonation of glyoxal-bis(4-phenyl-3-thiosemicarbazone) (H 2 gtsp) is a [3+3] trinuclear triangular prism. Recrystallization of this complex in the presence of either CO 2 , CS 2 , or CH 3 CN leads to the formation of [4+4] open-ended charge-neutral tetranuclear coordination nanotubes, approximately 2 nm in length and with internal dimensions large enough to accommodate linear guest molecules, which serve to template their formation. Upon removal of the templating molecules the nanotubes demonstrated reversible sorption of CO 2 with an isosteric enthalpy of sorption of 28 kJ mol -1 at low loading., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The uptake of inhalation anesthetics by three topologically identical frameworks is described. The 3D network materials, which possess square channels of different dimensions, are formed from the relatively simple combination of Zn II centres and dianionic ligands that contain a phenolate and a carboxylate group at opposite ends. All three framework materials are able to adsorb N 2 O, Xe and isoflurane. Whereas the framework with the widest channels is able to adsorb large quantities of the various guests from the gas phase, the frameworks with the narrower channels have superior binding enthalpies and exhibit higher levels of retention. The use of ligands in which substituents are bound to the aromatic rings of the bridging ligands offers great scope for tuning the adsorption properties of the framework materials., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new divergent homopiperazine-derived ligand N,N'-bis(4-carboxyphenyl)-1,4-diazacycloheptane H 2 L has been prepared, containing a semirigid saturated heterocyclic core which is capable of providing multiple distinct bridging geometries. Reaction of H 2 L with zinc acetate in DMSO gives a two-dimensional parallel interpenetrated polyrotaxane structure 1 in which the loops and rods are formed by the bent cis-(eq,ax) twist boat and trans-(ax,ax) twist chair conformers, respectively. By matching the distances between the solvated metal sites in the structure of 1, a related material 2 can be prepared incorporating the pillaring ligand trans-1,2-bis(4-pyridyl)ethylene bpe. Compound 2 displays a similar polyrotaxane interpenetration mode, permitted by the presence of both cis and trans ligand conformers, but displays a three-dimensional 2.6 9 topology related to the dia diamondoid network. The guest exchange and gas adsorption properties of both materials were investigated; while compound 1 displays poor stability to guest exchange and negligible gas uptake, the higher connectivity microporous compound 2 shows facile guest exchange and a surprisingly high CO 2 capacity of 12 wt % at 1 bar and 273 K, and a zero-loading enthalpy of adsorption of -32 kJ mol -1 . High-pressure adsorption isotherms also show moderate physisorption of H 2 and CH 4 within the material.

The combination of lightweight metal cations with a range of dicarboxylate ligands has led to the generation of ionic network materials that possess channels occupied by solvent molecules. The compounds [Li 2 (2,2-bpdc)(DMF) 2 ] and [Mg(2,2-bpdc)(DMF) 2 ] (2,2-bpdc=2,2-dipyridyl-4,4-dicarboxylate) adopt a similar structure in which parallel metal-carboxylate chains are linked to four equivalent chains to generate a 3 D network in which DMF molecules occupy channels. [Li 4 (3,5-pdc) 2 (DMF)]⋅solvate (3,5-pdc=3,5-pyridine dicarboxylate) adopts a similar structure but the chains are more complex. As with the other structures, coordinated DMF molecules occupy network channels. [Li 4 (3,5-pdc) 2 (DMF)]⋅solvate is able to adsorb carbon dioxide at elevated pressures with the adsorption following a type V isotherm; hysteresis is apparent upon desorption. The final compound, Li[Mg 3 OH(2,2-bqdc) 3 (DMF/H 2 O) 3 ]⋅solvate (2,2-bqdc=2,2-biquinoline-4,4-dicarboxylate) has a distinctly different structure in which a trio of magnesium centres bound to a central μ 3 -hydroxide ion serves as a 6-connecting, trigonal prismatic node within a 3 D network that has the point symbol, 4 9 6 6 . Solvent-filled intraframework spaces represent over 50 % of the crystal volume and are occupied by highly disordered solvent and Li + ions. Immersion of Li[Mg 3 OH(2,2-bqdc) 3 (DMF/H 2 O) 3 ]⋅solvate in a solution of Fe(2,2-bipyridine) 3 2+ results in the incorporation of the Fe II complex into the large channels of the anionic network., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of solid-state structural transformations are found to accompany desolvation of relatively simple coordination polymers to yield materials that exhibit unexpected gas sorbing properties. Reaction of 1,2,4,5-tetrahydroxybenzene with M(II) salts (M = Mg, or Zn) in an alcohol/water solution in the presence of air affords cis-M(II)(C6H2O4(-II))(H2O)2·2H2O·xROH, (M = Mg, or Zn), crankshaft-like chains in which the absolute configurations of the chiral metal centres follow the pattern Δ Δ Λ Λ Δ Δ Λ Λ, and are hydrogen bonded together to generate spacious channels. When crystals of the crankshaft chain are air dried the crystals undergo a single crystal-to-powder rearrangement to form linear trans-M(II)(C6H2O4(-II))(H2O)2 chains. Further dehydration yields microporous solids that reversibly sorb H2, CH4 and CO2 with high sorption enthalpies.

The structure of Li(inox)⋅2/3 DMF (inox(-) =the N-oxide of the isonicotinate anion) consists of a 3D framework with solvent-filled, square cross-section channels of approximate dimensions 5.5×5.5 Å. Unfortunately, the Li(inox) framework is unstable upon removal of DMF from the channels. When the structurally related 4-hydroxybenzoic acid (H2 hba) was used in place of Hinox, and Zn(2+) in place of the Li(+) , a structurally similar but more robust network, Zn(hba), was obtained; the isostructural compound, Co(hba), may also be prepared. Longer ligands with phenolate and carboxylate functional groups at opposite ends, such as the dianions of 4-coumaric acid (H2 cma) and 4'-hydroxy-4-biphenylcarboxylic acid (H2 hbpc), in combination with Zn(2+) yield Zn(cma) and Zn(hbpc) frameworks, respectively, with the same PtS topology but with larger channels. The coordination polymers remain intact after desolvation and exhibit microporosity, showing the ability to sorb significant quantities of CO2 , CH4 , and H2 ., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reaction between LiOH and isonicotinic acid (inicH) in the appropriate solvent or mixture of solvents affords a family of variously solvated forms of a simple ionic lithium salt, viz., Li(+)inic(-)·S (where S = 0.5 morpholine, 0.5 dioxane, 0.25 n-hexanol, 0.5 N-methylpyrrolidinone, 0.5 N,N-dimethylformamide, 0.5 n-propanol, 0.5 cyclohexanol, 0.5 pyridine, 0.5 t-butanol, 0.5 ethanol, and 0.5 methanol). Three-dimensional Li(+)inic(-) frameworks containing solvent-filled channels are present in all of these except for the MeOH and EtOH solvates. The nondirectional character of the electrostatic interactions between the Li(+) and inic(-) ions bestows an element of "plasticity" upon the framework, manifested in the observation of no less than five different framework structures within the family. Unusual single-crystal-to-single-crystal transformations accompany desolvation of Li(+)inic(-)·S in which the Li(+)inic(-) framework undergoes a major rearrangement (from a structure containing "8484 chains" to one with "6666 chains"). The "before and after" structures are strongly suggestive of the mechanism and the driving force for these solid state framework rearrangements: processes which further demonstrate the "plasticity" of the ionic Li(inic) framework. A solid-state mechanism for these desolvation processes that accounts very satisfactorily for the formation of the channels and for the diverse geometrical/topological aspects of the transformation is proposed. The reverse process allows the regeneration of the solvated 8484 form. When the 6666 Li(+)inic(-) form is immersed in carbon disulfide, a single-crystal-to-single-crystal transformation occurs to generate Li(+)inic(-)·0.25CS2. The hydrate, Li(+)inic(-)·2H2O which consists of discrete Li(inic)·H2O chains obtained by recrystallizing the salt from water, can also be obtained by hydration of the 6666 form. A dense 3D network with the formula, Li(inic) can be obtained in a reversible process by the removal of the water from the hydrated form and also by crystallization from a t-amyl alcohol solution.

The synthesis, structural and gas sorption studies of a porous Cu(II) coordination polymer featuring 1H-indazole-5-carboxylic acid (H(2)L) are presented. [Cu(HL)(2)] is a thermally and hydrolytically robust 4-connected 3D coordination polymer of NbO topology and is replete with 1D channels that permit selective and hysteretic sorption of CO(2).