Photo- and Stress-Induced Bending of (E)-1,2-Bis(pyridinium-4-yl)ethene Dinitrate Crystals.

We report on the elastic and photodynamic properties of (E)-1,2-bis(pyridinium-4-yl)ethene dinitrate [HEbpe](NO), whose needle-like crystals can be reversibly deformed by applying external mechanical stress. The macro-scale mechanical properties of [HEbpe](NO) crystals were quantified by a three-point bending test, which gave a stress-strain curve with an elastic modulus of 1.18 GPa, and its values are lower than those of other flexible elastic organic crystals.

Nanotubule inclusion in the channels formed by a six-fold interpenetrated, triperiodic framework.

When reacted together with uranyl ions under solvo-hydrothermal conditions, a bis(pyridiniumcarboxylate) zwitterion (L) and tricarballylic acid (Htca) give the complex [NH][UO(L)][UO(tca)]·2HO (1). The two ligands are segregated into different units, an anionic nanotubule for tca and a six-fold interpenetrated cationic framework with topology for L. The entangled framework defines large channels which contain the square-profile nanotubules.

Inert Transition Metal Ion Complexes in Organic Synthesis: Protection and Activation.

Single-crystal X-ray diffraction studies for a variety of metal ion complexes of functionalised sarcophagines (sarcophagine=sar=3,6,10,13,16,19-hexa-azabicyclo[6.6.6]icosane) have further confirmed not only that the form of the metal ion/sar unit is unique for each metal, albeit with a sensitivity of the conformation to the associated counter anions, but also that for any given metal and ligand substituent, the dimensions (bond lengths and angles) of the complex and the substituent at the secondary nitrogen centres do not differ significantly from those of the isolated components.

Oligozwitterions in coordination polymers and frameworks - a structural view.

Zwitterions may take many forms and have found many applications, some of which are based on their capacity to act as ligands for a wide variety of metal ions. This brief review describes recent developments in this coordination chemistry involving oligozwitterion species, as reflected in solid state X-ray structural studies of the coordination polymers and frameworks formed and with a particular focus on uranyl ion systems.

Structural and conformational analysis of a biaryl phosphine integrating a calix[4]arene cavity. Can the phosphorus atom behave as an introverted donor?

The conformational preference of a cavity-based biaryl phosphine, namely 5-(2-diphenylphosphinyl-phenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (L) has been investigated by density functional theory calculations. The analysis showed that the barrier to rotation about the C-C axle of the biaryl unit is only 10.7 kcal mol, this rendering possible access to conformers of two types, those in which the P lone pair sits at the cavity entrance and points to the calixarene interior, others with a more open structure where the P atom is located outside the cavity.

Enhanced catalytic performance derived from coordination-driven structural switching between homometallic complexes and heterometallic polymeric materials.

A bifunctional ligand 4,4-dimethyl-1-(pyridin-4-yl)pentane-1,3-dione (HL) able to provide two distinct coordination sites, anionic β-diketonate (after deprotonation) and neutral pyridine, has been used in the synthesis of Ag(I), Pd(II) and Pt(II) complexes that then have been applied as metalloligands for the construction of new heterometallic polymeric materials. The ambidentate nature of L- enables switching between different modes of coordination within mononuclear complexes or their conversion into polymeric species in a fully controllable way. The coordination-driven processes can be triggered by various stimuli, a metal salt addition or acid-base equilibria, and presents an efficient strategy for the generation of metallosupramolecular materials.

Woven, Polycatenated, or Cage Structures: Effect of Modulation of Ligand Curvature in Heteroleptic Uranyl Ion Complexes.

Combining the flexible zwitterionic dicarboxylate 4,4'-bis(2-carboxylatoethyl)-4,4'-bipyridinium (L) and the anionic dicarboxylate ligands isophthalate (ipht) and 1,2-, 1,3-, or 1,4-phenylenediacetate (1,2-, 1,3-, and 1,4-pda), of varying shape and curvature, has allowed isolation of five uranyl ion complexes by synthesis under solvo-hydrothermal conditions. [(UO)(L)(ipht)] () and [(UO)(L)(1,2-pda)]·2HO () have the same stoichiometry, and both crystallize as monoperiodic coordination polymers containing two uranyl-(anionic carboxylate) strands united by L linkers into a wide ribbon, all ligands being in the divergent conformation. Complex , [(UO)(L)(1,3-pda)]·0.

Self-assembly of a fluorescent hydrogen-bonded capsule based on an amino-acid functionalised tetraphenylethylene.

Herein we report the self-assembly of an amino-acid substituted tetraphenylethylene (TPE) into a hydrogen-bonded dimeric capsule. Depending on the conditions applied the presented TPE derivative exhibits bluish photoluminescence with QYs up to 24% due to the AIE effect and excimer formation.

Flexible Aliphatic Diammonioacetates as Zwitterionic Ligands in UO Complexes: Diverse Topologies and Interpenetrated Structures.

''-Tetramethylethane-1,2-diammonioacetate (L1) and ''-tetramethylpropane-1,3-diammonioacetate (L2) are two flexible zwitterionic dicarboxylates which have been used as ligands for the uranyl ion, 12 complexes having been obtained from their coupling to diverse anions, mostly anionic polycarboxylates, or oxo, hydroxo and chlorido donors. The protonated zwitterion is a simple counterion in [HL1][UO(2,6-pydc)] (), where 2,6-pydc is 2,6-pyridinedicarboxylate, but it is deprotonated and coordinated in all the other complexes. [(UO)(L2)(2,4-pydcH)] (), where 2,4-pydc is 2,4-pyridinedicarboxylate, is a discrete, binuclear complex due to the terminal nature of the partially deprotonated anionic ligands.

Zwitterionic and Anionic Polycarboxylates as Coligands in Uranyl Ion Complexes, and Their Influence on Periodicity and Topology.

The three zwitterionic di- and tricarboxylate ligands 1,1'-[(2,3,5,6-tetramethylbenzene-1,4-diyl)bis(methylene)]bis(pyridin-1-ium-4-carboxylate) (L1), 1,1'-[(2,3,5,6-tetramethylbenzene-1,4-diyl)bis(methylene)]bis(pyridin-1-ium-3-carboxylate) (L1), and 1,1',1″-[(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)]tris(pyridin-1-ium-4-carboxylate) (L2) have been used as ligands to synthesize a series of 15 uranyl ion complexes involving various anionic coligands, in most cases polycarboxylates. [(UO)(L1)(cbtc)(HO)]·10HO (, cbtc = ,,1,2,3,4-cyclobutanetetracarboxylate) is a discrete, dinuclear ring-shaped complex with a central cbtc pillar. While [UO(L1)(NO)] (), [UO(L1)(OAc)] (), and [UO(L1)(HCOO)] () are simple chains, [(UO)(L1)(1,3-pda)] (, 1,3-pda = 1,3-phenylenediacetate) is a daisy chain and [UO(L1)(pdda)]·10HO (, pdda = 1,2-phenylenedioxydiacetate) is a double-stranded, ribbon-like chain.

Modulation of the structural information in shape-defined heterocyclic strands: the case of a (pyridine-hydrazone)pyrazine ligand.

Metal ions (Ag, Cd, Eu, Sm) and protons can, through coordination and protonation, modulate in three specific ways the structural information contained in the pyrazine-based heterocyclic strand L (obtained from 2,5-bis(methylhydrazino)pyrazine and 2 equivalents of 2-pyridinecarboxaldehyde), thus generating two linear rod-like conformations and a bent one. This conformational diversity is associated with a structural one that consists of two diprotonated forms (HL(PF) and HL(CFSO)), a polymeric architecture [AgL](CFSO), two rack-like complexes ([EuHL(CFSO)](PF) and [SmHL(CFSO)](PF)) and a grid-like structure ([CdL](CFSO)).

Pd(II) Complexes with Pyridine Ligands: Substituent Effects on the NMR Data, Crystal Structures, and Catalytic Activity.

A wide range of functionalized pyridine ligands have been employed to synthesize a variety of Pd(II) complexes of the general formulas [Pd](NO) and [PdY], where = 4-X-py and Y = Cl or NO. Their structures have been unambiguously established via analytical and spectroscopic methods in solution (NMR spectroscopy and mass spectrometry) as well as in the solid state (X-ray diffraction). This in-depth characterization has shown that the functionalization of ligand molecules with groups of either electron-withdrawing or -donating nature (EWG and EDG) results in significant changes in the physicochemical properties of the desired coordination compounds.

Ni(2,2':6',2″-Terpyridine-4'-carboxylate) Zwitterions and Carboxylate Polyanions in Mixed-Ligand Uranyl Ion Complexes with a Wide Range of Topologies.

The zwitterionic complex formed by Ni and 2,2':6',2″-terpyridine-4'-carboxylate, Ni(tpyc), has been used as a coligand with a diverse group of polycarboxylates in uranyl ion complexes synthesized under solvo-hydrothermal conditions, thus giving a series of 14 mixed ligand, heterometallic compounds. Both [(UO)(-1,2-chdc)Ni(tpyc)(NO)]·4CHCN () and [(UO)(tdc)Ni(tpyc)(NO)] (), where -1,2-chdc is -1,2-cyclohexanedicarboxylate and tdc is 2,5-thiophenedicarboxylate, display discrete UNi dinickelatetrauranacycles, a motif which is also found as part of a daisychain coordination polymer in [(UO)(bdc)Ni(tpyc)(NO)]·2CHCN·2HO (), where bdc is 1,4-benzenedicarboxylate. Similar UNi rings associate to form a nanotubular polymer in [(UO)(tca)Ni(tpyc)(NO)]·2CHCN·2HO (), where tca is tricarballylate.

Contrasting Networks and Entanglements in Uranyl Ion Complexes with Adipic and ,-Muconic Acids.

Adipic (hexane-1,6-dicarboxylic, adpH) and ,-muconic (,-hexa-2,4-diene-1,6-dicarboxylic, mucH) acids have been reacted with uranyl cations under solvo-hydrothermal conditions, yielding nine homo- or heterometallic complexes displaying in their crystal structure the effects of the different flexibility of the ligands. The complexes [PPh][(UO)(adp)] () and [Ni(bipy)][(UO)(muc)]·5HO (), where bipy is 2,2'-bipyridine, crystallize as diperiodic networks with the topology, the layers being strongly puckered or quasiplanar, respectively. Whereas [(UO)(adp)Ni(cyclam)]·2HO (), where cyclam is 1,4,8,11-tetraazacyclotetradecane, crystallizes as a diperiodic network, [(UO)(muc)Ni(cyclam)]·2HO () is a triperiodic framework in which the Ni cations are introduced as pillars within a uranyl-muc framework with the topology.

Hydrogen Bonding Directed Self-Assembly of a Binuclear Ag(I) Metallacycle into a 1D Supramolecular Polymer.

An Ag(I) metallacycle obtained unexpectedly during the preparation of Pd(II) complexes of the bifunctional ligand 5-([2,2'-bipyridin]-5-yl)pyrimidine-2-amine () has been characterized using X-ray structure determination as a binuclear, metallacyclic species [Ag](SbF), where both the bipyridine and pyrimidine-N donors of are involved in coordination to the metal. The full coordination environment of the Ag(I) defines a case of highly irregular 4-coordination. In the crystal, the Ag-metallacycles assemble into one-dimensional supramolecular metalladynamers linked together by hydrogen-bonding interactions.

A chiral uranyl-Kemp's tricarboxylate cubic framework: structure-directing effect of counterions with three-fold rotational symmetry.

In the presence of PPhMe cations, Kemp's tricarboxylate (kta) complexes the uranyl cation to give [PPhMe][UO(kta)] (1), a triperiodic framework with cubic symmetry and srs topology. The PPhMe cation is held by weak interactions into cavities with matching three-fold rotational symmetry. Comparison with the diperiodic hemi-hydrate polymorph previously reported points to the disrupting role of OHO hydrogen bonds in the latter.

2,5-Thiophenedicarboxylate: An Interpenetration-Inducing Ligand in Uranyl Chemistry.

Seven uranyl ion complexes have been crystallized under solvo-hydrothermal conditions from 2,5-thiophenedicarboxylic acid (tdcH) and diverse additional, structure-directing species. [UO(tdc)(DMF)] () is a two-stranded monoperiodic coordination polymer, while [PPhMe][UO(tdc)(HCOO)] () is a simple chain with terminal formate coligands. Although it is also monoperiodic, [C(NH)][HNMe][(UO)(tdc)(HCOO)] () displays an alternation of tetra- and hexanuclear rings.

1D Mn(III) coordination polymers exhibiting chiral symmetry breaking and weak ferromagnetism.

Mn(iii) complexes with achiral ligands, (E)-N-(2-((2-aminobenzylidene)amino)-2-methylpropyl)-5-X-2-hydroxybenzamide (HLX, X = H, Cl, Br, and I), crystallise as chiral conglomerates containing amide oxygen-bridged one-dimensional coordination polymers that exhibit weak ferromagnetism. The bulk products exhibit symmetry breaking in that they do not contain equal amounts of enantiomers, though which is the dominant species depends on the substituent X.

The Impact of Human Papillomavirus (HPV) Associated Oropharyngeal Squamous Cell Carcinoma (OPSCC) on Nutritional Outcomes.

Patients undergoing (chemo) radiotherapy for oropharyngeal squamous cell carcinoma (OPSCC) are at high risk of malnutrition during and after treatment. Malnutrition can lead to poor tolerance to treatment, treatment interruptions, poor quality of life (QOL) and potentially reduced survival rate. Human papillomavirus (HPV) is now known as the major cause of OPSCC.

Cavity Formation in Uranyl Ion Complexes with Kemp's Tricarboxylate: Grooved Diperiodic Nets and Polynuclear Cages.

Kemp's triacid (-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, Hkta) was reacted with uranyl nitrate under solvo-hydrothermal conditions in the presence of diverse counterions or additional metal cations to give eight zero- or diperiodic complexes. All the coordination polymers in the series, [PPhMe][UO(kta)]·0.5HO (), [PPh][UO(kta)] (), [C(NH)][UO(kta)] (), [Cd(bipy)][UO(kta)] (), and [Zn(phen)][UO(kta)]·2HO () (bipy = 2,2'-bipyridine, phen = 1,10-phenanthroline) crystallize as networks with the topology, the ligand being in the chair conformation with the three carboxylate groups equatorial, except in , in which the axial/diequatorial boat conformation is present.

Dynamer and Metallodynamer Interconversion: An Alternative View to Metal Ion Complexation.

A bifunctional molecule containing both a bidentate binding site for metal ions and an aminopyrimidine H-bond donor-acceptor site has been synthesized, and its properties, in its free and coordinated forms, have been established in solution and in the solid state by analytical and spectroscopic methods as well as by X-ray structure determinations. Structural characterization has shown that it forms a one-dimensional H-bonded polymeric assembly in the solid state, while spectroscopic measurements indicate that it also aggregates in solution. The reaction of a simple Fe(II) salt with this assembly results in the emergence of two geometrical isomers of the complex: [FeL](BF4)·9HO- (meridional, ) and [FeL](SiF)(BF)·12HO- (facial, ).

Uranyl Tricarballylate Triperiodic and Nanotubular Species. Counterion Control of Nanotube Diameter.

Tricarballylic acid (propane-1,2,3-tricarboxylic acid, H tca) was reacted with uranyl nitrate hexahydrate under solvo-hydrothermal conditions and in the presence of different additional cations, yielding four complexes which have been crystallographically characterized. [(UO)Ba(tca)(HO)] (), isomorphous to the Pb analogue previously reported, crystallizes as a triperiodic framework in which diperiodic uranyl-tca subunits with the (honeycomb) topology are linked by carboxylate-bound Ba cations. Triperiodic polymerization is also found in [(UO)(tca)Ni(cyclam)] () and [(UO)(tca)Cu(-Mecyclam)] (), but here the diperiodic uranyl-tca subunits have the (square lattice) topology, and the frameworks formed through bridging by Ni or Cu cations have different topologies, in and in .

Functionalized Aromatic Dicarboxylate Ligands in Uranyl-Organic Assemblies: The Cases of Carboxycinnamate and 1,2-/1,3-Phenylenedioxydiacetate.

2-Carboxycinnamic acid (ccnH) and the isomeric 1,2- and 1,3-phenylenedioxydiacetic acids (1,2- and 1,3-pddaH) have been used to synthesize eight uranyl ion complexes under solvo-hydrothermal conditions. In the four complexes [PPh][UO(ccn)(NO)] (), [PPh][UO(ccn)(dibf)] (), [UO(ccn)(bipy)] (), and [Ni(,-Mecyclam)][UO(ccn)(HCOO)] (), the ccn dianion retains a nearly planar geometry, which favors the formation of the centrosymmetric [UO(ccn)] dimeric unit. Additional terminal ligands, either neutral (bipy = 2,2'-bipyridine) or anionic (nitrate, dibf = 1,3-dihydro-3-oxo-1-isobenzofuranacetate, and formate, the two latter formed in situ), complete the uranyl coordination sphere, leading in all cases to discrete, dinuclear species.

Structure-Directing Effects of Coordinating Solvents, Ammonium and Phosphonium Counterions in Uranyl Ion Complexes with 1,2-, 1,3-, and 1,4-Phenylenediacetates.

The three isomers 1,2-, 1,3-, and 1,4-phenylenediacetic acids (1,2-, 1,3-, and 1,4-pdaH) have been used to synthesize 16 uranyl ion complexes under solvo-hydrothermal conditions and in the presence of various coligands and organic counterions. The two neutral and homoleptic complexes [UO(1,2-pda)]·CHCN () and [UO(1,3-pda)] () crystallize as diperiodic assemblies with slightly different coordination modes of the ligands, but the same sql topology. Introduction of the coordinating solvents -methyl-2-pyrrolidone (NMP) or ,'-dimethylpropyleneurea (DMPU) in the uranyl coordination sphere produces the four complexes [UO(1,2-pda)(DMPU)] (), [UO(1,3-pda)(NMP)] (), [UO(1,4-pda)(NMP)] (), and [UO(1,4-pda)(DMPU)] (), which are either monoperiodic () or diperiodic species with the fes ( and ) or 3,4L13 () topology.

Zero-, mono- and diperiodic uranyl ion complexes with the diphenate dianion: influences of transition metal ion coordination and differential U chelation.

Diphenic acid (H2dip) has been used to synthesize nine homo- or heterometallic uranyl ion complexes under solvo-hydrothermal conditions. The diphenate ligand dip2- adopts different coordination modes, mixtures of κ2-O,O'-chelation by individual carboxylate groups, chelation involving both carboxylate groups, and bridging, resulting in different associations of the cations present. [UO2(dip)] (1), [UO2(dip)(bipy)] (2), and [UO2(dip)(phen)] (3) crystallize as monoperiodic coordination polymers, complex 1 with the bridging and both chelation modes of the ligand, and 2 and 3 with only the bis-κ2-O,O'-chelated mode and further chelation by 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen).