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New photoswitchable pyridyl-azo-phenyl-decorated tripodal host ligands (Laz) that belong to the cyclotriveratrylene family have been synthesized, and their photoswitching behavior and crystal structures determined. The latter includes a remarkable 7-fold Borromean-weave entanglement of π-π stacked layers. Trigonal bipyramidal {[Pd(en)]3(Laz)2}6+ metallo-cryptophanes (en = ethylenediamine) were formed from these and a previously known pyridyl-azo-phenyl-decorated tripodal host ligand. These coordination cages dissociate at low concentrations and are less robust to photoswitching of the Laz ligands than were previously reported Ir(III)-linked metallo-cryptophanes with similar ligands, reflecting the greater lability of the Pd-N bonds. The {[Pd(en)]3(Laz)2}6+ cages all act as hosts, binding octyl sulfate anions, or N-[2-(dimethylamino)ethyl]-1,8-naphthalimide in a dimethyl sulfoxide solution.

Sensors are routinely developed for specific applications, but multipurpose sensors are challenging, due to stability and poor functional design. We report organic materials that operate in solution and gas phase. They show a strong response behaviour to at least three types of environmental changes: pH, amine and metal ion binding/detection. We have confirmed and validated our findings using various analytical and computational methods. We found that the changes in polarity of the solvent and pH not only red shift the tail of the absorption spectra, but also extend the peak optical absorption of these structures by up to 100 nm, with consequential effects on the optical gap and colour changes of the materials. Acid–base response has been studied by spectrophotometric titrations with trifluoroacetic acid (TFA) and triethyl amine (TEA). The experiments show excellent reversibility with greater sensitivity to base than acid for all compounds. Analysis into metal sensing using Zn(II) and Cu(II) ions as analytes show that the materials can successfully bind the cations forming stable complexes. Moreover, a strong suppression of signal with copper gives an operative modality to detect the copper ion as low as 2.5 × 10−6 M. The formation of the metal complexes was also confirmed by growing crystals using a slow diffusion method; subsequent single crystal X-ray analysis reveals the ratio of ligand to metal to be 2 to 1. To test sensitivity towards various amine vapours, paper-based sensors have been fabricated. The sensors show a detection capability at 1 ppm of amine concentration. We have employed CIE L*a*b* colour space as the evaluation method, this provides numeric comparison of the samples from different series and allows comparison of small colour differences, which are generally undetectable by the human-eye. It shows that the CIE L*a*b* method can assess both sensitivity to a particular class of analytes and a specificity response to individual amines in this subclass offering an inexpensive and versatile methodology.

Metal complexes of the ligand N-benzylimidazole (BnIm) and their in vitro antibacterial study are reported. The complexes of Co(II), Ni(II), Cu(II), Zn(II), and Ag(I) were synthesized by the reaction of the ligand with appropriate metal salt in 1:4 metal to ligand mole ratio. All the synthesized ligand and their complexes were characterized by physicochemical and spectroscopic techniques. Further, the compounds were screened for their antibacterial activity against a multi-resistance strain of Staphylococcus aureus (MRSA) using ciprofloxacin as a standard antibiotic. In general, all the tested compounds showed antibacterial activities at minimum inhibition concentration (MIC) level. How to cite this article: Al-Saadi, Z.N., Salman, A.W., Arkawazi, H.D. and Hardie, M.J. (2019). Synthesis, Characterization and Antibacterial Activity of Some Transition Metal Complexes Derived From The Ligand N-Benzylimidazole Against Methicillin-Resistantt Staphylococcus Aureus (Mrsa). International Journal of Drug Delivery Technology, 9(4): 666-670. Source of support: Nil. Conflict of interest: None.

The trinuclear complexes [{PdI2(pyCl)}3(L1)] C1 and [{PdI2(pyCl)}3(L2)] C2, where pyCl = 3-chloropyridine, L1 = methyl(cyclotriguaiacylenyl)methylbenzimidazol-2-ylidene and L2 = benzyl(cyclotriguaiacylenyl)methylbenzimidazol-2-ylidene, each feature three palladium N-heterocyclic carbene (NHC) centres tethered onto a host-type cyclotriguaiacylene scaffold. Crystal structures of different solvates of complex C1 reveal different host-guest motifs including intra-cavity binding of dioxane guests concomitant with intramolecular halogen bonding interactions of C1. Mononuclear NHC analogues of C1 and C2, namely [PdI2(pyCl)(L3)] C3 and [PdI2(pyCl)(L4)] C4, where L3 = (3-chloropyridyl)-1-(2-methoxyphenyoxy)methyl-3-methylbenzimidazol-2-ylidene and L4 = (3-chloropyridyl)-1-(2-methoxyphenyoxy)methyl-3-benzylbenzimidazol-2-ylidene, were also synthesised and their crystal structures determined. Complexes C1-C4 are competent catalysts for Suzuki Miyaura cross-coupling, and interestingly exhibit a switch in the normal regioselectivity observed for reactions of 2,4-dibromopyridine with aryl boronic acids, usually C2-selective, yielding C4-arylated product preferentially over C2-arylated product.

The hexapodal ligand hexakis(isonicotinoyl)cyclotricatechylene (L1) belonging to the cyclotriveratrylene family of host-molecules has been synthesised and used in the assembly of a series of coordination polymer materials with Re(I), Co(II), Cu(II), Ni(II) and Ag(I) salts. Single crystal structures of the coordination polymers [Re3(L1)2Br3(CO)3] 1, and an isomorphic [M3L2] series where M = Co, Cu or Ni, reveal 2D framework structures with a simplified topology of 36 or hxl. These are composed of M6(L1)2 metallo-cages linked together in a pair-wise fashion through each metal centre. Compound 1 is a rare example of a rhenium coordination polymer and was investigated for guest uptake from solution, complexing I2. The mixed-ligand species [Cu2(L1)(CF3CO2)3(isonicotinate)] forms a (3,4,5)-connected 2D coordination polymer, while [Ag2(L1)(DMF)2]·2BF4·2(H2O)·6(DMF) features a 2D network of (3,6)-connectivity and with kagome dual (kgd) topology.

The chiral self-sorting process during the self-assembly of homochiral Pd6L8 capsules from cyclotriveratrylene (CTV)-based chiral tritopic ligands (L) and (Py*: 3-chloropyridine) was investigated by an NMR-based approach (QASAP: quantitative analysis of the self-assembly process). From the beginning to the formation of the immature capsules (ICs), enantiomeric ligands are distributed in the intermediates in a non-self-sorting manner, which leads to the isomers of heterochiral ICs over 99% yield. The mismatch of the chirality in the heterochiral ICs prevents intramolecular ligand exchanges in ICs to form the heterochiral capsules. The correction of the chirality in the heterochiral ICs (chiral self-sorting) takes place very slowly to finally lead to the homochiral capsules. The reason why the chiral self-sorting took place in the late stage of the self-assembly (after the formation of the heterochiral ICs) would be due to the relatively high flexibility of the CTV-based ligand.

Metal complexes Mn(II), Co(II), Cu(II), Zn(II) and Ag(I) of the ligand 1,6-bis(1-benzimidazolyl)hexane were synthesized by the reaction of the ligand and appropriate metal salts in l: 1 mole ratio. The ligand and its complexes were characterized using IR, Uv-Vis, 1H and 13C NMR, Mass spectroscopy, and elemental analysis CHN. Depending on the abovementioned techniques, a polymeric structure was proposed to the prepared complexes. Further, all the synthesized compounds were tested against some of the soil-borne fungi namely; Rhizoctonia solani, Fusarium oxysporum, Fusarium solani and Pythium aphanidermatum. The results showed that the tested compounds have an effect on the growth of pathogenic fungi. This leads to thinking that these compounds could be used one day as new chemical pesticides as an alternative to chemical compounds that have been shown to be resistant to pathogens.

Pyramidal molecular hosts related to cyclotriveratrylene (CTV) form self-assembled cages including organic cages, hydrogen-bonded cages, and metallocages. The latter include M3L2, M4L4, M6L8, and M12L8 assemblies, including topologically complicated structures. Metallocages may show ligand exchange and/or homochiral sorting of the C3-symmetric CTV-analog ligands. Cages also occur within coordination networks.

Trinuclear rhenium fac-tricarbonyl bromide complexes have been synthesized coordinated to the host ligands tris(4-[4-methyl-2,2′-bipyridyl]methyl)cyclotriguaiacylene (L1), tris(4-[4-methyl-2,2′-bipyridoyl])cyclotriguaiacylene (L2), and tris(4-[2,2′,6′,2″-terpyridyl]benzyl)cyclotriguaiacylene (L3). The structure of L1 and complexes [{Re(CO)3Br}3(L1)] (1) and [{Re(CO)3Br}3(L3)] (3) have been elucidated through X-ray single-crystal diffraction, with complex 3 crystallizing as a conglomerate. The steady-state luminescent properties and time-resolved fluorescence studies of the complexes have been conducted and revealed an unusual dual-emission phenomenon for complex 2. Complexes 1 and 2 show red-shifted emission wavelengths in comparison with those typical of monometallic Re(CO)3-bipy-Br complexes, while complex 3 showed an unusual excitation-dependent variation of emission wavelength.

Cryptophanes with flexible linkers derived from (±)‐tris‐(4‐formyl‐phenyl)‐cyclotriguaiacylene with either bisoxydi(ethylamine) or bis(aminopropyl)ether were isolated as single crystals, the crystal structures of which showed the proposed, but previously uncharacterised, out‐in conformation, in which both cyclotriguaiacylene fragments adopt a crown conformation with one crown sitting inside the other. The usual cage‐like out‐out conformation of the cryptophanes was observed when crystals were dissolved upon heating, and the molecules collapsed back to the out‐in isomers over time. In contrast, a cryptophane also derived from (±)‐tris‐(4‐formyl‐phenyl)‐cyclotriguaiacylene but with rigid dibenzalhydrazine linkers was isolated as the more usual out‐out isomer.

This work was supported by The Leverhulme Trust (RPG-2014-148), EPSRC (EP/M02105X/1, 1238852 (VEP), equipment grant EP/K039202/1). This work was carried out with support of Diamond Light Source (MT-10344). Cyclotriguaiacylene has been functionalised with 3- or 4-pyridyl-azo-phenyl groups to form a series of molecular hosts with three azobenzene-type groups that exhibit reversible photo-isomerisation. Reaction of the host molecules with [Ir(C^N)2(NCMe)2]+ where C^N is the cyclometallating 2-phenylpyridinato, 2-(4-methylphenyl)pyridinato or 2-(4,5,6-trifluorophenyl)pyridinato results in the self-assembly of a family of five different [{Ir(C^N)2}3(L)2]3+ coordination cages. Photo-irradiation of each of the cages with a high energy laser results in E → Z photo-isomerisation of the pyridyl-azo-phenyl groups with up to 40% of groups isomerising. Isomerisation can be reversed by exposure to blue light. Thus, the cages show reversible structure-switching while maintaining their compositional integrity. This represents the largest photo-induced structural change yet reported for a structurally-integral component of a coordination cage. Energy minimised molecular models indicate a switched cage has a smaller internal space than the initial all-E isomer. The [Ir(C^N)2(NCMe)2]+ cages are weakly emissive, each with a deep blue luminescence at ca. 450 nm. Publisher PDF

Two new heteroleptic metal-organic framework materials show strong adsorption of H2 and ethanol. [Co2(L1)(bdc)2], where L1 = N1,N4-bis(4-pyridinylmethyl)-2,5-dimethylbenzene-1,4-diamine and bdc is benzene-1,4-dicarboxylate, has a twofold interpenetrating pillared layer structure with pcu topology. It has a stepped, hysteretic EtOH adsorption that can be related to complicated phase and structural transformation behaviour that occurs on de-solvation and re-solvation, including major conformational changes to the geometry of the flexible L1 ligand. [Co2(L1)(bpdc)2], where bpdc = biphenyl-4,4’-dicarboxylate, has a unique six-connected self-catenating framework structure. Solvation changes occur without significant structural change and a partially-hydrolysed material binds its own decomposition products as guests.

The racemic ligand (±)-tris-(4-methylthiazolyl)cyclotriguaiacylene forms a homochiral crystalline Ag12L8 cube with spontaneous resolution. The ligand itself likewise crystallises in a chirally pure fashion in two clathrate complexes. Ag12L8 is the first example of a cyclotriguaiacylene-type coordination cube and a rare example of a M12L8-type metallo-cube.

A review of the emerging field of cyclotriveratrylene-derived coordination cages is presented. Ligand-functionalised cyclotriveratrylene (CTV) derivatives self-assemble with a range of metal cations to afford coordination cages, polymers and topologically non-trivial constructs, such as [2]catenanes and a self-entangled cube. Increased control over their self-assembly allows for the controlled and predictable formation of well-defined coordination cages for application in host-guest and recognition chemistry, with surfactant binding and single-crystal-to-single-crystal (SCTSC) uptake of small-molecule guests being observed.

Three complexes of cyclotricatechylene (H6ctc), [{PtL}3(μ3-ctc)], have been synthesised: (L = 1,2-bis(diphenylphosphino)benzene {dppb}, 1; L = 1,2-bis(diphenylphosphino)ethane {dppe}, 2; L = 4,4′-bis(tert-butyl)-2,2′-bipyridyl {tBu2bipy}, 3). The complexes show three low-potential, chemically reversible voltammetric oxidations separated by ca. 180 mV, corresponding to stepwise oxidation of the [ctc]6− catecholato rings to the semiquinonate level. The redox series [1]0/1+/2+/3+ and [3]0/1+/2+/3+ have been characterised by UV/vis/NIR spectroelectrochemistry. The mono- and di-cations have class II mixed valent character, with reduced radical delocalisation compared to an analogous bis-dioxolene system. The SOMO composition of [1˙]+ and [3˙]+ has been delineated by cw EPR, ENDOR and HYSCORE spectroscopies, with the aid of two monometallic model compounds [PtL(DBsq˙)]+ (DBsqH = 3,5-bis(tert-butyl)-1,2-benzosemiquinone; L = dppe or tBu2bipy). DF and time-dependent DF calculations confirm these interpretations, and demonstrate changes to spin-delocalisation in the ctc macrocycle as it is sequentially oxidised.

The simple linear linking ligand diazabicyclo[2.2.2]octane (dabco) combines with silver(I) to form three-dimensional (3D) coordination polymers which have either a zeolitic mtn topology structure or a (10,3)-b ths network according to the counteranion used. The tetrahedral anions BF4- or ReO4- promote formation of [Ag(dabco)2]·X, which has a 3D four-connected mtn framework of fused 512 and 64512 cages, and the material shows modest absorption of iodine. The bulky anion [Co(C2B9H11)2]- and an excess of dabco promote formation of complex [Ag2(dabco)3(CH3CN)2]·2[Co(C2B9H11)2] with a three-connected (10,3)-b network, while use of 1 equiv of dabco gives a previously reported [Ag(dabco)]·[Co(C2B9H11)2], which has a one-dimensional coordination chain structure. (Chemical Equation Presented).

Pd3L2 metallo-cryptophane cages with cyclotriveratrylene-type L ligands can be stabilized by use of a bis-N-heterocyclic carbene as an auxiliary cis-protecting ligand, while use of more common protecting chelating ligands such as ethylenediamine saw a Pd3L2 to Pd6L8 rearrangement occur in solution. The crystalline Pd3L2 complexes act as sponges, taking up 1,2-dichorobenzene or iodine in a single-crystal-to-single-crystal fashion despite not exhibiting conventional porosity.

The C3-symmetric chiral propylated host-type ligands (±)-tris(isonicotinoyl)-tris(propyl)-cyclotricatechylene (L1) and (±)-tris(4-pyridyl-4-benzoxy)-tris(propyl)-cyclotricatechylene (L2) self-assemble with PdII into [Pd6L8] 12+ metallo-cages that resemble a stella octangula. The self-assembly of the [Pd6(L1)8]12+ cage is solvent-dependent; broad NMR resonances and a disordered crystal structure indicate no chiral self-sorting of the ligand enantiomers in DMSO solution, but sharp NMR resonances occur in MeCN or MeNO2. The [Pd 6(L1)8]12+ cage is observed to be less favourable in the presence of additional ligand, than is its counterpart, where L=(±)-tris(isonicotinoyl)cyclotriguaiacylene (L1a). The stoichiometry of reactant mixtures and chemical triggers can be used to control formation of mixtures of homoleptic or heteroleptic [Pd6L8] 12+ metallo-cages where L=L1 and L1a. All sorted: Stella octangular [Pd6L8]12+ metallo-cages with chiral propylated cyclotriveratrylene-type ligands exhibit homochiral self-sorting in MeCN or MeNO2 but not in DMSO. Furthermore, differences in the favourability of the metallo-cage with propylated or methylated ligands can be used to control speciation in solution from heteroleptic to predominantly single homoleptic to dual homoleptic metallo-cages.

Three diplatinum(II) complexes [{PtL}2(μ-thea)] (H4thea=2,3,6,7-tetrahydroxy-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene) have been prepared, with diphosphine or bipyridyl “L” co-ligands. One-electron oxidation of these complexes gave radical cations containing a mixed-valent [thea ]3− ligand with discrete catecholate and semiquinonate centers separated by quaternary methylene spacers. The electronic character of these radicals is near the Robin–Day class II/III border determined by UV/Vis/NIR and EPR spectroscopies. Crystal-structure determinations and a DFT calculation imply that oxidation of the thea4− ligand may lead to an increased through-space interaction between the dioxolene π systems.

A novel series of metal–organic frameworks (MOFs) based on Ag(I) and the nitrogen-bridging ligand 1,4-diazabicyclo[2.2.2]octane (dabco) along with the incorporation of distinct carbaborane anions were synthesized and isolated as crystalline materials. Single-crystal X-ray diffraction analysis unveiled novel materials formulated as [Ag(dabco)][Cobdc] (1), [Ag(dabco)(PhCB9H9)] (2), [Ag(dabco)(PhCB9H8I)] (3), and [Ag(dabco)(PhCB11H5I6)] (4), which were further characterized by Fourier-transform infrared spectroscopy and elemental analysis. Interestingly, despite the use of distinct carbaborane anions, all the materials feature one-dimensional (1D) coordination networks with most of the bulky anions, particularly all the phenyl-carbaborane anion [PhCB9H9]−, [PhCB9H8I]−, and [PhCB11H5I6]−, incorporated in the coordination networks through Ag···H–B coordinative interactions or Ag···I–B coordination bonds. However, the influence of the distinct carbaborane anions is clearly reflected in the coordination features...

A series of [4]pseudorotaxanes composed of three-way axle threads based on the cyclotriguaiacylene family of crown-shaped cavitands and three threaded macrocyclic components has been achieved. These exploit the strong affinity for electron-poor alkyl-pyridinium units to reside within the electron-rich cavity of macrocycles, in this case dimethoxypillar[5]arene (DMP). The branched [4]pseudorotaxane assemblies {(DMP)3∙L}3+,where L = N-alkylated derivatives of the host molecule (±)-tris-(isonicotinoyl)cyclotriguaiacylene, were characterised by NMR spectroscopy and mass spectrometry, and an energy-minimised structure of {(DMP)3∙(tris-(N-propyl-isonicotinoyl)cyclotriguaiacylene)}3+ was calculated. Crystal structures of N-ethyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate and N-propyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate each show ‘hand-shake’ self-inclusion motifs occurring between the individual cavitands.

Trigonal bipyramidal metallo-cage species [Pd3(dppp)3(L)2]∙6OTf (where dppp = bis(diphenylphosphino)propane, OTf = triflate and L is tris(iso-nicotinoyl)cyclotriguaiacylene (L1) or tris(fluoro-iso-nicotinoyl)cyclotriguaiacylene (FL1)) have been characterised in solution to exist predominantly as the anti-isomers. The crystal structure of [Pd3(dppp)3(FL1)2]∙6OTf, however, was found to be the achiral syn-isomer. The complex [Pd3Cl3(L2)2] (where L2 = tris(methylbenzimidazolyl)cyclotriguaiacylene) is a trans-linked M3L2 cage, observed by mass spectrometry and in the solid state as the anti-isomer. Ligand L2 also forms a 1:1 co-crystal with cyclotriguaiacylene.

Pyridyl functionalized host molecules are oxidized to their N-oxide analogues and form a series of coordination polymers and discrete complexes with transition metal cations. Complex {[Ag(3)(NMP)(6)(L1)(2)]·3(ClO(4))}(∞) where L1 = tris(isonicotinoyl-N-oxide)cyclotriguaiacylene, NMP = N-methylpyrrolidone, is a three-dimensional (3-D) 3,6-connected coordination polymer of pyrite-like (pyr) topology and features ligand unsupported argentophilic interactions, while two-dimensional (2-D) 3,6-connected coordination polymers with the rarely reported kagome dual (kgd) topology are found for [M(L1)(2)](2+) where M = Zn, Cd, Cu. Ligand L2 = tris(nicotinoyl-N-oxide)cyclotriguaiacylene forms a 2-D coordination polymer with 4(4) (sql) grid topology in complexes {[M(L2)(2)(DMF)(2)]·2ClO(4)·8(DMF)}(∞) M = Cd or Cu, DMF = N,N'-dimethylformamide, and a double-linked chain structure in {[Co(L2)(2)(DMF)(2)]·2NO(3)·4(DMF)·H(2)O}(∞), and both types of structure feature hand-shake self-inclusion motifs either within or between the polymers. 2-D coordination networks with 6(3) (hcb) topologies are found in complexes {[M(L3)(NO(3))(2)]·2(DMF)}(∞) (M = Cd, Zn) and {[Cu(5)(L3)(2)Cl(10)(NMP)(4)]}(∞) where L3 = tris(2-pyridylmethyl)cyclotriguaiacylene, while [Ag(2)(L3)(2)(NMP)(4)]·2(BF(4))·2(NMP) has a discrete dimeric structure which again shows hand-shake host-guest interactions supported by π-π stacking.

In this article, we report the synthesis, solid-state and solution-state conformational studies of O-alkylated aromatic benzamides based on two scaffolds. Intramolecular hydrogen bonding provides conformational pre-organization and side chains can interact with each other within a molecule. In the solid-state three-dimensional arrangement, the molecules further interact with each other through non-covalent interactions. Given, the demonstrated potential of this class of scaffolds to act as helix mimetics for the inhibition of protein–protein interactions (PPIs), these results provide key insight for future inhibitor design.

Transition metal complexes of the ligand 2,2′-bipyridine-4,4′-diamine (bpy4da) form three-dimensional (3D) hydrogen bonding networks with the [M(bpy4da)3]2+ species, a hydrogen donor metallo-tecton with carboxylate counteranions as hydrogen bond acceptors within the complexes [[Ni(bpy4da)3]·(Hbpc)(bpc)0.5(dmf)n, [Ni(bpy4da)3].(bpc)(dmf)n, and [Ni(bpy4da)3]·(Htma)·4(dmf) where H2bpc = biphenyl-4,4′-dicarboxylic acid, H3tma = trimesic acid, and dmf = dimethylformamide. Terephthalate, on the other hand, bridges between Cu(II) centers in complexes [Cu2(bpy4da)4(tpa)]·2(NO3)·5(dmf) and [Cu2(bpy4da)4(tpa)]·2(NO3)·4.5(dmf)·(H2O) (where H2tpa = terephthalic acid) whose structures both feature different 3D hydrogen bonded networks. The crystal structures of hydrated [Cd(bpy4da)3]·2Cl and [Co(bpy4da)2(NO3)]2·2(NO3)·4.5(dmf) are also reported.

Artificial allosterism: A ditopic ligand, which contains both bipyridine and tetra-aza-crown binding sites, coordinates one Cu(II) through all four N-donors of the tetradentate aza-crown unit. Reaction at the bipyridine site with another Cu(II) allosterically changes the aza-crown from being a tetradentate to a tridentate N-donor unit, a change in coordination mode that causes the successive binding of two Cu(II) ions to proceed with severe negative cooperativity (see scheme).

Five new coordination polymers based on a new 2,2'-bipyridine derived ligand N,N'-bis(pyridin-4-yl)-2,2'-bipyridine-5,5'-dicarboxamide (=L) are reported herein. Isostructural three-dimensional coordination polymers with a rare (4,6)-connected network of {4(4).6(2)}(3){4(6).8(9)}(2) topology were synthesised from Cu(NO(3))(2), Zn(NO(3))(2) or a mixture of Cu(NO(3))(2)/Fe(BF(4))(2) with L in complexes {[Cu(5)L(6)]·(NO(3))(10)·(H(2)O)(18)}(∞) (1), {[Zn(5)L(6)]·(NO(3))(10)·(H(2)O)(18)}(∞) (2) and {[Fe(x)Cu(y)L(6)]·(NO(3))(10)·(H(2)O)(18)}(∞) (3; where x+y=5). Complexes with two-dimensional grid structures resulted from treatment with CoCl(2) or Cd(NO(3))(2) with L in complexes {[CoLCl(2)]·DMF}(∞) (4) and {CdL(NO(3))(2)}(∞) (5).

Dark blue [CTC]2·(TCNE)·6THF and dark green [CTC]2·(TCNQ)·4THF are both exclusion complexes, with the cyanoalkene acceptor being sandwiched between the catechol rings of two cyclotricatechylene (CTC) host molecules. There is also extensive hydrogen bonding between the CTC and tetracyanoethene (TCNE) or tetracyanoquinodimethane (TCNQ) molecules, which is unusual for crystals containing these cyanoalkenes. Crystallographic, IR and UV–vis data show that these are typical donor–acceptor complexes, with strong charge–transfer interactions between the CTC and cyanoalkene acceptors. These are the first donor–acceptor complexes of a cyclotriveratrylene (CTV)-derived host, and the first crystallographically characterised adducts between TCNE or TCNQ and an organic cavitand. The solvate CTC·3.5THF·0.5H2O adopts a novel nanoporous crystal lattice, composed of undulating hydrogen-bonded sheets of CTC molecules. In contrast, the clathrates CTC·2EtOH, CTC·3DMA and CTC·5DMSO all adopt structures that are related to prev...

Cyclotriveratrylene (CTV) and related C3-symmetric hosts are host molecules with a pyramidal shape and electron-rich molecular cavities. Appropriately functionalized CTV derivatives can self-assemble into nano- scale cage-like assemblies through metal–ligand interactions or hydrogen bonding. Examples of such assemblies include metallo-cryptophanes and hydrogen bonded capsules, M4L4 and M4L6 tetrahedra, M6L8 stella octangulas, along with cages with unusual topological features.

Tris-allyl-cyclotriguaiacylene combines with silver salts to give a range of crystalline network structures and one discrete complex. A number of different coordination modes are found within the complexes including η(2)-allyl, aryl, and OR groups binding to Ag(I). AgSbF(6) gives two types of three-dimensional (3-D) coordination polymer with unusual topologies, along with a discrete Ag(2)L(2) capsule dependent on reaction stoichiometry and reaction conditions. Isostructural coordination chain structures are found with AgBF(4) and AgClO(4), while use of Ag(CF(3)SO(3)) gives two-dimensional (2-D) and 3-D coordination polymers through bridging triflate anions.

New chemistry of the cyclic molecular host cyclotriveratrylene (CTV) includes applications such as in sensors and separations; in self-organised materials such as gels, liquid crystals, dendritic systems, and self-assembled monolayers; and in metallo-supramolecular chemistry. This tutorial review covers aspects of CTV chemistry interest to supramolecular, coordination and host-guest chemists as well as those interested in self-organised systems.

Metallosupramolecular chemistry relies on self-assembly processes in which complicated species form through labile dative-covalent interactions. Two remarkable areas of this chemistry are the synthesis of topologically complicated threaded assemblies and of three-dimensional (3D) polyhedral assemblies. Very few polyhedral 3D metallosupramolecular assemblies show threaded motifs within them. Here we report an example of a new type of threaded 3D metallosupramolecular assembly built from four organic ligands and four palladium ions, a Pd(4)L(4) so-called 'Solomon's cube' in which interweaving and twisting of the ligands form both Solomon's links and figure-of-eight ring motifs. In the solid state, six of these Pd(4)L(4) tetramers assemble into a hollow spheroid that closely resembles a stellated truncated hexahedron.

A series of ligands LPh, Lnaph and Lanth, which contain two bidentate pyrazolyl–pyridine termini separated by an aromatic (1,2-phenyl, 2,3-naphthyl or 2,3-anthracenyl, respectively) spacer have been used to prepare tetrahedral cage complexes of the form [M4L6]Xn, in which a bis-bidentate bridging ligand spans each of the six edges of the M4 tetrahedron and one anion is bound in the central cavity. Several new examples have been structurally characterised, including an example with a new ligand (Lanth), the first example with a second-row transition metal ion [Cd(II)], and the first example of a cage containing a dianionic guest (hexafluorosilicate). The series of structurally similar Co(II) complexes [Co4L6(BF4)](BF4)7 (L = LPh, Lnaph and Lanth) have been examined in detail by NMR spectroscopy. The 1H NMR spectra are highly shifted between −110 and +90 ppm, but the spectra can be completely assigned by correlation of measured T1 relaxation times with distances of the protons in the complexes from the paramagnetic Co(II) centres. 1H DOSY measurements have been used to estimate diffusion constants which confirm the structural integrity of the cages in solution, and 19F DOSY measurements on the anions show that (i) the trapped [BF4]− anion diffuses at the same rate as the cage superstructure surrounding it, indicating that it is trapped inside the cage cavity; and (ii) the ‘free’ [BF4]− anions have diffusion rates consistent with substantial retardation due to ion-pairing with the 7+ complex cation.

The crystalline compounds (Hbipy) 2 [Ge(C 2 O 4 ) 3 ] ( 1 ) and (Hphen) 2 [Ge(C 2 O 4 ) 3 ] · 2(H 2 O) ( 2 ) [Hbipy + is the 2,2′-bipyridinium cation (C 10 H 9 N 2 ), and Hphen + is the 1,10′-phenathrolinium cation (C 12 H 9 N 2 )] were isolated from mild hydrothermal syntheses and their structures were elucidated from single-crystal X-ray diffraction. The two compounds were further characterised by vibrational spectroscopy (FT-IR and FT-Raman), thermogravimetric analysis (TGA) and CHN elemental composition. Compounds 1 and 2 comprise the tris(oxalato-O,O′)germanate dianion complex, [Ge(C 2 O 4 ) 3 ] 2− , which co-crystallises with Hbipy + (in 1 ), or Hphen + and water molecules (in 2 ). In 1 , the germanium oxalate anionic complex, [Ge(C 2 O 4 ) 3 ] 2− , and the Hbipy + organic residues interact mutually via N–H⋯O hydrogen bonding interactions, leading to supramolecular discrete hydrogen-bonded units which are further interconnected via π–π stacking. Compound 2 , on the other hand, exhibits a more complex hydrogen bonding network due to the presence of the water molecules of crystallisation which, along with π–π stacking between neighbouring Hphen + residues, mediate the crystal packing.

Complexes [Cu(phenpyzda)Cl2(H2O)]·H2O (1) and [Cu(phenpyzda)Br2(H2O)]·2H2O (2), where phenpyzda = pyrazino[2,3-f][1,10]phenanthroline-2,3-diamide, show similar molecular structures with square planar Cu(II). Each complex has a complicated three-dimensional (3D) hydrogen bonding network with 1 having an unusual 3,9-connectivity. Use of the corresponding carboxylic acid, pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarboxylic acid, results in the unexpected conversion of the ligand to 1H,3H-imidazol[2,3-f][1,10]phenanthroline (= imiphen) in the complex [CuCl3(imiphenH)]·2H2O, which has a 3D hydrogen bonded network structure of 3,6-connectivity. The more extended phenanthroline-based ligand 1,10-phenanthroline-5,6-[pteridine-2,4-diamine] was also synthesized, but no crystalline complexes of it were isolated. [Cu(bpy4diol)2](NO3)2·H2O (4), where bpy4diol = 2,2′-bipyridine-4,4′-diol, shows a two-dimensional (2D) hydrogen bonded network with hexagonal topology. [Cu(bpy4da)(NO3)2] (5) where bpy4da = 2,2′-bipyridine...

The hydrothermal synthesis and structural characterization of a number of complex compounds containing the divalent tris(oxalato-O,O¢)germanate anion, [Ge(C2O4)3]2-, or the neutral bis(oxalate-O,O¢)germanium fragment, [Ge(C2O4)2], with transition-metal (M) cationic complexes of 1,10¢-phenanthroline (phen) is reported: [M(phen)3]- [Ge(C2O4)3]âxH2O [where M2+ ) Cu2+ (1a and 1b), Fe2+ (2a and 2b), Ni2+ (3), Co2+ (4); x ) 0.2 for 2b], [MGe- (phen)2(í2-OH)2(C2O4)2] [where M2+ ) Cd2+ (5) and Cu2+ (6)]. The isolation of two polymorphs with Cu2+ (1a and 1b) and other pseudo-polymorphs for Fe2+ (2a and 2b) was rationalized based on slightly different molar ratios for the starting materials. All compounds have been characterized using EDS, SEM, vibrational spectroscopy (FT-IR and FT-Raman), thermogravimetry, and CHN elemental composition and their structure determined on the basis of single-crystal X-ray diffraction studies. The crystal packing of the different chemical moieties for each series of compounds was discussed on the basis of the various intermolecular interactions present (strong C-Hâââð and weak C-HâââO hydrogen-bonding interactions, C-Hâââð and ð-ð contacts). FCT - SFRH/BPD/9309/2002 FCT - SFRH/BPD/14410/2003 FEDER POCI - 2010

A series of new silver/4,4'-bipyridine [Ag(I)/bpy] and silver/2,3-bis-(2-pyridyl)pyrazine [Ag(I)/bppz] crystalline complexes with the C-phenyl-carbaborane anion [PhCB 9 H 9 ]- and the halogenated C-phenyl-carbaborane (HPC) anions [PhCB 9 H 8 Br] - , [BrC 6 H 4 CB 11 H 11 ]-, [PhCB 9 H 4 I 5 ] - , and [PhCB 11 H 5 I 6 ] - has been prepared and characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction analysis. While {Ag(bppz)[PhCB 9 H 8 Br]} (6) has been isolated as a discrete dimeric complex, all the remaining complexes feature 1D polymeric coordination chains. Among these 1D coordination chains, only [Ag-(bpy)][PhCB9H9](CH3CN) (1) and [Ag2(bppz)3][BrC 6 H 4 CB 11 H 11 ] 2 (CH3CN) (5) exhibit structures where the carbaborane anions act as simple counteranions and thus are not involved directly in the coordination network. In all the other species, significant framework-construction interaction of the silver center with the {BH} or {BI} units of the carbaborane anions is observed. Interestingly, in complex {Ag(bppz)[PhCB 9 H 9 ]} (CH 3 CN) 0.5 (4) the Ag(I) center has an octahedral geometry with two Ag···H-B interactions between the silver atom and phenyl-carbaborane anion. The influence of the carbaborane anions on the structural features of coordination chains is analyzed and discussed, and the preparation of the [NEt 4 ] + salts of the [PhCB 9 H 8 Br]-, [BrC 6 H 4 CB 11 H 11 ] - and [PhCB 9 H 4 I 5 ] - anions is also presented.

The complex [Co(bpydiol-H)3]·H2O, where bpydiol is 2,2′-bipyridine-3,3′-diol, features a simple octahedral tris-chelate complex that forms a honeycomb-like six-connected 3-D network of 4966 topology through weak C–H⋯O hydrogen bonding. The network shows significant channels and the material is remarkably robust. The water guest molecules can be solvent exchanged for 1,2-dibromobenzene molecules. Cu(II) complexes of bpydiol are also reported: [Cu(bpydiol-H)X], where X = Cl−, Br−, or NO3−, which all have coordination chain structures. The coordination chains in [Cu(bpydiol-H)(NO3)] assemble through weak CH..ONO2 hydrogen bonds to form a corrugated 2-D network.

A review of the emerging field of cyclotriveratrylene-derived coordination cages is presented. Ligand-functionalised cyclotriveratrylene (CTV) derivatives self-assemble with a range of metal cations to afford coordination cages, polymers and topologically non-trivial constructs, such as [2]catenanes and a self-entangled cube. Increased control over their self-assembly allows for the controlled and predictable formation of well-defined coordination cages for application in host–guest and recognition chemistry, with surfactant binding and single-crystal-to-single-crystal (SCTSC) uptake of small-molecule guests being observed.

The use of carboranes as counter-anions for metal-organic frameworks or coordination polymers is reviewed. While carboranes are weakly coordinating they can form interactions to Ag(I) as well as other metal centers. Thus carboranes may have one of a number of roles in transition metal networks: as a non-coordinating templating counter-anion; as a bulky terminal ligand, and thus topologically trivial but likely to be structure-directing to some degree; or as a bridging ligand.

A series of three-dimensional (3-D) hydrogen-bonded structures of lanthanide aquo ions and 4,4'-bipyridine (bpy) or protonated bpyH + as ligands and hydrogen-bonding tectons have been characterized by single-crystal X-ray crystallography, with both Cl - and [Co(C 2 B 9 H 11 ) 2 ] - counteranions. All show related structures with unidirectional rectangular channels filled by additional bpy molecules for the complexes [Yb(H 2 O) 8 ](bpy) 2.5 Cl 3 ·6.5(H20) and [Yb(H20)8]4(bpy) 9.5 Cl 12 ·24.5(H20) or by [Co(C 2 B 9 H 11 ) 2 ] - anions for the complexes [Ln(bpy)(H20)8]2(bpy) 10 [Co(C 2 B 9 H 11 ) 2 ] 6 ·1.5(EtOH)·15(H20) where Ln = La, Ce, [Sm(H 2 O) 5 (bpy)2(EtOH)]-[Sm(H20)6(bpyH)(EtOH)](bpyH)(bpy) 10 [Co(C 2 B 9 H 11 ) 2 ] 8 ·EtOH·9(H20), and [Ln(H20)6(bpy)(bpyH 0.5 )] 2 [Ln(H20)7(bpy)](bpyH)2-(bpy)i4[Co(C 2 B 9 H 11 ) 2 ] 12 ·n(EtOH)·5(H20) where Ln = Gd, Tb, and Ho. The smaller (CB 11 H 12 )- anion does not template a similar structure; instead the complex [(bpyH)3(bpy)(CB 11 H 12 ) 3 ] is isolated with a one-dimensional (1-D) hydrogen-bonded ladder structure.

Cyclotriveratrylene (CTV) derived host molecules with ethyl, propyl, allyl or propargyl functional groups have been synthesised using standard or solventless reaction methodologies. The known structural and clathrate chemistry of cyclotriveratrylene (CTV) and these analogues has been extended. Crystal structures of the hexa(ethyl), tri(ethyl), tri(propargyl) analogues have been determined, and show either intra-cavity host-guest binding or self-stacking motifs. Two new clathrates of CTV have also been structurally characterised, namely CTV.(DMSO)2.(H2O)2 with intra-cavity complexation of DMSO, and CTV.(EtOH)0.25 which has a γ-phase CTV structure.

The extended structures of transition metal complexes of the phenanthroline-based ligand 6,7-dicyanodipyridoquinoxaline (dicnq) are reported, including the mixed ligand complex [{Cu(dicnq)Br}2H2btca] 1.7(CH 3 OH), where H 2 btca = doubly deprotonated 1,2,4,5-benzenetetracarboxylic acid, which shows 1-D coordination chains that organize into a 2-D net through hydrogen bonding. [Cu(dicnq)Br 2 ] has square-pyramidal geometry and forms 1-D zigzagging coordination chains that pack into a 2-D herringbone motif. In complex [Ni(dicnq)3]Br2·3H 2 O, the octahedral complex cations show unusual CN···π interactions and form a porous 3-D structure. Both complexes [Co(dicnq) 2 Br 2 ] and [Cu(dicnq) 2 Br 2 ][Cu(dicnq) 2 Br]Br·(CH 3 CN)-2(H 2 0) show roughly octahedral complexes that show weak C-H···N hydrogen bonding along with π-π stacking interactions to form 3-D network structures such as a 3-fold interpenetrating diamondoid structure. Complex [Ag(dicnq) 2 ](CF 3 SO 3 ) forms zigzagging chains through π-π stacking interactions.

The crystalline complex {Ag3[Tris(2-pyridylmethyl)cyclotriguaiacylene] 2 }(PF6)3 has been synthesized and shown by X-ray crystallography to have a disordered three-dimensional cubic coordination network structure. The coordination network features a back-to-back stacking of the molecular host-type ligands into tetrahedral clusters, and the PF 6 - anions act as both intracavity guests and lattice-type guests. Disentangling the network disorder gives a 4-fold interpenetrating (10,3)-a net.

Crystals of γ- and ∊-hexanitrohexaazaisowurtzitane (γ- and ∊-HNIW, space groupP21/nfor both crystals) have been investigated in the 100–298 K temperature range using single-crystal X-ray diffraction techniques. Temperature-dependent changes of their crystal lattices have been evaluated from the second-rank thermal expansion tensors. Both lattices undergo anisotropic thermal expansion, that of γ-HNIW being more anisotropic than that of the ∊ phase. Comparison with previously reported predictions from molecular dynamics calculations indicates significant differences. Although there are many short (less than van der Waals) intermolecular interactions in both polymorphs, there is no obvious relationship between the short distances and the difference in thermal expansion behavior. Non-linear temperature dependence of the atomic displacement parameters is indicative of anharmonicity of the crystal mean field potential.

Exploration into the host-guest supramolecular chemistry of p-sulfonatocalix[6]arene with pyridine N-oxide and 4,4'-dipyridine N,N'-dioxide has resulted in the characterization of three new structural motifs with the calixarene in the "up-down" double partial cone conformation. Two are hydrogen-bonded network structures formed with pyridine N-oxide and either nickel or lanthanide metal counterions (1 and 2, respectively). Complex 1 displays host-guest interactions between pyridine N-oxide and the calixarene in the presence of hexaaquanickel(II) counterions. Complex 2 demonstrates selective coordination modes for different lanthanides involving the calixarene and pyridine N-oxide. The third structure, 3, is a coordination polymer which is formed with 4,4'-dipyridine N,N'-dioxide molecules which span a hydrophilic layer and join lanthanide/p-sulfonatocalix[6]arene fragments. Although complexes 1-3 all have the calixarene in the "up-down" double partial cone conformation, 1 and 3 form bilayer arrangements within the extended structures while 2 forms a previously unseen corrugated bilayer arrangement.

A previously elusive “molecular capsule” and various other structural motifs incorporating p-sulfonatocalix[4]arene are accessible by controlling the pH and by varying the stoichiometry of the calixarene relative to potential guest molecules and trivalent metal ions. The “molecular capsule” has monoprotonated 1-aza-18-crown-6 shrouded by two calixarenes, which hydrogen bond to aquated lanthanide ions. In contrast, the presence of 1-aza-15-crown-5 forms a complex devoid of the crown ether, with lanthanide ions directly bound to sulfonate groups. Also reported are a coordination polymer incorporating monoprotonated 1,4-diazabicyclo[2.2.2]octane in the cavity of one calixarene which forms chelate rings to lanthanide ions and the structure of a capsule with 4,13-diaza-18-crown-6 surrounded by two calixarenes which hydrogen bond to homoleptic aquated trivalent gallium ions.