Inclusion compounds of the copper(<Emphasis Type="SmallCaps">ii</Emphasis>) and zinc(<Emphasis Type="SmallCaps">ii</Emphasis>) complexes with cyclam in cucurbit[8]uril: synthesis and structure

Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8], C₄₈H₄₈N₃₂O₁₆) with the copper(ii) and zinc(ii) complexes with the tetraazamacrocyclic ligand cyclam, {[Cu(cyclam)(H₂O)₂]@CB[8]}Cl₂·18H₂O (1) and {[Zn(cyclam)]@CB[8]}Cl₂·13H₂O (2), were synthesized. The compounds were characterized by X-ray diffraction analysis, electrospray mass spectrometry, IR spectroscopy, and elemental analysis. The ¹H and ¹³C NMR method revealed only one trans-isomer of the zinc(ii) complex with cyclam in an aqueous solution of inclusion compound 2.     

Inclusion of nickel(<Emphasis Type="SmallCaps">II</Emphasis>) and copper(<Emphasis Type="SmallCaps">II</Emphasis>) complexes with aliphatic polyamines in cucurbit[8]uril

The inclusion compound of macrocyclic cavitand cucurbit[8]uril (CB[8]) with the nickel(II) complex containing the tetraazamacrocyclic ligand cyclam, {[Ni(cyclam)]@CB[8]}Cl₂··16H₂O (1), and the inclusion compounds of CB[8] with the copper(II) bis-ethylene-diamine complex, {trans-[Cu(en)₂(H₂O)₂]@CB[8]}Cl₂·{CB[8]}·42H₂O (2a) and {trans-[Cu(en)₂(H₂O)₂]@CB[8]}Cl₂·17H₂O (2b), were synthesized and characterized by X-ray diffraction analysis, IR and ESR spectroscopy, and electrospray mass spectrometry. Guest—host inclusion compounds can be directly synthesized starting from a metal complex and cucurbit[8]uril, as was exemplified by the preparation of compounds 2a and 2b.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2414–2419, November, 2004.     

Synthesis and guest exchange reactions of inclusion compounds of cucurbit[8]uril with nickel(II) and copper(II) complexes

Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8]) with the nickel(II) complex, {trans-[Ni(en)₂(H₂O)₂]@CB[8]}Cl₂ · 23.5H₂O, the copper(II) complex, {2[Cu(dien)(bipy)(H₂O)]@CB[8]}(ClO₄)₄ · 11H₂O, and the organic molecules, 2(pyCN)@CB[8]} · 16H₂O and {2(bpe)@CB[8]} · 17H₂O, where bipy is 4,4′-bipyridyl, pyCN is 4-cyanopyridine, and bpe is trans-1,2-bis(4-pyridyl)ethylene, were synthesized. The inclusion compounds with organic molecules were synthesized starting from inclusion compounds of cucurbit[8]uril with cyclam and ethylenediamine complexes of copper(II) and nickel(II) by the guest exchange method, which is based on the replacement of one guest with another in the cavity of the cavitand The resulting compounds were characterized by X-ray diffraction, ESR, ¹H NMR, IR, and electronic absorption spectroscopy, and electrospray mass spectrometry. Photochemically induced [2+2]-cycloaddition of two 1,2-bis(4-pyridyl)ethylene molecules included in cucurbit[8]uril was studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 25–34, January, 2006.     

Cucurbit[8]uril-based inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with cyclam and cyclen as guest molecules: Synthesis and crystal structures

New inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with the cyclic polyamine ligands cyclam and cyclen in the macrocyclic cavitand cucurbit[8]uril (CB[8]) were obtained: {trans-[Fe(Cyclam)(CO)(OCHO)]@CB[8]}Cl · 15H₂O, {cis-[Co(Cyclen)(H₂O)Cl]@CB[8]}Cl₂ · 20H₂O, and {cis-[Ni(Cyclen)(H₂O)Cl]@CB[8]}Cl · 12H₂O. According to X-ray diffraction data, the complexes are in the cavity of each CB[8] molecule. The complexes of the above molecular formulas were isolated in the solid state as supramolecular compounds with CB[8] and structurally characterized for the first time.     

Formation of aqua and tetraammine Cu(II) complexes inside the cavities of cucurbit[6,8]urils: A DFT forecast

Results of DFT calculations of the structure and thermodynamics of formation of aqua and tetraammine Cu(II) complexes inside CB[n] (n = 6,8) are presented in this study. Formation thermodynamics of the complexes in the cavitands was evaluated by taking into account the most probable number of water molecules inside CB[n]. In this methodology, the complexation was first considered as a substitution reaction in which the guest complex displaces partially or completely the water molecules that are located inside the cavity. The water molecules present in the cavitand were shown to play an important role in the fixation of the guest complex inside the cavity due to the hydrogen bonds with the oxygen portals. The hydration of Cu(II) ion inside CB[6] leads to the formation of an inclusion compound with the formula {[Cu(H₂O)₄]²⁺·2H₂O}@CB[6] while in CB[8] {[Cu(H₂O)₆]²⁺·4H₂O}@CB[8] is formed. For the binding of tetraammine Cu(II) complex, CB[8] was determined to be a significantly more suitable “container” than CB[6]. Both a direct embedding of this complex into the CB[8] and another mechanism in which ammonia molecules replace the water molecules in the Cu(II) aqua complex, preexisting in CB[8] were determined to be thermodynamically possible. Both these lead to the formation of the resultant inclusion compound described by the formula {[Cu(NH₃)₄(H₂O)₂]²⁺·4H₂O}@CB[8].     

Synthesis and crystal structure of [Na2(μ-H2O)(H2O)CB[5]]Cl2 · 6H2O, [Na3(μ-H2O)4(H2O)4(CNPy@CB[6])]Cl3 · 8H2O, and [Rb2(μ-H2O)2(CNPy@CB[6])]Cl · 8H2O

The chain coordination polymers [Na₂(μ-H₂O)(H₂O)CB[5]]Cl₂ · 6H₂O (I), [Na₃(μ-H₂O)₄(H₂O)₄(CNPy@CB[6])]Cl₃ · 8H₂O (II), and [Rb₂(μ-H₂O)₂(CNPy@CB[6])]Cl₂ · 8H₂O (III) were prepared by heating (110°C) of a mixture of sodium or rubidium chloride, cucurbit[n]uril (CB[n], where n = 5, 6), 4-cyanopyridine, and water. According to X-ray diffraction data, binding of polynuclear cations with CB[n] in I–III occurs through coordination of the oxygen atoms of the cucurbit[n]uril portals to alkali metal atoms. Complexes I–III of the above composition isolated to the solid phase as supramolecular compounds with CB[n] were structurally characterized for the first time.     

Anion encapsulation by Ln(III)/K(I) heterobismetal-capped cucurbit[5]uril

Three Ln(III)/K(I) (Ln = La, Ce and Nd) heterobismetal-capped cucurbit[5]uril molecular capsules, {[LaK(C₃₀H₃₀N₂₀O₁₀)Cl]Cl(H₂O)₃}Cl₂·8H₂O (1), {[CeK(C₃₀H₃₀N₂₀O₁₀)Cl]Cl(H₂O)₃}Cl₄(H₃O)₂ ^2 + ·8H₂O (2) and {[NdK(C₃₀H₃₀N₂₀O₁₀)Cl]Cl(H₂O)₃}Cl₂·12.5H₂O (3), were synthesised by self-assembly in aqueous solution, and their anion encapsulation property was confirmed by X-ray crystallography. The effect of the lanthanide cation radius on the structure of the heterobismetal-capped cucurbit[5]uril molecular capsules has been investigated.     

Thermal transformations of the supramolecular compound of cucurbit[8]uril with cobalt(III) complex {<Emphasis Type="Italic">trans</Emphasis>-[Co(en)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>]@CB[8]}Cl·17 H<Subscript>2</Subscript>O

The thermal decomposition of hydrated cucurbit[8]uril C₄₈H₄₈N₃₂O₁₆·20H₂O (CB[8]) and the inclusion compound of cucurbit[8]uril with cobalt(III) complex {trans-[Co(en)₂Cl₂]@CB[8]}Cl·17 H₂O was studied in the inert atmosphere by TG, TM, and DSC methods. The dehydration of (C₄₈H₄₈N₃₂O₁₆)·20H₂O (at 320–390 K), and the decomposition of cucurbituril itself (at 620–720 K) are accompanied by a decrease in the sample volume. The inclusion compound loses water molecules at 320–380 K; dehydration is accompanied by an increase in the sample volume. The decomposition (pyrolisis) of the anhydrous compound takes place at 620–720 K; the decomposition is forestalled by a continued increase in the sample volume with an endothermic peak (490–600 K), and only the mass loss (620–720 K) is accompanied by a decrease in the sample volume. The included guest complex does not lose amines until the decomposition process is complete; the previously observed increase in the sample volume is explained by the expansion of cavitand molecules due to a distortion of the included [Co(en)₂Cl₂]⁺ complex on heating.     

New lanthanide-based complexes constructed from cucurbit[6]uril: Synthesis,structures and properties

Three lanthanide-based complexes, {Gd₂(H₂O)₁₀(CB[6])₂}·CB[6]·6Cl·12H₂O (1), {[Gd₂(H₂O)₈CB[6]₂]·(CuCl₄)·4Cl·46H₂O}_n (2), and {Dy₂(NO₃)₂(H₂O)₁₀(CB[6])}·4NO₃·14H₂O (3) (CB[6] = cucurbit[6]uril), were prepared with cucurbit[6]uril (CB[6]). These complexes were characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, UV–Vis spectroscopy, thermogravimetric analysis and magnetization measurements. Crystallographic results showed that 1 and 3 are dinuclear and crystallize in the triclinic space group Pī, whereas 2 is a 1-D zigzag supramolecular chain that crystallizes in the monoclinic system in C2/c. The results indicated that temperature has a big effect on the supramolecular assemblies and a different structure inducer also leads to the formation of different coordination polymers. Frequency dependence in the ac susceptibility signals was observed in 3.     

二甲基取代五元瓜环与钾离子和钆离子的配位结构

利用X-射线单晶衍射技术表征了2个二甲基取代五元瓜环(DMeQ[5])与金属离子形成的配合物的晶体结构,2个配合物分别为{[K2(H2O)3DMeQ[5]}I2.5H2O(1)和{[Gd(H2O)3][K(H2O)][(NO3)@DMeQ[5]]}(NO3)3.5H2O(2)。与DMeQ[5]和钆离子形成的配合物的结构不同的是,配合物1和2中每个DMeQ[5]端口的所有羰基氧原子都和钾离子或钆离子配位,形成全封闭结构。     

Water structuring inside the cavities of cucurbit[n]urils (n = 5–8): a quantum-chemical forecast

In this work we report findings of the quantum-chemical examination of water structuring in the cavities of cucurbit[n]urils (CB[n]), n?=?5–8 obtained within the density functional theory. The thermodynamically most stable structures of inclusion compounds (H₂O)_m@CB[n] were determined for different numbers m of H₂O molecules inside the cavities. From the viewpoint of thermodynamics, the most probable numbers m of water molecules in the CB[n] homologues are the following: m?=?2 for CB[5], m?=?4 for CB[6], m?=?8 for CB[7] and m?=?10 for CB[8]. For the case of CB[6] synthesized in aqueous solution, we compared its experimental IR spectrum with that calculated quantum-chemically for the model inclusion systems (H₂O)_m@CB[6] where m ranges from 1 to 6. The best agreement between the experimental and theoretical spectra was observed for (H₂O)₄@CB[6], in complete agreement with the conclusion made based on the thermodynamic estimations. Our results are also in good agreement with other available estimates of the most probable number of water molecules in CB[n].     

Metal ion-assisted assembly of one-dimensional polyrotaxanes incorporating cucurbit[6]uril

Three cucurbit[6]uril (CB[6])-based polyrotaxanes [Cu(H₂ C6N4)(CB[6])]Cl₄·12H₂O (1), [Co(H₂ C6N4)(CB[6])]Cl₄·14H₂O (2) and [Ag(C6N4)(CB[6])]NO₃·7H₂O (3) are prepared using N,N′-bis(4-pyridylmethyl)-1,6-hexanediamine (C6N4) threading into CB[6]'s and metal ions' assistance. Single-crystal X-ray diffraction analyses reveal that polyrotaxanes 1, 2 and 3 all have 1D chain structure where 1 and 2 are linear and 3 has two shapes, linear and sawtooth, respectively. The effects of guest molecules, metal and counter ions as well as intermolecular weak interactions on the architectures of polyrotaxanes are discussed.     

pH-Dependent Assembly of Two Novel Organic–inorganic Hybrids Based on Vanadoantimonate Clusters

Two novel organic–inorganic hybrid vanadoantimonate compounds, [Zn₂(dien)₃][{Zn(dien)}₂V₁₆Sb₄O₄₂(H₂O)]·4H₂O (1) and [Zn(dien)₂]₂ [{Zn(dien)}₂(V₁₄Sb₈O₄₂)₂(H₂O)]·4H₂O (2) (dien = Diethylenetriamine), have been synthesized hydrothermally at different pH value, and structurally characterized by elemental analyses, FT-IR, XPS, TGA and single crystal X-ray diffraction analysis. Compound 1 is composed of the rare [V₁₆Sb₄O₄₂]⁸⁻ cluster covalently linked by two [Zn(dien)]²⁺ coordination cations to yield a novel one-dimensional linear chain. Compound 2 exhibits a one-dimensional zigzag chain constructed from the [V₁₄Sb₈O₄₂]⁴⁻ cluster and [Zn(dien)]²⁺ coordination polymer. The two examples represent the first one-dimensional assemblies based on vanadoantimonate cluster and the metal–organic complex moieties.     

New supramolecular adducts of chloroaquacomplexes [M3(μ3-S)S3?xSexCly(H2O)9?y](4?y)+ (M = Mo, W) with cucurbit[6]uril

New supramolecular adducts of cucurbit[6]uril with triangular cluster chloroaquacomplexes of Mo and W with mixed sulfido-selenido bridging ligands, {[W₃S₃Se(H₂O)₇Cl₂]₂(C₃₆H₃₆N₂₄O₁₂)}Cl₂·15H₂O (1), {[W₃S_1.5Se_2.5Cl_1.5(H₂O)_7.5]₂(C₃₆H₃₆N₂₄O₁₂)}Cl₅·18.5H₂O (2), and {[Mo₃SSe₃(H₂O)_7.5Cl_1.5]₂× (C₃₆H₃₆N₂₄O₁₂)}C_l5·11H₂O (3) are obtained treating the mixture of products in Mo-S-Se-Br and W-S-Se-Br systems, isolated, and structurally characterized. In all compounds, the supramolecular structure is based on hydrogen bonded associates of cucurbit[6]uril molecule with two cluster cations.     

Two new 2-D frameworks based on tetra-copper(II)-substituted sandwich-type polyoxotungstate anions and [Cu2(dien)2(OH)]3+ cations

Two new organic–inorganic polyoxometalates [Cu(dien)(H₂O)]₂{[Cu₂(dien)₂(OH)]₂[Cu₄(B-α-XW₉O₃₃)₂]}·4H₂O (X?=?Sb, 1; X?=?As, 2) (dien?=?diethylenetriamine) were hydrothermally synthesized and characterized by elemental analysis, IR spectra, thermogravimetric (TG) analyses, and single-crystal X-ray diffraction. Both compounds are constructed from one four-coordinate [Cu(dien)(H₂O)]²⁺, one {[Cu₂(dien)₂(OH)]₂[Cu₄(B-α-XW₉O₃₃)₂]} building unit, and four water molecules of crystallization. Structural analysis shows that the sandwich-like polyoxotungstate cluster anions [Cu₄(B-α-XW₉O₃₃)₂]^10? are linked by six adjacent dimeric cations [Cu₂(dien)₂(OH)]³⁺ into a 2-D architecture with a (6,3)-connected topology. Magnetic measurements of 1 and 2 exhibit the presence of antiferromagnetic interactions within the tetranuclear-Cu^II cluster.     

Supramolecular Systems Based on Ca2+, [Mo3O2S2Cl6(H2O)3]2s-, [Mo3S4Cl6.75Br0.25(H2O)2]3s- and Cucurbit[6]uril

Adducts of cucurbit[6]uril with Ca²⁺ and trinuclear cluster chloroaquacomplexes (H₉O₄)₂(H₇O₃)₂[(Ca(H₂O)₅)2(C₃₆H₃₆N₂₄O₁₂)]Cl₈·0.67H₂O (1) and [(Ca(H₂O)₅)₂(C₃₆H₃₆N₂₄O₁₂)]× [Mo₃O₂S₂Cl₆(H₂O)₃]₂·13H₂O (2) are obtained and structurally characterized. The structures of both compounds contain polymeric [Ca(H₂O) _n ]₂² CB[6]∞ cations that form infinite columns; the space between them is filled with Cl^s- (1) and [Mo₃O₂S₂Cl₆(H₂O)₃]^2s- (2). A new (H₇O₃)₂(H₅O₂)× [Mo₃S₄Cl_6.25Br_0.25(H₂O)₂](C₃₆H₃₆N₂₄O₁₂)·CH₂Cl₂·6H₂O complex (3) is also obtained and structurally characterized.     

Synthesis and characterization of two new inorganic–organic hybrid cobalt molybdenum(V) phosphates

Two new inorganic–organic hybrid cobalt phosphomolybdates (Hdien)₂[Co(dien)]₂[Co(dien)(H₂O)]₂[CoMo₁₂O₂₄(HPO₄)₂(H₂PO₄)₂(PO₄)₄(OH)₆]?···?5H₂O (1) and (H₂dien)₂[Co(dien)]₂[Co(H₂O)₂]₂[CoMo₁₂O₂₄(HPO₄)₄(PO₄)₄(OH)₆]?···?7H₂O (2) (dien?=?diethylenetriamine), involving molybdenum in the V oxidation state and covalently bonded transition metal complexes, have been prepared under mild hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, TG analyses, and single-crystal X-ray diffraction. Compound 1 exhibits a one-dimensional (1D) chain framework, in which dien molecules adopt two kinds of coordination modes. Compound 2 shows a two-dimensional (2D) layer framework with three types of unusual tunnels. To the best of our knowledge, it is the first time [Co(dien)] units are directly incorporated into 1D and 2D skeletons of reduced molybdenum phosphates. The electrochemical properties of the two compounds were studied via the method of bulk-modified carbon paste electrodes. Furthermore, the magnetic properties of compound 2 are reported.     

Supramolecular compounds of chloroaquacomplexes [Mo3Q4(H2O)9−x Clx](4−x )+ (Q = S, Se; x = 2, 3, 5) with cucurbit[n]urils

The following adducts of cucurbit[6]uril and cucurbit[8]uril with triangular cluster chloroaquacomplexes have been prepared and characterized: {[Mo₃S₄(H₂O)₇Cl₂]₂(CB[₆])}Cl₄·13H₂O (I), (H₃O)₂{[Mo₃Se₄×(H₂O)₆Cl₃](CB[6])}Cl₃·3.5H₂O (II) and (H₃O)₂{[Mo₃S₄(H₂O)₄Cl₅](CB[8])}Cl·14H₂O (III). It is shown that the formation of complementary hydrogen bonds in the systems cucurbit[6]uril/[M₃Q₄(H₂O)_9?x Cl_x]^(4?x)+ (x = 1–3) results in a selective isolation of isomers containing chlorine atom in the trans-position to the capping μ₃-ligand. For large x, a selective inclusion of one or another form into the supramolecular compound is also affected by other factors (a system of hydrogen bonds, S?S and S…Cl interactions between cluster complexes, packing effects etc.).     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Synthesis and Crystal Structure of Cucurbit[6]uril Adduct of Hydrogen-bonded Cluster Complex [Mo3(μ3-Se)(μ2-O)3(H2O)6Cl3]+

Reaction of [MoOCl₅]²⁻ with in situ generated H₂Se under hydrothermal conditions (4M HCl, 140 °C) leads to reduction of Mo(V) to Mo(IV) with the formation of a triangular cluster Mo₃(μ₃-Se)(μ-O)₃⁴⁺ in high yield. It is present in HCl solutions as aqua chlorocomplex [Mo₃(μ₃-Se)(μ-O)₃(H₂O)₆Cl₃]⁺ which was isolated and structurally characterized as supramolecular adduct with cucurbit[6]uril (CB[6]), {[Mo₃(μ₃-Se)(μ-O)₃(H₂O)₆Cl₃]₂CB[6]}Cl₂·15H₂O. Dedicated to Professor Dieter Fenske on the Occasion of his 65th Birthday