Synthesis and crystal structure of a supramolecular adduct of trinuclear molybdenum oxocluster with macrocyclic cavitand cucurbit[5]uril containing the included ionic associate Na<Superscript>+</Superscript>...Cl...Na<Superscript>+</Superscript>

The compound of composition [{Mo₃O₄(H₂O)₆Cl₃}₂(Na₂Cl⊂ C₃₀H₃₀N ₂₀O₁₀)]Cl₃⋅14H₂O (1) was prepared by evaporation of a hydrochloric acid solution containing NaCl, the trinuclear aqua complex [Mo₃O₄(H₂O)₉]⁴⁺, and the macrocyclic cavitand cucurbit[5]uril (C₃₀H₃₀N₂₀O₁₀). X-ray diffraction analysis demonstrated that the cucurbit[5]uril molecule is closed on both sides by the cluster cations through hydrogen bonding between the CO groups of the cucurbit[5]uril portals and the aqua ligands of the oxo cluster. The inner cavity of the supramolecular adduct includes an unusual ionic associate Na⁺...Cl...Na⁺. The sodium cations are coordinated by five carbonyl oxygen atoms of each portal of the macrocycle. Compound 1 is the first structurally characterized complex, in which the macrocyclic cucurbit[5]uril ligand is directly coordinated to the alkali metal cation. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1513–1517, July, 2005.     

Synthesis and crystal structure of (H3O)2{(Na2(OH)CB[5])2[HV4O12]}Cl · 14H2O

The compound (H₃O)₂{(Na₂(OH)CB[5])₂[HV₄O₁₂]}Cl · 14H₂O is synthesized by heating (120°C) of a mixture of sodium vanadate, cucurbit[5]uril (CB[5]), rubidium chloride, and water in a sealed ampule. According to the X-ray diffraction data, the binding of the [Na₂(OH)]⁺ binuclear cation with CB[5] occurs due to the bidentate coordination of the oxygen atoms of the portals of cucurbit[5]uril to the sodium atoms. The tetranuclear vanadium complex [HV₄O₁₂]^3? serves as a bridge, joining infinite chains {Na₂(OH)CB[5]} _∞ ⁺ in pairs.     

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.     

Synthesis and crystal structures of supramolecular compounds of polynuclear aluminum(III) aqua hydroxo complexes with cucurbit[6]uril

Supramolecular compounds of the di-, trideca-, and triacontanuclear aluminum aqua hydroxo complexes, viz., [Al₂(OH)₂(H₂O)₈]⁴⁺, [Al₁₂(AlO₄)(OH)₂₄(H₂O)₁₂]⁷⁺, and [Al₃₀O₈(OH)₅₆(H₂O)₂₆]¹⁸⁺, respectively, with the organic macrocyclic cavitand cucurbit[6]uril (C₃₆H₃₆N₂₄O₁₂) were prepared by evaporation of aqueous solutions of aluminum nitrate and cucurbit[6]uril after the addition of pyridine, ammonia, KOH, or NaOH at pH 3.1–3.8. X-ray diffraction study demonstrated that the aqua hydroxo complexes are linked to the macrocycle through hydrogen bonds between the hydroxo and aqua ligands of the polycations and the portal oxygen atoms of cucurbit[6]uril. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 261—268, February, 2006.     

Synthesis and crystal structures of sumpramolecular compounds of cucurbit[n]urils (n = 6, 8) with polynuclear strontium aqua complexes

Crystals of the {[Sr₄(H₂O)₁₂(NO₃)₄](C₃₆H₃₆N₂₄O₁₂)}(NO₃)₄·3H₂O and {[Sr₂(H₂O)₁₂][Sr(H₂O)₃(NO₃)₂]₂(C₄₈H₄₈N₃₂O₁₆)}(NO₃)₄·8H₂O were prepared by slow concentration of aqueous solutions containing strontium nitrate and macrocyclic cavitands, viz., cucurbit[6]uril and cucurbit[8]uril ([C₆H₆N₄O₂] _n , n = 6 and 8), respectively. According to the results of X-ray diffraction analysis, the crystal structures of these supramolecular compounds are built from polymeric chains, which consist of the alternating cucurbit[n]uril molecules and Sr²⁺ cations linked through the bridging aqua ligands and nitrate anions. The supramolecular compound of cucurbit[8]uril provides the first example of compounds in which this macrocycle is bound to metal aqua complexes.     

A Pseudorotaxane System Containing γ-Cyclodextrin Formed via Chiral Recognition with an AuI6AgI3CuII3 Molecular Cap

Solvent-mediated crystal-to-crystal transformations of [Au₆Ag₃Cu₃(H₂O)₃(d -pen)₆(tdme)₂]³⁺ (d -[ 1 (H₂O)₃]³⁺; pen²⁻= penicillaminate, tdme=1,1,1-tris(diphenylphosphinomethyl)ethane) to form unique supramolecular species are reported. Soaking crystals of d -[ 1 (H₂O)₃]³⁺ in aqueous Na₂bdc (bdc²⁻=1,4-benzenedicarboxylate) yielded crystals containing d -[ 1 (bdc)(H₂O)₂]⁺ due to the replacement of a terminal aqua ligand in d -[ 1 (H₂O)₃]³⁺ by a monodentate bdc²⁻ ligand. When γ-cyclodextrin (γ-CD) was added to aqueous Na₂bdc, d -[ 1 (H₂O)₃]³⁺ was transformed to d -[ 1 (bdc@γ-CD)(H₂O)₂]⁺, where a γ-CD ring was threaded by a bdc²⁻ molecule to construct a pseudorotaxane structure. While the use of dicarboxylates with an aliphatic carbon chain instead of bdc²⁻ afforded analogous pseudorotaxanes, such pseudorotaxane species were not formed when crystals of [Au₆Ag₃Cu₃(H₂O)₃(l -pen)₆(tdme)₂]³⁺ (l -[ 1 (H₂O)₃]³⁺) enantiomeric to d -[ 1 (H₂O)₃]³⁺ were soaked in aqueous Na₂bdc and γ-CD, affording only crystals containing l -[ 1 (bdc)(H₂O)₂]⁺.     

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.     

Supramolecular approach to crystallization of polynuclear chromium(III) aqua hydroxo complexes: synthesis and crystal structures of complexes [Cr2(OH)2(H2O)8]4+ and [Cr4(OH)6(H2O)12]6+ with cucurbit[n]uril (n = 7, 8)

Supramolecular compounds of the compositions {[Cr₂(OH)₂(H₂O)₈](C₄₂H₄₂N₂₈O₁₄)₂}-(NO₃)₄·18.75H₂O (1) and {[Cr₄(OH)₆(H₂O)₁₂](C₄₈H₄₈N₃₂O₁₆)₃(NO₃)₆·55H₂O (2) were synthesized from aqueous solutions of chromium(III) nitrate and the macrocyclic cavitand cucurbit[n]uril (C_6n H_6n N_4n O_2n , where n = 7 or 8, respectively). According to the X-ray diffraction study, the polynuclear chromium aqua complexes are disposed in cavities formed by the cucurbit[n]uril molecules and are linked to these molecules through hydrogen bonds between the hydroxo and aqua ligands of the polycations and the portal oxygen atoms of the macrocycles. Compound 1 is the first example of supramolecular compounds of cucurbit[7]uril with metal aqua complexes. The isolation of the supramolecular adduct with cucurbit[8]uril 2 in the single-crystalline state allows the determination of the structure of the tetranuclear chromium aqua complex having an adamantane-like structure, [Cr₄(μ₂-OH)₆(H₂O)₁₂]⁶⁺, which has been previously unknown in the solid state.     

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     

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.).     

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.     

Investigation of commercial sodium cacodylate trihydrate: penta‐μ‐aqua‐disodium(I) bis(dimethylarsenate) and di‐μ‐aqua‐bis[triaquasodium(I)] bis(dimethylarsenate)

Crystals from commercial samples of sodium cacodylate trihydrate, NaO₂As(CH₃)₂·3H₂O, were analyzed by single‐crystal X‐ray diffraction and two phases were identified, viz. penta‐μ‐aqua‐disodium(I) bis(dimethylarsenate), {[Na₂(H₂O)₅](C₂H₆AsO₂)₂}_n, (I), and di‐μ‐aqua‐bis[triaquasodium(I)] bis(dimethylarsenate), [Na₂(H₂O)₈](C₂H₆AsO₂)₂, (II). Both (I) and (II) form layered structures in which hydrated Na⁺ ions form layers in the ab plane, the cacodylate ions being located in between the layers. In (I), the two non‐equivalent Na⁺ ions (located at twofold axes) and the three non‐equivalent aqua ligands (one of which also lies on a twofold axis) form infinite polymeric layers, but in (II), layers of discrete centrosymmetric [Na₂(H₂O)₈]²⁺ ions are present. One of the commercial samples analyzed contained almost exclusively crystals of the tetrahydrate (II), while another sample consisted of a mixture of the two phases.     

Synthesis and crystal structure of a supramolecular adduct of the aqua nitrato complex of gadolinium [Gd(NO<Subscript>3</Subscript>)(H<Subscript>2</Subscript>O)<Subscript>7</Subscript>]<Superscript>2+</Superscript> with macrocyclic cavitand cucurbit[6]uril

A supramolecular adduct of gadolinium aqua nitrato complex and cucurbit[6]uril { [Gd(NO₃)(H₂O)₇](C₅H₅N)@(C₃₆H₃₆N₂₄O₁₂)}(NO₃)₂·10H₂O is obtained by slow diffusion of methanol into an aqueous solution containing gadolinium nitrate, pyridine, and cucurbit[6]uril. According to single crystal X-ray diffraction data, water molecules coordinated to metal atom make hydrogen bonds to polarized carbonyl groups of the macrocycle. The heptaaquanitratogadolinium(III) [Gd(NO₃)(H₂O)₇]²⁺ cation is structurally characterized for the first time. Crystal system is triclinic, space group \(P\overline 1 \), a = 12.3137(4) Å, b = 14.2334(5) Å, c = 19.5629(6) Å; α = 80.850(1)°, β = 86.879(1)°, γ = 68.855(1)°; V = 3157.15(18) ų, Z = 2. Oriented hydrogen-bonded chains of alternating cucurbit[6]uril molecules and gadolinium aqua cations form in the crystal structure.     

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.     

Stabilization of tautomeric forms P(OH)3 and HP(OH)2 and their derivatives by coordination to palladium and nickel atoms in heterometallic clusters with the Mo3MQ44+ core (M = Ni, Pd; Q = S, Se)

The cluster aqua complexes [Mo₃(MCl)Q₄(H₂O)₉]³⁺ (M = Pd or Ni) in hydrochloric acid solutions induce isomerization of the hydrophosphoryl compounds (HO)₂P(O)H, (HO)P(O)H₂, PhP(O)(OH)H, and Ph₂P(O)H into the hydroxo tautomers P(OH)₃, HP(OH)₂, PhP(OH)₂, and Ph₂P(OH), which are stabilized by coordination of the phosphorus atom to the Pd or Ni atoms. The reactions were studied by ³¹P NMR and UV-Vis spectroscopy. The kinetics of the reactions of phosphorous acid with [Mo₃(PdCl)Q₄(H₂O)₉]³⁺ was investigated by spectrophotometry. The [Mo₃(Pd(PhP(OH)₂))S₄(H₂O)₂Cl₇]³⁻ complex was isolated as a supramolecular adduct with cucurbit [8]uril, and the [Mo₃(Ni(P(OH)₃))S₄(H₂O)₈Cl]³⁺ complex was isolated as an adduct with cucurbit [6]uril. The structures of both compounds were established by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 606–613, March, 2005.     

Coordination of Bimuth(III) to Cucurbit[8]uril. Preparation and X‐ray Structure of [{Bi(NO3)(H2O)5}2(Q8)][Bi(NO3)3(H2O)4]2[Bi(NO3)5]2·Q8·19H2O

Bi(NO₃)₃ reacts with cucurbit[8]uril, (Q8), in 3M HNO₃ to give the title complex whose structure includes three discrete Bi complexes: [{Bi(NO₃)(H₂O)₅}₂(Q8)]⁴⁺ (CN of Bi = 9, both NO₃^— and cucurbit[8]uril are bidentate), [Bi(NO₃)₅]^2— (CN of Bi = 10, all NO₃^— are bidentate), and [Bi(NO₃)₃(H₂O)₄] (CN of Bi = 10, all NO₃^— are bidentate).     

Synthesis and crystal structures of PrIII and NdIII complexes with the macrocyclic cavitand cucurbit[6]uril

The [{Pr(NO₃)₂(H₂O)₃}{Pr(NO₃)(H₂O)₄} (C₃₆H₃₆N₂₄O₁₂)](NO₃)₃·4H₂O and [{Nd(NO₃)(H₂O)₄} ₂(NO₃@C₃₆H₃₆N₂₄O₁₂)][Nd(NO₃)₆] complexes were prepared by heating a mixture of lanthanide nitrates, cucurbit[6]uril, and water in a sealed tube. X-ray diffraction study demonstrated that the metal atoms in the former complex are linked to the macrocycle through tridentate coordination of the portal oxygen atoms of cucurbit[6]uril to the praseodymium(III) cation. The neodymium(III) complex is the first example of lanthanide compounds with cucurbit[6]uril belonging to coordination polymers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1511–1517, September, 2006.     

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.     

Understanding behaviour of vitamin-C guest binding with the cucurbit[6]uril host

The present study describes non-covalent interaction and complexation behaviour of sodium ascorbate (SA) with cucurbit[6]uril (CB[6]) at neutral pH in aqueous Na₂SO₄ solution. The interaction behaviour is investigated using various analytical techniques like NMR, UV–Vis, fluorescence, TGA and DRS. The substantial increase in the intensity of emission and absorption spectra of sodium ascorbate is observed. The Benesi–Hildebrand evaluation method is used to determine the stoichiometry and equilibrium constant of the cucurbit[6]uril–sodium ascorbate complex, which suggested the 1:1 complex. Time-dependent ¹H NMR, ¹³C CP MAS and CD studies also echoed non-covalent interaction between SA with CB[6].     

Preparation and characterization of a novel single crystal of Th(IV) with cucurbit[6]uril

One new single crystal [Th(NO₃)₂(H₂O)₆](CB₆)(NO₃)2·2H₂O was prepared using Th(NO₃)4·4H₂O and cucurbit[6]uril (CB₆) as reagents in HNO₃ aqueous solution by slow evaporation. The coordination number of Th⁴⁺ is ten. Th⁴⁺ is coordinated with six monodentate water molecules and two symmetric bidentate chelating nitrate ions, while other two nitrate ions act as the counterion anions. CB₆ is a second-sphere ligand which is hydrogen bonded to the water molecules of [Th(NO₃)₂(H₂O)₆]²⁺. Besides, there are also two free water molecules in the crystal system.