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The interactions between a series of lanthanide cations (Ln3+) and a methyl-substituted cucurbit[6]uril derived from 3α-methyl-glycoluril (SHMeQ[6]) in the presence of [CdCl4]2 − as a structure-directing agent in aqueous HCl solutions (6.0 mol·L − 1) have been investigated. The formation of ionic radius-dependent complexes, the crystal structures of six of which have been obtained, shows the recognition ability of SHMeQ[6] towards lanthanide cations. For example, SHMeQ[6] forms molecular capsule-like complexes with the two lightest lanthanide cations, La3+ and Ce3+; molecular pairs with Nd3+, Sm3+, Eu3+ and Gd3+, and no solid crystals are formed with the heavier lanthanides.

The host–guest interactions between a symmetrical α,α′,δ,δ′-tetramethyl-cucurbit[6]uril and three 4-pyrrolidinopyridine derivatives, specifically 4-pyrrolidinopyridine, N-butyl-4-pyrrolidinopyridine, and N-amyl-4-pyrrolidinopyridine, have been investigated both in aqueous solution and in the solid state using NMR spectroscopic methods, electronic absorption spectroscopy, isothermal titration calorimetry (ITC), and single-crystal X-ray diffraction analysis. In aqueous solution, TMeQ[6] forms 1 : 1 inclusion complexes with these guests. Generally, TMeQ[6] preferentially accommodates the pyridyl moiety of these guests, which was confirmed by the crystal structures of its complexes with 4-pyrrolidinopyridine and N-butyl-4-pyrrolidinopyridine. Moreover, TMeQ[6] can form a thermodynamic inclusion complex with 4-pyrrolidinopyridine at elevated temperatures. The unthreading and rethreading of the TMeQ[6] ring can simulate a molecular-level plug/socket system, that can be reversibly driven by Ba2+/SO42−, and is accompanied by obvious changes in the UV absorption spectrum, both in wavelength and intensity.

The coordination of pentacyclohexanocucurbit[5]uril (PCyHQ[5]) to alkali metal cations and the formation of supramolecular assemblies in the absence and presence of [CdCl4]2– or [ZnCl4]2– anions as inorganic structure inducers have been investigated by single-crystal X-ray diffraction analysis. Studies of the crystal structures have revealed that the [CdCl4]2– or [ZnCl4]2– anions do not form honeycomb structures owing to the presence of alkyl substituents on the surface of the outer walls of PCyHQ[5], which can seriously perturb the interaction of the anions with the outer walls. Moreover, in the presence of [ZnCl4]2– anions, the formation of a new Rb-PCyHQ[5]-based 2D six-membered “bracelet” network suggests that larger ions such as Ba2+ and even Ra2+ could form this new type of supramolecular assembly.

Sym -bis(benzimidazole)-2,2′-ethylene cations act as a new axle template for threading cucurbit[6]uril derivatives on, forming [2] pseudo rotaxane and [3] pseudo rotaxane. These new complexes have been studied using 1 H NMR, UV–vis absorption spectroscopy and X-ray analysis. Changes in the 1 H NMR spectra indicate that the two types of pseudo rotaxane can be formed by varying the host concentration. UV–vis absorption titration experiments at different pH values demonstrate that interesting p K a shifts of the bis-benzimidazole derivatives can be induced by the host–guest complexation. The associated constants were calculated to be 2.81 × 10 4 L/mol and 9.06 × 10 6 L/mol for the [2] pseudo rotaxanes and [3] pseudo rotaxanes, respectively. Furthermore, X-ray diffraction studies of the solid state structures provide unequivocal proof of the host concentration dependent pseudo rotaxane, which is strongly in line with the evidences in solution.

In the present study, the lanthanide(III) contraction effect induced coordination architectures of HCyHQ[6] have been studied. The results, including fifteen crystal structures, indicate that although lanthanide metal ions have similar chemical properties mostly, their slightly different ionic radii play a key role in the formation of different supramolecular self-assembly types of HCyHQ[6]. As a result, the ionic radius-dependent complexes of HCyHQ[6] can be structurally classified into four groups: HCyHQ[6]-pair, HCyHQ[6]-molecular bowl, Ln–HCyHQ[6] one dimensional coordination polymer, and HCyHQ[6]-molecular capsule.

In the present study, we report three crystal structures of heterometallic Q[5]-based complexes. They are complexes of heterometallic cadmium and potassium ions/Q[5] capsules with a stoichiometry of {(CdCl)[K(H 2 O)][Cl@Q[5]]} + [CdCl 3 (H 2 O) 2 ] − 7H 2 O ( 1 ), heterometallic praseodymium and calcium/Q[5] pairs with a stoichiometry of 2{[Ca(H 2 O)(OH)]- μ -[Pr(H 2 O) 3 [Cl@Q[5]]]} 3+ 6Cl − 32H 2 O ( 2 ) and discrete heterometallic neodymium and potassium ions/Q[5] capsules with a stoichiometry of {[Nd(H 2 O) 3 ][(NO 3 )@Q[5]][K(H 2 O)][Nd(H 2 O) 3 (NO 3 ) 4 ]} 2+ 2(NO 3 ) − 8H 2 O ( 3 ).

A bromide salt of 2,2′-(hexane-1,6-diyl) diisoquinolinium (K6) was designed, synthesized and introduced to construct a novel framework induced by π···π stacking of 2,2′-(alkylene-1,ω-diyl)diisoquinolinium from Q[6]-based pseudo-rotaxanes. The crystal structure of the compound revealed that the assembled framework based on the Q[6]-2,2′-(alkylene-1,6-diyl)diisoquinolinium pseudo-rotaxanes have stoichiometries of {(K6)@(Q[6])}2+·2Br−·7(H2O). The compound 1 has a novel three-dimensional framework constructed of two different channels―one containing stacked isoquinolyl moieties from the K6@Q[6] pseudorotaxanes and the other containing the bromide anions. 1H NMR spectra analysis was performed and confirmed the pseudorotaxane interaction model in which the 2,2′-(alkylene-1,6-diyl)diisoquinolinium guest threads into the cavity of Q[6] with the alkyl chain included inside the cavity and the two end isoquinolyl moieties protruding from the two opening portals. Absorption spectrophotometric and fluorescence spectroscopic analyses of the host–guest inclusion complex in aqueous solution found that the complexes were most stable at a host:guest mole ratio of 1:1. At this ratio, the complex has binding constants (K) ~106.

Five crystals based on para-dicyclohexanocucurbit[6]uil (DCyHQ[6]) were synthesized and structurally characterized by single-crystal X-ray diffractions. They are {Dioxane@DCyHQ[6]}·18H2O (1), { [ Cu ( H 2 O ) 6 ] 2 DCyHQ [ 6 ] } 4 + · 2 SO 4 2 - · 10 H 2 O (2), { [ Zn ( H 2 O ) 6 ] 2 DCyHQ [ 6 ] } 4 + · 2 SO 4 2 - · 10 H 2 O (3), { [ Sr ( H 2 O ) 5 ] 2 DCyHQ [ 6 ] } 4 + · 5 Cl - · ( H 3 O ) + · 8 H 2 O (4), { [ Na ( H 2 O ) 4 ] 2 DCyHQ [ 6 ] } 2 + · 4 Br - · 2 ( H 3 O ) + · 14 H 2 O (5). The compound 1 which is a dioxane@DCyHQ[6] inclusion host–guest complex; the other three crystal structures of the compounds 2, 3 and 4 show supramolecular assemblies comprising of DCyHQ[6] and metal ions or their aqueous complexes through hydrogen bonding; while the crystal structure of the compound 5 shows a one-dimensional supramolecular polymer through direct coordination of sodium cations to the portal carbonyl oxygen atoms of the DCyHQ[6].

1,4-Butylidenedipyridinium (C 4 DP 2+ ) and 1,10-decylidenedipyridinium (C 10 DP 2+ ) cationic guests form highly stable 1:1 inclusion complexes in aqueous solution with a cucurbit[8]uril (Q[8]) host. Single-crystal structure analysis of the inclusion complexes revealed that the alkyl chain of the C n DP 2+ (n = 4, 10) cationic guest adopts an unconventional contorted conformation, which is attributed to favorable host-guest interactions (including charge―dipole and hydrophobic interactions) when bound within the cavity of the Q[8] host. Moreover, their crystal structures suggest that the alkyl chain and the aromatic group can be encapsulated into the Q[8] host simultaneously, and the alkyl chain is more favorably encapsulated into the Q[8] host than the aromatic group.

The formation of 3D fused 10-membered “bracelet” frameworks derived from the alkyl-substituted curcurbit[5]urils (SQ[5]s), 1,2,4-hexamethylcucurbit[5]uril (1,2,4-HMeQ[5]), and pentacyclopentanocucurbit[5]uril (PCyHQ[5]) and K+ ions is described. These remarkable catenated structures feature trigonal-planar branching units involving three SQ[5]s connected via their bound K+ ions in a triangular manner in which the coordination of each K+ ion to the five portal carbonyl oxygen atoms of one SQ[5] as well as to a bridging portal carbonyl oxygen from an adjacent SQ[5] draws the edges of three portals into close proximity. The corresponding offset angle at each junction provides the basis for the 3D assembly of the observed fused 10-membered SQ[5] bracelet frameworks.

Three one-dimensional methyl-substituted cucurbituril-based polyrotaxanes, [Ag(H2O)(C4N3)(TMeQ[6])](NO3)3H2O (1), [Cu(H2O)2Cl2(C4N4)(TMeQ[6])]2H2O (2), and [Ag2(H2O)3(C4N4)(TMeQ[6])]2(NO3)14H2O (3) have been prepared with N,N′-bis(3-pyridylmethyl)-1,4-butanediamine (C4N3) and N,N′-bis(4-pyridylmethyl)-1,4-butane diamine (C4N4), incorporating a symmetrical α,α′,δ,δ′-tetramethyl-cucurbit[6]uril (TMeQ[6]) using methods assisted by silver(I) and copper(II) ions. X-ray diffraction analyses reveal that all three polyrotaxanes have basically 1D linear chain structures with different shapes. However, the π···π stacking of the protruded pyridyl ring of the guest is observed and leads to the formation of two-dimensional networks in compound 1. Unlike most cases in which a metal ion coordinates to both of the terminal pyridyl nitrogen atoms of two neighboring pseudorotaxanes, the silver ion coordinates to only one terminal pyridyl nitrogen atom and simultaneously coordinates to two carbonyl oxygen atoms of the neigh...

Three supramolecular assemblies [(C 14 H 17 N 2 ) 2 ⊂C 48 H 48 N 32 -O 16 ]Cl 2 ·23H 2 O (1), {[C 14 H 17 N 2 Cu(H 2 O) 5 ] 2 ⊂C 48 H 48 N 32 O 16 }-[(C 14 H 17 N 2 ) 2 ⊂C 48 H 48 N 32 O 16 ]Cl 4 (NO 3 ) 4 ·32H 2 O (2), and {[C 14 H 17 N 2 Ni(H 2 O) 5 ] 2 ⊂C 48 H 48 N 32 O 16 }[(C 14 H 17 N 2 ) 2 ⊂C 48 H 48 -N 32 O 16 ]Cl 2 (NO 3 ) 6 ·22H 2 O (3) were synthesized in aqueous solution and characterized by X-ray diffraction. The crystal structures of these supramolecular assemblies show that Q[8] can selectively encapsulate either the bipyridinium or butyl moiety of the 1-butyl-4,4'-bipyridinium guest in its hydrophobic cavity to form ternary complexes through the influence of metal-ligand coordination. The main driving force of the selective formation of these supramolecular assemblies may be due to ion-dipole interactions.

Nine supramolecular self-assembly entities consisting of cucurbit[5]uril, potassium salts, and hydroxybenzene or its derivatives were constructed by conventional methods. In this supramolecular architectural system, Q[5]s and the metal ions (K+) form infinite chains through coordination and ion−dipole interaction, and the stacking of these supramolecular chains then forms wavelike “walls”. The layers of hydroxybenzene or its derivatives are sandwiched by these wavelike walls, and the counteranions are captured in the molecular channels formed by the supramolecular chains. The gap between the adjacent walls is dependent on the size of the hydroxybenzene or its derivatives.

The crystal structure of {K[(H 2 O)@Q[5]][Zn(H 2 O) 3 Cl]} ZnCl 4 ·6(H 2 O) ( 1 ) is reported. It consists of an infinite 1D supramolecular chain constructed of heterometallic zinc and potassium ions/cucurbit[5]uril capsules held together through ion–dipole interactions and hydrogen bonding, and forms a novel hexagonal open framework.

Four host–guest complexes, {(gI)@(CyH) 6 Q[6]}·3H 2 O ( 1 ), {(gIIH 2 ) 2+ @(CyH) 2 Q[6]}·2Cl − ·21H 2 O ( 2 ), {(gIII)@Q[6]}·27H 2 O ( 3 ), and {(gIVH) + @(CyH) 2 Q[6]}·Cl − ·13H 2 O ( 4 ), have been prepared from cyclohexanocucurbit[6]uril, {(CyH) 6 Q[6]}, symmetrical dicyclohexanocucurbit[6]uril {(CyH) 2 Q[6]}, and cucurbit[6]uril {Q[6]} as hosts, and four different guests, namely 2-phenyl-2 H -imidazole (gI), the HCl salt of N 1 , N 4 -bis(pyridin-3-ylmethyl)butane-1,4-diamine (gII), benzylamine (gIII), and the HCl salt of 4-(1 H -imidazolyl)phenol (gIV). Their crystal structures have been characterized by single-crystal X-ray diffraction analyses and revealed that these hosts can form supramolecular assemblies through iondipole interactions, hydrogen bonding, CH···π or NH···π interactions, and π···π stacking.

Four crystal structures of inclusion complexes of amino acid and cucurbit[n]uril have been synthesized and characterized by X-ray diffractions. The used four amino acids are l -Glutamate ( l -Glu), l -Tyrosine ( l -Tyr), l -Hisdine ( l -His), l -Leucine ( l -Leu) and the hosts are α,α′,δ,δ′-tetramethylcucurbit[6]uril (TMeQ[6]), the normal cucurbit[8]uril (Q[8]). The corresponding compounds based on the inclusion complexes of amino acid and cucurbit[n]uril have stoichiometry of { l -Glu@TMeQ[6]} + ·Cl − ·13H 2 O ( 1 ), {( l -Tyr) 2 @Q[8]}·27H 2 O ( 2 ), {( l -His) 2 @Q[8]}·19H 2 O ( 3 ) and {( l -Leu) 2 @Q[8]} 2+ ·2Cl − ·32H 2 O ( 4 ). The crystal structure of the compound 1 reveals that a l -Glu molecule is captured by a host TMeQ[6] with a 1:1 host:guest ratio. The crystal structures of compounds 2 , 3 and 4 show that all three inclusion complexes of l -Tyr@Q[8], l -His@Q[8] and l -Leu@Q[8] are in 1:2 host:guest ratio. The host Q[8] can include not only two aromatic moieties from two same guests (such as in the cases of 2 and 3 ) but also two alkyl chains of two l -Leu molecules (the case of 4 ).

The crystal structure of compound {3[Cd2(C36H36N24O12)]·10Cl·10(H2O)}·2Cl·39(H2O) (1) is reported. It consists of complexes of cucurbituril and cadmium cations formed through ion-dipole interactions, in which a novel two-dimensional network is created by the complexation of cucurbituril and cadmium ions. Binding constants determined from voltammetric data indicate that Cd2+ has a high binding affinity for Q[6] ( K Cd 2 + = 9.95 × 10 9 M - 2 by CV) and forms a 2:1 (M2+/Q[6]) complex.

Three host–guest complexes of methylsubstituted cucurbit[6]urils host and anthracene derivatives guests were synthesized and structurally characterized by single crystal X-ray diffractions and 1H NMR technique. The hosts are dodecamethylcucurbit[6]uril (DDMeQ[6]), α,α′,δ,δ′-tetramethylcucurbit[6]uril (TMeQ[6]), and hexa-methylsubstituted cucurbituril (HSMeQ[6]) made from 3a-methyl-glycoluril. The guests are 9,10-bis[N-(aminoethylene)aminomethyl]anthracene (AN1), 9,10-bis[N-(aminopropylene) aminomethyl]anthracene (AN2) and 9,10-bis[N-(aminobutylene)aminomethyl]anthracene (AN3). The crystal structures show the compounds 1–3 with stoichiometry of {DDMeQ[6]-AN1}2+2NO3−24H2O (1), {TMeQ[6]-AN2}2+4NO3− 2H3O+10H2O (2) and {2HSMeQ[6]-AN3}2+2Cl−25H2O (3) respectively, and the formation of an exclusion or inclusion host–guest complex is dependent on the length of the substituted alkyl chains on the anthracene.

Four molecular capsules based on three different cucurbit[5]urils, which are Dimethyl cucurbit[5]uril (DMeQ[5]), decamethylcucurbit[5]uril (Me 10 Q[5]) and the normal cucurbit[5]uril, were synthesized and structurally characterized by single-crystal X-ray diffractions. They are {[Gd 2 (H 2 O) 9 ][DMeQ[5]@Cl]} 5+ ·5Cl − ·13(H 2 O) ( 1 ), {[Nd 2 (H 2 O) 8 Cl][Me 10 Q[5]@Cl]} 4+ ·4Cl − ·9(H 2 O) ( 2 ), {K(H 2 O) 2 Cl·{[[Dy 2 (H 2 O) 6 Cl][Q [5]@Cl]} 2 } 8+ ·2{[Dy 2 (H 2 O) 7 Cl][Q[5]@Cl]} 4+ ·16Cl − ·44(H 2 O) ( 3 ) and 2{[Y 2 (H 2 O) 8 ][Me 10 Q[5]@Cl]} 5+ ·10Cl − ·48(H 2 O) ( 4 ). In the crystal structure of these compounds, molecular capsules included a Cl − anion and lidded with lanthanide cations were observed.

Four molecular capsules based on three methyl-substituted cucurbit[5]urils, which are α,β,δ-hexamethyl cucurbit[5]uril (α,β,δ-HMeQ[5]), decamethylcucurbit[5]uril (Me10Q[5]) and a pentamethylcucurbit[5]uril constructed of a monomethyl-glycouril (PMeQ[5]), were synthesized and structurally characterized by single crystal X-ray diffractions. They are {[α,β,δ-HMeQ[5]@Cl][Sr(H2O)2]2}3+3·Cl−·13(H2O) (1), {[α,β,δ-HMeQ[5]@(NO3)][Sr(NO3)(H2O)]2}+[NO3]−HNO3·4(H2O) (2), {[Me10Q[5]@(NO3)][Sr(NO3)(H2O)]2}+(NO3)−8(H2O) (3) and {[PMeQ[5]@Cl][Sr(H2O)2]2}3+3·Cl−·22(H2O) (4). In the crystal structure of these compounds, molecular capsules included a Cl− or a NO 3 - anion and lidded with strontium cations were observed.

Interaction between the normal cucurbit[n]urils (n = 6,7,8; Q[6], Q[7], Q[8]) and a sym-tetramethyl-substituted cucurbit[6]uril derivative (TMeQ[6]) with the hydrochloride salts of some imidazole derivatives N-(4-hydroxylphenyl)imidazole (g1), N-(4-aminophenyl)imidazole (g2), 2-phenylimidazole (g3) in aqueous solution was investigated by using 1H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy, as well as by using a single crystal X-ray diffraction determination. The 1H NMR spectra analysis established a basic interaction model in which inclusion complexes with a host:guest ratio of 1:1 forms for the Q[6]s and Q[7] cases, while with a host:guest ratio of 1:2 form for the Q[8] cases. It was common that the hosts selectively bound the phenyl moiety of the guests. Absorption spectrophotometric and fluorescence spectroscopic analysis in aqueous solution defined the stability of the host–guest inclusion complexes at pH 5.8 with a host:guest ratio of 1:1 form quantitatively as logK values between 4 and 5 for the smaller hosts Q[6 or 7]s, while with a host:guest ratio of 1:2 form quantitatively as logK values between 11 and 12 for the host Q[8]. Two single crystal X-ray structures of the inclusion complexes TMeQ[6]-g2 · HCl and TMeQ[6]-g3 · HCl showed the phenyl moiety of these two guests inserted into the host cavity, which supported particularly the 1H NMR spectroscopic study in solution.

Three new alkyl-substituted cucurbit[6]urils, symmetrical tetracyclopentano cucurbit[6]uril {TCyPQ[6]}, meta-tricyclopentano cucurbit[6]uril {m-TriCyPQ[6]} and meta-dicyclopentano cucurbit[6]uril {m-(CyP)2Q[6]}, were synthesized by using the controlled synthesis utilizing the readily available dimer of the unsubstituted glycouril, diether of cyclopentano glycoluril and the unsubstituted glycouril. These partial cyclopentano-substituted cucurbit[6]urils were characterized by single-crystal X-ray diffractions. In the crystal structure of compounds 2{TCyPQ[6]}·57H2O (1) and {m-TriCyPQ[6]}·23H2O (2), both of Q[6]s formed a molecular capsule included water molecules, and the capsules assembled one-dimensional supramolecular chains through the hydrogen bonding. In the crystal structure of compound 2{m-(CyP)2Q[6]}·(HV)2+·4Cl−·2(H3O)+·44H2O (3), a dumbbell shape host–guest inclusion complex N,N-dihexyl-4,4′-bipyridinium(HV2+) with m-(CyP)2Q[6] was formed, the m-(CyP)2Q[6] host selectively included the alkyl moiety of the guest through the hydrophobic cavity interaction and the ion-dipole interaction.

Using probe guests, three host–guest inclusion complexes of two new alkyl-substituted cucurbit[6]uril hosts, ortho -tetramethyl cucurbit[6]uril ( o -TMeQ[6]) and symmetrical tetracyclohexano cucurbit[6]uril (TCyHQ[6]) have been characterized successfully by single crystal X-ray diffractions. They are { o -TMeQ[6]-5,5′dimethyl-2,2′-bispyridine ( DMBPY ) + }Cl − 21H 2 O( 1 ), {( o -TMeQ[6]) 2 -1,6-bisbenzoimidazolylhexane ( SBH ) 2+ } 2Cl − 52H 2 O ( 2 ) and {TCyHQ[6]- dioxane }14H 2 O ( 3 ). Moreover, two similar crystal structure of two inclusion complexes of other two partial substituted cucurbit[6]urils, meta -hexamethyl cucurbit[6]uril ( m -HMeQ[6]) and symmetrical dicyclohexano cucurbit[6]uril ( p -(CyH) 2 Q[6]) with HCl salt of DMBPY were also reported. They were { p -(CyH) 2 Q[6]- DMBPY + }Cl − 16H 2 O ( 4 ) and { m -HMeQ[6]- DMBPY + }Cl − 15H 2 O ( 5 ). The driving force for the information of the host–guest inclusion complexes can be attributed to not only the cavity interaction (host), but also the hydrogen bonding and ion–dipole interaction between the carbonyl oxygen at the portals of the host and the protonated nitrogen of the guest.

Three host–guest complexes, {(H2O)2@(CyH)2Q[6]} (4,4′-bpyH)+·Cl−·10H2O (1), {(1,4-dioxane)@m-TriCyHQ[6]}(4,4′-bpyH)+·Cl−·19H2O (2), {(4,4′-bpyH2)2+@TMeQ[6]}·2Br−·11H2O (3), were prepared with three different alkyl substituted cucurbit[6]urils, symmetrical dicyclohexanocucurbit[6]uril {(CyH)2Q[6]}, meta tricyclohexanocucurbit[6]uril (m-TriCyHQ[6]), symmetrical tetramethylcucurbit[6]uril (TMeQ[6]), and a HCl salt 4,4′-dipyridyl(4,4′-bpyHCl) or a HBr salt 4,4′-dipyridyl[4,4-bpy(HBr)2] guest. Their crystal structures characterized by single-crystal X-ray diffractions revealed that these hosts can form supramolecular assemblies with the halogen hydride salts of the guest 44bpy through the ion–dipole interaction, hydrogen bonding, C–H⋯π or N–H⋯π interaction and π⋯π stacking. The substituted alkyl group could affect the interaction model and assembled characteristic of the host and the guest.

Three supramolecular assemblies based on three new partial methyl-substituted cucurbit[5]urils, which are tetramethylcucurbit[5]uril (α,γ-TMeQ[5]), hexamethyl cucurbit[5]uril (α,β,δ-HMeQ[5]), Nonamethylcucurbit[5]uril (NMeQ[5]), were synthesized and structurally characterized by single-crystal X-ray diffractions. For the comparison with these new Q[5]s, crystal structure of an assembly constructing with normal Q[5] and K2PtCl6 was also reported. They are (α,γ-TMeQ[5])·15(H2O) (1), (α,β,δ-HMeQ[5])·2Cl−·2(H3O)+·7(H2O) (2), (NMeQ[5])·14(H2O) (3), ( Q [ 5 ] ) 2 · [ K ( H 2 O ) ] 2 + · [ PtCl 6 ] 2 - · 24 ( H 2 O ) (4). In the corresponding crystal structures, the molecular encapsulates included a water molecule and lidded water molecules at both of the portals were observed. Moreover, these molecular encapsulates are connected through hydrogen bonding and formed supramolecular chains or joined in pair.

Interaction between tetramethylcucurbit[6]uril and 3-amino-5-phenylpyrazole hydrochloride in aqueous solution has been investigated by using 1H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy, as well as by a single crystal X-ray diffraction determination. The 1H NMR spectra analysis established a basic interaction model in which an inclusion complex with a host:guest ratio of 1:1 forms, in which the host selectively binds the phenyl moiety of the guest. Absorption spectrophotometric and fluorescence spectroscopic analysis in aqueous solution defined the stability of the host–guest inclusion complexes quantitatively as 6.8 × 105 mol− 1 L at pH 2.6; the interaction is pH dependent, decreasing as pH rises. The single crystal X-ray structure of the isolated inclusion complex shows the phenyl moiety of the guest inserted into the host cavity, which supports particularly the 1H NMR spectroscopic study in solution. In the crystal structure of the inclusion complex, the host–gu...

Three supramolecular assemblies based on substituted cucurbit[6]uril: α,δ-tetramethylcucurbit[6]uril (TMeQ[6]) and α,γ,e-tricyclohexylcucurbit-[6]uril (m-TriCyHQ[6]), and α,γ,e-hexamethylcucurbit[6]uril (m-HMeQ[6]) with different metal ions were synthesized and structurally characterized by single-crystal X-ray diffractions. They are {TMeQ[6]@acetone[Ca(H2O)3]}2+·(CdCl4)2−10H2O (1), {[m-TriCyHQ[6]@dioxane][Na(H2O)2Cl]}15H2O (2) and {[m-HMeQ[6]]K2(H2O)4 Cl}Cl·15H2O (3). The crystal structures of these complexes showed the different interaction modes between these partial alkyl-substituted cucurbit[6]urils and the metal ions. In compound 1, a one-dimensional supramolecular chain of alternating TMeQ[6] molecules and [Ca(H2O)3]2+ complexes assembled through coordination bonding of the cation and the carbonyl oxygen of TMeQ[6]. The compound 2 was the first reported crystal structure of the m-TriCyHQ[6] with metal ion through the coordinate bonds, and the compound 3 was the first reported crystal structure of m-HMeQ[6]. It was unexpected that an ionic bonded chloride anion was at the portal of the two meta-substituted cucurbiturils.

Four supramolecular assemblies based on two partial substituted cucurbituril, α,δ-tetramethylcucurbit[6]uril (TMeQ[6]) and α,δ-dicyclohexanocucurbit[6]uril ((CyH)2Q[6]), with different metal ions were synthesized and structurally characterized by single-crystal X-ray diffractions. They are {[TMeQ[6]@2H2O]·[Zn(H2O)4]}·[ZnCl4]·12H2O (1), {[TMeQ[6]@H2O]·[Sr2Cl2]}·[Cl]2·10H2O (2), {TMeQ[6]·[CaCl]}·[Cl]·17.5H2O (3), {[(CyH)2Q[6]@acetone]·1.5[Ni(H2O)6]}·(NO3)32H2O (4). The crystal structures of these complexes showed that supramolecular chains were formed through different interaction modes. In complex 1, the transition metal ion Zn2+ was coordinated not only with water molecules but also directly with carbonyl oxygens of a portal of TMeQ[6]. The Zinc aqua complexes served as a bridge between TMeQ[6]s in the 1D supramolecular chains. In complex 2, each Sr2+ ion was coordinated directly with two carbonyl oxygen atoms at a portal of two TMeQ[6], and each TMeQ[6] was coordinated with four Sr2+ ions, resulting in the formation of supramolecular chains consisted of alternating metal ions and TMeQ[6]. In complex 3, two TMeQ[6] molecules were coordinated by two Ca2+ ions to form a assembled unit. The assembled units were connected through hydrogen bonds, leading to the formation of supramolecular chains. In complex 4, supramolecular chains consisted of alternating [Ni(H2O)]2+ complex cation and (CyH)2Q[6] were formed through hydrogen bonding.

Three host–guest complexes, {acetone@m-TriCyHQ[6]}19H2O (1), {acetone@m-TriCyHQ[6]}{app}+Cl−12H2O (2), and {55dmbpy@m-TriCyHQ[6]}+ Cl−17H2O (3) were prepared with meta-tricyclohexyl cucurbit[6]uril (m-TriCyHQ[6]) and acetone, 3-amino-5-phenylpyrazole(app), and 5,5′-dimethyl-2,2′dipyridyl(55dmbpy), respectively. Their crystal structures along with that of {m-TriCyHQ[6]}22H2O (4) were characterized by single-crystal X-ray diffractions. The crystal structures of these host–guest complexes revealed that the host m-TriCyHQ[6] had a strong selectivity for different guest molecules, which were readily included in the cavity of m-TriCyHQ[6]. Small organic compounds, such as acetone and dioxane, showed a relatively strong tendency to interact only with the cavity of m-TriCyHQ[6]. However, guest 3-amino-5-phenylpyrazole hydrochloride preferred to interact with the portals of m-TriCyHQ[6] and guest 5,5′-dimethyl-2,2′-dipyridyl showed strong interactions with both the cavity and portals of m-TriCyHQ[6]. Basically, these guests form inclusion host–guest complexes with m-TriCyHQ[6], which were stabilized by the hydrophobic interactions in the cavity and the hydrophilic interactions at the portals.

In the crystal structure of the title compound, 2C36H36N24O12·2C16H22N22+·4Br−·13H2O, the host cucurbituril is threaded by the guest hexane-1,6-diyldipyridinium cation to form a pseudorotaxane. Two Br− anions form hydrogen bonds with two solvent water mol­ecules, while the other solvent water mol­ecules inter­act with the carbonyl O atoms at the rims of the cucurbituril.

In the crystal structure of the title compound, C16H23N2+·Cl−·H2O, the mol­ecules and ions are linked through N—H⋯Cl, O—H⋯Cl, O—H⋯N and N—H⋯O hydrogen bonds. In addition, π–π stacking between pyridine rings leads to a tail-to-tail arrangement.

A number of linear coordination polymers have been assembled from lanthanide cations (Ln3+) and cucurbit[7]uril (Q[7]) in the presence of [CuCl4]2−or [CoCl4]2− anions acting as inorganic structure inducers in HCl solution. X-ray diffraction analysis has revealed that they form three groups of isomorphous structures. Generally, the complexes of Q[7] with light lanthanide cations (those with atomic number below that of neodymium (Nd3+)) are in one group. The other two groups, in which the lanthanide cation has atomic number greater than that of europium (Eu3+), seem to follow no obvious rule. For example, the complexes of Q[7] with Eu3+ and Gd3+cations are in the second group in the presence of [CuCl4]2− anions, while they are in the third group in the presence of [CoCl4]2− anions. However, whatever group a given complex belongs to, they all show a common honeycomb-patterned supramolecular assembly, in which [CuCl4]2−or [CoCl4]2− anions form a honeycomb structure. The Ln3+ cations then coordinate to neighboring Q[7] molecules to form 1D coordination polymers that are inserted into the channels of the honeycomb framework, such that each individual coordination polymer is surrounded by [CuCl4]2−or [CoCl4]2− anions.

Similar to the larger members of the cucurbituril family, such as cucurbit[8]uril (Q[8]), the smallest member, cucurbit[5]uril (Q[5]), can also induce room-temperature phosphorescence (RTP) of α-naphthol (1) and β-naphthol (2). The relationship between the RTP intensity of 1 and 2 and the concentration of Q[5] or Q[8] suggests that the mechanism underlying the Q[5] complex-induced RTP is different from that of the Q[8]-induced RTP for these luminophores. The crystal structures of 1-Q[5]-KI, 2-Q[5]-KI, 1-Q[5]-TlNO(3), and 2-Q[5]-TlNO(3) systems show that in each case Q[5] and the respective metal ions, K(+) or Tl(+), form infinite ···Q[5]-M(+)-Q[5]-M(+)··· chains that surround the luminophores. Although these tube- or wall-like structures are likely destroyed in solution, the key interaction between the convex-shaped outer walls of Q[5] and the plane of the aromatic naphthols, via π···π stacking and C-H···π interactions, is postulated to be essentially maintained leading to a microenvironment that holds the luminophore and the heavy atom perturber together; such a model is supported by the observed Q[5] complex-induced RTP of the above naphthols. With respect to this, a high Q[5]/luminophore concentration was employed in an endeavour to promote the formation of π···π stacking and C-H···π interactions similar to those observed in the crystal structures of the 1- or 2-Q[5]-K(+) and -Tl(+) systems. In keeping with the proposed model, the RTP of each system is quenched when Q[5] is replaced by the alkyl-substituted Q[5] derivatives, decamethylQ[5] and pentacyclohexanoQ[5]. This is in agreement with the substituent groups on the surface of the metal-bond Q[5] obstructing the naphthol molecule from accessing the convex glycouril backbone of Q[5].

In the title compound, C12H11N3O3S·H2O, the pyridine ring makes a dihedral angle of 24.78 (14)° with the phenyl ring. Intramolecular N—H...O and intermolecular O—H...O hydrogen bonds are observed and stabilize the packing in the crystal structure.

The organic cation of the title salt, C17H12N4O2+·2Cl−·H2O, is nearly planar, the dihedral angle between two pyridine rings being 2.53 (16)° and that between the pyridinum and furan rings being 4.17 (19)°. Molecules are linked via N—H...O, N—H...Cl and O—H...Cl hydrogen bonds, forming a three-dimensional framework and π–π stacking interactions help to stabilize the crystal structure [the imidazole–pyridine and imidazole–benzene centroid–centroid distances are 3.501 (3) and 3.674 (3) Å; respectively].

The asymmetric unit of the title compound, C5H8O6S2, consists of two spiro[5.5]undecane molecules. The nonplanar six-membered rings adopt chair conformations. In the crystal structure, weak intermolecular C—H...O interactions, together with close O...S contacts in the range 3.308 (3)–3.315 (3) Å, stabilize the packing.

The asymmetric unit of the title compound, (C24H26N2)[ZnCl4], consists of two 2,2′-(hexane-1,6-di­yl)diisoquinolinium cations and two [ZnCl4]2− complex anions. The [ZnCl4]2− anions have a distorted tetra­hedral geometry. The dihedral angles between the isoquinoline rings of the two cations are nearly equal [16.1 (2) and 16.3 (2)°]. In the crystal structure, the ordered linear formation is aggregated by weak inter­molecular π–π stacking inter­actions between neighboring isoquinoline pyridine rings with a centroid–centroid distance of 3.779 (4) A.

In the crystal structure of the title compound, C13H11N4O3+·Cl−, the dihedral angle between the two pyridine rings is 9.72 (9) Å. Ions are linked via N—H...Cl, O—H...Cl and O—H...O hydrogen bonds, forming a three-dimensional framework.

In the crystal structure of the title compound, C(6)H(8)N(2)O·CH(4)N(2)O·H(2)O, mol-ecules are linked via N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, forming a three-dimensional framework.

In the title compound, C24H26N44+·4Cl−·2H2O, the cation possesses a crystallographically imposed centre of symmetry. The crystal structure is stabilized by inter­molecular N—H⋯Cl, N—H⋯O and O—H⋯Cl hydrogen bonds, and by π–π stacking inter­actions.

The cation of the title compound, C26H28N42+.2 Cl−·4H2O, is centrosymmetric while the two Cl− anions are each located on a twofold rotation axis. Hydrogen-bonding and π–π stacking inter­actions help to stabilize the crystal structure.

We introduce an approach for the synthesis of networks based on the coordination of alkyl-substituted cucurbit[5]uril (SQ[5]), dimethylcucurbit[5]uril (DMeQ[5]), 1,3-dicyclohexanocucurbit[5]uril (1,3-DCyHQ[5]), 1,2,4-tricyclohexanocucurbit[5]uril (1,2,4-TriCyHQ[5]), 1,2,3-cyclohexanocucurbit[5]uril (1,2,3-TriCyHQ[5]), and pentacyclopentanocucurbit[5]uril (PCyPQ[5]) with K+ ions in the absence of a structure inducer. These novel SQ[5]-K+-based networks feature trigonal-planar branches constructed from three SQ[5]s and K+ ions in a triangular manner, in which the coordination of each K+ ion to the five portal carbonyl oxygen atoms of one SQ[5] as well as to a bridging portal carbonyl oxygen from an adjacent SQ[5] draws the edges of three portals into close proximity. Thus, a 3-K+-cation junction is formed at each portal of the S[5] and there are four 3-K+-cation junctions in which one or two coordinated water molecule(s) are shared by the three K+ cations in the trigonal-planar branch. Detailed inspection of the relationship of the planes at the 3-K+ junction has revealed that the dihedral angles between the junction plane and the center junction plane have a strong influence on the supramolecular assembly of SQ[5] with K+ ions into 2D-networks or 3D-frameworks. Moreover, these dihedral angles determine the structural conformation of the SQ[5]-K+-based networks and the superimposition of 2D-networks in the compounds.

Eight coordination complexes, {LnCl2(H2O)3Q*[5]}·NO3·18.5H2O [isomorphous for Ln = La (1), Ce (2) and Pr (3)], {LnCl2(H2O)2Q*[5]}·NO3·14H2O [isomorphous for Ln = Nd (4) and Sm (5)], {Dy(H2O)2[Cl ⊂ Q*[5]]Dy(H2O)6}·5Cl·20H2O (6), {LnCl(H2O)[Cl ⊂ Q*[5]]Ln(H2O)6}·4Cl·13H2O [isomorphous for Ln = Ho (7) and Er (8)], were obtained by reactions of the corresponding lanthanide species with the macrocyclic ligand pentacyclohexanocucurbit[5]uril (Q*[5]) in aqueous solution, and their structures were determined by single-crystal X-ray diffraction. Crystal structure analysis reveals that, in complexes 1–5, each Q*[5] coordinates to one lanthanide(III) ion to form an opened molecular capsule structure, and then adjacent molecular capsules bridge each other to form a 1-D coordination polymer structure, while in complexes 6–8, each Q*[5] coordinates to two lanthanide(III) ions to form a 0-D half-opened molecular capsule structure. These complexes show that their structural variations are ascribed to the effect of lanthanide contraction.

A strategy of using organic guest-induced formation of polymers or frameworks based on the coordination of metal ions and cucurbit[n]urils was developed. Using this strategy, a compound with a stoichiometry of {Rb2(μ-OH)(H2O)2(Hyq@Q[7])2}·Cl has been synthesized. X-ray crystallography, shows the crystal structure to be a novel three dimensional infinite framework, constructed by the Q[7] pairs through the hydroquinone-induced coordination of the rubidium unit to the portal oxygens of the Q[7]s.

In the crystal of the title compound, [Cu(NO(3))(2)(C(18)H(24)N(2))], the Cu(II) ion is coordinated by two N atoms of the bipyridine ligand and four O atoms from the two nitrate anions in a distorted octahedral fashion. The dihedral angle between the planes of the two pyridine rings is 11.52 (10)°. In the crystal structure, weak C-H⋯O inter-actions may help to establish the packing.

In the title compound, C10H12N8O4·H2O, prepared from the reaction of glycoluril with paraformaldehyde, the organic molecule has mm symmetry. The asymmetric unit comprises one quarter of the molecule and a half-molecule of water. The dimer is formed by bridging two glycoluril molecules with methylene groups at the 1 and 6 positions. In the crystal structure, molecules are linked via N—H...O and O—H...O hydrogen bonds, forming a two-dimensional framework.

In the crystal structure of the title compound, C16H16N2O6, the mol­ecule is centrosymmetric. The two benzene rings are linked by a diether strand, forming a non-coplanar structure with a dihedral angle of 5.18 (12)° between the benzene ring and the central chain. The mol­ecular packing is controlled by C—H⋯π inter­actions and π–π stacking, with a Cg1⋯Cg1(1 − x, 1 − y, 1 − z) distance of 3.7687 (12) A (Cg1 is the centroid of the benzene ring).

In the crystal structure of the title compound, C16H22N22+·2Br−·2H2O, the organic cation exhibits an extended zigzag structure. The Br− anions link with the solvent water mol­ecules by O—H⋯Br hydrogen bonding. π–π stacking is observed between nearly parallel pyridine rings of adjacent mol­ecules, the centroid-to-centroid distance between these rings being 3.887 (6) A.