Search

In this paper, the host-guest interaction of cucurbit[7]uril (Q[7]) and chromone (CMO) has been developed as a fluorescent probe for the highly selective detection of Zn2+ and Cd2+ in water based on a chelation-enhanced fluorescence (CHEF) mechanism. There was a good linear relationship between the fluorescence intensity of the CMO@Q[7] probe and the concentration of Zn2+ or Cd2+ in the range of 0–3.0 × 10–5 mol/L and the detection limit for Zn2+ and Cd2+ was found to be 2.03 × 10–6 mol/L and 1.89 × 10–6 mol/L, respectively. The X-ray crystal structure indicated that different coordination fashions were triggered by Zn2+ and Cd2+ in the CMO@Q[7] complexes, respectively. However, both metal ions coordinated with the carbonyl oxygen of CMO, which was encapsulated in the cavity of Q[7], thus leading to the enhancement of recognition fluorescence emission of CMO.

Curcurbit[n]uril (Q[n])-based supramolecular frameworks (QSFs) constructed from the outer surface interaction of Q[n]s (OSIQ) have the characteristic of simplicity, diversity and modulability. Their simplicity is reflected in their simple composition and preparation methods used for QSFs. The diversity of supramolecular organic frameworks (SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs, as well as the variety of structural directing agents and basic building blocks used to prepare QSFs. The modulability is reflected by the controllable channel size in the QSFs, which can be adjusted using different sizes of Q[n]s. In this work, the first reported cucurbituril Q[6] was selected as the basic building block and three Q[6]-based supramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl4]2− respectively. The OSIQs are the main driving forces for the formation of these frameworks. This study shows the diversity of the QSFs.

Cucurbit[n]uril(Q[n])-based supramolecular frameworks assembled through outer surface interactions are characterized by their simple composition, convenient preparation, high yields and controllable structures. The most prominent characteristic of these frameworks is their diversity, with various synthesis methods, structural characteristics, structure directing agents and basic building blocks of Q[n]s. In this work, a symmetric tetramethyl-substituted Q[6] (TMeQ[6]) is selected as the basic building block, with three different TMeQ[6]-based supramolecular frameworks obtained from 1-, 3- and 5 mol/L aqueous H2SO4 solutions, respectively. The outer surface interactions between TMeQ[6] and the adjacent SO42− anions or TMeQ[6] units are the main driving forces for the formation of these frameworks, which exhibit adsorption properties for fluorophore dyes and organic isomers. These adsorption characteristics may lead to the application of these frameworks in the synthesis of solid fluorescent sensors for volatile organic compounds and the adsorptive separation of alkane isomers.

The coordination of alkaline earth metal cations (AE2+ = Mg2+, Ca2+, Sr2+, Ba2+) with inverted hexamethylcucurbit[3,3]uril {iMe6Q[3,3]} has been investigated in the presence of polychlorido cadmium anions as structure directing agent. Single-crystal X-ray diffraction analysis has revealed that the interactions of iMe6Q[3,3] with AE2+ cations result in the formation of linear iMe6Q[3,3]-based coordination polymers from iMe6Q[3,3]-AECl2-CdCl2-HCl systems. Generally, Cd2+ cations can form [CdCl4]2− anions that serve as structure directing agent in the formation of iMe6Q[3,3]/AE2+-based coordination polymers. Moreover, iMe6Q[3,3]-AECl2-CdCl2-HCl systems exhibit high affinity for the heavier AE2+, such as Sr2+, and Ba2+.

Q[8]-based honeycomb-like frameworks can be obtained in [AuCl4]--free aqueous HNO3 solution and aqueous HCl and HNO3 solutions that contain [AuCl4]-. The outer surface interaction of Q[8] with planar inorganic anions [AuCl4]- and NO3- is the main driving force. These frameworks exhibit a high selectivity for imprisoning [AuCl4]- that could establish a process for gold recovery.

Two perhydroxylated cucurbit[6]uril-based supramolecular assemblies have been obtained via crystallization of perhydroxylated cucurbit[6]uril {(HO)12Q[6]} from aqueous HCl solutions of different concentrations. Single-crystal X-ray diffraction (unit cell) analysis revealed that (HO)12Q[6] molecules interacted with water molecules through hydrogen bonding, thereby forming solid supramolecular assemblies with different kinds of channels. These selected channels were formed from the stacking of (HO)12Q[6] molecules in a portal-to-portal manner and between the outer surfaces of (HO)12Q[6] molecules. Unlike normal or alkyl-substituted Q[n]-based supramolecular assemblies, which generally exhibit highly selective absorption of methanol, the (HO)12Q[6]-based supramolecular assemblies exhibit highly selective absorption of polychloromethanes.

We report the preparation and single crystal X-ray diffraction analysis of three supramolecular self-assemblies based on perhydroxycucurbit[5]uril {(HO)10Q[5]}, Keggin-type heteropolyacids (HPAs), and potassium or barium cations. Crystallographic data revealed that all 3D self-assemblies are constructed by a stack of 2D layered structures composed of (HO)10Q[5]/K+ or (HO)10Q[5]/Ba2+ complexes cations and HPAs anions. Although there are differences in 2D layered structures, all the driving force comes from the outer surface interactions of (HO)10Q[5] including: (1) typical hydrogen bonding by hydroxyl groups and atypical hydrogen bonding by methylene on the outer surface of (HO)10Q[5]; (2) dipole interaction between the positively charged methylene or carbonyl carbon atoms of (HO)10Q[5] and the negatively charged oxygen atoms of the HPAs; (3) The electrostatic interaction between the (HO)10Q[5]/metal cations and the HPAs anions plays a main role in self-assembling.

Cucurbit[10]uril (Q[10] or CB[10]), with the largest rigid cavity (ca. 1.0 nm) yet characterized in the cucurbiturils family, and indeed among all artificial macrocyclic receptors to date, has been successfully exploited to construct a novel Q[10]–[Cd4Cl16]8–-based pillared diamond porous supramolecular framework. Single-crystal X-ray diffraction analysis revealed that the three-dimensional open-nanotube-type porous framework is constructed from free Q[10] molecules and [Cd4Cl16]8– cluster anions through the outer surface interactions of Q[10]. Notably, the Q[10]-based porous framework host can accommodate guest dyes, such as rhodamine B (G1), pyrenemethanamine hydrochloride (G2), and bathocuproine hydrochloride (G3), to form solid materials with efficient red-green-blue (RGB) fluorescence. This work not only exemplifies a facile approach for the construction of macrocycle-based porous frameworks but also offers a simple, lower cost, yet still highly efficient means of preparing multi-emitting, including ...

We investigated the interactions in an inverted cucurbit[6]uril ( i Q[6]) with a series of 1, ω -alkyldimins and their supramolecular assemblies in the presence of the tetrachlorozincate anion ([ZnCl 4 ] 2− ) structure directing agent. i Q[6] forms an outer surface interaction with [ZnCl 4 ] 2− to form different i Q[6]/[ZnCl 4 ] 2− -based supramolecular assemblies with different length 1,ω-alkyldimins. Interestingly, most 1,ω-alkyldimins were not visible in crystals structures in the presence of concentrated HCl. The porous i Q[6]/[ZnCl 4 ] 2− -based supramolecular assemblies could be used as materials for adsorbing volatile compounds.

The binding interactions of CyP6Q[6] with a series of alkyl diammonium (+H3N(CH2)nNH3+, n = 2, 4, 6, 8, 10, 12) and aryl diammonium (p-phenylenediammonium and p-xylenediammonium) ions both in aqueous solution and in the solid state have been studied by 1H NMR spectroscopy, X-ray crystallography, and isothermal titration calorimetry (ITC) techniques. 1H NMR data indicate that all guests exhibit endo binding with CyP6Q[6] except for the ethanediammonium ion, which bound exo to CyP6Q[6]. p-Xylenediammonium ions show mixed behavior (exo and endo binding with CyP6Q[6]). X-ray crystallography clearly displays the extended and contorted conformations of the guests when bound within CyP6Q[6]. The ITC study points out that the CyP6Q[6] complex formations with all guests are mainly driven by enthalpy, which arises from the ion–dipole interactions and the hydrophobic effects.

The interaction of a series of lanthanide cations (Ln3+) with a di-hydroxylated symmetrical octamethyl-substituted cucurbituril {(OH)2OMeQ[6]} has been investigated. Single-crystal X-ray diffraction analysis has revealed that the interaction results in the formation of adducts of (OH)2OMeQ[6] with aqua complexes of lanthanide cations ([Ln(H2O)8]3+), Ln = Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in (OH)2OMeQ[6]–Ln(NO3)3–H2O systems. However, no solid crystals were obtained from systems containing La, Ce, Pr, Nd and Sm. X-ray diffraction analysis has revealed that although the solid adducts fall into two isomorphous groups, there are no significant differences in the interactions between (OH)2OMeQ[6] and [Ln(H2O)8]3+ complexes and in the corresponding supramolecular assemblies. Thermodynamic parameters for the interaction between (OH)2OMeQ[6] and [Ln(H2O)8]3+ complexes based on isothermal titration calorimetry experiments show two periods corresponding to the above two systems, with the lighter lanthanide cations preferring to remain in solution and the heavier lanthanide cations forming crystalline solids. Energy dispersive spectroscopy (EDS) has shown that the interaction of OMeQ[6] with lanthanide cations could provide a means of isolating heavier lanthanide cations from their lighter counterparts.

Interactions of alkali cations (A+ = Na+, K+, Rb+, Cs+) with a symmetrical octamethyl-substituted cucurbituril (OMeQ[6]) have been investigated in the presence of different structure-directing agents. Single-crystal X-ray diffraction analysis has revealed that the interaction results in the formation of coordination complexes of OMeQ[6] with K+ and Cs+ cations in OMeQ[6]–ACl–HCl systems, whereas no complexes were obtained from systems containing Na+ and Rb+ in the presence of polychloride cadmium anions such as [Cd2Cl8]4−, [CdCl4]2−, or [Cd2Cl7]3− as structure-directing agents; in the presence of p-hydroxybenzoic acid (Hyb) as a structure-directing agent, the interaction results in the formation of coordination complexes of OMeQ[6] with Na+ and Cs+ cations in OMeQ[6]–ACl–H2O systems. More importantly, in the presence of these different structure-directing agents, OMeQ[6] or OMeQ[6]/A+ complexes can form different supramolecular assemblies based on the outer surface interaction of Q[n].

In this study, fully substituted cyclopentano cucurbit[5]uril (CyP 5 Q[5]) were coordinated with an alkaline earth cations (AE 2+ ) in the presence of tetrachlorozincate anions ([ZnCl 4 ] 2− ). Single-crystal X-ray diffraction analysis revealed that the CyP 5 Q[5]–Mg 2+ –[ZnCl 4 ] 2− –HCl interaction system yielded an Mg 2+ /Cl − @CyP 5 Q[5]-type molecular bowl, with a chloride anion in the cavity of the CyP 5 Q[5] moiety. The CyP 5 Q[5]–Ca 2+ and Sr 2+ –[ZnCl 4 ] 2− –HCl interaction systems yielded isolated AE 2+ /CyP 5 Q[5]/AE 2+ -type molecular capsules, again with a chloride anion in the CyP 5 Q[5] cavity. A honeycomb effect was evident in all three systems, in which the of the [ZnCl 4 ] 2− anions surround the CyP 5 Q[5] molecules through outer surface interactions between Q[n] and electrostatic interactions with AE 2+ cations, resulting in the formation of porous supramolecular assemblies. Direct coordination between Ba 2+ and CyP 5 Q[5] yielded zigzag coordination polymers. The CyP 5 Q[5]/AE 2+ -based supramolecular assemblies (AE = Mg, Ca, Sr, Ba) presented different porous conformations and displayed differential absorption of volatile compounds.

Coordination of an inverted cucurbit[7]uril (iQ[7]) with a series of alkali cations (A+), revealed that iQ[7] can interact with potassium to form iQ[7]-K+-based porous coordination polymer in the presence of [ZnCl4]2 − anions as a structure directing agent. Unexpectedly, isothermal titration calorimetry revealed no obvious interaction of iQ[7] with any A+ cation. Moreover, the iQ[7]-K+-based porous coordination polymer showed selective sorption of polar volatile organics, which may have potential applications for molecular sieves, sensors, and absorption and separation processes.

Two new twisted cucurbiturils, cucurbit[13]uril (tQ[13]) and cucurbit[15]uril (tQ[15]), have been synthesized and separated, and their structures have been confirmed by NMR spectroscopy and MALDI-TOF mass spectrometry together with the X-ray structures of two new complexes, {Dy(H2O)4Cd(H2O)4tQ[13]}·2.5[CdCl4]·65H2O and {Cd0.5(H2O)2tQ[15]}·[CdCl4]·47H2O. tQ[15] is the largest cucurbit[n]uril (Q[n]) in the Q[n] family reported to date. The X-ray diffraction studies of both complexes indicated that these large tQ[n]s effectively exhibit two different cavities-a central cavity and two side cavities. Preliminary host-guest behavior by each of the new systems was investigated by NMR studies.

Coordination of lanthanide cations (Ln3+) and a symmetrical dicyclohexanocucurbit[6]uril (1,4-DiCyHQ[6]) in the presence of tetrachlorozincate was investigated. X-ray single crystal diffraction analysis revealed that with [ZnCl4]2− anions as a structure directing agent, the interaction of lighter lanthanide cations and 1,4-DiCyHQ[6] results in the formation of fast precipitation, whereas the interaction of heavier lanthanide cations and 1,4-DiCyHQ[6] results in solid crystals. This provides a potential strategy for separating lighter and heavier lanthanide cations.

Molecular interactions between an inverted cucurbit[6]uril (iQ[6]) with α,ω-alkyldiammonium guests (H3N(CH2)xNH3Cl2, x = 2, 4, 6, 8, 10, and 12 named 1–6) were investigated in aqueous and acidic solutions by various techniques. 1H NMR spectroscopy revealed that only compounds 3 and 4 underwent an equilibrium interaction with the iQ[6] host, with association constants in acidic solution of ~83 and ~41 L mol−1, respectively, while the other guests showed no obvious interaction. Only two host–guest interaction systems gave rise to single crystals in the presence of polychloride transition metal anions as structure-directing agents. X-ray diffraction revealed that guests 1 and 3 interacted with iQ[6] through portal and cavity interactions, respectively.

Two Q[n]-based porous compounds, Q[5]·[PtCl6]2 −·2H3O·12H2O and 2Q[8]·[PtCl6]2 −·2H3O·74H2O in cooperating the hexachloroplatinate(IV) anion ([PtCl6]2 −) as an inorganic structure directing agent are demonstrated. The driving forces for the formation of such novel Q[n]-based porous compounds are considered to be the outer surface interactions of Q[n]s, including dipole interactions between Q[n]s and ion-dipole interactions between [PtCl6]2 − anions and Q[n]s. Moreover, the Q[5]-based porous compound displays absorption distinctness for tetrachloromethane, whereas the Q[8]-based porous compound displays absorption distinctness for methanol.

Coordination of fully substituted cyclopentano cucurbit[5]uril (CyP5Q[5]) with an alkali cation (A+) in the presence of tetrachloridezicate anions was investigated. Single-crystal X-ray diffraction analysis revealed that the CyP5Q[5]–Na+ and K+–[ZnCl4]2−–HCl interaction systems yielded an A+/Cl−@CyP5Q[5]/A+-type molecular capsule, and that a chloride anion was included in the cavity of the CyP5Q[5] molecule. [ZnCl4]2− anions were not involved in direct coordination with the A+/Cl−@CyP5Q[5]/A+ capsule. The CyP5Q[5]–Rb+ and Cs+–[ZnCl4]2−–HCl interaction systems yielded an A+/CyP5Q[5]/A+-type molecular capsule shell, and no chloride anions were included in the cavity of the CyP5Q[5] molecule. [ZnCl4]2− anions directly interacted with coordinated Rb+ or Cs+ cations through electrostatic interaction, and [ZnCl4]2− anions in particular played the role of linkers, resulting in the formation of a linear supramolecular assembly ⋯[ZnCl4]2−–A+/Cl−@CyP5Q[5]/A+–[ZnCl4]2−–A+/Cl−@CyP5Q[5]/A+⋯. Close inspection revealed that the obtained CyP5Q[5]/A+-based supramolecular assemblies (A = Na, K, Rb, Cs) presented different porous conformation and could show different absorption properties.

Four new complexes have been prepared and characterized from reaction of the tetrapodal Schiff base ligand 1,1,1,1-tetrakis[(3-methoxysalicylaldimino)methyl]methane (H4L) with Cu(II), Ni(II) and Cd(II). X-ray diffraction experiments revealed that 1 ([Cu2L·2H2O]·H2O) and 2 ([Cu2L·2CH3OH]·3H2O) are dinuclear complexes, with the same tetragonal pyramidal coordination geometries around their Cu(II) ions. Complex 3 ([Ni2L]·2H2O) is dinuclear with two square planar Ni(II) ions coordinated to two pairs of the pendant branches of H4L. Complex 4 ([Cd3(HL)2]·3H2O) is a linear trinuclear species with three Cd(II) ions, which were intermolecularly coordinated to three pendant branches of two H4L ligands via an uncommon intermolecular phenoxo oxygen face-sharing mode. The in vitro antimicrobial activities of H4L and its complexes were evaluated against four micro-organisms (Colibacillus, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis) using the tube-dilution method. The results revealed t...

The [CdCl 4 ] 2− anion as a structure inducer has proved to be useful in the construction of cucurbit[ n ]uril-metal coordination architectures and materials. In order to better understand the role and influence of the structure inducer in Q[ n ] systems, we report herein the self-assembly of Q[6] solely in the presence of [CdCl 4 ] 2− anions and in the presence of both a linear cationic organic guest and [CdCl 4 ] 2− anions. X-ray diffraction analysis revealed that 1D Q[6] porous channels were formed by the noncovalent interactions between Q[6] and [CdCl 4 ] 2− anions, but the “honeycomb effect” was not observed in the present study. However, it seems that the “honeycomb effect” and the self-assembly of Q[6] with [CdCl 4 ] 2− anions can be significantly modified and switched in the presence of a linear cationic dibutylamine guest through some unusual noncovalent interactions.

The interaction of the alkaline-earth metal ions Mg2+, Ca2+, Sr2+ and Ba2+ with the symmetrical octamethyl-substituted cucurbituril, OMeQ[6], in the presence of [CdCl4]2−/[Cd2Cl8]4− anions as structure-directing agent(s) in 3 M HCl has been investigated. Ca2+ and Sr2+ yielded closely related metallosupramolecular assemblies whose X-ray structures show that in the former, [Cd2Cl8]4− anions are arranged to form parallelogram-like frameworks that surround linear OMeQ[6]/Ca2+ polymeric units. The structure of the OMeQ[6]/Sr2+ assembly is similar except that the [Cd2Cl8]4− anions in the OMeQ[6]/Ca2+ assembly are replaced by [Cd2(H2O)2Cl8]4− anions. In contrast to the above structures, interaction of the larger Ba2+ ion with OMeQ[6] gives rise to a different assembly type displaying a porous linear polymeric arrangement incorporating two different Ba2+ coordination modes; [Cd2Cl4]4− anions are associated with the Ba2+ bridges linking adjacent OMeQ[6] units in the polymeric chain. In contrast to Ca2+ and Sr2+, the smaller Mg2+ ion under similar synthetic conditions failed to yield a solid product. Isothermal titration calorimetry (ITC) studies revealed that OMeQ[6] interacts with Ca2+, Sr2+ and Ba2+, but not Mg2+, in neutral aqueous solution. The respective X-ray structures reveal the presence of both channels and other voids in the three assemblies. Following application of a vacuum until constant weight was obtained, samples of the Sr2+ and Ba2+ assemblies were subjected to the saturated vapour of each of the following volatile ligands: acetonitrile, methanol, ethanol, acetone, diethylether, dichloromethane, cyclohexane and n-hexane. The respective absorption profiles show maximum absorption for methanol, with reduced uptake for the remaining larger and/or less polar guest molecules.

Coordination and supramolecular assemblies of a fully substituted cyclopentanocucurbit[6]uril (CyP6Q[6]) with a series of lanthanide cations (Ln3+) have been investigated in the presence of tetrachlorozincate anion ([ZnCl4]2–). X-ray single-crystal diffraction analysis has revealed that the interaction of CyP6Q[6] and a series of Ln3+cations unexpectedly results in the formation of at least seven different CyP6Q[6]-based coordination complex adduct and supramolecular assemblies groups, including with (1) La3+, Ce3+cations; (2) Pr3+, Nd3+cations; (3) Eu3+, Gd3+, Tb3+, Dy3+ with P1 or P1 space group, in which CyP6Q[6] molecules coordinate alternatively with Ln3+cations and form linear coordination polymers; (4) CyP6Q[6] molecules interact alternatively with [Ho(H2O)8]3+ aqueous complexes and form linear supramolecular chains; CyP6Q[6] molecules can assemble two different Ln3+ free porous supramolecular assemblies from CyP6Q[6]–Ln(NO3)3–ZnCl2–HCl systems, Ln = Tm, Yb, and Lu; however, no solid crystals were...

Compared to isolated, simple Ln3+/Q[6] complexes in the absence of polychloridometallate ions, linear coordination polymers have been assembled from lanthanide cations (Ln3+) and cucurbituril (Q[6]) in the presence of polychloridometallate ions as inorganic structure inducers in HCl solution. X-ray diffraction analysis has revealed that not only [CuCl4]2− anions but also [FeCl2(H2O)4]+ cations can induce the coordination of Ln3+ cations to Q[6] so as to form Ln3+/Q[6]-based tubular coordination polymers. The driving forces are considered to be interaction of the electron-deficient carbon sites of the carbonyl dipoles of Q[n] molecules with the chloride ends of the Md-block−Cl bonds in the [Md-blockClx]n− anions or [Md-blockClx]m+ cations, as well as unusual hydrogen bonding between the methine and methylene groups on the back of adjacent Q[n] molecules and the chlorine atoms of the [Md-blockClx]n− ions. We have classified such interactions as ‘back-interaction of Q[n]s’.

Coordination of supramolecular assemblies was investigated by reacting a series of lanthanide cations (Ln3+) with an inverted cucurbituril (iQ[6]) in the presence of tetrachloride zincate anion [ZnCl4]2−, as an structure directing agent in aqueous HCl (3.0 mol/L). Single crystal X-ray diffraction analysis revealed that the coordination of iQ[6] with Ln3+ gave rise to different interaction products and isomorphous groups with increasing atomic number. The interaction of iQ[6] with La3+ and Ce3+ immediately yielded precipitations and single crystal solids containing Pr3+ and Nd3+. No solids resulted from coordination of iQ[6] with Sm3+ and Eu3+, whereas single crystals solids were obtained from coordination of iQ[6] with heavy Ln3+, such as Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+ and Lu3+. Such coordination characteristics may offer a strategy for isolating a series of Ln3+ cations in patches.

The coordination and supramolecular assemblies of lanthanide cations and perhydroxycucurbit[5]uril {(HO)10Q[5]} in the presence of [SiW12O40]4– anions and transition metal salts show significant differences as the lanthanide atomic number increases. The molecular capsule (HO)10Q[5] coordinates with the light lanthanide cations Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, and Tb3+ but does not coordinate with heavier Ln3+ cations. However, (HO)10Q[5]/Na+-based molecular capsules form in the presence of the heavier lanthanide cations Ho3+, Er3+, Tm3+, Yb3+, and Lu3+ under the same synthetic conditions. These differences could be key in establishing a strategy for the isolation of light lanthanides from their heavier counterparts.

The supramolecular assemblies formed from lanthanide cations (Ln3+) and a new alkyl-substituted cucurbituril, the ortho-tetramethyl substituted cucurbituril (o-TMeQ[6]), in neutral solution were investigated. X-ray single crystal diffraction analysis revealed that interactions of the aqua complexes of lanthanide cations with o-TMeQ[6] gives rise to an isomorphous group of compounds when heavy lanthanide cations such as Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+ and Lu3+ are employed. Interestingly, no solid crystals were obtained from o-TMeQ[6]–Ln3+ systems of La, Ce, Pr, Nd, Sm, Eu or Gd, suggesting that these interactions could be used for the isolation of heavier lanthanide cations from their lighter counterparts.

Coordination assemblies have been investigated by reactions between alkali metal salts and a meta-hexanomethyl-substituted cucurbit[6]uril (m-HMeQ[6]) in aqueous solutions. X-ray diffraction analysis revealed that each m-HMeQ[6] coordinates with three alkali metal ions, K+, Rb+ or Cs+ and forms a 1:2, m-HMeQ[6]:Malkali+ complex. This complex forms a one-dimensional supramolecular chain through hydrogen bonding. The m-HMeQ[6]/Malkali+ complex-based chains often form honeycomb-like frameworks in which each channel is filled with counter anions and water molecules. The driving forces resulting in the formation of such supramolecular assemblies could be attributed to the outer-surface interaction of Q[n]s.

The interaction of alkaline-earth cations (AE2+) with hexanohydroxyhexanomethylcucurbit[6]uril (HHQ[6]) in the presence of CdCl2 in aqueous HCl solution was investigated. Single crystal X-ray diffraction analysis revealed that the interaction results in the formation of one-dimensional coordination polymers of HHQ[6] with AE2+ (Ca, Sr or Ba). In addition, compounds containing Ca and Sr are isomorphous. Moreover, the compound obtained from the HHQ[6]–MgCl2–CdCl2–HCl system contained only a metal-free HHQ[6]-based supramolecular assembly. ITC experiments showed that the interaction between HHQ[6] and Mg2+ could not be effectively measured, and that the interaction of Ca2+ or Sr2+ with HHQ[6] are driven by ΔH and ΔS, whereas the interaction between Ba2+ and HHQ[6] is driven by ΔH.

Coordination in supramolecular assemblies in aqueous HCl solutions was investigated by reacting alkaline-earth cations (AE2+) and inverted cucurbit[6]uril (iQ[6]) in the presence of the structure-directing agent, tetrachloride zincate ion. Single-crystal X-ray diffraction analysis revealed that the iQ[6]–Mg2+–[ZnCl4]2––HCl interaction system yielded a supramolecular assembly of iQ[6] and [ZnCl4]2– without forming coordination complexes of Mg2+ or Zn2+ with iQ[6]. In contrast, interaction of Ca2+ or Sr2+ with iQ[6] in the presence of [ZnCl4]2– gave rise to linear coordination polymers, which formed a honeycomb-like framework in which the linear polymers occupy cells of the framework. The iQ[6]–Ba2+–[ZnCl4]2––HCl interaction system immediately produced precipitates, thus preventing isolation of single crystals under similar synthetic conditions.

In the present work, we demonstrate the formation of a typical cucurbit[6]uril (Q[6])-based porous material in the presence of the hexachloroplatinate(IV) anion [PtCl6]2– as an inorganic structure inducer. The driving forces for the structure directing effect of the [PtCl6]2– anion could be attributed to ion–dipole and hydrogen-bonding interactions between the anion and the ≡CH or =CH2 groups on the back of the Q[6] molecule.

A Cu(II) Schiff base coordination polymer, {[Cu 3 L( μ 2 - NO 3 ) 2 ·(H 2 O) 2 ].3H 2 O} n , is readily prepared by complexation of the tetrapodal Schiff base, H 4 L (H 4 L = 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane), with cupric nitrate trihydrate. It has been demonstrated that the coordination polymer consists of linear trinuclear Cu(II) entities, and displays a cooperative coordination mode for nitrate anions, coordinated water molecules, and Schiff base ligands to Cu(II) ions. In addition, variable-temperature magnetic susceptibility measurements reveal a strong antiferromagnetic coupling interaction between adjacent copper(II) ions with large J value of − 289.66 cm − 1 .

Five silver coordination polymers, namely, {[Ag(3,3′-daps)2]·BF4}n (1), {[Ag(3,3′-daps)2]·NO3}n (2), [Ag(3,3′-daps)(CF3SO3)]n (3), {[Ag(4,4′-daps)]·CF3SO3}n (4), and {[Ag(4,4′-daps)]·ClO4}n (5) (3,3′-daps=di(3′-aminodiphenyl)sulfone, and 4,4′-daps=di(4′-aminodiphenyl)sulfone) have been synthesized and structural characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction analyses. Complex 1 displays a 1D ladder-like chain with four-connected Ag ions and bridged 3,3′-daps. Complex 2 shows other 1D ladder chain modified by tentacles. Complex 3 is a 2D layer structure with both Ag ions and 3,3′-daps are 3-connected nodes. Complex 4 is another 1D ladder chain with three-connected Ag ions and 4,4′-daps. Complex 5 shows a 2D 44-sql net with Ag ions and 4,4′-daps as 4-connected nodes. Moreover, their solid state luminescence and thermal stabilities also have been investigated.