Structure and photoluminescence of a benzil nanocolumn in a C-methylcalix[4]resorcinarene-based framework

A new framework based on C-methylcalix[4]resorcinarene and the flexible nonconjugated spacer 1,4-bis(imidazol-1yl-methyl)benzene encloses a large one-dimensional channel, containing benzil nanocolumns. Unlike in a previously reported series of benzil-containing supramolecular solids with conjugated linker molecules, benzil luminescence is observed, but the lifetime of 580 ns at 77 K is considerably shorter than the 145 micros reported for neat benzil at room temperature.     

A novel scoop-shaped conformation of C-methylcalix[4]resorcinarene in a bilayer structure

A new scoop-shaped conformation of C-methylcalix[4]resorcinarene has been identified; it is a hybrid of the previously observed crown- and flattened cone conformations.     

Anion binding to a tetracopper resorcinarene-based complex

UV–vis and electron paramagnetic resonance (EPR) spectroscopic studies have been carried out on the multinuclear copper(II) complex Cu₄BpaRes. The copper atoms are in a tetragonal distorted geometry with nitrogens from bispicolylamine (Bpa) coordinating in the equatorial plane and water molecules or anions completing four coordination sites. The interaction of anions with this polynuclear copper complex in aqueous solution supports the formation of different complex species, which depend on the type and the concentration of the anions. In the presence of excess anions, frozen solution EPR parameters show the formation of species in which the in-plane coordination is characterised by the presence of three nitrogen atoms coming from the ligand and a donor atom from the specific anion. For the bidentate anion ligands and especially for malonate, UV–vis titrations indicate the formation of a 1:4 (Cu₄BpaRes:anion) species. EPR experiments support the formation of such a species and indicate that the four copper centres are equivalent and reach penta-coordination via the coordination of both oxygens from the bidentate ligand.     

A novel pillar[5]arene-cucurbit[10]uril based host-guest complex: Synthesis,characterization and detection of paraquat

The macrocyclic family comprising pillar[n]arenes and cucurbit[n]urils have received much attention recently. However, studies on the construction of supramolecular complexes formed directly with derivatized pillar[n]arenes and cucurbit[n]urils are scant. Given the interest in such systems, herein we have synthesized a new type of naphthalene-derivatized pillar[n]arene NTP5 and selected Q[10] as the host molecule. The 4-[2-(1-naphthalenyl)ethenyl]pyridine of NTP5 is encapsulated by Q[10] and formed a host-guest complex in water-acetic acid (1:1) solution accompanied by enhanced fluorescence, which changed the morphology of NTP5 from a sphere to a porous form. In addition, the fluorescence of Q[10]-NTP5 can be quenched by the addition of the highly toxic pesticide paraquat (PQ), and the mechanism was shown to be the formation of a new charge transfer ternary system of Q[10]-NTP5-PQ. This work provides new ideas for the contribution of supramolecular assemblies based on derivatized pillar[n]arenes and their combination with cucurbit[n]urils and reveals their potential applications.     

一种新型的偶氮间苯二酚杯[4]芳烃对Ni2+的显色剂

研究了5,11,17,23 四(5 喹啉)偶氮基 2,8,14,20 四苯基间苯二酚杯[4]芳烃(AQR)与Ni2 的选择性显色反应,在碱性介质中,Ni2 和AQR形成的配合物为1∶1,Ni2 浓度在2.6×10-7～5.8×10-6mol/L范围内符合比耳定律,配合物AQR Ni2 的表观摩尔吸收系数为1.66×105L·mol-1·cm-1(610nm),检出限为2.2×10-7mol/L(S/N=3)。     

Amidoamine calix[4]resorcinarene-based oligomers and polymers as efficient sorbents of azo dyes from water

The sorption behaviour of three kinds of macrocyclic sorbents – amidoamine tetradodecyloxyphenylencalix[4]resorcinarene 1 and tetramethyloxyphenylencalix[4]-resorcinarene 2; composition of calix[4]resorcinarene 1+2, and novel P.1 and P.2 polymers with amidoamine calix[4]resorcinarene units towards three water-soluble azo dyes – methyl orange (MO), acid orange (AO5) and Congo red (CR) was studied. All sorbents form supramolecular complexes with the aforesaid dyes. The best sorbent for MO was shown to be polymer P.1, for the AO5 – composition 1+2 and for the CR – macrocycle 2, with high sorption capacities (373, 497 and 625 mg/g, respectively). The main factor in the binding of dyes by all studied sorbents proved to be surface electrostatic interactions. In addition to the Coulomb interactions, the most important factor for the polymers appeared to be the ‘net’ structure of the polymer with a high concentration of binding sites, providing electrostatic, hydrogen, dipole–dipole and hydrophobic interaction. Hydrophobic substituents in the sorbents exert a significant influence on the dye sorption. The increase of the sorbents' hydrophobicity leads to a lower sorption capacity for MO and CR and a higher sorption capacity for AO5. It was shown that sorption efficiency of the sorbent depends on the ‘dye–sorbent’ structure conformity.     

杯[4]间苯二酚芳烃Schiff碱衍生物的合成及其离子萃取性能

通过控制条件,使两种乙氧基羰基甲氧基杯[4]间苯二酚芳烃2a和2b的酯基与1,6-己二胺的一个氨基反应形成酰胺3a和3b,剩余的一个氨基再与水杨醛反应,得到了相应的杯芳烃Schiff碱衍生物4a和4b,对其进行了金属离子的液-液萃取性能研究.结果表明,Schiff碱基团的引入能大大增强杯芳烃与金属离子的配位能力,而杯芳烃空腔的存在又能提高Schiff碱与金属离子的配位选择性.     

Surprises in the energetics of host-guest anion binding to calix[4]pyrrole

Contrary to common expectation, calorimetric measurements do not corroborate the preference of calix[4]pyrrole for fluoride over chloride in acetonitrile solution.     

Kinetics of formation of the host-guest complex of a viologen with cucurbit[7]uril

Host-guest complexation between the dicationic viologen 1-tri(ethylene glycol)-1'-methyl-m-xylyl-4,4'-bipyridinium and cucurbit[7]uril (CB7) was studied at pH = 4.5 in water. The stability constants of the mono- and bis-CB7 adducts were determined at 25 °C by UV-vis spectroscopy. Stopped-flow kinetic experiments were performed to measure the formation and dissociation rate constants of the monoadduct: k(1) = (6.01 ± 0.03) × 10(6) M(-1)s(-1) and k(-1) = 52.7 ± 0.4 s(-1), respectively. Possible mechanisms of complexation are discussed in view of the kinetic results.     

Dimeric Calix[4]resorcinarene-based Porous Organic Cages for CO2/CH4 Separation

Investigating gas separation by emerging porous organic cage(POC) solids is still on its initial stage. In this work, two novel [2+4] organic cages with distinguished structures have been prepared based on the Schiff-based condensation reaction between tetraformyl-functionalized calix[4]resorcinarene building blocks and xylylenediamine(XDA) isomers. Specifically, the use of para-position XDA affords lantern-shaped cage(CPOC-105) with a medium cavity of ca. 0.526 nm³, while the meta-position produces peanut-shaped structure(CPOC-106) with two small cavities of ca. 0.181 nm³. Both CPOC-105 and CPOC-106 exhibit high selectivity capture of CO₂ over CH₄ with calculated selectivity coefficients of 4.5 and 3.1, respectively, under ambient conditions, and are capable of separating CO₂/CH₄ mixtures by fixed-bed column breakthrough experiments.     

The reaction ofC-phenylcalix[4]resorcinarene-based polymer with quaternary ammonium and potassium cations

The resol polycondensation ofC-phenylcalix[4]resorcinarene with formaldehyde affords a corss-linked polymer possessing ion-exchange ability. The ion-exchange capacity of the polymer with respect to NH₄ ⁺, Me₄N⁺, Et₄N⁺, Bu₄N⁺, and K⁺ cations was determined. The equilibrium in the systemsC-phenylcalix[4]resorcinarene-based polymer—binary or ternary aqueous solutions of electrolytes was studied by potentiometric titration and quantumchemical MNDO/PM3 calculation Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1475–1477, August, 2000.     

Synthesis and host-guest studies of chiral N-linked peptidoresorc[4]arenes

Four cone resorc[4]arene octamethyl ethers (10, 11, ent-10, and ent-11) tetrafunctionalized at the feet with valyl-leucine [LL- (6); DD- (ent-6)] and leucyl-valine [LL- (9); DD- (ent-9)] methyl esters have been synthesized. These compounds, obtained by conjugation of macrocycle tetracarboxylic acid chlorides with the appropriate terminal amino groups of the above dipeptides, are N-linked peptidoresorc[4]arenes. We found that these macrocycles (M) are capable of recognizing the homologue dipeptides as guests (G), both in solution and in the gas phase, by forming relatively stable host-guest complexes ([M.G]), resistant to chromatographic purification but not to heating. Complexation phenomena between M and G in solution were investigated by NMR methods, including NMR DOSY experiments, for the detection of translational diffusion. Heteroassociation constants of 2030 and 186 M(-1) were obtained by the Foster-Fyfe method for the complexes [10.6] and [10.ent-6], respectively, the latter being comparable to the self-association constant of dipeptide itself. Conversely, the structural features of the proton-bound complexes [M.H.Gn]+ (n = 1, 2), generated in the gas phase by electrospray ionization mass spectrometry (ESI-MS), were investigated by collision-induced dissociation (CID) experiments. In both cases, the four N-linked peptidoresorc[4]arenes were shown to act as synthetic receptors and to recognize the homologue dipeptide by means of hydrogen bonds.     

多酸导向的间苯二酚杯[4]芳烃[Co8]配位笼的组装及电化学性质

基于多金属氧酸盐（POM）的超分子配位笼的设计和组装引起了广泛的研究兴趣,但在合成过程中仍然存在挑战。本文中,我们报道了一例基于POM-杯芳烃的大型[Co₈]配位笼[Co₈（MTR4A）₆Cl₈]（α-SiW₁₂O₄₀）₂·30DMF·74EtOH （cage-1）,该配位笼由6个碗状间苯二酚杯[4]芳烃（MTR4A）分子、8个Co(Ⅱ)阳离子、2个α-SiW₁₂O₄₀^4-抗衡阴离子和8个Cl^-阴离子组装而成。值得注意的是,α-SiW₁₂O₄₀^4-阴离子通过氢键夹在层与层之间,形成一个三维超分子结构。此外,作为锂离子电池的负极材料,cage-1表现出良好的锂离子存储能力。cage-1也能够实现对亚硝酸盐（NO₂^-）的还原和抗坏血酸（AA）的氧化,是一种具有高活性的双功能催化剂。     

一种新型杯[4]芳烃的合成

本文通过对特丁基杯[4]芳烃的酚羟基烷基化和苯环特丁基位上的IPSO-硝化制备了一系列对硝基杯[4]芳烃烷基醚,烷基分别是n-C~4H~9(3a)、n-C~8H~1~7(3b)、n-C~1~2H~2~5(3c)和n-C~1~6H~3~3(3d)。^1HNMR表明所有新的杯[4]芳烃都具有锥形(cone)构象。     

Initial example of a triangular single-molecule magnet from ligand-induced structural distortion of a [MnIII3O]7+ complex

The reaction of [Mn3O(O2CR)6(py)3](ClO4) (R = Me, Et) with methyl 2-pyridyl ketone oxime (mpkoH) in a 1:3 molar ratio in MeOH/MeCN leads to [Mn3O(O2CR)3(mpko)3](ClO4) in 80-90% isolated yield. Ferromagnetic exchange interactions between the three MnIII ions in the nonplanar [MnIII3O]7+ triangular core lead to a spin ground state of S = 6; single-crystal studies reveal the temperature and sweep rate dependent hysteresis loops expected for a single-molecule magnet.     

Molecular dynamics of host-guest complexes of small gas molecules with calix[4]arenes

The unexpected sorption of gases by a low-density p-tert-butylcalix[4]arene crystal polymorph raises fundamental questions about differential gas transport and sequestration in the organic solid state. To gain insight into the processes underlying these observations, we have used molecular dynamics simulations, augmented with calculations of potentials of mean force, to investigate the stability of isolated host-guest complexes and the relationship between the dynamics of these complexes and the dynamics of a solvated host molecule. Thermal fluctuations of the calixarenes themselves are found to be consistent with proposed mechanisms for gas entry into the host cavities, while relative host-guest stabilities correlate well with experimental absorption-desorption isotherms in some cases (CO2 and CH4) but not in others (C2H2). In these isolated systems, stable complexes characteristically form when the attractive interactions of the guest with the ring of negative charge density on the inner surface of the host cavity are not disrupted by thermal motion. The experimentally observed efficient uptake of gases such as C2H2 by the host crystals suggests, however, that stabilization of host-guest complexes in some systems may derive from dynamical constraints imposed by the crystal lattice.     

Ionic galleries: a bilayered host-guest cocrystal of C-propyl pyrogallol[4]arene with an ionic liquid

We report on a cocrystal between C-propyl pyrogallol[4]arene and the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate exhibiting a remarkable bilayer topology comprising two unique host-guest complexes resulting from the ionic liquid cation binding in two distinctive orientations relative to the macrocycle.     

Transformation of a [4+6] Salicylbisimine Cage to Chemically Robust Amide Cages

In recent years, interest in shape‐persistent organic cage compounds has steadily increased, not least because dynamic covalent bond formation enables such structures to be made in high to excellent yields. One often used type of dynamic bond formation is the generation of an imine bond from an aldehyde and an amine. Although the reversibility of the imine bond formation is advantageous for high yields, it is disadvantageous for the chemical stability of the compounds. Amide bonds are, in contrast to imine bonds much more robust. Shape‐persistent amide cages have so far been made by irreversible amide bond formations in multiple steps, very often accompanied by low yields. Here, we present an approach to shape‐persistent amide cages by exploiting a high‐yielding reversible cage formation in the first step, and a Pinnick oxidation as a key step to access the amide cages in just three steps. These chemically robust amide cages can be further transformed by bromination or nitration to allow post‐functionalization in high yields. The impact of the substituents on the gas sorption behavior was also investigated.     

Lewis acid-catalyzed synthesis of dodecamethoxycalix[4]arene from 1,3,5-trimethoxybenzene and its conformational behavior and host-guest property

Lewis acid-catalyzed condensation of 1,2- and 1,3-dimethoxybenzenes with paraformaldehyde afforded an ortho-bridged cyclic trimer (1) and a meta-bridged cyclic tetramer (2), respectively. Furthermore, condensation of 1,3,5-trimethoxybenzene with paraformaldehyde in the presence of Lewis acid catalyst successfully rendered the first dodecamethoxy-substituted calix[4]arene (3) with high yield. From X-ray crystallography, it was found that 3 formed the partial cone conformation. The conformational behavior of 3 in the solution was investigated by variable temperature ¹H NMR measurements. The partial cone structure observed in the solid state was retained in the solution at low temperatures. Furthermore, because of the slow conformational exchanges of 3 on the NMR time scale, bimodal conformational exchanges were found. The host-guest property of 3 with the electron accepting guest, tetracyanoethylene (TCNE) was examined by UV-Vis measurements, and the ability to associate with the 3-TCNE complex was three times higher than that of the 2-TCNE complex. The observation is due to the superior electron donating property and slow conformational exchanges of 3 compared with those of analogous 2.     

Synthesis and host-guest properties of pillar[6]arenes

A facile method for the synthesis of pillar[6]arenes was developed.A series of pillar[6]arenes were prepared with FeCl 3 as catalyst and chloroform as solvent at room temperature in moderate yields(30%-40%).Their host-guest properties with n-cetyltrimethyl ammonium bromide were investigated by 1 HNMR.The results showed that high selectivity in the host-guest relationship became apparent between pillar[6]arenes and pillar[5]arenes based on the different size of the inner cavity.