Tetraphosphinitoresorcinarene complexes: cationic silver(I) and copper(I) halide complexes as mercurate(II) anion receptors

The reactions of mercury(II) halides with the tetraphosphinitoresorcinarene complexes [P4M5X5], where M=Cu or Ag, X=Cl, Br, or I, and P4=(PhCH2CH2CHC6H2)4(O2CR)4(OPPh2)4 with R=C6H11, 4-C6H4Me, C4H3S, OCH2CCH, or OCH2Ph, have been studied. The reactions of the complexes with HgX2 when M=Ag and X=Cl or Br occur with elimination of silver(I) halide and formation of [P4Ag2X(HgX3)], but when M=Ag and X=I, the complexes [P4Ag4I5(HgI)] are formed. When M=Cu and X=I, the products were the remarkable capsule complexes [(P4Cu2I)2(Hg2X6)]. When M=Ag and X=I, the reaction with both CuI and HgI2 gave the complexes [P4Cu2I(Hg2I5)]. Many of these complexes are structurally characterized as containing mercurate anions weakly bonded to cationic tetraphosphinitoresorcinarene complexes of copper(I) or silver(I) in an unusual form of host-guest interaction. In contrast, the complex [P4Ag4I5(HgI)] is considered to be derived from an anionic silver cluster with an iodomercury(II) cation. Fluxionality of the complexes in solution is interpreted in terms of easy, reversible making and breaking of secondary bonds between the copper(I) or silver(I) cations and the mercurate anions.     

Synthesis and solid-state study of supramolecular host-guest assemblies: Bis[6-O,6-O'-(1,2:3,4-diisopropylidene-alpha-D-galactopyranosyl)thiophosphoryl] dichalcogenides

A complementary approach for studying structural details of complex solid materials formed by symmetrical and unsymmetrical dichalcogenides, which employs both X-ray diffraction (XRD) and solid-state NMR (SS NMR), is presented. The new diagnostic technique allows reversible crystallographic space group change and very subtle distortion of host geometry to be followed during guest migration in the crystal lattice. Bis[6-O,6-O'-(1,2:3,4-diisopropylidene-alpha-D-galactopyranosyl)]thiophosphoryl selenenyl sulfide, a representative of wheel-and-axle host (WAAH) molecules, can be synthesized in the solid state by grinding and gentle heating of disulfide 1 and diselenide 2. Full characterization of disulfide 1 in the solid phase has been reported (J. Org. Chem. 1995, 60, 2549). In the current work, the synthesis and both XRD and SS NMR studies of the isostructural diselenide substrate 2 are presented. A (31)P cross polarization magic angle spinning experiment is employed to follow the progress of synthesis of selenenyl sulfide 3 in the solid state. It is concluded that selenenyl sulfide exists in equilibrium with disulfide and diselenide in a 1:1:1 ratio in both the liquid and the powdered solid. A mixture of isostructural dichalcogenides crystallized from different solvents form three-component host-guest inclusion complexes with columnar architecture. In the host-guest complex of diselenide 2 with toluene (space group C2), columns of host molecules are in parallel orientations along all the axes, whereas in the structures of diselenide 2 with propan-2-ol and propan-1-ol (space group P3 2), the columns of host molecules lay along the 3-fold symmetry axis. Thermal processes effecting structural changes in the host lattice and the kinetics of reversible guest molecule diffusion were investigated using SS NMR spectroscopy. Finally, the Se/S scrambling phenomenon and limitations in the X-ray structure refinement of organic compounds containing selenium and sulfur in chains are discussed.     

Hydrogen-bonded metal-complex sulfonate (MCS) inclusion compounds: effect of the guest molecule on the host framework

Soft molecular host frameworks made of the hydrogen-bonded metal complex (MC) Co(NH3)(6)3+ and 4,4'-biphenyldisulfonate (BPDS) include different guest molecules to form inclusion compounds of the type (MC)2(BPDS)3.n(guest). Structurally characterized were six compounds with guest molecules of DMSO, DMF, piperidine, acetone, acetonitrile, and THF. The metal-complex sulfonate frameworks in all of them are of the pillared layer type where the layers are constructed of extensively hydrogen-bonded metal-complex cations and sulfonate (S) anions (and some hydrogen-bonded water) while the organic residues of the 4,4'-biphenyldisulfonate serve as pillars. The hydrogen-bonded MCS layers and the orientations of the pillars adjust and rearrange in order to generate cavities that would accommodate different guest molecules. The steric, electronic, and hydrogen-bonding needs of the guest molecules mold the soft framework into different structures. These MCS host-guest frameworks are very close structural analogues of the well-studied guanidinium sulfonate (GS) networks and mimic their flexibility and overall durability.     

Solid-phase synthesis and screening of macrocyclic nucleotide-hybrid compounds targeted to hepatitis C NS5B

A convergent strategy for the synthesis of cyclic nucleotide-hybrid molecules on controlled pore glass is reported. A major advantage of the approach is the lack of restrictions on the sequence and structural variation, allowing the incorporation of modified ribonucleosides (such as 2'-OMe-ribonucleotides), as well as threoninol derivatives. This methodology allows a fully automated assembly by means of standard phosphoramidite chemistry and is based on a recently published procedure for the preparation of cyclic oligodinucleotides in the DNA series (M. Smietana, E. T. Kool, Angew. Chem. 2002, 114, 3856-3859; Angew. Chem. Int. Ed. Engl. 2002, 41, 3704-3707). A library of potential cyclic hybrid inhibitor compounds targeting hepatitis C virus NS5B enzyme (the replicating polymerase of HCV) was generated by means of the parallel-pool strategy. Screening of the library revealed that cyclic hybrid c(C(OME)EthenodA) was a significant inhibitor of NS5B, with an IC(50) of 40 microM. Preliminary structure-activity studies of this lead compound are described.     

Supramolecular architectures of metal–organic host–guest compounds

Metal?Corganic frameworks are a class of materials with new and interesting properties (Angew Chem Int Ed 43:2334, 2004; Coorg Chem Rev 38:1213, 2009; Adv Mater 23:249, 2011). In particular, porous metal organic systems are attracting considerable interest because of their potential use as sensors, catalysts and, in general, in host?Cguest chemistry (Acc Chem Res 43:1115, 2010). The so-called ??wheel and axle?? compounds play an important role in the developing of supramolecular chemistry and there are a lot of studies dealing with their inclusion properties and host?Cguest chemistry (Comprehensive supramolecular chemistry, 1996). Classical ??wheel and axle?? molecules have a long, thin, central part (the axle) with two bulky ends (the wheels). Here, new compounds with host properties are described, that we called ??wheel and axle metal?Corganic?? diols (WAMOD), that are decorated with OH groups in the wheel. In particular, their clathration properties are discussed in connection with their crystal structures. A modular strategy is applied to obtain WAMODs: coordination chemistry is used together with soft interactions (H-bond, ?ШC?? interaction), with the aim to realize a dynamic framework that is able to reversibly capture and release a guest. The coordination bond is robust and permits to obtain WAMODs with different arrangements of the axle; the hydrogen bonds and/or the other soft interactions are responsible for the thin adjustments in the crystal packing that allow reversible adsorption/desorption of the guest.     

环双(对-蒽基-对草快)的分子识别与谱学性质

环双(对-蒽基-对草快)是一种新型的缺电子大环仿生主体, 分子识别是其最重要的应用之一. 考察主体对一系列客体分子如水、氨、醇及杂环等的识别能力, 用密度泛函理论(DFT)中的B3LYP/3-21G基组对主客体复合物的结构进行优化. 在B3LYP/6-31G(d)水平上进行单点能计算, 校正后得到复合物的结合能. 用B3LYP/3-21G方法计算13C和3He化学位移. 结果表明, 主体对客体分子的识别主要靠客体上的杂原子与主体上的氢原子之间的氢键进行. 复合物的稳定化能受氢键的数目和距离影响. 氢键的形成导致部分复合物LUMO与HOMO能隙增大, 同时导致与氢键相连的C—H键上C原子的化学位移向低场移动. 复合物的芳香性与其结合能的大小及结合方式有关. 主体的芳香性因其与客体之间的弱相互作用而提高, 但太强的相互作用及客体在主体空腔内都将影响主体的环电流, 从而削弱其芳香性.     

Functionalities of one-dimensional dynamic ultramicropores in nickel(II) coordination polymers

Ni(II) coordination polymers with a 4,4'-azobis(pyridine) (azpy) ligand, {[Ni2(NCX)4(azpy)4].G}n (X = S, G (guest molecule) = MeOH (1.MeOH); X = S, G = EtOH (1.EtOH); X = S, G = H2O (1.H2O); X = S, G = no guest (1); X = Se, G = MeOH (2.MeOH); X = Se, G = H2O (2.H2O); X = Se, G = no guest (2)), have been synthesized and structurally characterized with their porosity. These compounds have one-dimensional periodic ultramicropores that contain the small guest molecules, H2O, MeOH, or EtOH, whose hydroxy groups interact with the S or Se atoms of isothiocyanate or isoselenocyanate, respectively, via -S(Se)...HO- hydrogen bonds. Although the molecular dimensions of the MeOH guest are considerably larger than the window size of the ultramicropore, 1.MeOH and 2.MeOH easily release their guest molecules without decomposition of the framework to form 1 and 2 without any guest molecules. This shows that 1 and 2 have dynamic ultramicropores constructed from the interpenetrating framework. The guest desorption experiments using 1.MeOH and 1.EtOH reveal that the difference in the desorption behavior is due to van der Waals interactions that depend on the molecular shape of the guest molecule in the ultramicropores and/or an entrance blocking effect that depends on the minimum dimensions of the guest molecule for the pore windows. A marked difference in the N2 and CH4 adsorption isotherms was observed and is associated with the strength of the host-guest interaction.     

Improving the balance of carrier mobilities of host-guest solid-state light-emitting electrochemical cells

We report efficient host-guest solid-state light-emitting electrochemical cells (LECs) utilizing a cationic terfluorene derivative as the host and a red-emitting cationic transition metal complex as the guest. Carrier trapping induced by the energy offset in the lowest unoccupied molecular orbital (LUMO) levels between the host and the guest impedes electron transport in the host-guest films and thus improves the balance of carrier mobilities of the host films intrinsically exhibiting electron preferred transporting characteristics. Photoluminescence measurements show efficient energy transfer in this host-guest system and thus ensure predominant guest emission at low guest concentrations, rendering significantly reduced self-quenching of guest molecules. EL measurements show that the peak EQE (power efficiency) of the host-guest LECs reaches 3.62% (7.36 lm W(-1)), which approaches the upper limit that one would expect from the photoluminescence quantum yield of the emissive layer (～0.2) and an optical out-coupling efficiency of ～20% and consequently indicates superior balance of carrier mobilities in such a host-guest emissive layer. These results are among the highest reported for red-emitting LECs and thus confirm that in addition to reducing self-quenching of guest molecules, the strategy of utilizing a carrier transporting host doped with a proper carrier trapping guest would improve balance of carrier mobilities in the host-guest emissive layer, offering an effective approach for optimizing device efficiencies of LECs.     

Importance of packing coefficients of host cavities in the isomerization of open host frameworks: guest-size-dependent isomerization in cholic acid inclusion crystals with monosubstituted benzenes

The crystal structures of inclusion compounds of cholic acid (CA) with 28 monosubstituted benzenes have been systematically investigated. All of the crystals belong to the monoclinic space group P2(1) and have bilayer structures with one-dimensional molecular channels that can include guest compounds. They are classified into four types of host frameworks that depend on the conformations and stacking modes of the host compound. The host frameworks and the host-guest ratios depend primarily on the molecular volumes of the guest compounds. The packing coefficient of the host cavity (PCcavity), which is the volume ratio of the guest compound to the host cavity, is used to clarify the relationship between the guest volume and isomerization of the host frameworks. The value of PCcavity, for stable inclusion compounds lies in the range of 55-70%. Compounds out of this range induce isomerization of the host frameworks. The packing coefficients of other host-guest compounds, in which the guest components are included in the host cavities through steric dimensions and van der Waals forces, are also in this range. These results indicate that PCcavity is a useful parameter correlation for guest recognition and isomerization of the host frameworks.     

Synthesis and properties of new thiourea-functionalized poly(propylene imine) dendrimers and their role as hosts for urea functionalized guests

Five generations of poly(propylene imine) dendrimers have been modified by palmityl and adamantyl endgroups via a thiourea linkage. The synthesis of the thiourea dendrimers DAB-dendr-(NHCSNHAd)(n) and DAB-dendr-(NHCSNHC(16)H(33))(n) (n = 4, 8, 16, 32, 64) proceeds smoothly via the amino-terminated DAB dendrimer and the adamantyl and palmityl isothiocyanates, respectively. The properties of the thiourea dendrimers have been studied by IR and (1)H NMR, including relaxation (T1, T2) measurements. The thiourea dendrimers are used as multivalent hosts for a number of guest molecules containing a terminal urea-glycine unit in organic solvents. The host-guest interactions have been investigated using 1D- and NOESY-NMR. These investigations show that the guest molecules bind to the dendritic host via thiourea (host)-urea (guest) hydrogen bonding, and ionic bonding between the terminal guest carboxylate moiety and the outer shell tertiary amines of the dendrimer. The ability to bind guest molecules of the adamantyl- and palmitylthiourea dendrimers has been compared with their respective urea containing dendrimer analogues, by NMR-titration, and competition experiments. Upon complexation, the thiourea dendrimer hosts show a larger downfield NH shift than the corresponding urea dendrimer hosts, indicative of stronger hydrogen bonding in the complexed state. Furthermore, microcalorimetry has been used to determine binding constants for formation of the host-guest complexes; the binding constants are typically in the order of 10(4) M(-1). Both NMR and microcalorimetric studies show that the thiourea dendrimers bind the urea containing guests with somewhat higher affinity than the corresponding urea dendrimers.     

Organic intercalation material: reversible change in interlayer distances by guest release and insertion in sandwich-type inclusion crystals of cholic acid

Cholic acid (CA) forms inclusion crystals that have a sandwich-type lamellar structure constructed by the alternative stacking of host bilayers and guest layers. Five disubstituted benzenes, o-toluidine, m-fluoroaniline, o-chlorotoluene, o-bromotoluene, and indene, are accommodated in the two-dimensional void space between the host bilayers at 1:2 host-guest stoichiometries. Thermal gravimetric analysis of the inclusion crystals revealed that all the guest molecules, except o-toluidine, are released in two separate steps, indicating the formation of intermediate crystals after the first guest release. Adequate heat treatment of the four inclusion crystals induces release of half or three quarters of the guest molecules. X-ray diffraction patterns of the intermediate crystals revealed that the crystals have a bilayer structure the same as those of the common CA inclusion crystals. They have one-dimensional cavities, in which the guest molecules are included at a 1:1 or 2:1 host-guest stoichiometry. These facts indicate that the host bilayers move 1.6-4.5 A perpendicular to the layer direction by desorption of the guest molecules. Furthermore, a reverse structural change is also achieved by absorption of the guest molecules to regenerate the starting sandwich-type inclusion crystals. This reversible change in the host bilayer by the guest sorption and desorption is a novel example of organic intercalation materials.     

微孔化合物生成中的结构导向与模板作用

本文详细总结了各种客体分子或离子在无机微孔化合物生成中的结构导向与模板作用。讨论了不同合成体系中,客体与无机骨架间的非键相互作用对生成骨架结构的影响以及分子模拟在研究主-客体关系、结构导向剂设计与筛选等方面的进展。无机或有机客体与无机骨架间关系规律的研究,有助于进一步理解结构导向剂(3ＤＡ)作用的机理和微孔化合物的晶化与生成机制,对特定结构微孔化合物的定向合成具有一定的意义。     

Atom-atom potential analysis of the complexing characteristics of cyclodextrins (host) with benzene and p-dihalobenzenes (guest)

Abstract

Intermolecular interaction and modelling calculations on the complexes of α-, β- and γ-cyclodextrins (host) with benzene and p-dihalobenzenes (guest) were performed. The complex formation mechanism between the host and guest molecules was evaluated from three-dimensional potential maps generated by the atom-atom potential method, and the molecular packing of the complexed compounds was visualized by a space-fill representation. Stable inclusion complexes only form when both the host and guest molecules experience a significant decrease in the complexing potential. The host and guest molecules have a maximum molecular surface contact at the minimum potential, which depends on both the cavity size and the molecular volumes of the guest molecules. The calculated interaction energies can be correlated to the association constants of complex formation determined from experiment. The molecular dynamics of the guest molecules are also discussed.     

Advances in the study of the host-guest interaction by using coronene as the guest molecule

This review supplied direct insight of host-guest molecule system by using COR as the guest molecule.     

Cyclic tetranuclear and hexanuclear palladium(II) complexes and their host-guest chemistry

Cyclic tetrameric complexes have been prepared by the reaction of Pd(en)Cl2 or Pd(dapol)Cl2, or their nitrato analogues, with Na2(5'GMP) in aqueous solution, where en=1,2-diaminoethane, dapol=1,3-diamino-2-propanol, and 5'GMP=guanosine 5'-monophosphate. Addition of certain small molecules containing hydrophobic groups resulted in the expansion of the tetramer to a cyclic hexamer with strong bonding of one guest per hexameric host. At pH 5-6, the guest molecule can be a cation, anion, or neutral, and those species containing trimetylsilyl and t-butyl groups bonded the most strongly. The size of the central cavity of the [Pd(en)(5'GMP)]6 host has been estimated to be 5.2 A. Formation of the host-guest complex caused a large upfield shift (Deltadelta) of 2.5-2.9 ppm in the 1H NMR spectrum of the most highly affected guest protons, which were those in closest proximity to the guanine nucleobases. NOESY spectra were used to determine the interaction sites between the host and the guest. Apparent association constants determined at 26 degrees C and pD 5.4 for the [Pd(en)(5'GMP)]6-DSS and [Pd(en)(5'GMP)]6-t-butanol systems, where DSS is 3-(trimethylsilyl)-1-propanesulfonate anion, were 1.36+/-0.11x10(4) and 2.74+/-0.95x10(4) M(-3/2), respectively. The Pd(dapol)-5'GMP system forms hexameric host-guest complexes, similar in nature to those of the Pd(en)-5'GMP system. The molecular and crystal structures of Pd(dapol)Cl2 are also reported.     

Preparation and Optical Properties of (Nanometer MCM-41)-CdS Composite Materials

The nanometer and micrometer molecular sieves MCM-41 were prepared by a hydrothermal method. Cadmium (II) was exchanged into the molecular sieves by ion-exchange, and thioacetamide was then used as a precursor of hydrogen sulfide for sulphidizing the (MCM-41)-cadmium samples to prepare the host-guest composite materials (MCM-41)-CdS. By means of chemical analysis, powder X-ray diffraction, infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid state diffuse reflectance absorption spectroscopy and luminescence, the prepared materials were characterized. The chemical analysis shows that the guest is successfully trapped in the molecular sieves. The powder X-ray diffraction suggests that the frameworks of the molecular sieves in the prepared host-guest composite materials are retained during the preparative process. They are intact and the degrees of crystallinity are still very high. The infrared spectra show that the frameworks of the prepared host-guest materials keep intact. The low temperature nitrogen adsorption-desorption studies indicate that the pore volumes, the pore sizes and the surface areas of the prepared composite materials decrease relative to those of the MCM-41 molecular sieve hosts. This shows that the guests are successfully encapsulated in the channels of the molecular sieves. The solid state diffuse reflectance absorption spectra of the prepared host-guest composites show some blue-shifts relative to that of bulk cadmium sulfide, indicating that the guests are trapped in the channels of the molecular sieves. This shows the obvious stereoscopic confinement effect of the molecular sieve host on the nanometer cadmium sulfide guest. The (nanometer MCM-41)-CdS and (micrometer MCM-41)-CdS samples show obvious luminescence.     

Propyne Gas Adsorption in a Cyclic Hexapeptoid: A Combined In Situ XRPD and DFTB Study**

Cyclic peptoids are macrocyclic N-substituted oligoglycines, with remarkable structural, chemical and physical properties. The gas adsorption properties of a permanently porous hexameric cyclopeptoid decorated with four propargyl and two methoxyethyl side chains were monitored by in situ X-ray powder diffraction (XRPD). High-resolution XRPD data together with Rietveld and density functional based tight binding (DFTB) method allowed us to locate propyne guest molecules inside the host channels, even though the powder sample contains more than one phase. We were able to characterize the host-guest interactions, providing useful information on the host recognition sites and discuss host adaptiveness and host–guest chemical affinity in comparison with analogous compounds.     

反式9, 10-二氢-9, 10-二苯基-9, 10-菲二醇包结性能的研究

合成了一种具有螯形结构的反式-9, 10-二氢-9, 10-二苯基-9,10-菲二醇(1)作为主体分子。它能与许多有机小分子化合物, 诸如DMF, DMSO, 吡啶, 哌啶, 喹啉, 异喹啉等形成包结化合物。本文还报道了这些包结化合物的IR, 粉末XRD的表征, 用^1H NMR谱测定了它们的分子摩尔比。DMF包结物的单晶四圆X衍射结果表明主体分子1与客体分子形成的包结物为配位笼状包合物。     

A Simple Correlation between the Structures of Different Crystal Modifications of a Given Host–Guest Complex and their Crystallization Temperatures

The formation of different crystal modifications of a given host-guest complex depending on the crystallization temperature (pseudopolymorphism) is studied. It is shown that such pseudopolymorphism is a characteristic feature of versatile host compounds. A very important rule for host-guest chemistry is derived from the results of the X-ray structural investigations of pseudopolymorphs: the higher the crystallization temperature of the modification the more closed is the space occupied by guest molecules. On the basis of the formulated rule a recommendation for the topological control and solution of some central problems of supramolecular chemistry is proposed.