Anion,cation and ion-pair recognition by bis-urea based receptors containing a polyether bridge

Two bis-urea type receptors were synthesized containing a polyether bridge and two 4-nitrophenyl groups as chromogenic units, R1 and R2. Molecular recognition studies of receptors towards different tetraalkylammonium and alkali metal salts were carried out in DMSO by UV-Vis and ¹H-NMR spectroscopy. The receptors were found to have high affinity for diverse anions and ion-pairs, showing the highest affinities towards the tetramethylammonium and sodium salts. The cation binding ability of the receptors was evidenced by means ¹H NMR, mass spectrometric ESI⁺ studies and the crystal structures of some precursors. Additionally, the molecular modelling at the DFT level of the tetramethylammonium acetate complexes illustrates the potential ion-pair binding ability of the receptors: the anion is recognized through strong hydrogen bonds from the NH─ groups from the two urea sites, while the cation is bound by a combination of cation─π, C-H···O and C-H···π interactions.     

[WNCl3 · 0,5 HN3]4; Kristallstruktur und IR-Spektrum

[WNCl₃ · 0.5 HN₃]₄: Crystal Structure and I.R. Spectrum [WNCl₃ · 0.5 HN₃]₄ is formed from tungsten hexachloride and iodine azide in dichloro methane solution yielding dark red and needleshaped crystals. The crystal structure was determined by aid of X-ray diffraction data. The compound crystallises in the triclinic space group P1 with one formula unit per unit cell (R = 0.08, 2 811 independent reflexions). The four metal atoms are arranged in a square, the edges being formed by almost linear W?N? W bridge bonds of alternating length (168 and 210 pm). Two opposite tungsten atoms are coordinated by theαN atom of a HN₃ molecule and by three terminal chloro ligands. The other tungsten atoms achieve coordination number 6 by two terminal and two bridging Cl atoms, linking the tetrameric units to bands along [010]. The i.r. spectrum is reported and assigned.     

Synthesis and crystal structure of the synthetic analogue of mineral minyulite K[Al2F(H2O)4(PO4)2]. Structural correlations with AlPO4-CJ2

The validation of our program of simulation for the prediction of unknown dehydrated structures needs accurate information of the mother hydrated structure at the starting point. This paper describes the synthesis (95°C, 10 days, autogenous pressure) and the structure (space group Pba2; a=9.3477(2), b=9.7571(1), c=5.5280(1) Å, V=503.91 Å³, Z=2) of the synthetic homologue of two-dimensional mineral minyulite K[Al₂F(H₂O)₄(PO₄)₂]. The ²⁷Al, ¹⁹F and ³¹P solid state NMR characteristics are reported, as well as the thermal decomposition which confirms the prediction of a collapse of the structure. Finally, structural correlations between minyulite and AlPO₄-CJ2 are given.     

Formation of a Hydrogen‐Bonded Heptazine Framework by Self‐Assembly of Melem into a Hexagonal Channel Structure

Self‐assembly of melem C₆N₇(NH₂)₃ in hot aqueous solution leads to the formation of hydrogen‐bonded, hexagonal rosettes of melem units surrounding infinite channels with a diameter of 8.9 Å. The channels are filled with strongly disordered water molecules, which are bound to the melem network through hydrogen bonds. Single‐crystals of melem hydrate C₆N₇(NH₂)₃ ? xH₂O (x≈2.3) were obtained by hydrothermal treatment of melem at 200 °C and the crystal structure (R $\bar 3$ c, a=2879.0(4), c=664.01(13) pm, V=4766.4(13)×10⁶ pm³, Z=18) was elucidated by single‐crystal X‐ray diffraction. With respect to the structural similarity to the well‐known adduct between melamine and cyanuric acid, the composition of the obtained product was further analyzed by solid‐state NMR spectroscopy. Hydrolysis of melem to cyameluric acid during syntheses at elevated temperatures could thus be ruled out. DTA/TG studies revealed that, during heating of melem hydrate, water molecules can be removed from the channels of the structure to a large extent. The solvent‐free framework is stable up to 430 °C without transforming into the denser structure of anhydrous melem. Dehydrated melem hydrate was further characterized by solid‐state NMR spectroscopy, powder X‐ray diffraction, and sorption measurements to investigate structural changes induced by the removal of water from the channels. During dehydration, the hexagonal, layered arrangement of melem units is maintained whereas the formation of additional hydrogen bonds between melem entities requires the stacking mode of hexagonal layers to be altered. It is assumed that layers are shifted perpendicular to the direction of the channels, thereby making them inaccessible for guest molecules.     

UV-Raman and NMR spectroscopic studies on the crystallization of zeolite A and a new synthetic route

UV-Raman and NMR spectroscopy, combined with other techniques, have been used to characterize crystallization of zeolite A. In situ UV-Raman spectroscopy shows that the starting gel for crystallization of zeolite A contains a lot of four-ring (4R) building units and the appearance of six-ring (6R) building blocks is the signal for crystal formation. (29)Si NMR spectroscopy results suggest that the starting gel is double four-ring (D4R) rich and during crystallization of zeolite A both α and β cages appear. (27)Al NMR spectroscopy results indicate the absence of Al (2Si) species in the starting gel, suggesting the absence of single 4R building units in the starting gel. Furthermore, composition analysis of both solid and liquid samples shows that the solid rather than liquid phase predominates for the crystallization of zeolite A. Therefore, it is proposed that the crystallization of zeolite A mainly occurs in the solid phase by self-assembly or rearrangement starting from the zeolite building units mainly consisting of D4R. The essential role of D4R is directly confirmed by successful conversion from a solution of D4R to zeolite A in the presence of NaCl, and the importance of solid phase is reasonably demonstrated by the successful synthesis of zeolite A from a dry aluminosilicate gel. By considering that the solid phase has a major contribution to crystallization, a novel route was designed to synthesizing zeolite A from the raw materials water glass (Na(2)SiO(3) in aqueous solution) and NaAlO(2), without additional water and NaOH; this route not only simplifies synthetic procedures, but reduces water consumption.     

锌与烟酰胺苦味酸根配合物的合成与晶体结构

烟酰胺（NA）与苦味酸锌（Zn（Pic）2）在乙醇水混合液中反应,制得氢键连接的超分子配合物[Zn（NA）2·4H2O]·（Pic）2。该配合物的晶体属三斜晶系,空间群为P1,晶胞参数为a=0.7050（1）,b=0.8839（3）,c= 1.4035（3）nm,α=81.16（2）,β=81.92（2）,γ=66.55（2）°,V=0.7898（3）nm3,Z=1,Dc=1.762g/cm3,F（000）=428;μ=0.886mm-1,最终偏离因子R=0.0419,wR=0.1094。结构单元中Zn原子与两个NA和四个水分子配位,配位水又通过氢键与Pic-和相邻单元的NA结合,同时NA上的氨基又与本单元和相邻结构单元中的Pic-上硝基氧形成氢键,形成了三维网状氢键的超分子化合物。     

Order-disorder in the super-sodalite Zn3Al6(PO4)12, 4tren, 17H2O (MIL-74): a combined XRD-NMR assessment

A new mixed zinc-aluminum phosphate Zn(3)Al(6)(PO(4))(12), 4tren, 17H(2)O (MIL-74) has been hydrothermally synthesized with the tris(2-aminoethyl)amine (tren) as a structure-directing agent (453 K, 36 h, autogenous pressure). The solid was characterized by a nonclassical method combining single-crystal X-ray diffraction and several solid-state NMR experiments, RFDR, C7 double quantum ((31)P), and 3QMAS ((27)Al). Its crystal structure is cubic, a = 16.7942(1) A, but the choice of the space group does not follow usual routes of structure determination, due to some "disorder" between Zn and Al. It can be assigned as well to I-43m or to P-43n. The open-framework is built up from an enneameric unit (T = Zn, Al) containing five TO(4) and four PO(4) tetrahedra (one of the P-O bonds is terminal). A central TO(4) tetrahedral unit shares all of the corners with four phosphates groups. Two phosphate groups are connected to two other peripheral TO(4) units. It results in the formation of a "pseudo" planar building block T(5)P(4) consisting of four square 4-rings. The connection of the T(5)P(4) units generates a three-dimensional framework, which defines a super-sodalite topology. The resulting cavities (diameter of 10 A) are bound by 12-ring windows in which are located the tren species in interaction with the phosphate groups (mainly terminal P-O bonds) through hydrogen bonds. A cluster of 17 water molecules occupies the center of the super-sodalite cage. The cationic (Zn, Al) occupancy is discussed for this specific topology.     

Tetraglymes as Prochiral Host Reagents for Ammonia Borane

The molecular structure of the complex of ammonia borane (AB) with acyclic ether tetraglyme Me(OCH₂CH₂)₄OMe ( 1 ), 1· (AB)₂ was determined by single‐crystal X‐ray structure analysis for the first time. The crystal structure features two AB molecules, bonded by dihydrogen bonds, per one tetraglyme unit. The intermolecular BH ··· HN distances of 1.94 Å are shorter than those in the solid ammonia borane (2.02–2.32 Å). A comparison of the hydrogen and dihydrogen bonds in 1· (AB)₂ and in the complexes of AB with crown‐ethers (CE) was carried out. The complex formation with both the CE and the acyclic polyether 1 activates the B–H bond in AB via N–H ··· O hydrogen bonds and therefore increases the reducing activity of AB. Supposedly, the structure of 1· (AB)₂ is related to the initial steps of the AB activation in a polyether solution. The effect of the substituents on the complexation of the substituted derivatives of 1 comes down to a structural adjustment minimizing steric repulsion. Computations reveal that the complexation of diastereomeric disubstituted glymes with AB leads to the formation of diastereomeric complexes that differ noticeably in stability. This is a prerequisite for inducing stereoselectivity, which makes such complexes attractive for potential synthetic applications.     

4-(2'-羟基苯甲酰肼)苯亚甲基／亚乙基－5－甲基－2－苯基－2，4－二氢－吡唑啉酮－3超分子化合物的合成与晶体结构

报道了4-(2'－羟基苯甲酰肼)苯亚甲基－5－甲基－2－苯基－2，4－二氢－吡 唑啉酮－3（B_1）和4-(2'－羟基苯甲酰肼)亚乙基－5－甲基－2－苯基－2，4－二 氢－吡唑啉酮－3（B_2）的合成、表征及晶体结构分析，B_1晶体属单斜晶系， C2/c空间群，所得晶胞参数为：a = 1.4201(2) nm, b = 1.65542(2) nm, c = 1. 8455(3) nm, β = 101.32(1)°，V = 4.2541(10) nm~3, Z = 8, D_c = 1.344 g/cm~3, μ = 0.094 mm~(-1), F(000) = 1808, R = 0.0442, wR = 0.1037。该 化合物由水分子通过氢键连接成沿ac面无限延伸的二维网络结构的超分子。B_2晶 体属三斜晶系，P1空间群，a = 1.2120(2) nm, b = 1.2223 (2) nm, c = 1.4159 (3) nm, α = 70.38 (1)°, β = 74.91 (1)°, γ = 63.64(1)°, V = 1.7549 (5)° nm~3, Z = 4, D_c = 1.326 g/cm~3, μ = 0.092 mm~(-1), F(000) = 736, R = 0.0436, wR = 0.1076。此化合物通过分子间氢键形成沿α轴无限延伸的一维 链状结构的超分子，由于分子间的作用力使其分子又沿b轴呈层状堆积。     

Rigid unit modes (RUMs) of distortion, local crystal chemistry and the inherent displacive flexibility of microporous AlPO4-11

Electron diffraction is used to investigate the average structure of microporous AlPO₄-11 as well as the zero-frequency rigid unit mode (RUM) modes of distortion of the ideal AlPO₄-11 tetrahedral framework. Direct experimental evidence (in the form of a highly structured, characteristic diffuse intensity distribution) has been found for the (presumably dynamic) excitation of numerous zero-frequency RUM modes of distortion. The lattice dynamic program CRUSH is used to confirm the existence of zero-frequency RUM modes of distortion with wave-vectors falling on the observed diffuse distribution. The simultaneous (presumably dynamic) excitation of such RUM modes of distortion needs to be taken into account in order for the local crystal chemistry of AlPO₄-11 to be understood.     

Inclusion complexes of α‐cyclodextrin and (AB)n block copolymers

Cyclodextrins thread onto polymer chains to form inclusion complexes, especially when the polymer is hydrophobic relative to the solvent. Selective threading might occur when the polymer architecture contains both hydrophobic and hydrophilic segments. α‐Cyclodextrin formed crystalline inclusion complexes with (AB)_n microblock copolymers, where the A block was a linear alkyl segment containing a single double bond and the B block was an exact length segment of poly(ethylene oxide). The complexes were isolated and characterized by solution and solid‐state NMR, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. Each method confirmed complex formation and showed that the physical properties of the complexes were distinct from those of its individual components. The X‐ray data were consistent with known inclusion complexes having a channel or column crystal structure. The stoichiometry of the complex formation, 2.3 α‐cyclodextrin rings per polymer repeat unit, was determined by NMR analysis of the complexes and from an analysis of the inclusion complex yields. The data suggest that the inclusion complex stoichiometry is defined by the increasing insolubility of the polymer–cyclodextrin complex. Solid‐state NMR data were consistent with a preference for threading onto hydrophobic segments of the (AB)_n polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2731–2739, 2001     

Host-Guest Interactions and Laser Activity in AlPO4-5/Laser Dye Composites

In situ inclusion of the laser dyes coumarin 466, coumarin 7, pyridine 2 and DCM has been conducted successfully in AlPO₄-5 crystals. The charged molecule pyridine 2 interacts with the framework and leads to bundle-like morphologies with increasing dye content. Uncharged molecules (DCM, coumarin 7, coumarin 466) are included, although corresponding molecular dimensions are exceeding pore size. These dyes probably induce local defects in the pore walls of AlPO₄-5 which are healed during crystal growth leading to well-developed hexagonal prisms. Spectroscopic studies show interactions of the dyes with the solid-state matrix which are reflected by shifts of absorption and emission maxima of the dyes. For the first time, laser activity is demonstrated on a perfect hexagonal single AlPO₄-5/DCM crystal.     

Low Temperature Syntheses of Highly-ordered Framework Materials: The Aluminium Phosphate Ammonium Taranakite

The formation of a highly crystalline ammonium analogue of the aluminium phosphate mineral taranakite at ambient temperature and above is described. The high crystallinity and ordering of the products obtained when ammonium is used as a templating agent suggests that it is intimately involved in the structure. At long crystallization times and at higher temperatures, transformation to the framework structure of AlPO₄-15 occurs. Results from powder x-ray diffraction, solid state NMR, electron microscopy, thermal and element analyses are presented and discussed. They demonstrate the high degree of crystallinity and ordering of the taranakite samples synthesized by this method. These results – in particular the very mild synthesis conditions – suggest the possibility that there may be sequestering of ammonium phosphate fertilizers in form of NH₄-taranakite from their interaction with clay materials in soils.     

The structure of interlocked helical supramolecule formed by the self-assembly of mono-6-(4-cyano-phenyl)-β-cyclodextrin

The supramolecular self-assembly formed by newly synthesized mono-6-(4-cyano-phenyl)-β-cyclodextrin through the molecular interpenetration has been investigated and compared in both solution and the solid state, which was characterized by X-ray crystallography, fourier transform infrared spectroscopy, NMR spectroscopy and atomic force microscopy. The crystal structure clearly revealed that the benzonitrile group is consecutively inserted into the adjacent cyclodextrin cavity from the second side, thus giving rise to an unusual interlocked helical supramolecular self-assembly in which the benzonitrile group acts as bridge between the cyclodextrin units. As compared with crystal, the conformation in aqueous solution indicates that the benzonitrile group prefer to be self-assembled included into another cavity from the second side of cyclodextrin to form the self-assembly.     

Die Kristallstruktur von (AsPh4)2[W2NCl10]

Crystal Structure of (AsPh₄)₂[W₂NCl₁₀] The title compound is formed by a slow reaction of AsPh₄[WNCl₄] in acetonitrile solution in form of dark brown crystals. The crystal structure was solved by X-ray diffraction methods (R = 4.7%; 1461 observed, independent reflexions). (AsPh₄)₂[W₂NCl₁₀] crystallizes in the monoclinic space group P2₁/n with two formula units per unit cell. The structure consists of AsPh₄^θ and [W₂NCl₁₀]^2θ ions. The tungsten atoms with oxidation numbers five and six respectively, are linked by a linear, asymmetric nitrido bridge (r WN = 171 and 203 pm). The trans-effect of the W? N-multiple bonds causes a significant difference between axial (W? Cl_ax 243 pm) and equatorial (mean W? Cl_eq 230 pm) bond lengths.     

Reactions of metalloalkynes. New C2 bonding mode in a trimetallic complex

The reaction of the silver complexes [((Ru(CO)2(eta-C5H4R))2(mu-C identical to C))3Ag3][BF4]3 (R = H or Me) with [RuCl(CO)2(eta-C5H4R)] at room temperature gave the new trimetallic complexes [(Ru(CO)2(eta-C5H4R))3(eta 1:eta 2-C identical to C))][BF4] which contain the C2(2-) ligand surrounded by ruthenium atoms; these complexes do not contain metal-metal bonds and were characterised by single crystal X-ray studies; the solid state structure is not retained in solution, where it is found to be fluxional on the NMR timescale and the dynamic process postulated could be described as 'bearing-like'.     

Synthesis and adsorption properties of zeolite-like aluminophosphates

Zeolite-like aluminophosphates AlPO₄-5, AlPO₄-18, and AlPO₄-20, were prepared in conditions which differ from those described in the literature. The adsorption isotherms of H₂O, CH₃OH, n-C₄H₉OH, and i-C₄H₄₉OH at 18°C and Ar at –196°C were investigated. The observed molecular-sieve effect is in agreement with the concepts on the structure of these aluminophosphates. An unusual shape of the water adsorption isotherms was observed. Similarities were observed in the isobaric absorption of water molecules by crystal hydrates and the zeolite-like aluminophosphates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2409–2414, November, 1989.     

Formation of a hydrogen-bonded heptazine framework by self-assembly of melem into a hexagonal channel structure

Self-assembly of melem C(6)N(7)(NH(2))(3) in hot aqueous solution leads to the formation of hydrogen-bonded, hexagonal rosettes of melem units surrounding infinite channels with a diameter of 8.9 ?. The channels are filled with strongly disordered water molecules, which are bound to the melem network through hydrogen bonds. Single-crystals of melem hydrate C(6)N(7)(NH(2))(3)?xH(2)O (x≈2.3) were obtained by hydrothermal treatment of melem at 200 °C and the crystal structure (R ?3c, a=2879.0(4), c=664.01(13) pm, V=4766.4(13)×10(6) pm(3), Z=18) was elucidated by single-crystal X-ray diffraction. With respect to the structural similarity to the well-known adduct between melamine and cyanuric acid, the composition of the obtained product was further analyzed by solid-state NMR spectroscopy. Hydrolysis of melem to cyameluric acid during syntheses at elevated temperatures could thus be ruled out. DTA/TG studies revealed that, during heating of melem hydrate, water molecules can be removed from the channels of the structure to a large extent. The solvent-free framework is stable up to 430 °C without transforming into the denser structure of anhydrous melem. Dehydrated melem hydrate was further characterized by solid-state NMR spectroscopy, powder X-ray diffraction, and sorption measurements to investigate structural changes induced by the removal of water from the channels. During dehydration, the hexagonal, layered arrangement of melem units is maintained whereas the formation of additional hydrogen bonds between melem entities requires the stacking mode of hexagonal layers to be altered. It is assumed that layers are shifted perpendicular to the direction of the channels, thereby making them inaccessible for guest molecules.     

新型磷酸铝分子筛AlPO_4-CJ_2的合成与结构研究

在Al_2O_3-P_2O_5-六次甲基四胺-H_2O体系中,水热合成出新型磷酸铝分子筛(AlPO_4-CJ_2),培养了单晶,经多晶X射线衍射、四圆单晶结构测定及红外光谱研究证明,AlPO_4-CJ_2具有空旷的骨架结构,沿(100)和(001)方向具有8元环孔道,骨架中Al原子以AlO_5(三角双锥)和AlO_5F(扭曲八面体)形式存在,水分子氧的桥联产生Al—O—Al连接模式。