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181.
Cametti M Nissinen M Dalla Cort A Mandolini L Rissanen K 《Journal of the American Chemical Society》2005,127(11):3831-3837
Hard anions have long been known to bind strongly to the uranium of uranyl-salophen complexes. Upon functionalization of the salophen framework with one or two benzyloxy substituents, efficient ditopic receptors for alkali metal ions are obtained. The solid-state structures of complexes formed by the two-armed receptor 1 with CsF and with the chlorides of K+, Rb+, and Cs+ reported here reveal the existence of dimeric supramolecular assemblies in which two receptor units assemble into capsules fully enclosing (MX)2 ion quartets. In addition to the strong coordinative binding of the anion to the uranyl center and to electrostatic cation-anion interactions, stabilizing interactions arise from coordination of each cation to six oxygens, three from each receptor, and most importantly, to two aromatic sidearms belonging to different receptors. There are marked differences in organization at the supramolecular level in the CsCl complex of the one-armed receptor 3, in that four uranyl-salophen units instead of two are assembled in a capsule-like arrangement housing a (CsCl)2 ion quartet. However, both receptors achieve the common goal of having each metal cation in close contact with carbon atoms of two aromatic rings. 1H NMR data provide strong evidence that cation-pi(arene) interactions with the sidearms participate in binding also in solution. 相似文献
182.
Ngong K. Beyeh Domonkos Fehér Minna Luostarinen Christoph A. Schalley Kari Rissanen 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(3-4):381-394
The syntheses and characterization of new chiral tetrabenzoxazine and tetrakis-(dialkylaminomethyl) resorcinarenes can be
achieved through the reaction of resorcinarene with chiral amines and formaldehyde. In order to examine their host–guest chemistry,
chiral quaternary ammonium guests were synthesized by methylation of different amines and amino acid methyl esters through
a reductive methylation followed by addition of methyl iodide. Subsequent anion exchange of the iodide against tetraphenylborate
helps to improve solubility of the salts in organic solvents. After characterization in solution, mass spectrometry is used
to examine the resorcinarenes’ chemistry in the gas phase. Interesting implications of the fragmentation behavior for their
solution phase chemistry arise, for which a first example is presented. Ammonium ion binding is indicated by mass spectrometry.
Nevertheless, chiral recognition between the chiral hosts and pseudoracemic 1:1 mixtures of appropriately deuterium-labeled
chiral guest cations is however not observed. 相似文献
183.
Identification of the hydrolysis products of AlCl3.6H2O by electrospray ionization mass spectrometry
Sarpola A Hietapelto V Jalonen J Jokela J Laitinen RS 《Journal of mass spectrometry : JMS》2004,39(4):423-430
The hydrolysis reactions of AlCl3 in 0.1 M aqueous solutions at pH 3.27-4.20 were monitored by electrospray ionization time-of-flight mass spectrometry (ESI-ToF MS) as a function of time. The cationic and anionic ESI mass spectra of aluminum(III) solutions gave strong evidence of the presence of a variety of monomeric and polymeric complexes. Competition between the OH- and Cl- ligands within the same aluminum core was observed. The influence of the sample cone voltage on the product distribution was also explored. The optimum sample cone voltage for the cationic spectra was 70 V. For the anionic spectra no optimum sample cone voltage was found and the appearance of the anionic spectra was strongly dependent on the sample cone voltage within the whole range explored. 相似文献
184.
Alaviuhkola T Bobacka J Nissinen M Rissanen K Ivaska A Pursiainen J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(7):2071-2080
Five aromatic borate anions, namely tetrakis(4-phenoxyphenyl)borate (1), tetrakis(biphenyl)borate (2), tetrakis(2-naphthyl)borate (3), tetrakis(4-phenylphenol)borate (4), and tetrakis(4-phenoxy)borate (5), have been prepared and tested as ion-recognition sites in chemical sensors for certain aromatic cations and metal ions. To gain further insight into the complexation of the cations, some complexes have been prepared and structurally characterized. The complexation behavior of 1 and 2 towards N-methylpyridinium (6), 1-ethyl-4-(methoxycarbonyl)pyridinium (7), tropylium (8), imidazolium (9), and 1-methylimidazolium (10) cations has been studied, and the stability constants of the complexes of 1 with cations 6 and 8 have been measured to compare them with the values for the previously studied complexes of tetraphenylborate. The structures of the borate anions and their complexes have been characterized by NMR and mass spectrometric methods. X-ray crystal structures have been determined for potassium tetrakis(4-phenoxyphenyl)borate (K(+)1), N-methylpyridinium tetrakis(4-phenoxyphenyl)borate (61), 1-ethyl-4-(methoxycarbonyl)pyridinium tetrakis(4-phenoxyphenyl)borate (71), tropylium tetrakis(4-phenoxyphenyl)borate (81), and imidazolium tetrakis(biphenyl)borate (92). The results show that borate derivatives are potential candidates for a completely new family of charged carriers for use in cation-selective electrodes. 相似文献
185.
Jorma T. Kumpulainen Helena Hyvärinen Margareta Hägg Sirkka Plaami Raija Tahvonen 《Analytical and bioanalytical chemistry》1995,352(1-2):102-106
As part of the analytical assurance system of the FAO European Cooperative Research Network on Trace Elements programme an ARC/CL-coded carrot flakes powder (CFP) candidate reference material (RM) has been prepared from a lot of commercial carrot flakes. The candidate RM has been homogenized using a Robot Coupe blender fitted with titanium blades, carefully homogenized in large teflon/polypropylene containers, bottled in 1000 numbered polyethylene containers (20 g samples) and tested for homogeneity. Interlaboratory comparison studies for 9 essential elements, cadmium and total dietary fiber (TDF) based on the AOAC-method resulted in the characterization of the contents of those compounds in the above material. After exclusion of outliers, mean values from at least nine different laboratories based altogether on three independent analytical principles have been used to calculate the recommended concentration ranges for mineral elements. Testing of homogeneity and stability for β-carotene over a period of one year has been additionally carried out. The mean water content in the material amounted to 4.97% and remained stable over a one-year period. Homogeneity of the RM was within 3.0% for almost all included mineral elements as tested for a sample size of 0.5 g. The 95% confidence limits for the mean values of the established recommended concentrations of mineral elements in the present ARC/CL Carrot Powder candidate RM fell within 5% for all the other elements and TDF except for Fe (6.3%) and B (5.7%). The stability of β-carotene in the present candidate RM stored in darkness over a one-year period at room temperature was within 6.3%. 相似文献
186.
Jorma Matikainen Seppo KaltiaMaija Ala-Peijari Ninna Petit-GrasKirsi Harju Jaakko HeikkiläRaija Yksjärvi Tapio Hase 《Tetrahedron》2003,59(4):567-573
Heating a mixture formed by alkali isomerization of methyl linolenoate (1) produces a complex mixture with the bicyclic hexahydroindenoic esters 4β-(7-methoxycarbonylheptyl)-5α-methyl-2,3,3aα,4,5,7aαhexahydroindene (CL5) and 4β-ethyl-5α-(6-methoxycarbonylhexyl)-2,3,3aα,4,5,7aα-hexahydroindene (CL6) as main components. Similar isomerization reactions of three synthetic model compounds, methyl 9Z,13E,15Z-octadecatrienoate (2), 9Z,14E,16E-octadecatrienoate (4) and 9Z,11E,15Z-octadecatrienoate (5) corroborated the results obtained with alkali isomerized methyl linolenoate. 相似文献
187.
Sari Kiviniemi Maija Nissinen Tanja Kolli Jorma Jalonen Kari Rissanen Jouni Pursiainen 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(1-2):153-159
Crown ether complexes of six-membered N-heteroaromatic cations and the closely related bicyclic purinium cation (6) have been studied by 1H NMR, mass spectrometric and crystallographic methods. The stability constants for the complexes were determined by 1H NMR titration in acetonitrile solution and the complexation stoichiometry by 1H NMR and ESI mass spectrometric methods. Altogether six crystal structures of complexes were determined to study the complexation in the solid state. Hydrogen bonding was observed to be the most important interaction for the complexation both in solution and in the solid state but – interactions also contribute to it. All crystal structures of the DB18C6 complexes with six-membered N-heteroaromatic cations, except for 4-hydroxypyridinium, are isomorphous to previously studied five-membered N-heteroaromatic cations and pyridinium complexes. Such a close resemblance is not observed in B18C6 and 18C6 complexes or DB18C6purinium (6). 相似文献
188.
A comparative study has been made on the reactions of RE oxides (RE = Y, La, Gd and Lu) with ammonium bromide, and of yttrium oxide with ammonium halides NH4X (X = F, Cl, Br and I) at different temperatures. Most of the reactions take place in three stages, with formation of two intermediate compounds, REX3 · 3 NH3 and REX3 · 1.5 NH3. The endothermic reactions begin between 200 and 300°C and the formation of the RE oxyhalide is completed between 340 and 470°C. These temperatures were observed to rise with the increasing atomic number of RE in the series LaOBrLuOBr, and of halide in the series YOFYOI. 相似文献
189.
The additions of chlorine, bromine and bromine chloride to trans methyl 2-butenoate 1, trans methyl 2-methyl-2-butenoate 2 and methyl 3-methyl-2-butenoate 3 under ionic conditions were studied. Bromine chloride addition always gave as a major regioisomer the 2-bromo-3--chloro compound,almost quantitatively in the case of 3. The mechanism of bromonium ion ring-opening (SN1 or SN2) is discussed with respect to the double bond substitution and regioisomer proportions. The dihalo products were identified by MS, 1H and 13C NMR. 相似文献
190.
Frey J Tock C Collin JP Heitz V Sauvage JP Rissanen K 《Journal of the American Chemical Society》2008,130(33):11013-11022
Variously substituted coordinating rigid rods have been synthesized which incorporate a central 4,7-phenanthroline nucleus attached to two 2-pyridyl groups via its 3 and 8 positions, so as to yield bis-bidentate chelates, the two-coordinating axes of the chelates being parallel to one another. Regardless of the nature of the substituents borne by the rods, the copper(I)-induced threading reaction of two such rods through the rings of two bis-macrocycles affords in a quantitative yield the 4-copper(I) threaded assembly. The [2]pseudorotaxane tetramers thus obtained have been fully characterized in solution and, for one of them, an X-ray structure could be obtained, confirming the threaded nature of the complex and providing important structural information. 相似文献