Dithia[3.3 ]phanes. 4—mass spectrometry of some dithia[3.3]-naphthalenophanes1

The mass spectral fragmentation of 23 dithia [3.3]naphthalenophanes is discussed. The most characteristic species for these compounds are the M⁺ ion and ions at m/z 115, 135 (or 136), 141, 155 (or 154) and 185.     

Allosteric coextraction of sodium and metal ions with calix[4]arene derivatives 1

Solvent extraction of three alkali metal ions with p-t-octylcalix[6]arene hexacarboxylic acid, p-t-octylcalix[4]arene tetracarboxylic acid, corresponding linear trimeric and monomeric analogs was investigated. Cyclic tetramer selectively extracts sodium ion among alkali ions at extremely low pH, while the corresponding cyclic hexamer, the trimer, and the monomer exhibited only poor extraction ability for all alkali metals examined. The detailed extractive investigation of sodium ions with the cyclic tetramer was carried out. It was found that two sodium ions are simultaneously extracted by a single molecule of calix[4]arene derivative and that the second sodium extraction is facilitated by the uptake of the first sodium. The self-coextraction mechanism of sodium ions proposed in the present paper also strongly supports allosteric coextraction of sodium and other metal ions. In the competitive extraction of four alkali metal ions, potassium ion was slightly extracted as the second ion at low pH region, whereas it was hardly extracted in the individual extraction system. The result also supports the coextraction mechanism and role of the first-extracted sodium ion as an allosteric trigger. The extraction equilibrium constants of the cyclic tetramer and two sodium ions, K _ex1 and K _ex2, were estimated.     

Potassium Sensing Calix[4]arene Crown Ethers

1,3-Alternate calix[4]arene crown-5 (1) and corresponding biscrown-5 (2) were synthesized and the complexation behavior with alkali metal ions examined. For both 1 and 2, potassium ion was selectively extracted from aqueous phase into organic phase over other alkali metal ions based on two phase extraction experiment. The complexation ratio between calix[4]arene biscrown-5 (2), in which two crown cavities connect to the calix[4]arene framework by 1,3-alternate fashion and potassium metal ion is found to 1:1 by proton NMR spectroscopy and extraction equilibria. Association constants (logK_a) for 1 and 2 were determined to give 2.51 and 3.49, respectively.     

Cesium Complex of an Unsymmetrical Calix[4]crown-dibenzocrown-6

An unsymmetrical calix[4]-bis-crown ether having both conventional crown-6 and dibenzocrown-6 rings in a fixed 1,3-alternate conformation was synthesized with good yield by the reaction of a monocyclic calix[4]crown-6 with dibenzodimesylate in the presence of cesium carbonate. The cesium ion selectivity among alkali metal ions increased compared to symmetrical calix[4]-bis-crown-6. The solid state structureof the ligand-cesium complex illustrates a 1:2 complex ratio. On the contrary, insolution, e.g., extraction equilibrium and ¹H NMR experiment gave a 1:1 complex ratio. From the result of the chemical shift change upon metal ion complex, the cesium ion seems to prefer the dibenzocrown loop to the conventional crown-6 ring.     

On Tetrachlorophosphonium Chlorometallates of Rhenium and Molybdenum: Syntheses,Crystal Structures,and Magnetism of [PCl4]2[Re2Cl10] and [PCl4]3[ReCl6]2, and the Magnetic Properties of [PCl4]2[Mo2Cl10]

MoCl₄, ReCl₄, and ReCl₅ react with PCl₅ in sealed glass ampoules at temperatures between 220° and 320° to [PCl₄]₂[Mo₂Cl₁₀] ( 1 ) [PCl₄]₂[Re₂Cl₁₀] ( 2 ), and [PCl₄]₃[ReCl₆]₂ ( 3 ). 2 crystallizes isotypically to the previously reported 1 and the respective titanium and tin containing analogues. The structure (triclinic, P1, Z = 1, a = 897.3(2), b = 946.0(2), c = 687.13(9) pm, α = 95.59(2)°, β = 95.80(2)°, γ = 101.07(2)°, V = 565.4(2) 10⁶ pm³) is built of tetrahedral [PCl₄]⁺ and edge sharing double octahedral [Re₂Cl₁₀]^2– ions and can be derived from a hexagonal closest packing of Cl^– ions with tetrahedral and octahedral holes partially filled by P(V) and Re(IV), respectively. 3 crystallizes isotypically to [PCl₄]₃[PCl₆][MCl₆] (M = Ti, Sn) (tetragonal, P 4₂/mbc, Z = 4, a = 1496.2(1), c = 1363.2(2) pm). Because no evidence was found for the presence of [PCl₆]^– ions, Re in 3 has to be of mixed valency with Re^IV and Re^V sharing the same crystallographic site. The structure can be derived from a cubic closest packing or alternatively from an only sparsely distorted body centered cubic arrangement of Cl^– ions which is rarely found for anion arrays. The tetrahedral and octahedral holes are partially filled by P^V and M^IV/V, respectively. Magnetic measurements show all three compounds to be paramagnetic and confirm the oxidation state IV for Mo and Re in 1 and 2 and the mixed valence (IV/V) for Re in 3 .     

Protonation of electroneutral p-tert-butylcalix[4]arenetetraacetic acid

Abstract  

Using ¹H NMR spectroscopy together with density functional theoretical calculations, it is shown that electroneutral p-tert-butylcalix[4]arenetetraacetic acid forms an equimolar complex with a proton in the form of the H₃O⁺ ion in nitrobenzene-d ₅. Protons were offered by hydrogen bis(1,2-dicarbollyl)cobaltate and converted to hydroxonium ions by traces of water. In the resulting complex, the H₃O⁺ cation is bound by strong hydrogen bonds to two phenoxy oxygen atoms of the parent calix[4]arene ligand and to one carbonyl oxygen of the corresponding COOH group of this ligand.     

Facile Interchange of 3d and 4f Ions in Single‐Molecule Magnets: Stepwise Assembly of [Mn4], [Mn3Ln] and [Mn2Ln2] Cages within Calix[4]arene Scaffolds

The central Mn^II ions in a series of calix[4]arene‐stabilised butterflies can be sequentially replaced with Ln^III ions, maintaining the structural integrity of the molecule but transforming its magnetic properties. The replacement of Mn^II for Gd^III allows for the examination of the transferability of spin‐Hamiltonian parameters within the family as well as permitting their reliable determination. The introduction of the 4f ions results in weaker intramolecular magnetic exchange, an increase in the number of low‐lying excited states, and an increase in magnetisation relaxation, highlighting the importance of exchange over single‐ion anisotropy for the observation of SMM behaviour in this family of complexes. The presence of the [TM^II/III(TBC[4])(OH)(solvent)] metalloligand (TM=transition metal, TBC=p‐tBu‐calix[4]arene) suggests that magnetic calix[n]arene building blocks can be employed to encapsulate a range of different “guests” within structurally robust “hosts”.     

Investigations into cluster formation with alkyl-tethered bis-calix[4]arenes

Abstract

Calix[4]arenes are versatile ligands capable of forming a wide range of cluster motifs when reacted with 3d, 4f or 3d/4f metal ions. Synthetic modification at the calix[4]arene methylene bridge offers a unique opportunity to explore cluster formation with these alternative building blocks. Here, we present the synthesis of a range of bis-calix[4]arenes that are tethered by alkyl chains, as well as exploratory structural studies into cluster-forming reactions. Single crystals were formed in four cases, and from the X-ray structures elucidated it is possible to conclude that sufficiently long alkyl tethers allow for the formation of established cluster topologies without disruption to the core coordination chemistry.     

Reactions of heteroaromatic chromophores with lanthanide complexes of p-sulfonatothiacalix[4]arene

The conditions for the formation of heteroleptic complexes of a lanthanide(iii) ion (Ln = La, Gd, and Tb) with p-sulfonatothiacalix[4]arene and a heteroaromatic chromophore in water were found using X-ray diffraction analysis, pH-metry, ¹H NMR and UV—Vis spectroscopy, and nuclear magnetic relaxation. In the resulting complexes, the heteroaromatic chromophore is in the calix[4]arene cavity and the lanthanide ion is coordinated by the electron-donating groups of the upper or lower calix[4]arene rim. Emission spectroscopic studies revealed changed emission properties of Tb^III ions in the terbium(iii)—p-sulfonatothiacalix[4]arene—bipy complex. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1871–1878, September, 2008.     

Die Kristallstrukturen von {Li3(12-Krone-4)2[HC(CN)2]3}, {Na(15-Krone-5)-[HC(CN)2]} und {Na[N(nBu)4][HC(CN)2]2 · THF}

The Crystal Structures of {Li₃(12-crown-4)₂[HC(CN)₂]₃}, {Na(15-crown-5)[HC(CN)₂]}, and {NaN(nBu)₄[HC(CN)₂]₂ · THF} The preparation and the crystal structures of the title compounds 1 — 3 are described. 1 forms a polymeric chain structure, in which one of the lithium ions is linked by Li…NCC(H)CN… bridges. The remaining lithium ions form (12-crown-4)Li[NCC(H)CN] units, which are coordinated by one of the nitrogen atoms of the dicyanomethanide ions with the lithium ions of the chain. 2 forms an ion pair, in which the sodium ion is coordinated by the five oxygen atoms of the crown ether molecule and by one nitrogen atom of the dicyanomethanide ion. 3 has a threedimensional network, in which the sodium ions are coordinated in a distorted tetrahedral manner by the nitrogen atoms of the dicyanomethanide ions. In the cavities of the network the tetrabutylammonium ions and the THF molecules are found.     

Mass spectrometric behaviour of 1-imino-substituted pyrazolo[1,2-a]-[1,2,4]triazoles under electron and chemical ionization

The spectra of five pharmacologically interesting substituted pyrazolo[1,2-a][1,2,4]triazole hydroiodides were measured under electron and chemical ionization. In the electron ionization spectra, in addition to the intense molecular ion peak of the free base (M⁺*), there was also a relatively intense molecular ion peak of the hydroiodide form, which is unusual since the hydroiodides are rarely so stable. The phenylimino and phenylamino substituents of the triazole ring affected the fragmentation behaviour of the compounds very much. The chemical ionization reagent gases used in this work were methane, isobutane, deuterated ammonia and acetone. In all the cases practically only [M+H]⁺ ions were observed, the only exception being acetone which also gave rise to intense [M+C₂H₃O]⁺ and [M⁺C₃H₇O]⁺ adduct ions. None of the reagent gases used was able to cause any fragmentation.     

Säurekatalysierte Dienon-Phenol-Umlagerungen von 6-Propargyl-6-methyl-cyclohexa-2,4-dien-1-onen; ladungskontrollierte,aromatische [1s, 2s]- und [3s, 4s]-sigmatropische Reaktionen

The acid catalysed dienone-phenol rearrangement of methyl substituted o-propargyl-cyclohexadienones (scheme 3) was investigated. The rearrangements were carried out in acetic anhydride containing about 1⁰/₀₀ sulfuric acid. Under these conditions acetoxy benzenium ions are formed as intermediates. These then undergo charge-controlled [3s, 4s]- and [1s, 2s]-sigmatropic rearrangements. Thus, the [3s, 4s]-process leads to the formation of the corresponding allenyl-phenol acetates ( 19 , 21 , 23 , 25 , 28 , 30 ) whereas the [1s, 2s]-process yields propargyl-phenol acetates ( 20 , 22 , 24 , 26 , 29 ), respectively (cf. scheme 4).     

Perfluoroalkylated Calix[4]pyrroles: Fluoride Ion Extraction from an Aqueous Medium

Octaalkenyl calix[4]pyrrole ((CH₂=CH(CH₂)₂)₈C4P) is highly useful for the postfunctionalization of different calix[4]pyrroles with desired functionalities. Functionalization with perfluoroalkyl chains [CF₃(CF₂)_n ; R_fn ] gave perfluoroalkyl calix[4]pyrroles (R_fn (CH₂)₄)₈C4P; n =6, 8), having >60 % fluorine content, which created a hydrophobic environment inside the calix[4]pyrrole cavity and recognized fluoride and chloride ions in solution as well as in the solid state. The fluoride ion is extracted efficiently from aqueous CsF and TBAF solutions by using (R_f6(CH₂)₄)₈C4P, as droplets. The fluorinated chain generated a hydrophobic environment which broke the hydration shell associated with the anion and separated out fluoride ions as droplets from aqueous medium. Furthermore, the fluoride ions competitively replaced chloride ions from the (R_f6(CH₂)₄)₈C4P cavity.     

Synthesis,antimicrobial activity,and ion transportation investigation of four new [1 + 1] condensed furan and thiophene-based cycloheterophane amides

Four new macrocyclic compounds with thiophene ( L1 and L2 ) and furan ( L3 and L4 ) rings were synthesized and characterized by IR, ¹H NMR, ¹³C NMR, and Q-TOF spectral data. Macrocyclic amides ( L1 , L2 , L3 , and L4 ) were tested for ion transportation with Na⁺ and K⁺ ions, and also, antimicrobial activities were investigated against the Gram-negative Escherichia coli ATCC 25922, Gram-positive Staphylococcus aureus ATCC 25923, Gram-negative Listeria monocytogenes ATCC 19115, Gram-negative Salmonella typhimurium ATCC 14028, Bacillus cereus bacteria, and Candida albicans ATCC 10231 for all amides.     

Reaction of cyclohexanone with [NH4]+ under chemical ionization conditions. 1—formation of protonated unsubstituted imines

High resolution and metastable decomposition spectra of the ions [M + NH₄]⁺ (and [M + ND₄]⁺) formed by reaction of [NH₄]⁺ (and [ND₄]⁺) with cyclohexanone have been measured. The results provide evidence that the m/z 98 ion, which is abundant in the chemical ionization (NH₃) spectrum of cyclohexanone, is in fact composed of two isobaric ions: a protonated imine ion and the molecular ion of cyclohexanone. The former is formed by a mechanism analogous to that occurring in solution.     

Lanthanoid coordination with a tetrazole-substituted calix[4]diquinone and calix[4]dihydroquinone

The tetrazole-functionalised calixdiquinone 5,17-di-tert-butyl-26,28-bis-(1H-tetrazole-5-ylmethoxy)-calix[4]-25,27-diquinone Q was synthesised by chemical oxidation of the bis-tetrazole calix[4]arene precursor using PbO₂/HClO₄. The single crystal X-ray structure determination of Q confirmed the structure and showed binding of a water molecule in the solid state. Chemical reduction of Q to the dihydroquinone QR was achieved using N,N-diethylhydroxylamine. Comparison of the solution phase photophysical properties of Q or QR in the presence of terbium ions showed significant excitation only with QR, suggesting redox switching of the photophysical response may be possible with this or similar receptor.     

A Proton Complex of p-tert-Butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide): NMR Evidence and Probable Structure

Using ¹H and ¹³C NMR together with density functional theoretical (DFT) calculations, it is shown that p-tert-butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide) (1) forms a stable equimolecular complex with proton in the form of hydroxonium ion in nitrobenzene-d ₅. Protons were offered by hydrogen bis(1,2-dicarbollyl) cobaltate (HDCC) and converted to hydroxonium ions by traces of water. The complex 1·H₃O⁺ adopts a slightly asymmetric but rapidly motionally averaged conformation, which is distinctly more cone-like than ligand 1. The hydroxonium ion H₃O⁺ is bound partly to thiocarbonyl sulphur atoms and partly to phenoxy oxygen atoms of 1 by strong hydrogen bonds and other electrostatic interactions.

     

Sodium picrate effect on extraction of lanthanum and lutetium by aminophosphonate calix[4]resorcinarenes

Aminophosphonate calix[4]resorcinarene derivatives extract lanthanum and lutetium ions from aqueous solutions to chloroform much more efficiently than O,O-diethyl[(4-nitrophenyl)aminobenzyl] phosphonate does. In an excess of the metal ion in the aqueous phase with respect to the amounts of the extracting agent and sodium picrate, extraction occurs at the 1 : 1 molar ratio of the metal ion to extracting agent. In a twofold excess of the extracting agent and a considerable excess of sodium picrate over the metal ion, the composition of the extracted complex depends substantially on both the length of the alkyl substituent in the (AlkO)₂P(O) group in the extracting agent and the number of lanthanide.     

Synthesis of some 4H,10H[1]benzoxepino[3,4-c]pyrazol-4-one derivatives

1H(or 2H)4H10H[1]Benzoxepino[3,4-c]pyrazol-4-ones were prepared from phenoxymethylpyrazolecarboxylic acids which in turn were synthesized from simple starting materials. Different pathways to allow the predominant formation of the N-1 or N-2 substituted derivatives are described. The isomeric 1 or 2-substituted structures were supported by ¹³C-nmr.     

A study of the electron impact induced retro-diels-alder process with selected 5,6,6a, 7,12,12a-hexahydrobenzo[a]anthracenes

The mass spectra of 5,6,6a,7,12,12a-hexahydrobenzo[a]anthracene and 2-methoxy, 3-methoxy-, 4-methoxy and 1-methyl-4-methoxy derivatives are reported. Among the fragment ions observed under electron impact ionization, [C₈H₈]^+· and [M? C₈H₈]^+· can be generated by a retro-Diels-Alder process. Studies of metastable ion reactions show these ions to be formed by fragmentation directly from the molecular ion. The CA spectra of the [C₈H₈]^+· ions from the subject compounds were compared with spectra from ions of the same composition from various sources. From these data, kinetic energy release measurements and stereochemical considerations, it is concluded that these ions are formed by a stepwise, rather than a concerted mechanism.