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• 88-89-1 2,4,6-Trinitrophenol 
• 88-88-0 2,4,6-trinitrochlorobenzene 

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• 1342299-69-7 C₆H₂N₃O₇^(1-)*C₁₁₄H₁₆₂N₆O₁₈*Cs⁽¹⁺⁾ 

Relevant academic research and scientific papers

Extraction and DFT study on interaction of the cesium cation with enniatin B

By using extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs+(aq) + A-(aq) + 1(nb)虠1·Cs+(nb) + A-(nb) taking place in the two-phase water-nitrobenzene system (A-= picrate, 1 = enniatin B; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex(1·Cs+, A-) = 2.3 ± 0.1. Further, the stability constant of the 1·Cs+complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log βnb(1·Cs+) = 4.2 ± 0.1. Finally, applying quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1·Cs+was derived. In the resulting 1·Cs+complex, which is most energetically favored, the central cation Cs+is bound by nine bonding interactions to the corresponding nine oxygen atoms of the parent enniatin B ligand. The interaction energy of the considered complex 1·Cs+was found to be -228.3 kJ/mol, confirming the formation of this investigated complex as well.

Buckyball-Based Spherical Display of Crown Ethers for de Novo Custom Design of Ion Transport Selectivity

Searching for membrane-active synthetic analogues that are structurally simple yet functionally comparable to natural channel proteins has been of central research interest in the past four decades, yet custom design of the ion transport selectivity still remains a grand challenge. Here we report on a suite of buckyball-based molecular balls (MBs), enabling transmembrane ion transport selectivity to be custom designable. The modularly tunable MBm-Cn (m = 4-7; n = 6-12) structures consist of a C60-fullerene core, flexible alkyl linkers Cn (i.e., C6 for n-C6H12 group), and peripherally aligned benzo-3m-crown-m ethers (i.e., m = 4 for benzo-12-crown-4) as ion-transporting units. Screening a matrix of 16 such MBs, combinatorially derived from four different crown units and four different Cn linkers, intriguingly revealed that their transport selectivity well resembles the intrinsic ion binding affinity of the respective benzo-crown units present, making custom design of the transport selectivity possible. Specifically, MB4s, containing benzo-12-crown-4 units, all are Li+-selective in transmembrane ion transport, with the most active MB4-C10 exhibiting an EC50(Li+) value of 0.13 μM (corresponding to 0.13 mol % of the lipid present) while excluding all other monovalent alkali-metal ions. Likewise, the most Na+ selective MB5-C8 and K+ selective MB6-C8 demonstrate high Na+/K+ and K+/Na+ selectivity values of 13.7 and 7.8, respectively. For selectivity to Rb+ and Cs+ ions, the most active MB7-C8 displays exceptionally high transport efficiencies, with an EC50(Rb+) value of 105 nM (0.11 mol %) and an EC50(Cs+) value of 77 nM (0.079 mol %).

Synthesis, binding properties and theoretical studies of p-tert-butylhexahomotrioxacalix[3]arene tri(adamantyl)ketone with alkali, alkaline earth, transition, heavy metal and lanthanide cations

p-tert-Butylhexahomotrioxacalix[3]arene tri(adamantyl)ketone (1b) was synthesized for the first time. Compound 1b was obtained in a cone conformation in solution at room temperature, as established by NMR spectroscopy (1H and 13C). The binding properties of ligand 1b for alkali, alkaline earth, transition, heavy metal and lanthanide cations have been assessed by phase transfer and proton NMR titration experiments. Molecular mechanics and ab initio techniques were also employed to complement the NMR data. The results are compared to those obtained with other closely related homooxacalixarene derivatives. Although triketone 1b is a weak extractant, it shows a strong peak selectivity for Na+ and also some preference for Ag+. Proton NMR titrations indicate the formation of 1:1 complexes between 1b and the cations studied, and also that they should be located inside the cavity defined by the phenoxy and carbonyl oxygen atoms. Although the molecular mechanics results show little correlation with the NMR data, a good agreement was obtained with the ab initio models.

Self-assembled ionophores

Ionophores having the capacity spontaneously assemble in solution and composed of hydrogen bonded monomers of 5′-(t-butyl-dimethylsilyl)-2′,3′-O-isopropylidene-isoguanosine, 5′-(t-butyl-dimethylsilyl)-2′,3′-O-isopropylidene-thio-isoguanosine or 2′,3′-Di-O-acetyl-5′-(t-butyl-dimethylsilyl)-isoguanosine are used to remove 137-cesium ions (137Cs+) from nuclear waste.

A study of C-F···M+ interaction: Alkali metal complexes of the fluorine-containing cage compound

The C-F···M+ interaction was investigated by employing a cage compound 1 that has four fluorobenzene units. The NMR (1H, 13C, and 19F) spectra and X-ray crystallographic analyses of 1 and its metal complexes showed clear evidence of the interaction. Short C-F···M+ distances (CF···K+, 2.755 and 2.727 A; C-F···Cs+ 2.944 and 2.954 A) were observed in the crystalline state of K+ ? 1 and Cs+ ? 1. Furthermore, the C-F bond lengths were elongated by the interaction with the metal cations. By calculating Brown's bond valence, it is shown that the contribution of the C-F unit to cation binding is comparable or greater than the ether oxygen in the crystalline state. Representative spectroscopic changes implying the C-F···M+ interaction were observed in the NMR (1H, 13C, and 19F) spectra. In particular, 133Cs-19F spin coupling (J = 54.9 Hz) was observed in the Cs+ complex.

Guest inclusion properties of calix[6]arene-based unimolecular cage compounds. On their high Cs+ and Ag+ selectivity and very slow metal exchange rates

The reaction of 1.3.5-tri-O-alkylated calix[6]arenes with 1,3,5- tris(bromomethyl)benzene yielded capped calix[6]arenes (2 with ten-butyl groups on the upper tim and 3 without tert-butyl groups) in unexpectedly high yields (80 - 91%). Combined studies of 2 and 3 by MM3 computation, X-ray analysis, and 1H NMR spectroscopy established that these calix[6]arenes feature a unique structure consisting of alternately-arranged three flattened mesitylene-linked phenyl units and three stand-up anisole units. Particularly, compound 2 possesses a closed ionophoric cavity: the upper hemisphere is closed by three ten-butyl groups of anisole units and the lower hemisphere is closed by a mesitylene cap and three anisole methoxy groups. The 1H NMR spectrum was scarcely changed at wide temperature range (30 ~ 130 °C), indicating that the structure is extremely rigidified. Both solvent extraction and spectroscopic studies established that this cavity shows the high selectivity toward Cs+ among alkali metal cations, the high affinity with Ag+, and the moderate affinity with RNH3+. Very surprisingly, the association-dissociation processes for 2 and cesium picrate was so slow that the rate could be followed by a conventional spectroscopic method. The thermodynamic parameters determined by kinetic studies disclosed that the major driving-force for Cs+ inclusion is the entropy term based on the desolvation.

New supramolecular hosts: Synthesis and cation binding studies of novel Troger's base-crown ether composites

A simple and straightforward synthesis of a novel class of supramolecular hosts containing the Troger's base moiety is reported. The cation binding properties of these macrocycles were investigated using Cram's picrate extraction method.

Ion Association. Comparison of Spectroscopic and Conductance Values of Association Constants

Molar conductances of potassium, rubidium, and cesium picrate and of cesium tetraphenylborate have been determined in 2-butanone at 25 deg C over a concentration range of 0.1-1.6 mmol L-1.These Λ,C data together with those for lithium and sodium already determined in this laboratory were fitted by using the Lee-Wheaton (LW), the Pitts (P), the Fuoss 78 (F), and the Justice (J) conductance equations to obtain values of ion association constants, KA, and limiting molar conductances.Spectrophotometric absorbance changes were measured for sodium and cesium picrate and remeasured for lithium and tetra-n-butylammonium picrate at 380 nm and 25 deg C over a concentration range of 0.02-1.4 mmol L-1.Values of the cesium-133 NMR chemical shifts of cesium picrate were determined over a concentration range of 0.1-3 mmol L-1 while those for cesium tetraphenylborate were determined over a range from 0.25 to 10 mmol L-1.We calculated values of ion assiciation constants for the various salts using this spectroscopic data.The values of KA determined spectroscopically and the values determined conductimetrically are the same within experimental error with one exception; for cesium tetraphenylborate, the NMR value depends on the concentration range of data included in the analysis.

FORMATION OF PICRATES IN THE REACTIONS OF PICRYL HALIDES PicX (X = F, Cl, I) WITH ORGANOMETALLIC SALTS R3EM (E = Se, Ge AND M = Li, K, Cs), BORATES, AND CARBANIONS. POSSIBLE REACTION MECHANISMS

The reaction of picryl halides PicX (X = F, Cl, I) with organometallic compounds Me3SnM (M= Li, K, Cs), Et3GeK, borates Me4NBR4 (R = Bu, CH2SiMe3, CH2GeMe3), and 9-fluorenylpotassium was investigated.It was shown that for picryl fluoride and picryl chloride the reaction leads to the corresponding picrate.In the case of picryl iodide 1,3,5-trinitrobenzene is formed in addition to the picrate.The formation of the picrate also accompanies the reaction of PicX (X = F, Cl, I) with potassioacetoacetic ester, the main product from which is picrylacetoacetic ester.Possiblemechanisms are considered for the reaction leading to the picrates.

Crown Ethers of Low Symmetry. Spiro Crown Ethers and 16-Crown-5 Derivatives

Spiro crown ethers 3a-c, spiro bis(crown ethers) 5a-e, and the related 16-crown-5 derivatives 6a-d were synthesized and their cation binding abilities were evaluated by study of the extraction of aqueous alkali picrates.Crown ethers carrying 13-crown-4 and 16-crown-5 skeletons showed significant changes in cation selectivity as compared with the corresponding 12-crown-4 and 15-crown-5.Spiro-13-crown-4 3a and spiro-bis 5a showed extremely low extractabilities for all cations examined, while the 16-crown-5-derivatives, including spiro-bis 5b and spiro-bis 5c, showed anomalously high Na+ selectivity.In a quantitative study of extraction equilibrium constants (Kex), 16-crown-5 was again found to have much higher selectivity for Na+ than 15-crown-5.This result is attributed to the less symmetrical spatial arrangement of donor oxygen atoms in 16-crown-5; the symmetry-extractability relationship is discussed on the basis of the size-fit concept.