Crystal and mol-ecular structure of 4-fluoro-1-pyrazole at 150 K.

Only two 4-halo-1-pyrazole crystal structures are known to date (chloro and bromo, the structure of 4-iodo-1-pyrazole has not been reported yet). The triclinic structure of 4-fluoro-1-pyrazole, CHFN ( ), reported here is not isomorphous with those of the chloro and bromo analogues (which are isomorphous, ortho-rhom-bic ). To avoid sublimation during the measurement, diffraction data were collected at 150 K.

Selective binding of anions by rigidified nanojars: sulfate carbonate.

Selective binding and transport of highly hydrophilic anions is ubiquitous in nature, as anion binding proteins can differentiate between similar anions with over a million-fold efficiency. While comparable selectivity has occasionally been achieved for certain anions using small, artificial receptors, the selective binding of certain anions, such as sulfate in the presence of carbonate, remains a very challenging task. Nanojars of the formula [anion⊂{Cu(OH)(pz)}] (pz = pyrazolate; = 27-33) are totally selective for either CO or SO over anions such as NO, ClO, BF, Cl, Br and I, but cannot differentiate between the two.

Selective, Ambient-Temperature C-4 Deuteration of Pyrazole Derivatives by DO.

A simple, inexpensive, and highly efficient procedure for the selective deuteration (up to >99% D atom %) of the C-4 position of pyrazole substrates activated by NH or OH groups at the C-3(5) position is reported. The deuteration reaction is carried out by simply dissolving the substrate in DO or other deuterated protic solvents, either in the absence of a catalyst with heating, or under acidic catalysis at ambient temperature; the products are obtained by simple evaporation of the solvent.

Reaction of Amines with Aldehydes and Ketones Revisited: Access To a Class of Non-Scorpionate Tris(pyrazolyl)methane and Related Ligands.

The reaction of amines with aldehydes and ketones has been exploited for over 150 years to produce Schiff bases, one of the most popular classes of compounds in both organic and coordination chemistry. In certain cases, however, compounds other than Schiff bases have been reported to result from such reactions. After conducting a representative reaction under various different conditions and identifying several reaction intermediates by NMR spectroscopy, mass spectrometry and X-ray crystallography, we now report a unified picture that explains the scattered and often inconsistent results obtained with 3(5)-aminopyrazole derivatives and other related molecules.

Accessing the inaccessible: discrete multinuclear coordination complexes and selective anion binding attainable only by tethering ligands together.

Novel multimetallic copper pyrazolate complexes, inaccessible using simple pyrazole ligands due to competing, alternative structural motifs, can be obtained by locking pairs of pyrazole ligands together with ethylene tethers. Nanojars based on this tethered pyrazole ligand display unexpected total selectivity for the carbonate over the sulfate ion.

Sulfate-Incarcerating Nanojars: Solution and Solid-State Studies, Sulfate Extraction from Water, and Anion Exchange with Carbonate.

A series of 9 homologous sulfate-incarcerating nanojars [SO⊂{Cu(OH)(pz)}] (Cu; n = 27-33; pz = pyrazolate), based on combinations of three [Cu(OH)(pz)] rings (x = 6-14, except 11)-namely, 6 + 12 + 9 (Cu), 6 + 12 + 10 (Cu), 8 + 13 + 8 (Cu), 7 + 13 + 9 (Cu), 8 + 14 + 8 (Cu), 7 + 14 + 9 (Cu), 8 + 14 + 9 (Cu), 8 + 14 + 10 (Cu), and 9 + 14 + 10 (Cu)-has been obtained and characterized by electrospray-ionization mass spectrometry (ESI-MS), variable-temperature H NMR spectroscopy, and thermogravimetry. The X-ray crystal structure of Cu (8 + 13 + 8) is described. Cu and Cu, which are the largest nanojars in this series, are observed for the first time.

From Ordinary to Extraordinary: Insights into the Formation Mechanism and pH-Dependent Assembly/Disassembly of Nanojars.

Nanojars are large (2 nm wide) anion-incarcerating coordination complexes of the composition [anion⊂{Cu(μ-OH)(μ-pz)}n] (n = 27-36), formed by the self-assembly of simple Cu(2+), HO(-), and pyrazolate (pz(-) = C3H3N2(-)) ions in the presence of certain anions with large hydration energy (e.g., CO3(2-), SO4(2-), PO4(3-), HPO4(2-)).

Adjacent Lone Pair (ALP) Effect: A Computational Approach for Its Origin.

The adjacent lone pair (ALP) effect is an experimental phenomenon in certain nitrogenous heterocyclic systems exhibiting the preference of the products with lone pairs separated over other isomers with lone pairs adjacent. A theoretical elucidation of the ALP effect requires the decomposition of intramolecular energy terms and the isolation of lone pair-lone pair interactions. Here we used the block-localized wavefunction (BLW) method within the ab initio valence bond (VB) theory to derive the strictly localized orbitals which are used to accommodate one-atom centered lone pairs and two-atom centered σ or π bonds.

Tuning the structure and solubility of nanojars by peripheral ligand substitution, leading to unprecedented liquid-liquid extraction of the carbonate ion from water into aliphatic solvents.

Nanojars, a novel class of neutral anion-incarcerating agents of the general formula [Cu(II)(OH)(pz)]n (Cun; n = 27-31, pz = pyrazolate anion), efficiently sequester various oxoanions with large hydration energies from water. In this work, we explore whether substituents on the pyrazole ligand interfere with nanojar formation, and whether appropriate substituents could be employed to tune the solubility of nanojars in solvents of interest, such as long-chain aliphatic hydrocarbons (solvent of choice for large-scale liquid-liquid extraction processes) and water. To this end, we conducted a comprehensive study using 40 different pyrazole ligands, with one, two or three substituents in their 3-, 4- and 5-positions.

Survival of the Fittest Nanojar: Stepwise Breakdown of Polydisperse Cu27-Cu31 Nanojar Mixtures into Monodisperse Cu27(CO3) and Cu31(SO4) Nanojars.

Nanojars are emerging as a class of anion sequestration agents of unparalleled efficiency. Dinegative oxoanions (e.g.

Drastic Deprotonation Reactivity Difference of 3- and 5-Alkylpyrazole Isomers, Their I2-Catalyzed Thermal Isomerization, and Telescoping Synthesis of 3,5-Dialkylpyrazoles: The "Adjacent Lone Pair Effect" Demystified.

N-Protected 3-alkylpyrazoles are easily deprotonated by (n)BuLi at the 5-position of the aromatic ring, while the 5-alkyl isomers are completely unreactive under the same conditions. Using computational analysis, we reveal that electron pair repulsion within the deprotonated anion is not the reason behind the lack of reactivity of 5-alkylpyrazoles. Instead, diminished π-resonance and attractive electrostatic interactions within the pyrazole ring are responsible for the observed effect.

Immunoblastic follicular lymphoma: a very unusual transformation of low-grade follicular lymphoma.

A 73-year-old man, in clinical remission 17 years after radiation therapy for a localized low-grade follicular lymphoma (FL), developed extensive lymphadenopathy, ascites, and splenomegaly with splenic masses. Axillary lymph node biopsy showed FL composed of nodules of centrocytes side by side with nodules of immunoblasts rather than centroblasts. Immunophenotyping revealed conventional FL markers (BCL-2, BCL-6, and CD10) as well as MUM-1 in the immunoblastic component, suggesting postgerminal center differentiation.

Deprotonation of methyl-substituted, five-membered aromatic molecules: a surprising case of mixed conjugation, rehybridization, and induction contributions.

Methyl-substituted, six-membered aromatic molecules are deprotonated to benzylic carbanions, which are stabilized by π conjugation. In contrast, deprotonation of 3(5)-methylpyrazole (NH protected) occurs at an endocylic CH group. Computational analyses showed that the reduction of π conjugation in substituted five-membered rings plays a major role, while the reduced bond angles, in addition to the strengthened induction of Csp(2) versus Csp(3), further favor the deprotonation of endocyclic carbon sites rather than that of the methyl group.

Transformation of the 5q- syndrome to acute lymphoblastic leukemia: a report of two cases and review of the literature.

Myelodysplastic syndrome (MDS) with an isolated deletion of the long arm of chromosome 5 (5q- syndrome) is a distinct subtype of MDS with an indolent course that rarely transforms to acute leukemia. Deletion of the long arm of chromosome 5 has also been reported in rare cases of de novo B-lymphoblastic leukemia. We present two cases of 5q- syndrome with a similar and unusual course of transformation to lymphoblastic leukemia while on Lenalidomide.