Framework Mobility in the Metal−Organic Framework Crystal IRMOF-3: Evidence for Aromatic Ring and Amine

a b s t r a c t The framework motions in IRMOF-3 (Zn 4 O(BDC-NH 2 ) 3 ), where BDC-NH 2 represents 2-amino-1,4-ben zenedicarboxylate, have been investigated with 1 H NMR relaxation measurements. Isotopic enrichment of the 2-amino group with 15 N was critical in elucidating the lattice dynamics and enhancing spectral resolution. These results indicate a low energy process associated with rotation of the amino group, with an activation energy of 1.8 ± 0.6 kcal/mol, and full 180°rotation of the phenylene group in the BDC-NH 2 moiety with an activation energy of 5.0 ± 0.2 kcal/mol. A relatively low pre-exponential factor for amine rotation (1.3 Â 10 7 s À1 ) is tentatively associated with the need to break a hydrogen bond as the rate-limiting step. Both amine rotation and the aromatic ring flip occur at frequencies that provide an effective relaxation mechanism for the 99.6% natural abundance quadrupola

Radical Reactions with Double Memory of Chirality ( 2 MOC) for the Enantiospecific Synthesis of Adjacent Stereogenic Quaternary Centers in Solution: Cleavage and Bonding Faster than Radical Rotation

The solution photochemistry of bis(phenylpyrrolidinonyl)ketones (R,R)-1b and (S,S)-1b exhibited a remarkably high memory of chirality. Stereospecific decarbonylation to products (R,R)-3b and (S,S)-3b, respectively, occurred with an ee of ca. 80%. The reaction is thought to occur along the single state manifold by sequential Norrish type-I α-cleavage decarbonylation, and radical–radical combination in a time scale that is comparable to that required for the radical intermediate to expose its other enantiotopic face by rotation about an axis perpendicular to that of the p orbital (ca. 3–7 ps). The absolute configuration of a key intermediate and that of ketone (R,R)-1b were determined by single-crystal X-ray diffraction and the ee values of the photochemical products with the help of chiral shift reagent (+)-Eu(tfc)3 and chiral LC-MS/ MS. On the basis of the ee and de values at 25 °C, it could be determined that ca. 70% of the bond forming events occur with double memory of chirality, ca. 21% occur after rotation of one radical to form the meso product (R,S)-3b, and only 9% occur after double rotation to form the opposite enantiomer. This report represents the first example of a doubly enantiospecific Norrish type-I and decarbonylation reaction in solution and illustrates potentially efficient ways to obtain compounds with adjacent stereogenic quaternary centers

An A91V SNP in the perforin gene is frequently found in NK/T-cell lymphomas

NK/T-cell lymphoma (NKTCL) is the most frequent EBV-related NK/T-cell disease. Its clinical manifestations overlap with those of familial haemophagocytic lymphohistiocytosis (FHLH). Since PERFORIN (PRF1) mutations are present in FHLH, we analysed its role in a series of 12 nasal and 12 extranasal-NKTCLs. 12.5% of the tumours and 25% of the nasal-origin cases had the well-known g.272C>T(p.Ala91Val) pathogenic SNP, which confers a poor prognosis. Two of these cases had a double-CD4/CD8-positive immunophenotype, although no correlation was found with perforin protein expression. p53 was overexpressed in 20% of the tumoral samples, 80% of which were of extranasal origin, while none showed PRF1 SNVs. These results suggest that nasal and extranasal NKTCLs have different biological backgrounds, although this requires validation