Reversible gas-phase redox processes catalyzed by Co-exchanged MFU-4l(arge)

Postsynthetic metal ion exchange in a benzotriazolate-based MFU-4l(arge) framework leads to a Co(II)-containing framework with open metal sites showing reversible gas-phase oxidation properties.     

5‐Ethynyl‐2′‐deoxycytidine: a DNA building block with a `clickable' side chain

The title compound [systematic name: 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐5‐ethynylpyrimidin‐2(1H)‐one], C₁₁H₁₃N₃O₄, shows two conformations in the crystalline state. The N‐glycosylic bonds of both conformers adopt similar conformations, with χ = −149.2 (1)° for conformer (I‐1) and −151.4 (1)° for conformer (I‐2), both in the anti range. The sugar residue of (I‐1) shows a C2′‐endo envelope conformation (²E, S‐type), with P = 164.7 (1)° and τ_m = 36.9 (1)°, while (I‐2) shows a major C3′‐exo sugar pucker (C3′‐exo‐C2′‐endo, ₃T², S‐type), with P = 189.2 (1)° and τ_m = 33.3 (1)°. Both conformers participate in the formation of a layered three‐dimensional crystal structure with a chain‐like arrangement of the conformers. The ethynyl groups do not participate in hydrogen bonding, but are arranged in proximal positions.     

2‐Amino‐8‐(2‐deoxy‐2‐fluoro‐β‐d‐arabinofuranosyl)imidazo[1,2‐a][1,3,5]triazin‐4(8H)‐one monohydrate,a 2′‐deoxyguanosine analogue with an altered Watson–Crick recognition site

The title compound, C₁₀H₁₂FN₅O₄·H₂O, shows an anti glycosyl orientation [χ = −123.1 (2)°]. The 2‐deoxy‐2‐fluoroarabinofuranosyl moiety exhibits a major C2′‐endo sugar puckering (S‐type, C2′‐endo–C1′‐exo, ²T₁), with P = 156.9 (2)° and τ_m = 36.8 (1)°, while in solution a predominantly N conformation of the sugar moiety is observed. The conformation around the exocyclic C4′—C5′ bond is −sc (trans, gauche), with γ = −78.3 (2)°. Both nucleoside and solvent molecules participate in the formation of a three‐dimensional hydrogen‐bonding pattern via intermolecular N—H...O and O—H...O hydrogen bonds; the N atoms of the heterocyclic moiety and the F substituent do not take part in hydrogen bonding.     

Dibromodiphenylstannane: isolated centrosymmetric dimers as a new structure motif for the intermolecular association of diorganotin(IV) dihalides

In the crystalline state, the low‐melting title compound [common name: diphenyltin(IV) dibromide], [SnBr₂(C₆H₅)₂], consists of distorted tetrahedral molecules with compressed halide and enlarged carbon opening angles of 102.741 (9) and 123.53 (8)°, respectively, and Sn—C and Sn—Br bond lengths of 2.109 (2)/2.113 (2) and 2.4710 (3)/2.4947 (3) Å, respectively. Intermolecular Sn...Br interactions, typical for diorganotin(IV) dihalides, R₂SnHal₂ (with Hal = Cl, Br, I), and sterically less demanding organic groups lead to the formation of a hitherto unknown association pattern consisting of centrosymmetric dimers with an antiparallel orientation of the dipole moments and two weak intermolecular Sn...Br distances of 3.8482 (3) Å between one of the two Br atoms and its neighbouring Sn atom, and vice versa. The second Br atom is not involved in intermolecular interactions and lies somewhat outside the association plane that, therefore, is not coplanar [interplanar angle = 1.750 (2)°] with the tin–halide plane. The new structure motif of intermolecular tin–halide interaction can be classified as 2a_i, which indicates the number of molecules (i.e. `2') composing the oligomer, the antiparallel orientation (i.e. `a') of their dipole moments and the centre of symmetry (i.e. `i') giving rise to the association pattern.     

1,N6‐Etheno‐2′‐deoxytubercidin hemihydrate

The title compound [systematic name: 7‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐7H‐imidazo[1,2‐c]pyrrolo[2,3‐d]pyrimidine hemihydrate], 2C₁₃H₁₄N₄O₃·H₂O or (I)·0.5H₂O, shows two similar conformations in the asymmetric unit. These two conformers are connected through one water molecule by hydrogen bonds. The N‐glycosylic bonds of both conformers show an almost identical anti conformation with χ = −107.7 (2)° for conformer (I‐1) and −107.0 (2)° for conformer (I‐2). The sugar moiety adopts an unusual N‐type (C3′‐endo) sugar pucker for 2′‐deoxyribonucleosides, with P = 36.8 (2)° and τ_m = 40.6 (1)° for conformer (I‐1), and P = 34.5 (2)° and τ_m = 41.4 (1)° for conformer (I‐2). Both conformers and the solvent molecule participate in the formation of a three‐dimensional pattern with a `chain'‐like arrangement of the conformers. The structure is stabilized by intermolecular O—H...O and O—H...N hydrogen bonds, together with weak C—H...O contacts.     

A 2′‐deoxycytidine long‐linker click adduct forming two conformers in the asymmetric unit

The title compound {systematic name: 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐5‐[6‐(1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)hex‐1‐ynyl]pyrimidin‐2(1H)‐one}, C₂₄H₂₈N₆O₄, shows two conformations in the crystalline state, viz. (I‐1) and (I‐2). The pyrimidine groups and side chains of the two conformers are almost superimposable, while the greatest differences between them are observed for the sugar groups. The N‐glycosylic bonds of both conformers adopt similar anti conformations, with χ = −168.02 (12)° for conformer (I‐1) and χ = −159.08 (12)° for conformer (I‐2). The sugar residue of (I‐1) shows an N‐type (C3′‐endo) conformation, with P = 33.1 (2)° and τ_m = 29.5 (1)°, while the conformation of the 2′‐deoxyribofuranosyl group of (I‐2) is S‐type (C3′‐exo), with P = 204.5 (2)° and τ_m = 33.8 (1)°. Both conformers participate in hydrogen‐bond formation and exhibit identical patterns resulting in three‐dimensional networks. Intermolecular hydrogen bonds are formed with neighbouring molecules of different and identical conformations (N—H...N, N—H... O, O—H...N and O—H...O).     

Synthesis and Vesicle Formation of Ethyl 2-[2′-(F-alkyl)ethyl] 2-alkyl Malonic Acid Disodium Salts

Abstract

A series of new di-anionic perfluoroalkylated amphiphiles with mixed F-alkyl/alkyl long chains and a malonic acid disodium salt head group has been synthesized. Among these new F-alkyl-containing amphiphiles, some were found to self-assemble in stable vesicles by hand shaking in water at room temperature. The vesicular aggregates were viewed by freeze-fracture electron microscopy and measured with photon correlation spectroscopy. Surface-activity of all amphiphiles was also investigated. Their CMCs were in particular determined from curves giving surface tension versus concentration.