2′‐Deoxy‐5‐methylisocytidine

In the title compound, 2‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pento­furan­osyl)‐5‐methyl­pyrimidin‐4(1H)‐one, C₁₀H₁₅N₃O₄, the conformation of the N‐glycosidic bond is syn and the 2‐deoxy­ribo­furan­ose moiety adopts an unusual ^OT₁ sugar pucker. The orientation of the exocyclic C4′—C5′ bond is +sc (+gauche).     

Amarisolide monohydrate,a 2‐(β‐glu­cosyl)­neoclerodane

The absolute configuration of the neoclerodane glycoside amarisolide, presented here as the monohydrate, C₂₆H₃₆O₉·H₂O, has been determined by association with the known configuration of the glucose moiety. Its structure was established as 2β‐(O‐β‐d ‐gluco­pyran­osyl)­neocleroda‐3,13(16),14‐trien‐15,16‐epoxy‐18,19‐olide. Extensive hydrogen bonding among the hydroxyl groups of the sugar moiety forms layers which are interconnected by water mol­ecules.     

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.     

Poly[[di‐μ2‐aqua‐di‐μ5‐croconato(2–)‐nickel(II)dipotassium(I)] tetra­hydrate]

In the title compound, {[K₂Ni(C₅O₅)₂(H₂O)₂]·4H₂O}_n, the Ni atom lies on an inversion centre. Two inversion‐related croconate [4,5‐dihydroxy‐4‐cyclo­pentene‐1,2,3‐trionate(2−)] ligands and an Ni^II ion form a near‐planar symmetrical [Ni(C₅O₅)₂]²⁻ moiety. The near‐square coordination centre of the moiety is then extended to an octa­hedral core by vertically bonding two water mol­ecules in the [Ni(C₅O₅)₂(H₂O)₂]²⁻ coordination anion. The crystal structure is characterized by a three‐dimensional network, involving strong K⋯O⋯K binding, K⋯O—Ni binding and hydrogen bonding.     

Anthraquinone Redox Relay for Dye‐Sensitized Photo‐electrochemical H2O2 Production

Anthraquinone (AQ) redox mediators are introduced to metal‐free organic dye sensitized photo‐electrochemical cells (DSPECs) for the generation of H₂O₂. Instead of directly reducing O₂ to produce H₂O₂, visible‐light‐driven AQ reduction occurs in the DSPEC and the following autooxidation with O₂ allows H₂O₂ accumulation and AQ regeneration. In an aqueous electrolyte, under 1 sun conditions, a water‐soluble AQ salt is employed with the highest photocurrent of up to 0.4 mA cm^?2 and near‐quantitative faradaic efficiency for producing H₂O₂. In a non‐aqueous electrolyte, under 1 sun illumination, an organic‐soluble AQ is applied and the photocurrent reaches 1.8 mA cm^?2 with faradaic efficiency up to 95 % for H₂O₂ production. This AQ‐relay DSPEC exhibits the highest photocurrent so far in non‐aqueous electrolytes for H₂O₂ production and excellent acid stability in aqueous electrolytes, thus providing a practical and efficient strategy for visible‐light‐driven H₂O₂ production.     

1‐[4‐(Methyl­sulfonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole derivatives

Three related compounds containing a pyrazole moiety with vicinal phenyl rings featuring a methyl­sulfonyl substituent are described, namely 3‐methyl‐1‐[4‐(methyl­sulfonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole, C₁₇H₁₆N₂O₂S, ethyl 1‐[4‐(methyl­sul­fonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole‐3‐carboxyl­ate, C₁₉H₁₈N₂O₄S, and 1‐[4‐(methyl­sulfonyl)­phenyl]‐3‐[3‐(morpholino)­phenoxy­methyl]‐5‐phenyl‐1H‐pyrazole, C₂₇H₂₇N₃O₄S. The design of these compounds was based on celecoxib, a selective cyclo­oxy­genase‐2 (COX‐2) inhibitor, in order to study the influence of various substituents on COX‐2 and 5‐lipoxy­genase (5‐LOX) inhibition.     

5′‐Allyl‐2′‐benzoyloxy‐3′‐methoxy‐4‐nitroazobenzene

The structure of the title compound, 4‐allyl‐2‐methoxy‐6‐[(4‐nitrophenyl)diazenyl]phenyl benzoate, C₂₃H₁₉N₃O₅, displays the characteristic features of azobenzene derivatives. The azobenzene moiety of the molecule has a trans configuration and in this moiety, average C—N and N=N bond lengths are 1.441 (3) and 1.241 (3) Å, respectively.     

Dual Mechanism of an Intramolecular Charge Transfer (ICT)–FRET‐Based Fluorescent Probe for the Selective Detection of Hydrogen Peroxide

A dual‐mechanism intramolecular charge transfer (ICT)–FRET fluorescent probe for the selective detection of H₂O₂ in living cells has been designed and synthesized. This probe used a coumarin–naphthalimide hybrid as the FRET platform and a boronate moiety as the recognition group. Upon the addition of H₂O₂, the probe exhibited a redshifted (73 nm) fluorescence emission, and the ratio of fluorescence intensities at λ =558 and 485 nm (F ₅₅₈/F ₄₈₅) shifted notably (up to 100‐fold). Moreover, there was a good linearity (R ²=0.9911) between the ratio and concentration of H₂O₂ in the range of 0 to 60 μm , with a limit of detection of 0.28 μm (signal to noise ratio (S/N)=3). This probe could also detect enzymatically generated H₂O₂. Importantly, it could be used to visualize endogenous H₂O₂ produced by stimulation from epidermal growth factor.     

A 3,7‐Dihydroxyphenoxazine‐based Fluorescent Probe for Selective Detection of Intracellular Hydrogen Peroxide

A novel N‐borylbenzyloxycarbonyl‐3,7‐dihydroxyphenoxazine fluorescent probe (NBCD) for detecting H₂O₂ in living cells is described. The probe could achieve high selectivity for detecting H₂O₂ over other biological reactive oxygen species (ROS). In addition, upon addition of H₂O₂, NBCD exhibited color change from colorless to pink, which makes it a “naked‐eye” probe for H₂O₂ detection. NBCD could not only be used to detect enzymatically generated H₂O₂ but also to detect H₂O₂ in living systems by using fluorescence spectroscopy, with a detection limit of 2 μm . Importantly, NBCD enabled the visualization of epidermal growth factor (EGF)‐stimulated H₂O₂ generation inside the cells.     

A Dual‐Response Fluorescent Probe Reveals the H2O2‐Induced H2S Biogenesis through a Cystathionine β‐Synthase Pathway

The two signaling molecules H₂S and H₂O₂ play key roles in maintaining intracellular redox homeostasis. The biological relationship between H₂O₂ and H₂S remains largely unknown in redox biology. In this study, we rationally designed and synthesized single‐ and dual‐response fluorescent probes for detecting both H₂O₂ and H₂S in living cells. The dual‐response probe was shown to be capable of mono‐ and dual‐detection of H₂O₂ and H₂S selectively and sensitively. Detailed bioimaging studies based on the probes revealed that both exogenous and endogenous H₂O₂ could induce H₂S biogenesis in living cells. By using gene‐knockdown techniques with bioimaging, the H₂S biogenesis was found to be majorly cystathionine β‐synthase (CBS)‐dependent. Our finding shows the first direct evidence on the biological communication between H₂O₂ (ROS) and H₂S (RSS) in vivo.     

The effect of Cl...π interactions on the conformations of 4‐chloro‐5‐(2‐phenoxyethoxy)phthalonitrile and 4‐chloro‐5‐[2‐(pentafluorophenoxy)ethoxy]phthalonitrile

4‐Chloro‐5‐(2‐phenoxyethoxy)phthalonitrile, C₁₆H₁₁ClN₂O₂, (I), and 4‐chloro‐5‐[2‐(pentafluorophenoxy)ethoxy]phthalonitrile, C₁₆H₆ClF₅N₂O₂, (II), show different types of electrostatic interaction. In (I), the phenoxy and phthalonitrile (benzene‐1,2‐dicarbonitrile) moieties are well separated in an open conformation and intermolecular C—H...π interactions are observed in the crystal packing. On the other hand, in (II), the pentafluorophenoxy moiety interacts closely with the Cl atom to form a folded conformation containing an intramolecular halogen–π interaction.     

N8‐(2′‐O‐Methyl­ribofuranos­yl)‐8‐aza‐7‐deaza­adenine monohydrate

In the title compound, 4‐amino‐2‐(2‐O‐methyl‐β‐d ‐ribofuranos­yl)‐2H‐pyrazolo[3,4‐d]pyrimidine monohydrate, C₁₁H₁₅N₅O₄·H₂O, the conformation of the N‐glycosylic bond is syn [χ = 20.1 (2)°]. The ribofuran­ose moiety shows a C3′‐endo (³T₂) sugar puckering (N‐type sugar), and the conformation at the exocyclic C4′—C5′ bond is −ap (trans). The nucleobases are stacked head‐to‐head. The three‐dimensional packing of the crystal structure is stabilized by hydrogen bonds between the 2′‐O‐methyl­ribonucleosides and the solvent mol­ecules.     

2-萘-(OCH2CH2)n-金刚胺与6-单取代环糊精衍生物的光诱导电子转移反应

A number of naphthalene donor compounds that possess an adamantanamine binding moiety and an (OCH2CH2)n (nn1, 2, 3, 4, 6, 8) spacer were synthesized. The fluorescence quenching between these donor substrates and mono-6-O-p-nitrobenzoyl-β-cyclodextrin (pNBCD) and mono-6-O-m-nitrobenzoyl-β-cyclodextrin(mNBCD) was studied in detail. It was found that very efficient fluorescence quenching could occur in these supramolecular systems. This quenching was attributed to the photoinduced electron transfer inside the supramolecular assembly between the naphthalene donors and cyclodextrin acceptors. Detailed Stern-Volmer constants were measured and they were partitioned into dynamic Stern-Volmer quenching constants and static binding constants. It was demonstrated that the binding constants between all the naphthalene compounds and cyclodextrins are the same as they possess the same binding site, i.e., adamantanamine.     

5‐Fluoro‐1‐octanoyl­uracil

The crystal structure of 5‐fluoro‐1‐octanoyl­uracil [5‐fluoro‐1‐octanoyl­pyrimidine‐2,4(1H,3H)‐dione, C₁₂H₁₇FN₂O₃], a lipophilic prodrug of 5‐fluoro­uracil, is described. The 5‐fluoro­pyrimidine‐2,4(1H,3H)‐dione moiety is similar to the known structure of 1‐acetyl‐5‐fluoro­uracil. The 1‐octanoyl group and the 5‐fluoro­uracil moiety are essentially coplanar, with the octanoyl carbonyl group oriented towards the the ring C—H group and away from the nearer ring carbonyl group. The torsion angle C—N—C—O (from the ring CH group to the octanoyl carbonyl group) of 9.2 (2)° is similar to the corresponding torsion angles reported for 1‐acetyl‐5‐fluoro­uracil (17.3 and 1.6°) and 1,3‐di­acetyl‐5‐fluoro­uracil (8.8°).     

A one‐dimensional zinc(II) coordination polymer with a three‐dimensional supramolecular architecture incorporating 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole and adipate

The synthesis of coordination polymers or metal–organic frameworks (MOFs) has attracted considerable interest owing to the interesting structures and potential applications of these compounds. It is still a challenge to predict the exact structures and compositions of the final products. A new one‐dimensional coordination polymer, catena‐poly[[[bis{1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole‐κN³}zinc(II)]‐μ‐hexane‐1,6‐dicarboxylato‐κ⁴O¹,O^1′:O⁶,O^6′] monohydrate], {[Zn(C₆H₈O₄)(C₉H₈N₆)₂]·H₂O}_n, has been synthesized by the reaction of Zn(Ac)₂ (Ac is acetate) with 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole (bimt) and adipic acid (H₂adi) at room temperature. In the polymer, each Zn^II ion exhibits an irregular octahedral ZnN₂O₄ coordination geometry and is coordinated by two N atoms from two symmetry‐related bimt ligands and four O atoms from two symmetry‐related dianionic adipate ligands. Zn^II ions are connected by adipate ligands into a one‐dimensional chain which runs parallel to the c axis. The bimt ligands coordinate to the Zn^II ions in a monodentate mode on both sides of the main chain. In the crystal, the one‐dimensional chains are further connected through N—H…O hydrogen bonds, leading to a three‐dimensional supramolecular architecture. In addition, the title polymer exhibits fluorescence, with emissions at 334 and 350 nm in the solid state at room temperature.     

Structural studies and antileishmanial activity of 2‐acetylpyridine and 2‐benzoylpyridine nitroimidazole‐derived hydrazones

Three imidazole hydrazone compounds, namely 2‐(4‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[1‐(pyridin‐2‐yl)ethylidene]acetohydrazide, C₁₂H₁₂N₆O₃, ( 1 ), 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[1‐(pyridin‐2‐yl)ethylidene]acetohydrazide, C₁₂H₁₂N₆O₃, ( 2 ), and 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[(phenyl)(pyridin‐2‐yl)methylidene]acetohydrazide, C₁₇H₁₄N₆O₃, ( 3 ), were obtained and fully characterized, including their crystal structure determinations. While all the compounds proved not to be cytotoxic to J774.A1 macrophage cells, ( 1 ) and ( 3 ) exhibited activity against Leishmania chagasi, whereas ( 2 ) was revealed to be inactive. Since both ( 1 ) and ( 3 ) exhibited antileishmanial effects, while ( 2 ) was devoid of activity, the presence of the acetyl or benzoyl groups was possibly not a determining factor in the observed antiprotozoal activity. In contrast, since ( 1 ) and ( 3 ) are 4‐nitroimidazole derivatives and ( 2 ) is a 2‐nitroimidazole‐derived compound, the presence of the 4‐nitro group probably favours antileishmanial activity over the 2‐nitro group. The results suggested that further investigations on compounds ( 1 ) and ( 3 ) as bioreducible antileishmanial prodrug candidates are called for.     

A new one‐dimensional ZnII coordination polymer based on 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole and benzene‐1,2‐dicarboxylate

Multidentate N‐heterocyclic compounds form a variety of metal complexes with many intriguing structures and interesting properties. The title coordination polymer, catena‐poly[zinc(II)‐bis{μ‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole}‐κ²N³:N^3′;N^3′:N³‐zinc(II)‐bis(μ‐benzene‐1,2‐dicarboxylato)‐κ²O¹:O²;κ³O¹,O^1′:O²], [Zn₂(C₈H₄O₄)₂(C₁₁H₁₀N₄)₂]_n, has been synthesized by the reaction of Zn(NO₃)₂ with 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole (imb) and benzene‐1,2‐dicarboxylic acid (H₂bdic) under hydrothermal conditions. There are two crystallographically distinct imb ligands [imb(A) and imb(B)] in the structure which adopt very similar coordination geometries. The imb(A) ligand bridges two symmetry‐related Zn1 ions, yielding a binuclear [(Zn1)₂{imb(A)}₂] unit, and the imb(B) ligand bridges two symmetry‐related Zn2 ions resulting in a binuclear [(Zn2)₂{imb(B)}₂] unit. The above‐mentioned binuclear units are further connected alternately by pairs of bridging bdic²⁻ ligands, forming an infinite one‐dimensional chain. These one‐dimensional chains are further connected through N—H...O hydrogen bonds, leading to a two‐dimensional layered structure. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.     

A two‐dimensional cadmium(II) coordination polymer constructed from 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate and 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate ligands

Crystals of poly[[aqua[μ₃‐4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylato‐κ⁵O¹O^1′:N³,O⁴:O⁵][μ₄‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ⁷N³,O⁴:O⁴,O^4′:O¹,O^1′:O¹]cadmium(II)] monohydrate], {[Cd₂(C₁₅H₁₄N₂O₄)(C₁₆H₁₄N₂O₆)(H₂O)]·H₂O}_n or {[Cd₂(Hcpimda)(cpima)(H₂O)]·H₂O}_n, (I), were obtained from 1‐(4‐carboxybenzyl)‐2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃cpimda) and cadmium(II) chloride under hydrothermal conditions. The structure indicates that in‐situ decarboxylation of H₃cpimda occurred during the synthesis process. The asymmetric unit consists of two Cd²⁺ centres, one 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate (Hcpimda²⁻) anion, one 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate (cpima²⁻) anion, one coordinated water molecule and one lattice water molecule. One Cd²⁺ centre, i.e. Cd1, is hexacoordinated and displays a slightly distorted octahedral CdN₂O₄ geometry. The other Cd centre, i.e. Cd2, is coordinated by seven O atoms originating from one Hcpimda²⁻ ligand and three cpima²⁻ ligands. This Cd²⁺ centre can be described as having a distorted capped octahedral coordination geometry. Two carboxylate groups of the benzoate moieties of two cpima²⁻ ligands bridge between Cd2 centres to generate [Cd₂O₂] units, which are further linked by two cpima²⁻ ligands to produce one‐dimensional (1D) infinite chains based around large 26‐membered rings. Meanwhile, adjacent Cd1 centres are linked by Hcpimda²⁻ ligands to generate 1D zigzag chains. The two types of chains are linked through a μ₂‐η² bidentate bridging mode from an O atom of an imidazole carboxylate unit of cpima²⁻ to give a two‐dimensional (2D) coordination polymer. The simplified 2D net structure can be described as a 3,6‐coordinated net which has a (4³)₂(4⁶.6⁶.8³) topology. Furthermore, the FT–IR spectroscopic properties, photoluminescence properties, powder X‐ray diffraction (PXRD) pattern and thermogravimetric behaviour of the polymer have been investigated.     

7‐Vinyl‐8‐aza‐7‐de­aza‐2′‐deoxy­adenosine monohydrate

In the title compound, 4‐amino‐1‐(2‐deoxy‐β‐d ‐eythro‐pento­furan­osyl)‐3‐vinyl‐1H‐pyrazolo­[3,4‐d]­pyrimidine monohydrate, C₁₂H₁₅N₅O₃·H₂O, the conformation of the gly­cosyl bond is anti. The furan­ose moiety is in an S conformation with an unsymmetrical twist, and the conformation at the exocyclic C—C(OH) bond is +sc (gauche, gauche). The vinyl side chain is bent out of the heterocyclic ring plane by 147.5 (5)°. The three‐dimensional packing is stabilized by O—H·O, O—H·N and N—H·O hydrogen bonds.     

9,10‐Di­phenyl‐9,10‐epi­dioxy­anthra­cene and 9,10‐di­hydro‐10,10‐di­methoxy‐9‐phenyl­anthracen‐9‐ol

9,10‐Di­phenyl‐9,10‐epi­dioxy­anthracene, C₂₆H₁₈O₂, (I), was accidentally used in a photo­oxy­genation reaction that produced 9,10‐di­hydro‐10,10‐di­methoxy‐9‐phenyl­anthracen‐9‐ol, C₂₂H₂₀O₃, (II). In both compounds, the phenyl rings are approximately orthogonal to the anthracene moiety. The conformation of the anthracene moiety differs as a result of substitution. Intramolecular C—H⃛O interactions in (I) form two approximately planar S(5) rings in each of the two crystallographically independent mol­ecules. The packing of (I) and (II) consists of molecular dimers stabilized by C—H⃛O interactions and of molecular chains stabilized by O—H⃛O interactions, respectively.