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This article explores the synthesis and properties of two 2'-deoxyadenosine mimics, dSA and dSO2A, which contain a thieno[3,2-d]pyrimidine ring. The authors aimed to investigate the enzymatic reactions, photophysical properties, and potential incorporation into oligonucleotides of these mimics. The synthesized adenosine mimics demonstrated high enzymatic stability and exhibited different absorption and fluorescence properties compared to natural adenosine. However, while one mimic successfully formed oligonucleotides, the other decomposed under basic conditions. Overall, this study suggests that dSA can be utilized as a stable adenosine congener with fluorescence properties in ON technologies. [Extracted from the article]

In solid-phase oligonucleotide (ON) synthesis, especially for 3′-modified ONs, a universal linker attached to a solid support is widely used. In this study, benzo-fused 7-oxabicyclo[2.2.1]heptane-2,3-diol derivatives are designed, synthesized, and evaluated as universal linkers. The designed linkers show reactivity comparable to that of a conventional universal linker for releasing the desired ONs. Additionally, these materials exhibit a more robust structure under basic conditions, as generally used in ON synthesis, and hydrophobic properties relative to the conventional universal linker. Notably, when diphenyl-substituted (terphenyl) and phenanthrene-type (PT) linkers are used, cyclic phosphodiesters derived from linker units as byproducts, which are produced by release of ONs from the linker units, are detected in the HPLC chromatograms. The PT linker is applicable to various ON syntheses using controlled pore glass (CPG) and polystyrene (PS) resins. These results demonstrate that the PT linker can serve as an alternative to conventional universal linkers. [ABSTRACT FROM AUTHOR]

In solid-phase oligonucleotide synthesis, a single oligonucleotide is generally acquired from a column loaded with a specific solid support. Herein, we have developed new cleavable spacer (CS) derivatives for tandem synthesis of multiple oligonucleotides on a single column-. Four CS analogues were designed, synthesized, and inserted between two oligonucleotide sequences using an automated oligonucleotide synthesizer. The CS derivatives bearing a cyclic cis -1,2-diol exhibited efficient release of the two oligonucleotides under commonly employed basic conditions of aqueous ammonia. Among the CS analogues, it was found that CS with a robust structure can potentially be applied as a spacer molecule in the tandem synthesis of multiple oligonucleotides in a single sequence. [ABSTRACT FROM AUTHOR]

Novel 2′‐O,4′‐C‐ethylene‐bridged nucleic acid (ENA) analogs with exocyclic methylene and (R)‐methyl groups at the 6′‐position were synthesized. The obtained 6′‐methylene‐ENA and 6′R‐Me‐ENA were incorporated into oligonucleotides, and their properties were compared with those of the corresponding natural, ENA‐, and 6′S‐Me‐ENA‐modified oligonucleotides. The duplex‐stabilizing ability of 6′‐methylene‐ENA and 6′R‐Me‐ENA with single‐stranded RNA (ssRNA) was similar to that of ENA and 6′S‐Me‐ENA under both dilute and molecular crowding conditions. On the other hand, oligonucleotides containing 6′‐methylene‐ENA and 6′R‐Me‐ENA formed stable triplexes with double‐stranded DNA (dsDNA) in comparison with those containing 6′S‐Me‐ENA. Their thermodynamic properties were also calculated to explore the influence of the substituents introduced at the 6′‐position of ENA. Moreover, oligonucleotides with ENA analogs exhibited excellent resistance against nucleases. These results suggest that 6′‐methylene‐ENA and 6′R‐Me‐ENA are promising candidates for targeting ssRNA and dsDNA. [ABSTRACT FROM AUTHOR]

Emissive push–pull‐type bisnaphthyridylamine derivatives (BNA‐X: X=Me, Et, Bzl, Ph, BuBr, and BuTEMPO) aggregate in aqueous methanol. Furthermore, a two‐step emission and aggregation process is controllable by varying the methanol‐to‐water ratio. At 2:3 MeOH/H2O, crystallization‐induced emission enhancement (CIEE) occurs via formation of an emissive crystal phase, whereas, at 1:9 MeOH/H2O, aggregation‐induced emission enhancement (AIEE) occurs, induced by emissive supramolecular nanoparticles (NPs). For BNA‐Ph, the emission quantum yield was 25 times higher in aqueous methanol than that in pure methanol. Despite the high hydrophobicity of BNA‐X (C log P=6.1–8.0), the spherical NPs were monodisperse (polydispersity indices <0.2). Moreover, the emissive NPs exhibited fluorescence resonance energy transfer (FRET) with pyrene; however, for BNA‐X bearing the TEMPO radical (BNA‐BuTEMPO), no FRET was observed because of quenching. In particular, the BNA‐BuTEMPO NPs have a slow rotational correlation time (1.3 ns), suggesting applications as magnetic resonance imaging contrast agents with large relaxivity. [ABSTRACT FROM AUTHOR]

Pyridocarbazole moieties are present in many natural products, such as olivacine and ellipticine, and their derivatives are well‐known anticancer agents. To develop functional therapeutic and diagnostic compounds, three emissive pyrido[3,2‐c]carbazole derivatives, PC‐X, containing secondary or tertiary amine groups, were synthesized from an aminoquinoline derivative using a palladium complex as the catalyst. X‐ray diffraction analyses revealed that PC‐X showed highly planar structures between the pyridine ring and the carbazole framework, exhibiting high fluorescence intensities along with solvatochromic behavior. Imaging of HeLa cells treated with PC‐X showed no specific accumulation into the organelles; however, a comparative examination showed that the accumulation in mitochondria was the highest as compared to nuclei and lysosomes. Cytotoxicity analysis using HeLa cells showed that PC‐H, containing a secondary amine group showed the highest cytotoxicity (IC50≈20 μm) as compared to another PC‐X having a tertiary amine group. Colocalization with MitoTracker, a typical mitochondrial staining dye, showed apoptosis‐like behavior with remarkable appearance of blebbing during irradiation with near UV light (403 nm), suggesting that the PC‐H may not only behave as a fluorescence probe for the imaging organelles, but also as a therapeutic agent for inducing apoptosis in HeLa cells, thereby functioning as a theranostic agent. [ABSTRACT FROM AUTHOR]

This image vividly portrays the N-N bond cleavage within the dihydropyridazine (DHP) ring, rotational motions around a C-C bond, and the subsequent recombination of N-N bonds. Keywords: dihydropyridazine; dual emission; Kekulé biradical; photoisomerization; photoracemization EN dihydropyridazine dual emission Kekulé biradical photoisomerization photoracemization 1 1 1 11/10/23 20231108 NES 231108 B Chirality control b of the title compound by photoracemization is depicted, inspired by "Jack and the Beanstalk". Dihydropyridazine, dual emission, Kekulé biradical, photoisomerization, photoracemization. [Extracted from the article]

A novel 1,3-diazaphenoxazinenucleoside derivative (nitroG-Grasp)bearing a thiol group with a urea linker forms multiple hydrogen-bondedcomplexes with 8-nitroguanosine and efficiently displaces the nitrogroup; thus, it is the first molecule that can covalently capture8-nitroguanosine. [ABSTRACT FROM AUTHOR]

Cover Feature: Push-Pull Bisnaphthyridylamine Supramolecular Nanoparticles: Polarity-Induced Aggregation and Crystallization-Induced Emission Enhancement and Fluorescence Resonance Energy Transfer (Chem. Eur. J. 9/2021) Keywords: emission; fluorescence; FRET; nanoparticles; radicals EN emission fluorescence FRET nanoparticles radicals 2885 2885 1 02/12/21 20210210 NES 210210 B An organic solution with a push-pull-type fluorophore b , which resembles the shape of a dragon in the cover image, exhibits aggregation-induced emission enhancement upon water addition. Emission, fluorescence, FRET, nanoparticles, radicals. [Extracted from the article]

Invited for the cover of this issue are the groups of Kazuteru Usui and Satoru Karasawa at Showa Pharmaceutical University and Yasuhiro Kobori of Kobe University. The image depicts chirality control of helical compounds through cycles of photocleavage and recombination under sunlight with a "Jack and the Beanstalk" motif. Read the full text of the article at 10.1002/chem.202302413., (© 2023 Wiley-VCH GmbH.)

In this study, 2'- O ,4'- C -methyleneoxy-bridged nucleic acid, a unique consecutive three-acetal-containing nucleic acid (TaNA), was designed. Pyrimidine derivatives of methylated TaNA (Me-TaNA) were also synthesized and introduced into oligonucleotides via solid-phase synthesis. The Me-TaNA-modified oligonucleotides exhibited higher stabilities when forming duplexes with single-stranded RNA or triplexes with double-stranded DNA, relative to the natural oligonucleotides and modified oligonucleotides containing another 2',4'-bridged 5-methyluridine, such as 2',4'-BNA/LNA and 2',4'-ENA. Furthermore, Me-TaNA within oligonucleotides significantly enhanced nuclease resistance.

Emissive push-pull-type bisnaphthyridylamine derivatives (BNA-X: X=Me, Et, Bzl, Ph, BuBr, and BuTEMPO) aggregate in aqueous methanol. Furthermore, a two-step emission and aggregation process is controllable by varying the methanol-to-water ratio. At 2:3 MeOH/H 2 O, crystallization-induced emission enhancement (CIEE) occurs via formation of an emissive crystal phase, whereas, at 1:9 MeOH/H 2 O, aggregation-induced emission enhancement (AIEE) occurs, induced by emissive supramolecular nanoparticles (NPs). For BNA-Ph, the emission quantum yield was 25 times higher in aqueous methanol than that in pure methanol. Despite the high hydrophobicity of BNA-X (C log P=6.1-8.0), the spherical NPs were monodisperse (polydispersity indices <0.2). Moreover, the emissive NPs exhibited fluorescence resonance energy transfer (FRET) with pyrene; however, for BNA-X bearing the TEMPO radical (BNA-BuTEMPO), no FRET was observed because of quenching. In particular, the BNA-BuTEMPO NPs have a slow rotational correlation time (1.3 ns), suggesting applications as magnetic resonance imaging contrast agents with large relaxivity., (© 2020 Wiley-VCH GmbH.)

Water-soluble donor-acceptor-type fluorophore 15Nap-Cl having two trifluoromethyl groups and a Cl group on a 1,5-aminonaphthyridine framework was prepared. Fluorophore 15Nap-Cl showed strong solvatochromic fluorescence, and, as the solvent polarity increased, a bathochromic shift was observed accompanied by an increase in the fluorescence quantum yield. In addition, in the presence of amines such as ethylamine, diethylamine, and aniline, further considerable bathochromic shifts in the fluorescence were observed. Density functional calculations identified the source of the fluorescence behavior as exciplex formation between 15-Nap-Cl and the corresponding amine. The fluorescence behavior was exploited to fabricate a sensor that can identify various primary, secondary, and tertiary amines., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)