Photochemistry-Enabled Nitrogen-Assisted Organostibines as an Efficient Alkyl Radical Precursor: Mechanistic Insights and Synthetic Applications.

Organostibines exhibit significant potential as functional handles for the construction of C─C-rich scaffolds owing to their orthogonal and robust reactivity features. At present, the transformation of C(sp)/C(sp)─Sb bonds into C─C bonds has established a mature methodology. However, breakthroughs in the C(sp)─Sb system still require systematic investigations into reaction mechanisms, catalyst design, and other aspects.

Steric hindrance engineering to construct NIR-II probe for high-sensitivity G4 imaging .

G-Quadruplexes play key roles in tumorigenesis, but detecting them remains challenging. We developed NIRGQ-3, a NIR-II fluorescent probe, with 25-fold fluorescence enhancement and improved sensitivity (limit of detection: 35 nM). It enables high-contrast tumor imaging (SBR = 25), providing a powerful tool to decipher G-quadruplex dynamics and advancing cancer diagnostics.

Mechanism-Driven Bioactive Indazole Frameworks: Photoinitiated Demethylation-Aromatization Synthesis and Biosensing Applications.

Indazole frameworks are pivotal in medicinal chemistry and fluorescent conjugate design. Herein, we reported a photochemical strategy enabling efficient N-demethylation and aromatic cyclization of N-methyl amines via UV-induced nitroso intermediates, offering an environmentally benign route to structurally diverse 2H-indazole scaffolds. Diverging from conventional methods, this protocol demonstrates exceptional substrate compatibility with various alkyl/aryl amines, facilitating streamlined assembly of functionalized 2H-indazole modules.

Constructing Stable and Wavelength-Extended Heptamethine Cyanines via Donor Ectopic Substitution for NIR-IIa/b Bioimaging.

Organic NIR-II dyes, particularly cyanine fluorophores, offer high molar extinction coefficients, biocompatibility, and structural tunability and are popular for noninvasive, high-resolution, and -contrast in vivo imaging. However, achieving stable, long-wavelength, and large Stokes shift NIR-II cyanine suitable for NIR-IIa/IIb bioimaging is still a formidable challenge. Herein, we introduce a novel strategy that extends the emission wavelength by the enhanced Highest occupied molecular orbital (HOMO)-Lowest occupied molecular orbital (LUMO) separation through simple donor ectopic substitution at the terminal structure of NIR-II cyanine.

Cu(II)/Base Synergistic Promoted [2 + 1 + 3] Cyclization of Cyclic Ketones with α,β-Unsaturated Aldehydes/Ketones and NHI to Access Fused Pyridines.

Herein, a practical three-component [2 + 1 + 3] cyclization of various cyclic ketones with α,β-unsaturated aldehydes/ketones and ammonium iodide (NHI) to access highly functional fused pyridines has been developed. The features of this transformation include mild reaction conditions, readily available starting materials, and excellent chemoselectivity. This protocol is compatible with various functional groups, and the preliminary studies on the mechanism of the reaction are also provided.

Base-Promoted Annulated Aromatization of Aryl Acetylenes with Dimethyl Sulfoxide to Access Symmetrical/Unsymmetric -Terphenyl.

A protocol for selective and efficient synthesis of symmetrical and unsymmetrical -terphenyls is presented among aryl acetylene and DMSO in the presence of KOH and methanol. In this reaction, two molecules of aryl acetylene contribute four carbons, and DMSO, as a dual carbon donor, provides two carbons to a new aromatic ring. This protocol can be tolerated for the electron-donating or disubstituted phenylacetylenes as well as the heterocyclic acetylene derivatives.

Rational Design of NIR-II G-Quadruplex Fluorescent Probes for Accurate In Vivo Tumor Metastasis Imaging.

Accurate in vivo imaging of G-quadruplexes (G4) is critical for understanding the emergence and progression of G4-associated diseases like cancer. However, existing in vivo G4 fluorescent probes primarily operate within the near-infrared region (NIR-I), which limits their application accuracy due to the short emission wavelength. The transition to second near-infrared (NIR-II) fluorescent imaging has been of significant interest, as it offers reduced autofluorescence and deeper tissue penetration, thereby facilitating more accurate in vivo imaging.

Molecular Design of NIR-II Polymethine Fluorophores for Bioimaging and Biosensing.

Organic polymethine fluorophores with emission in the NIR-II window (1000-1700 nm) are receiving enormous attention in biomolecular medicine and bioimaging, attributed to the high absorption coefficients, bright NIR-II emission, excellent biocompatibility, and molecule adjustability. Recently, researchers have devoted significant effort to designing and improving NIR-II polymethine fluorophores and making notable progress in the NIR-II fluorescence imaging performance. This review summarizes recent developments in the molecular engineering design mentality of polymethine fluorophores and probes and highlights their extensive bioimaging and biosensing applications.

Photo-Induced N-N Coupling of -Nitrobenzyl Alcohols and Indolines To Give -Aryl-1-amino Indoles.

A novel method to synthesize -aryl-1-amino indoles was established by the photoinduced N-N coupling reaction. This protocol is by treatment of -nitrobenzyl alcohols and indolines in the presence of TEAI and acetic acid with a 24 W ultraviolet (UV) light-emitting diode (LED) (385-405 nm) irradiation. The products bearing an aldehyde group can be further transformed to fluorescent probes based on Rhodamine 6G derivative , which shows a high specificity and sensitivity for Fe.

UV-Light-Induced N-Acylation of Amines with α-Diketones.

Herein, we develop a mild method for -acylation of primary and secondary amines with α-diketones induced by ultraviolet (UV) light. Forty-six examples with various functional groups are explored at room temperature with irradiation by three 26 W UV lamps (350-380 nm). The yield reaches 97%.

Iodine-Catalyzed Synthesis of '-Chelate Organoboron Aminoquinolate.

We disclose a novel method for the synthesis of fluorescent ,'-chelate organoboron compounds in high efficiency by treatment of aminoquinolates with NaBAr/R'COOH in the presence of an iodine catalyst. These compounds display high air and thermal stability. A possible catalytic mechanism based on the results of control experiments has been proposed.

CFSONa-Mediated, UV-Light-Induced Friedel-Crafts Alkylation of Indoles with Ketones/Aldehydes and Bioactivities of Products.

A concise, one-step route to produce 3,3'-diindolylmethanes (DIMs) from simple indoles and ketones or aldehydes is reported. The key step is the ready formation of indole derivatives that involves the in situ conversion of CFSONa reagent to ·CF under oxygen or air (1.0 atm) and UV irradiation.