New Soluble Near‐Infrared Dyes Based on Terrylene Diimides with Four Aromatic Heterocycles

Terrylene diimides with four aromatic heterocycles (AHTDIs) were synthesized under Stille Cross‐coupling conditions and fully characterized by NMR and mass spectrometry. The aggregation of the terrylene diimide (TDI) was suppressed by four heterocycles substituents on the bay region, and these AHTDIs exhibited good solubility in common organic solvents. The effects of the substituted groups on the optical and electrochemical properties were also investigated. The introduction of four aromatic heterocycles on the bay of TDI resulted in significant red‐shifts of the absorption peak (100 nm), corresponding to a decrease in the band gap from 1.82 to 1.50 eV. Furthermore, with four rich electron aromatic heterocycles, the AHTDIs showed 280 mV negative‐shifts of first oxidation potentials and a new oxidation wave, corresponding to an increase in the HOMO levels from??5.60 to??5.28 eV.     

Synthesis and Physical Properties of Benzopyridazine-Based Conjugated Molecules

A series of novel organic conjugated molecules （5a--5d） comprising 2,3-benzopyridiazine as electron-with- drawing core and thiophene derivatives as electron-donating arms have been synthesized successfully in good yields. The ultraviolet-visible （UV-Vis） absorption spectra and fluorescence spectra of 5a--5d revealed that the optical properties are strongly influenced by the interactions between nitrogen and sulfur atoms in the conjugated backbone, as well as the position of the alkyl chains in the thiophene rings. The experimental results and theoretical calculation data clearly indicated that the band gap and the energy levels of LUMO and HOMO could be fine-tuned by the po- sition of alkyl chains in the thiophene rings. Thus, the structure-property correlation of this class of conjugated molecules can be well established.     

Effects of Amino Group Substitution on the Photophysical Properties and Stability of Near-Infrared Fluorescent P-Rhodamines

A series of phosphine oxide-bridged rhodamines (P-rhodamines) bearing various acyclic and cyclic amine moieties, including dimethyl- and diethylamine, azetidine, pyrrolidine and 7-azabicyclo[2,2,1]heptane (7ABH), have been synthesized. The photophysical properties as well as chemical and photostability of these dyes have been studied in detail. Among these dyes, the 7ABH-substituted dye shows stronger fluorescence in the near-infrared (NIR) region, relative to the other P-rhodamines. This dye could be applied to live-cell imaging, wherein lysosomes were selectively stained in a pH-independent manner. It was also found that the ring fusion of the amine moieties gives rise to remarkably redshifted spectra, with absorption and emission maxima at 770 and 820 nm, respectively, spectrally close to that of indocyanine green (ICG). Importantly, the ring-fused P-rhodamines showed much higher photostability than ICG, indicative of their promising utility as the NIR-emissive dyes.     

Reaction of Tungsten–Phosphinidene and –Arsinidene Complexes with Carbodiimides and Alkyl Azides: A Straightforward Way to Four‐Membered Heterocycles

The reaction of the phosphinidene and arsinidene complexes [Cp*E{W(CO)₅}₂] (E=P ( 1 a ), As ( 1 b ); Cp*=C₅Me₅) with carbodiimides leads to the new four‐membered heterocycles of the type [Cp*C(NR)₂E{W(CO)₅}₂] (E=P: R=iPr ( 2 a ), Cy ( 3 a ); E=As: R=iPr ( 2 b ), Cy ( 3 b )). The reaction of phosphinidene complex 1 a with alkyl azides yields the triazaphosphete derivatives [Cp*P{W(CO)₅}N(R)NN{W(CO)₅}] (R=Hex, Cy) ( 4 ). These unprecedented N₃P four‐membered triazaphosphete complexes can be regarded as stabilized intermediates of the Staudinger reaction, which have not been previously isolated. All of the isolated products were characterized by NMR, IR spectroscopy, mass spectrometry, and by single‐crystal X‐ray diffraction analysis.     

Japanese试剂的环化反应

利用Japanese试剂与含活泼氢的双官能团化合物的环化反应,合成了含N-P-N,N-P-O的五元磷杂环化合物,并用IR,NMR和MS对新化合物进行了表征。     

Paving the Way to Novel Phosphorus‐Based Architectures: A Noncatalyzed Protocol to Access Six‐Membered Heterocycles

Phosphorus‐based heterocycles provide access to materials with properties that are inaccessible from all‐carbon architectures. The unique hybridization of phosphorus gives rise to electron‐accepting capacities, a large variety of coordination reactions, and the possibility of controlling the electronic properties through phosphorus postfunctionalization. Herein, we describe a new noncatalyzed synthetic protocol to prepare fused six‐membered phosphorus heterocycles. In particular, we report the synthesis of novel phosphaphenalenes. These fused systems exhibit the benefits of both five‐ and six‐membered phosphorus heterocycles and enable a series of versatile postfunctionalization reactions. This work thus opens up new horizons in the field of conjugated materials.     

Accessing Extended Fused Isoindolinones Via Sequential Anionic Intramolecular Cyclizations

Sequential anionic intramolecular cyclizations and modelling were used for the first time to access unusual fused heterocyclic frameworks in excellent yields. 5-Exo-dig cyclizations yielded isoindolinone motifs and a subsequent 6-exo- and 7-endo-dig cyclization was directed to provide either fused isoquinoline or azepine frameworks. Regioselectivities were controlled by exploiting stereoelectronic effects via n_C−→π*_(Ph) interactions, and modelling studies provided reaction scope.     

Synthesis and Tunable Optical Properties of C,N-Chelated Borate Luminophores Derived from Potassium Acyltrifluoroborates

A new class of borate luminophores has been synthesized by a simple two-step reaction using potassium acyltrifluoroborates (KATs) as starting materials. The hydrazones obtained from reactions between KATs and 2-hydrazinopyridines followed by a cyclization resulted in the unprecedented formation of C,N-chelated six-membered bora-heterocycles. Under consideration of the results of DFT and TD-DFT calculations, four luminophores based on such bora-heterocycles are designed and synthesized, which exhibit a tunable fluorescence range from blue to red in the solid state. Moreover, one of the luminophores exhibits mechanofluorochromism from blue to yellow/green. As a result of the aforementioned mechanochromism of one of these luminophores, white-color emission was achieved by simply mixing the four luminophores.     

具有生物活性的磷杂环化合物研究: XIV. Lawesson试剂与 含活泼氢的双官能团 化合物的环化反应

研究Lawesson试剂与含活泼氢的双官能团化合物的环化反应,合成了O-P-O,N-P-O,N-P-N型五元、六元及七元磷杂环。探讨了其成环可能性及其环化机理。初步的生物活性测定结果表明,应用Lawesson试剂所合成的磷杂环具有较好的选择性除草活性。     

Rainbow Perylene Monoimides: Easy Control of Optical Properties

Perylene dyes have been widely used as photoreceptors in organic photovoltaics because of their outstanding photo‐, thermal and chemical stability as well as their excellent photophysical properties. Herein we describe a novel generation of perylene dyes based on N‐(2,6‐diisopropylphenyl)‐perylene‐3,4‐dicarboximide. The optical properties of these novel perylenes can be finely tuned via the substituents in the 1‐, 6‐ and 9‐positions of the perylene core. The facile synthesis, tunable orbital and absorption properties, and electrochemical potentials help us to design efficient perylene sensitizers for solar‐cell applications.     

Metal‐Free Intramolecular Carbocyanation of Alkenes: Catalytic Stereoselective Construction of Pyrrolo[2,1‐a]isoquinolines with Multiple Substituents

The first catalytic stereoselective approach to prepare multiple substituted cyclic nitriles by means of a novel metal‐free intramolecular carbocyanation strategy has been developed, which provided an efficient protocol to construct densely functionalized diastereoenriched pyrrolo[2,1‐a]isoquinoline derivates under mild reaction conditions (up to 20/1 d.r., 98 % yield).     

Intramolecular Metalloamination of N,N‐Dimethylhydrazinoalkenes: A Versatile Method to Access Functionalized Piperidines and Pyrrolidines

Highly diastereoselective metalloamination/cyclization reactions of zinc(II) hydrazides obtained through reaction of diethylzinc with N,N‐dimethylhydrazinoalkenes are described. The resulting organozinc intermediates undergo facile allylation and acylation, in situ, to provide the corresponding functionalized piperidines and pyrrolidines.     

Tuning Thiophene with Phosphorus: Synthesis and Electronic Properties of Benzobisthiaphospholes

1,4‐Dimercapto‐2,5‐diphosphinobenzene and 3,6‐bis(hexyloxy)‐1,4‐dimercapto‐2,5‐diphosphinobenzene were synthesized and combined with various acid chlorides to obtain a series of benzobisthiaphospholes. Electrochemical and photophysical properties of the substituted benzobisthiaphospholes have been evaluated, and the observed reductions are more facile than the related benzothiaphospholes and 2,6‐diphenylbenzobisthiazole. A benzobisthiaphosphole with C₆H₄‐p‐CN substituents was reduced at E_1/2=?1.08 V (vs. saturated calomel electrode (SCE)). X‐ray diffraction data for several of these phosphorus heterocycles has been obtained, and DFT calculations at the B3LYP level have been performed.     

A Stable Crystalline Triarylphosphine Oxide Radical Anion

Triarylphosphine oxides (Ar₃P=O) are being intensely studied as electron‐accepting (n‐type) materials. Despite the widespread application of these compounds as electron conductors, experimental data regarding the structural and electronic properties of their negatively charged states remain scarce owing to their propensity for follow‐up chemistry. Herein, a carefully designed triarylphosphine oxide scaffold is disclosed that comprises sterically demanding spirofluorenyl moieties to shield the central phosphoryl (P=O) moiety. This compound undergoes chemical one‐electron reduction to afford an exceptionally stable radical anion, which was isolated and characterized by X‐ray crystallography for the very first time. The experimental data, corroborated by computational studies, shall allow for the construction of phosphine oxide materials with enhanced stability.     

PIII/PV=O Catalyzed Cascade Synthesis of N‐Functionalized Azaheterocycles

An organocatalytic method for the modular synthesis of diverse N‐aryl and N‐alkyl azaheterocycles (indoles, oxindoles, benzimidazoles, and quinoxalinediones) is reported. The method employs a small‐ring organophosphorus‐based catalyst (1,2,2,3,4,4‐hexamethylphosphetane P‐oxide) and a hydrosilane reductant to drive the conversion of ortho‐functionalized nitroarenes into azaheterocycles through sequential intermolecular reductive C?N cross coupling with boronic acids, followed by intramolecular cyclization. This method enables the rapid construction of azaheterocycles from readily available building blocks, including a regiospecific approach to N‐substituted benzimidazoles and quinoxalinediones.