Basic and Coordination Properties of Tetraphenylporphine Derivatives

Basic and coordination properties of 5,10,15,20-tetrakis(3,5-dibromophenyl)porphine and 5,10,15,20-tetrakis(4-methoxy-3-bromophenyl)porphine in acetonitrile have been investigated by means of spectrophotometry. The optimization of the geometry parameters of polysubstituted porphyrins has been performed using quantum-chemical method (РМ3). The relationship between geometric structure of the studied porphyrins and their coordination, basic, and spectral properties is discussed.     

Effect of Pyrrole Bromo-Substitution in Tetraphenylporphine on the Kinetics of Complexation with Zinc Acetate in Pyridine and Acetic Acid

Rate constants of zinc acetate complexation with 2,7,12,17-tetrabromo-5,10,15,20-tetraphenylporphine in toluene, pyridine, or acetic acid following the reaction H₂TPP(-Br)₄ + Zn(Ac)₂ ZnTPP(-Br)₄ + 2HAc are determined at four temperatures in the interval of 298–328 K, and the activation energies and entropies are calculated. The effect of bromo-substitution in pyrrole fragments of a tetraphenylporphine molecule on the complexation kinetics and mechanism is discussed.     

Bromination of Tetraazaporphine and Its β-Substituted Derivatives Using Pyridine as Solvent and Catalyst

The selectivity and degree of bromination of pyrrole rings in porphyrazine strongly depends on the brominating agent and solvent nature. The reaction of porphyrazine magnesium complex with molecular bromine and N-bromosuccinimide in pyridine gave magnesium complex of dibromotetraazaporphine. Increasing bromine substitution in porphyrazine enhances its acidic properties.     

新型吡啶衍生物的合成

以2-甲基吡啶为原料,经氧化、硝化、还原反应合成了重要中间体4-氨基-2-甲基吡啶(3); 3分别经1,4-加成反应、Heck反应及取代反应合成了11个吡啶类化合物(4~14),其中5, 6和8~14为新化合物,其结构经¹H NMR, ¹³C NMR, MS和HR-MS进行表征。     

亲水作用电色谱用于吡啶类化合物的分离

采用亲水电色谱对强极性吡啶类化合物进行了分离。以亲水性的强阳离子交换填料作固定相,乙腈-磷酸-三乙胺缓冲液作流动相,考察了流动相中有机改性剂含量、离子强度及流动相pH对吡啶类化合物保留行为的影响。结果表明,在亲水电色谱模式下,流动相中有机改性剂含量对吡啶类化合物保留有较大影响,随着流动相中乙腈含量的增加,吡啶类化合物的保留迅速增强;较高pH值有利于吡啶类化合物的峰形改善。实验证明,亲水电色谱是一种适用于极性化合物分离的新型微分离方法。     

Biodegradation of Pyridine and Pyridine Derivatives by Soil and Subsurface Microorganisms

Abstract

Large amounts of aromatic compounds are produced by various industries and two thirds of these are heterocyclic chemicals. Compared with the extensive information available on microbial degradation of homocyclic aromatic compounds, relatively little is known on the transformation and biodegradation of heterocyclic chemicals in soil. Recent concerns about the persistence of hazardous pollutants have led to a renewed interest in the biodegradation of heterocyclic compounds. Hence, we investigated the microbial degradation of pyridine and some of its alkylated derivatives under aerobic and anaerobic conditions in groundwater, subsurface sediment, and soil. Results of the investigation revealed that these compounds were degraded predominantly under aerobic conditions and, to a lesser extent, under anaerobic conditions, with nitrate or sulfate serving as electron acceptors. In groundwater polluted with various pyridine derivatives, biodegradation was limited by the absence of oxygen. Therefore, we conclude that, under appropriate conditions, bioremediation is a potentially feasible method for the clean-up of environments contaminated with heterocyclic chemicals and, in particular, pyridine derivatives.     

Recent Strategies for the Synthesis of Pyridine Derivatives

Recent advances in pyridine synthesis are described. Modification of traditional condensation strategies continues to be a recurrent theme in contemporary literature. Advancements in transition‐metal‐catalyzed cyclization and cross‐coupling procedures offer new routes to functionalized pyridine derivatives. These recently developed methodologies are a valuable addition to azaheterocycle synthesis.     

Tricyclic Pyridine Derivatives with High Affinity to the Central Benzodiazepine Receptor

Novel tricyclic heterocycles were prepared and evaluated for their affinity to the central benzodiazepine receptor. The most potent compounds with IC₅₀'s in the nanomolar range were; found among thienoquinolizines and benzo[a]quinolizines (cf. Tables 2–5). The central ring of the tricyclic ring system may be partially unsaturated (cf. Tables 2 and 4) or fully unsaturated (cf. Tables 3 and 5) without loss of the high affinity to the receptor. The position of the ester group in the pyridinone ring is crucial for good binding (cf. Tables 1 and 2). It may be replaced by a broad variety of functional groups, e.g. amides, alkyl carbamates, alkyl groups, and hydroxyalkyl groups (cf. Tables 2–5). In the benzo[a]quinolizines, shifting the halogen atom from C(10) to C(9) leads to complete loss of affinity to the benzodiazepine receptor (cf. Table 4).     

Synthesis of Bisacridine Derivatives with Pyridine and 1,2-Azole Fragments

Russian Journal of General Chemistry - A convenient one-step method for the synthesis of new bisacridine derivatives, containing fragments of 5-arylisoxazoles, 4,5-dichloroisothiazole, as well as...     

Photoisomerization of Styryl Derivatives of Pyridine N-Oxide

Russian Journal of Physical Chemistry A - The trans–cis- and cis–trans-isomerization of styryl derivatives of heterocyclic N-oxides in acetonitrile and ethanol is studied. The...     

钙钛矿材料制备中的溶剂配位效应

钙钛矿材料具有吸收系数大、载流子迁移率高、可溶液加工等特点,在太阳能电池、发光二极管、光电探测等领域具有潜在的应用价值。钙钛矿的光电性质与其维度、尺寸、形貌密切相关,因此研究材料的生长是实现高性能器件应用的基础。钙钛矿前驱体与溶剂之间的配位作用对钙钛矿的生长过程具有重要影响。本综述总结了钙钛矿前驱体与溶剂之间的配位作用对钙钛矿单晶、多晶薄膜、量子点三类体系制备的影响,讨论了在上述材料制备中的溶剂配位效应,特别是溶剂配位效应所形成的溶剂化物对材料生长过程,以及所制备的材料(形貌、晶相、缺陷、稳定性)的影响。最后,我们对这一研究方向存在的问题和挑战进行了分析和展望。     

Coordination Properties of Ga, In, and Tl Tetraphenylporphine Complexes in Reactions with Nitrogen-containing Extra Ligands

The formation of Ga^{3 +}, In^{3 +}, and Tl^{3 +} tetraphenylporphine mixed-ligand complexes (X)MTPP + L = (X)M(L)TPP (X = Cl^-, AcO^-, acac^-; L = N-methylimidazole, imidazole, pyridine, 3,5-dimethylpyrazole, dimethylformamide) in chloroform was studied by spectrophotometric titration and quantum-chemical calculations. The stability of the Ga, In, and Tl porphyrin extra complexes was found to depend on the nature of the acido and nitrogen-containing ligands. The geometric and energetic characteristics of the complexes of six-coordinate gallium and indium porphyrins were calculated. Correlations between calculated and experimental energies of formation and Gibbs energies were found. The cis- and trans-effects of ligands in the extra complexes of metal porphyrins were explained.     

Redox-Neutral Metal-Free Three-Component Carbonylative Dearomatization of Pyridine Derivatives with CO2

The TBD (1,3,5-triazabicyclodec-5-ene) assisted three-component carbonylation of pyridine-2-methanamines is documented by means of CO₂ as a benign CO surrogate. The redox-neutral methodology enables the realization of densely functionalized imidazo-pyridinones in high yields (up to 93 %) and excellent chemoselectivity. Combined computational and experimental investigations revealed an unprecedented RCOCl/TBD concerted electrophilic activation of carbon dioxide.     

Thermal and Infrared Study of Desorption of Pyridine and Pyridine Derivatives from Ni-exchanged Montmorillonite

Thermal analysis (TG, DTG) and infrared absorption spectra were used to study desorption of pyridine (py), 4-methylpyridine (4-Mepy) and 4-ethylpyridine (4-Etpy) from Ni(II)-exchanged montmorillonite (Ni-MMT). It is shown that the bonds between the derivatives of pyridine (R-py) and the montmorillonite exhibit predominantly Lewis acid character. The thermal stability of studied samples and the total amounts of R-py inserted in the porous structure of Ni-MMT increase in the following sequence: py/Ni-MMT<4-Mepy/Ni-MMT<4-Etpy/Ni-MMT, i. e. the influence of the substituent on the pyridine ring is evident. This revised version was published online in August 2006 with corrections to the Cover Date.     

Solvent and Media Effects on the Photophysics of Naphthoxazole Derivatives

The photophysical properties of 2‐phenyl‐naphtho[1,2‐d][1,3]oxazole, 2(4‐N,N‐dimethylaminophenyl)naphtho[1,2‐d][1,3]oxazole and 2(4‐N,N‐diphenylaminophenyl) naphtho[1,2‐d][1,3]oxazole were studied in a series of solvents. UV–Vis absorption spectra are insensitive to solvent polarity whereas the fluorescence spectra in the same solvent set show an important solvatochromic effect leading to large Stokes shifts. Linear solvation energy relationships were employed to correlate the position of fluorescence spectra maxima with microscopic empirical solvent parameters. This study indicates that important intramolecular charge transfer takes place during the excitation process. In addition, an analysis of the solvatochromic behavior of the UV–Vis absorption and fluorescence spectra in terms of the Lippert–Mataga equation shows a large increase in the excited‐state dipole moment, which is also compatible with the formation of an intramolecular charge‐transfer excited state. We propose both naphthoxazole derivatives as suitable fluorescent probes to determine physicochemical microproperties in several systems and as dyes in dye lasers; consequence of their high fluorescence quantum yields in most solvents, their large molar absorption coefficients, with fluorescence lifetimes in the range 1–3 ns as well as their high photostability.     

光谱法研究硝基苯基卟啉锌与咪唑类的轴向配位反应

采用紫外-可见光谱滴定法和荧光光谱法,考察了5-对硝基苯基-10,15,20-三苯基锌卟啉和5-邻硝基苯基-10,15,20-三苯基锌卟啉与3种咪唑类客体小分子进行轴向配位反应的光谱性质,并探讨取代基团在不同位置时的锌卟啉及具有不同结构特点的客体对该类轴配反应进行的影响。 实验结果表明,2种锌卟啉与咪唑类客体之间的轴配反应是按摩尔比1∶1进行,轴配反应的平衡常数均按K(2-MeIm)＞K(N-MeIm)＞K(Im)顺序依次减弱,其中5-邻硝基苯基-10,15,20-三苯基锌卟啉与2-甲基咪唑间的轴配反应有最大的平衡常数5.85×10⁵ L/mol。 轴配反应的平衡常数均随温度的升高而降低,温度升高不利于平衡反应的进行。 热力学参数表明,这类反应的驱动力是焓驱动,是自发进行的配位反应。 随客体浓度的增加,5-对硝基苯基-10,15,20-三苯基锌卟啉(荧光峰位：592.9、634.2 nm)与咪唑类客体的轴配体系具有荧光增强的效应,5-邻硝基苯基-10,15,20-三苯基锌卟啉(荧光峰位：583.6、629.8 nm)与咪唑类客体的轴配体系具有荧光猝灭的效应。 轴配体系的荧光效应是由锌卟啉中硝基基团的位置所决定的,而与客体的结构特点无关。     

Palladium-Catalyzed Electrophilic Functionalization of Pyridine Derivatives through Phosphonium Salts

Herein, we report a highly efficient and practical method for pyridine-derived heterobiaryl synthesis through palladium-catalyzed electrophilic functionalization of easily available pyridine-derived quaternary phosphonium salts. The nice generality of this reaction was goes beyond arylation, enabling facile incorporation of diverse carbon-based fragments, including alkenyl, alkynyl, and also allyl fragments, onto the pyridine core. Notably, the silver salt additive is revealed to be of vital importance for the success of this transformation and its pivotal role as transmetallation mediator, which guarantees a smooth transfer of pyridyl group to palladium intermediate, is also described.     

苝二酸酐与嘧啶衍生物的氢键组装

Semi-empirical AM1 method was used to study 1:1 and 1:2 hydrogen bond complexes formed with perylene dianhydride and pyridine derivatives. The weak interaction energy become bigger as the number of hydrogen bonds increases. The donor groups on the host and electron-withdrawing groups on the guest molecules favor hydrogen bonding interactions, and the formation of hydrogen bonding leads to electron density flow from the host to the guest molecules. Electronic spectra of these complexes were computed using INDO/SCI method. Blue-shift of the electronic absorption spectra for the complexes, comparing that of the host,takes place, and the first peaks for different complexes changed slightly. These are in agreement with the experimental results. The cause of blue-shift was discussed, and the electronic transitions were assigned based on theoretical calculations. The potential curve of double proton transfer in the complex was calculated, and the transition state and activated energy relative to the N-H bond were obtained.