2,4,6—三苯基氧Weng盐分子内旋转受阻对其发光行为的影响

研究了４－位苯基取代基旋转受阻和旋转自由的２，４，６－三苯基氧Ｗｅｎｇ盐的光物理性质。实验结果表明，当４－位苯基取代基旋转受阻时，氧Ｗｅｎｇ盐化合物在激发态时引起的分子内极化程度比４－位取代基旋转自由的氧Ｗｅｎｇ盐化合物大，即在激发态时旋转受阻氧Ｗｅｎｇ盐化合物发生的分子内电荷转移能力较强；４－位取代基旋转自由的化合物的荧光量子产率随溶剂粘度的增大而有所增大，但旋转受阻化合物在相同的条件下则出现相     

吖啶类衍生物的荧光性质

用比较法测得23种啶类衍生物的荧光量子效率（Φf)，以评估这些化合物的荧光性质，结果表明，N－烃基吖啶酮类化合物的荧光量子效率要比9－取代苯基吖啶类和9－取代苯亚甲基－10－甲基－9，10－二氢吖啶类化合物的荧光量子效率大，在非极性溶剂中，9－聚代苯亚甲基－9，10二氢吖啶分子内的强吸电子基NO2增强荧光量子效率，强推电子基OCH3降低荧光量子效率，这些测量结果与取代基的电子作用经验规律不相符，这种现象可以用分子内电荷转移理论进行解释。     

非平面扭曲构象对1,3—二苯基吡唑啉衍生物荧光性质的影响

研究了１，３－二基吡唑啉和１－苯基－３－（４－硝基苯基）吡唑啉在室温及７７Ｋ时不同溶剂中的荧光光谱，发现在非线性溶剂中７７Ｋ是ＤＰＰ荧光强度远比其在室温时的低，而ＰＮＰ则完全没有荧光，表明这些化合物激发态的构象松驰，形成非平面扭曲构象对分子的发光性质十分重要，同时发现这两个化合物具有不同的关键性扭曲部位，形成各自有利于发光的构象，Ｎ－１上及Ｃ－３上苯环的扭曲分别对ＤＰＰ和ＰＮＰ的发光态的形成起着重     

非平面扭曲构象对1，3－二苯基吡唑啉衍生物荧光性质的影响

研究了１，３－二苯基吡唑啉（ＤＰＰ）和１－苯基－３－（４－硝基苯基）吡唑啉（ＰＮＰ）在室温及７７Ｋ时不同溶剂中的荧光光谱，发现在非极性溶剂中７７Ｋ时ＤＰＰ的荧光强度远比其在室温时的低，而ＰＮＰ则完全没有荧光，表明这些化合物激发态的构象松驰，形成非平面扭曲构象对分子的发光性质十分重要。同时发现这两个化合物具有不同的关键性扭曲部位，形成各自有利于发光的构象，Ｎ－１上及Ｃ－３上苯环的扭曲分别对ＤＰＰ和ＰＮＰ的发光态的形成起着重要作用。     

某些结构受阻氧鎓盐的吸收和荧光

氧锅盐是一类带正电行的杂环化合物，作为一种合成中间体，氧锅盐在有机合成方面已得到广泛的应用［’］近年来人们对其发光和光谱性质的研究也给予足够的注意．这是由于很多氧锅盐化合物有着很强的荧光发射【’J，并且其中有些已被用作激光染料出或Q一开关材料卜1由于氧钠盐强烈的亲电特性，因而它在聚乙烯咋哇电照相体系中也受到特殊的注意，即通过它来捕获电子和诱导分子内正空穴向负电极方向迁移问染料分子的刚性化对激发分子的弛豫过程往往会带来巨大的影响，如非刚性化分子会通过分子内自由旋转使分子在激发态的弛豫过程中形成不同的…     

2-(2-巯苯基)苯并噁唑分子内质子转移取代基电子效应的密度泛函理论研究

在B3LYP/6-31G(d,p)和TDB3LYP/6-31++G(d,p)//CIS/6-31G(d,p)水平上研究了2-(2-巯苯基)苯并噁唑及其衍生物基态和激发态分子内质子转移现象,并探讨取代基电子效应对分子内质子转移的影响,研究结果表明,在基态时,硫醇式异构体为优势构象,供电子取代基使基态分子内正向质子转移能垒(烯醇式→酮式)升高;而吸电子取代基则可降低能垒,有利于基态分子内质子转移并有助于硫酮式异构体的稳定.在激发态时,硫酮式结构为优势构象,所研究的2-(2-巯苯基)苯并噁唑化合物及衍生物均可以发生无能垒或低能垒(≤1.5kJ/mol)的激发态分子内质子转移.巯苯基部分是激发态失活的主要活性部分,供电子基团有利于激发态的质子转移,吸电子基团使激发态跃迁困难,不利于激发态的质子转移.     

荧光酮类试剂的结构与荧光性能关系的研究

研究了苯基荧光酮，水杨基荧光酮，二甲氨基苯基荧光酮及其溴取代衍生物的荧光性能与结构的关系，试验表明，在分子中９－取代苯的间位（３’或５’位）上引入溴取代基后，激发及发射波长较相应未溴化的试剂均有红移，斯托克位移增大，分析性能有所致善，比较了六种试剂荧光猝灭法测定Ｚｒ（Ⅳ）和Ａｌ（Ⅲ）的条件，建立了相应的测定方法。     

取代氧鎓盐化合物的分子内电荷转移和光谱行为的研究

合成了一组带不同取代基的2,4,6-三芳基氧鎓盐化合物,对它们在不同溶剂中的光物理行为进行了研究表明:取代基的性质(推或拉电子)和位置(X轴或Y轴)对化合物的发光有很大影响.本工作还利用荧光去偏振方法研究了氧鎓盐化合物分子内的能量转移以及通过加入三氟醋酸使叔胺季铵盐化方法,为这类化合物提供了在非水溶剂中作为荧光指示剂应用的可能性.     

1－对甲苯磺酰基－3－芳基－4－苯基－1，4，2－二氮磷杂环戊－5－酮的合成及除草活性

通过１－苯基－３－对甲苯磺酰基脲与亚磷酸三苯酯和取代苯甲醛在甲苯中进行的类Ｍａｎ－ｎｉｃｈ反应合成１－对甲苯磺酰基－２－苯氧基－２－氧代－３－芳基－４－苯基－１，４，２－二氮磷杂环戊－５－酮．化合物的结构经元素分析、ＮＭＲ、ＭＳ及部分化合物的红外光谱所证实，对合成过程中所涉及到的副反应进行了初步探讨，生物测定实验表明，某些产物具有良好的选择性除草活性。     

1,3,5-三芳基-2-吡唑啉化合物光物理行为的研究

合成了一组带不同取代基的三芳基吡唑啉化合物,对它们在不同极性溶剂中的光物理行为(如荧光量子产率,荧光寿命等)进行了测定指出:这类化合物在光的激发下除存在有分子内共轭条件下的电荷转移行为外,还存在着分子内非共轭条件下的电子转移,本工作还以三芳基吡唑啉化合物为猝灭剂对氧鎓盐的荧光猝灭能力进行了研究,并对所得结果作了讨论。     

某些结构受阻氧鎓盐的吸收和荧光

A series of pyrylium compounds with different structures have been synthesized. The photophysical behavior of these compounds has also been measured. Results show that the structures of compounds and the polarities of solvents make great effects on the photophysical behaviors of compounds, especially when the structures of compounds are hindered. It indicats that the intramolecular rotation relaxation of compounds in excited state in closely related to the fluorescence quantum yields of compounds.     

Cyclic transmembrane charge transport mediated by pyrylium and thiopyrylium ions

Transient spectroscopy revealed that 2,4,6-trimethylpyrylium, 2,4,6-triphenylpyrylium, and 2,4,6-triphenylthiopyrylium ions oxidatively quench excited triplet [5,10,15,20-tetrakis(4-sulfonatophenyl)porphinato]zinc(II) to form the corresponding neutral radicals and the zinc porphyrin pi-cation. The measured quenching rate constants were proportional to the pyrylium one-electron reduction potentials, that is, the reaction driving force. In the presence of anionic dihexadecyl phosphate vesicles, only the fraction of pyrylium not bound to the vesicle was capable of reacting with the photoexcited zinc porphyrin. Nonetheless, the pyrylium radicals mediated highly efficient transmembrane reduction of tris(2,2'-bipyridine)cobalt(III) contained within the inner aqueous core of the vesicles with apparent quantum yields that approached unity. Permeability coefficients (P) determined for the pyrylium radicals, pyrylium cations, and the proton were 10(-4)-2 x 10(-5) cm/s, 10(-10) cm/s, and < 5 x 10(-7) cm/s, respectively, so that only the neutral radicals are membrane-permeable on the time scale of the transmembrane redox reactions. However, each electron carrier was demonstrated to transport up to 200 electrons, at which point the internal pool of electron acceptors was exhausted. Since the cations are membrane-impermeable, a reaction cycle is proposed that includes hydrolysis of the pyrylium cations formed within the aqueous core to the corresponding 1,5-diketones which, as neutral molecules, can diffuse across the bilayer. According to this mechanism, while undergoing redox cycling the pyrylium ions function as cyclical antiporters of OH(-) and the electron, thereby maintaining electroneutrality in the reaction compartments.     

Synthesis of 4,6,8-Trisubstituted Methyl Azulene-2-carboxylates

It is shown that sodium (methoxycarbonyl)cyclopentadienide ( 1 ), which is easily accessible from sodium cyclopentadienide and dimethyl carbonate in THF, reacts with 2,4,6-trisubstituted pyrylium tetrafluoroborates 2a–d in boiling MeOH to afford the corresponding methyl azulene-2-carboxylates 4a–d in good yields. The corresponding 1-carboxylates 3 were not found (cf. Schemes 1 and 2).     

Synthesis of 2-alkyl-6-phenyl-3, 4-c cycloheptenopyrylium salts

A method is given for synthesizing 2-alkyl-6-phenyl-3, 4-cycloheptenopyrylium perchlorates, obtained in 45–55% yields by acylating cycloheptenylacetophenone with anhydrides of aliphatic acids in the presence of 70% perchloric acid. Treatment of the pyrylium salts with ammonia gives a good yield of 2-alkyl-6-phenyl -3, 4-cycloheptenopyridine.     

Synthesis of pyridine and pyrimidine derivatives by reaction of pyrylium salts with ureas,thioureas, and isothioureas

2,4,6-Triphenylpyrylium perchlorate is converted to 2,4,6-triphenylpyridine in reactions with urea and N-acetyl- and N,N-dimethylureas, whereas it is converted to 1,2,4,6-tetraphenylpyridinium perchlorate on reaction with N,N-diphenylurea. The reaction of pyrylium perchlorates with thiosemicarbazide and semicarbazide leads to 1-thiocarbamido- and 1-carbamidopyridinium salts. The latter reacts with 2,4,6-triphenylpyrylium perchlorate to give 1-aminopyridinium salts, which were acylated with acetic anhydride. Difficult-to-obtain 2-alkylthio-4,6-diarylpyrimidines were synthesized in 40–93% yields by the reaction of 2,4,6-triarylpyrylium salts with S-alkylisothioureas.Translated from Khuniya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–328, March, 1979.     

NMR studies of the dynamic behavior of 2-anilino-6-chloro-4-methoxy-1,3,5-triazine in solution

2-Anilino-6-chloro-4-methoxy-1,3,5-triazine was synthesized and studied by dynamic NMR. The activation parameters of hindered internal rotation in unsymmetrically substituted arylamino-sym-triazine were determined for the first time. It was found that a sterically more hindered rotational isomer is thermodynamically more stable in this compound (slow-exchange NOE data).     

Photophysics and photochemical studies of 1,4-dihydropyridine derivatives

The absorption and fluorescence properties of nifedipine (NPDHP), felodipine (CPDHP) and a series of structurally related 1,4-dihydropyridines were studied in aqueous solution and organic solvents of different properties. The absorption and fluorescence spectra were found to depend on the chemical nature of the substituents at the position 4 of the 1,4-dihydropyridine ring (DHP) and on solvent properties. In aqueous solution, the fluorescence spectra of 4-phenyl substituted compounds are blue-shifted with respect to the alkyl substituted compounds. The more fluorescent compound is CPDHP. Nifedipine is not fluorescent. All compounds, with the exception of CPDHP, present monoexponential fluorescence decay with very short lifetime (0.2-0.4 ns). CPDHP showed a biexponential emission decay with a long-lived component of 1.7 ns; this behavior is explained in terms of different conformers because of the hindered rotation of the phenyl group by the ortho-substitution. Analysis of the solvent effect on the maximum of the absorption spectrum by using the linear solvent-energy relation solvato-chromic equation indicates the redshifts are influenced by the polarizability, hydrogen bonding ability and the hydrogen bond acceptance of the solvent. Whereas, the fluorescence characteristics (spectra, quantum yields and lifetimes) are sensitive to the polarizabilty and hydrogen bond ability of the solvents. Photo-decomposition of nifedipine is dependent on the solvent properties. Faster decomposition rates were obtained in nonprotic solvents. The 4-carboxylic derivative goes to decarboxylation. Under similar conditions, the other DHP compounds did not show appreciable photodecomposition.     

Ring transformations of heterocyclic compounds. XI. 2,4,6-triarylphenylquinolinium salts from methyl substituted derivatives via (thio)pyrylium ring transformations

The preparation of hitherto unknown 2,4,6-triarylphenyl substituted quinolinium perchlorates 3 from methylquinolinium derivatives 2 by a 2,6-[C₅+C] ring transformation of 2,4,6-triaryl(thio)pyrylium salts 1/4 in the presence of triethylamine/acetic acid is described. Spectroscopic data of the quinolinium perchlorates 3 and their formation via anhydrobases of the salts 2 are discussed.     

Ring transformations of heterocyclic compounds. X. A simple method for the conversion of methyl substituted pyridinium salts into 2,4,6-triarylphenyl derivatives: The first (thio)pyrylium ring transformations with heterocyclic anhydrobases as carbon nucleophiles

The synthesis of 2,4,6-triarylphenylpyridinium perchlorates 3 from methyl substituted derivatives 2 by a 2,6-[C₅+C] ring transformation of 2,4,6-triaryl(thio)pyrylium salts 1/4 in the presence of triethylamine/acetic acid in ethanol is reported. Spectroscopic data of the pyridinium perchlorates 3 and their formation via anhydrobases of the salts 2 are discussed.