Synthesis,thermal stability,heats of formation,and explosive properties of cyano-substituted di-, tri-, and tetraazidopyridines

A method of synthesis of 2,6-diazido-3,5-dicyanopyridine, 2,4,6-triazido-3,5-dicyanopyridine, and 2,3,4,5-tetraazido-6-cyanopyridine was developed. The heats of formation and explosive properties of compounds obtained were determined; kinetics and the composition of the gaseous thermolysis products were studied. The replacement of endocyclic nitrogen atoms by C-CN fragments in the aromatic ring of polyazides strongly reduces the explosive risk of these compounds with retention of the energetic properties of the molecules.     

Synthesis, crystal structure and theoretical investigation of two infinite two-dimensional supra-molecular compounds

Two supra-molecular compounds: (1,1′-biphenyl)-4,4′-diammonium bis(3,5-dinitrobenzoate) (1) and 4,4′-methylene bis(benzenammonium) bis(3,5-dinitrobenzoate) monohydrate (2) were synthesized and characterized by IR spectrum, UV spectrum and element analysis. The single crystal structure analysis indicates that these compositions in two compounds are linked through N–HO and O–HO hydrogen bonds into infinite two-dimensional structure. Moreover, theoretical investigation was performed by using RHF/6-31G(d) method, and their stabilities, frontier molecular orbital composition and Mulliken charge distribution were discussed.     

Boron dipyrromethene analogs with phenyl, styryl, and ethynylphenyl substituents: synthesis, photophysics, electrochemistry, and quantum-chemical calculations

Seven fluorescent boradiazaindacene-based compounds with one or two phenyl, ethenylphenyl, and ethynylphenyl substituents at the 3- (or 3,5-) position(s) were synthesized via palladium-catalyzed coupling reactions with the appropriate 3,5-dichloroBODIPY derivative. The effect of the various substituents at the 3- (or 3,5-) position(s) on the spectroscopic and photophysical properties were studied as a function of solvent by means of UV/vis absorption, steady-state, and time-resolved fluorometry, and theoretical modeling. The emission maxima of the symmetrically 3,5-disubstituted dyes are shifted to longer wavelengths (by 30 to 60 nm) relative to the related asymmetrically 3,5-disubstituted ones. Introduction of styryl substituents causes the largest red shift in both the absorption and emission spectra. BODIPY derivatives with ethynylaryl groups also shift the spectral maxima to longer wavelengths compared to aryl-substituted ones but to a lesser degree than the styryl compounds. The quantum-chemical calculations confirm these trends and provide a rationale for the spectral shifts induced by substitution. The fluorescence quantum yields of the ethenylaryl and ethynylaryl analogs are significantly higher that those of the aryl-substituted dyes. The 3,5-diethynylaryl dye has the highest fluorescence quantum yield (approximately 1.0) and longest lifetime (around 6.5 ns) among the BODIPY dyes studied. The differences in the photophysical properties of the dyes are also reflected in their electrochemical properties where the symmetrically 3,5-disubstituted dyes display much lower oxidation potentials when compared to their asymmetric counterparts.     

Synthesis and characterization of permethylated 1,3,5-tri- and 1,3,5,7-tetracarbonyl compounds

Permethylated 1,3,5-tri- and 1,3,5,7-tetracarbonyl compounds were prepared and structurally characterized. 2,2,4,4-Tetramethyl-3,5-dioxoesters were prepared by condensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with acid chlorides and subsequent reaction with methyl iodide. 2,2,4,4,6,6-Hexa-substituted 3,5-dioxopimelates were prepared by condensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with methyl 3-chloro-3-oxopropanoate and subsequent methylation. The use of caesium carbonate as the base for the methylation proved to be important to achieve good yields. The conformation of the products was studied by experimental and theoretical methods (DFT calculations).     

The protonation and dimerization of 2,4-, 2,5-, 2,6-and 3,5-dihydroxybenzoic acids in 0.5M sodium perchlorate medium

The protonation equilibria of 2,4-, 2,5-, 2,6- and 3,5-dihydroxybenzoic acids were studied by means of potentiometric titrations at I = 0.5 (NaClO(4)) and 25 degrees . The dimeric species H(6)L(2) and H(5)L(2) were found to form as well as the monomeric species H(p)L in the acidic solutions of 2,4- and 3,5-dihydroxybenzoic acids under the conditions studied. For the other two acids, the protonation scheme can be expressed exclusively in terms of the species H(p)L (p = 1, 2 or 3).     

Synthesis, spectral, electrochemical, and anion binding properties of 3,5-bis(dipyrromethanyl) boron-dipyrromethenes

Four new boron-dipyrromethenes (BODIPYs) containing dipyrromethanyl substituents at 3,5-positions, bis(3,5-dipyrromethanyl) BODIPYs 5-8, were synthesized by treating their corresponding 3,5-diformyl BODIPYs 1-4 with excess pyrrole under mild acid catalyzed reaction conditions. The compounds 5-8 are stable and freely soluble in common organic solvents. One-dimensional, two-dimensional NMR, high resolution mass spectrometry (HRMS), absorption, fluorescence, and electrochemical techniques were used to characterize the compounds. The spectral and electrochemical studies indicated that dipyrromethanyl groups at 3,5-positions of BODIPY are less electron deficient compared to formyl groups at the same positions. The anion binding studies indicated that bis(3,5-dipyrromethanyl) BODIPY compounds containing four pyrrole NH groups showed preferential binding with F(-) ion over other anions, as confirmed by using NMR, fluorescence, and electrochemical studies.     

N-取代邻苯二甲酰亚胺类衍生物的设计、合成及活性评价

结合中药脱皮马勃中分离得到的3,5-二羟基邻苯二甲酰亚胺和邻苯二甲酰亚胺类化合物的结构设计合成了一系列N-取代-3,5-二甲氧基邻苯二甲酰亚胺及N-取代-3,5-二羟基邻苯二甲酰亚胺类衍生物,其结构经¹H NMR,¹³C NMR和MS分析确证. 选取人肺腺癌细胞A549及人脐静脉血管内皮细胞HUEVC为测试细胞株,评价了所合成化合物的体外抗肿瘤及抗血管生成活性,结果表明,部分化合物表现出一定的活性.     

Synthesis,characterization, DNA binding,antibacterial, and antioxidant activity of new bis-phthalimides

New bis-phthalimides were synthesized by 2: 1 condensation of phthalic anhydride and tetrachlorophthalic anhydride with 1,2,4-triazole-3,5-diamine, pyridine-2,6-diamine, and 4-hydroxypyrimidine- 2,6-diamine. The synthesized compounds were characterized by elemental analyses and IR, ¹H NMR, and mass spectra. Their interaction with calf thymus DNA (ct-DNA) was studied by UV-Vis spectrophotometry, cyclic voltammetry, and viscosity measurements, which revealed intercalative mode of binding to ct-DNA. Antibacterial activity of the synthesized compounds against Escherichia coli and Streptococcus mutans was assessed in vitro by the agar well diffusion method. The antioxidant activity of these compounds was estimated by DPPH assay.     

Highly nonplanar, electron deficient, N-substituted tetra-oxocyclohexadienylidene porphyrinogens: structural, computational, and electrochemical investigations

The structures and electrochemistry of N-benzylated meso-tetrakis (3,5-di-tert-butyl-4-oxo-cyclohexa-2,5-dienylidene) porphyrinogens have been investigated. Structural determinations reveal the isomeric identity of the products obtained from the N-alkylation of the parent meso-tetra (oxo-cyclohexadienylidene) porphyrinogen. The compounds are subject to increased macrocyclic deformations upon increasing N-substitution culminating in the tetra-N-benzyl derivative, which has a buckling superimposed on the already highly puckered macrocycle. The electrochemical analyses emphasize the electron deficiency of the N-benzylated meso-tetra(oxo-cyclohexadienylidene) porphyrinogens and indicate that they can be considered as quinones conjugated via the unsaturated tetrapyrrolic macrocycle. The N-benzylated compounds studied form stable and well-defined pi-cation radical and pi-anion radical species because of their highly conjugated nature. Ab initio molecular orbital calculations at the B3LYP/3-21G() level confirmed the high degree of conjugation between tetrapyrrole and meso substituents and also gave good agreement between calculated and experimentally determined HOMO-LUMO band gap energies.     

Phospha-s-triazines. IV. Degradation studies of 1-diarylphospha-3,5-bis(perfluoroaliphatic)-2,4,6-triazines and 1,3,-bis(diarylphospha)-5-perfluoroaliphatic-2,4,6-triazines

Thermal and thermal oxidative stability evaluations were performed on mono- and diphospha-s-triazines at 235 and 316°C using sealed Pyrex ampoules. The specific compounds studied were: 1-diphenylphospa-3,5-bis(perfluoro-n-heptyl)-2,4,6-triazine, 1-diphenylphospha-3,5-bis(perfluoro-alkylether)-2,4,6-triazines, their respective pentafluorophenyl analogues, 1,3-bis(diphenylphospha)-5-perfluoro-n-heptyl-2,4,6-triazine and 1,3-bis(diphenylphospha)-5-perfluoroalkylether-2,4,6-triazine. All the compounds wherein phenyl groups were present on the phosphorous exhibited good thermal stability up to 316°C; the analogous pentafluorophenyl substituted materials were degraded extensively at these temperatures. The oxidative stability of both the mono- and diphospha-s-triazines was excellent at 235°C, but at 316°C some degradation was observed. This was more pronounced in compounds containing the perfluoroalkyl moiety on carbon than in the perfluoroalkylether substituted members of the series.     

Synthesis,Mass Spectrometric Studies,and Biological Evaluation of 3,5-Dimethoxyhomophthalic Acid and Related Compounds

3,5-Dimethoxyhomophthalic acid was synthesized in four steps from 3,5-dimethoxycinnamic acid via a series of reactions including cyclization of 3-(3',5'-dimethoxyphenyl)propionic acid to 5,7-dimethoxy-1-indanone and oxidative decomposition of methyl-2-hydroxy-2-[5,7-dimethyoxy-1-oxo-1H-inden-2(3H)-ylidene]acetate to 3,5-dimethoxyhomophthalic acid.The synthesized compounds were characterized by elemental analysis,IR,1H NMR,and MS.The biological evaluation experiments of 3,5-dimthoxyhomophthalic acid and the related synthesized compounds were also carried out.Naturally occurring biologically active isocoumarins were prepared in a single step by the condensation of the homophthalic acid with appropriate acid chlorides.     

Synthesis and pharmacological activity of urea and thiourea derivatives of 4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione

A series of nineteen new thiourea and urea derivatives of 10-isopropyl-8-methyl-4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione, 1-isopropyl-7-methyl-4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione and 1,7,8,9,10-pentamethyl-4-azatricyclo[5.2.1.0(2,6)]dec-8-ene-3,5-dione have been prepared and studied by (1)H-NMR. The compound k1a (1-(1,7,8,9,10-pentamethyl-3,5-dioxo-4-aza-tricyclo[5.2.1.0(2,6)]dec-8-en-4-yl)-3-phenyl-urea) was tested for pharmacological activity on animal central nervous system (CNS). The activities of synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells. Antimicrobial activity of the newly obtained derivatives was tested against some Gram-positive and Gram-negative bacteria and fungi of the Candida species.     

3,5-二甲氧基苯乙烯环酮类化合物的合成及表征

研发环氧合酶(COSX)/5-脂氧酶(5-LOX)双重抑制剂是降低非甾体抗炎药胃肠道(GI)副作用的有效途径之一[1]。大多数二叔丁基苯酚类化合物具有较强的COX/5-LOX双重抑制作用,例如达布飞龙甲磺酸盐(darbufelone mesilate)用于治疗类风湿性关节炎和骨关节炎,GI不良反应小且长效,目前处     

Combined experiments to measure low sublimation pressures and diffusion coefficients of organometallic compounds

Vapor pressures and sublimation pressures of organometallic (metalorganic) compounds are needed in several processes like chemical vapor deposition (CVD). Thermobalances at ambient pressures are often used to study the evaporation of such compounds. At least three strategies are found in the literature to evaluate the results using different theoretical approaches. In some of the frequently used approaches the diffusion out of a crucible is neglected. We present a simple theoretical approach which describes the interrelation between the observed mass transfer rate and the physical variables of typical TGA set-ups. It turns out that the mass transfer rate at a given total pressure and temperature is mainly a function of the diffusion coefficient and the vapor pressure of the sublimating substance. The vapor pressures may be determined from an independent measurement using the Knudsen cell and combined with the TGA to obtain the diffusion coefficients. Experiments have been performed with two well studied substances naphthalene and phenanthrene to check the present strategy. Further measurements were then performed for the metal organic CVD relevant compounds: ferrocene and Tris(2,2,6,6-tetramethyl-3,5-heptanedianato)cobalt III [Co(tmhd)₃].     

Preparation and properties of yttrium,lanthanum, and lanthanide 3,5-dinitrobenzoates

Summary The condition of the formation of rare earth 3,5-dinitrobenzoates were studied and their quantitative composition and solubilities in water at 298 K determined (their solubilities are of the order of 10^–4 mol dm^–3). From the values of solubilities in water the solubility products were established (in the order of 10^–12 mol⁴ dm^–12). The IR and X-ray spectra for the hydrated and dehydrated complexes were recorded and studied. All complexes are crystalline compounds. The condition of thermal decomposition of the complexes was also investigated. On heating above 573 K the 3,5-dinitrobenzoates decompose explosively and undergo a melting process at the same time. Accordingly, the thermal decomposition for the complexes was studied in the temperature range 273–573 K. The thermal stability data reveal them to dehydrate in two steps. From the obtained results it appears that during the dehydration process no izomerization of the nitro group to the nitrito group occurs.

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Herstellung und Eigneschaften von Y-, La- und Lanthaniden-3,5-Dinitrobenzoaten

Zusammenfassung Die Bedingungen zur Darstellung von Y-, La- und Lanthaniden-3,5-Dinitrobenzoaten wurden untersucht. Ihre quantitative Zusammensetzung und ihre Wasserlöslichkeit bei 298 K wurden bestimmt (die Löslichkeit ist in der Größenordnung 10^–4 mol dm^–3). Die Infrarot- und Röntgenspektren der erhaltenen Komplexe sowie der 3,5-Dinitrobenzoate der seltenen Erden nach der Dehydratisierung wurden gemessen. Es wurde festgestellt, daß es sich stets um kristalline Verbindungen handelt. Das thermische Verhalten der erhaltenen Komplexe wurde untersucht: sie zerfallen über 573 K explosiv und schmelzen zugleich. Der thermische Zerfall der erhaltenen 3,5-Dinitrobenzoate der seltenen Erden wurde im Temperaturbereich von 273–523 K untersucht. Es wurde festgestellt, daß die Y-, La-, und Lanthaniden — 3,5-Dinitrobenzoate bei Temperaturerhöhung oder im Dehydratisierungsprozeß keine Umgruppierung in die entsprechenden Nitritoverbindungen erleiden.

     

Multiple interactions in the self-association of porphyrin discotic mesogens

The conformational preferences and the self-associational behaviors of two hemin-derived porphyrin compounds, a tetramethyl ester and a liquid crystalline tetrakis(3,5-didodecyloxyphenyl)ester, have been studied by UV/vis and (1)H NMR spectroscopy in solution. Results indicate that the 3,5-didodecyloxyphenyl units play an important role in both the conformational and the self-associational behaviors of the mesomorphic tetraester. In the monomeric, nonassociated species, the two propionic 3,5-didodecyloxyphenyl esters establish mutual CH/pi interactions that restrict the fluctuative behavior of the chains. In the dimeric, self-associated species, intermolecular CH/pi interactions occur in addition to the pi-pi stacking of the porphyrin cores. The temperature-dependent addition of side CH/pi interactions to the pi-pi stacking of the porphyrin rings accounts for the observed tightening and for the slower dynamics of the dimeric structure. The relationship between the self-associational behavior and the mesomorphism of the hemin-derived porphyrin tetraesters is also discussed.     

Comparison of one-step and two-step methods of polyimidization and substitution effect in the synthesis of new poly(ester-imide)s with bulky pendent group

New naphthalene-ring containing ester diamines, as new monomers for the preparation of polyimides were synthesized via two successive reactions. Nucleophilic reaction of 3,5-dinitrobenzoylchloride with 1-naphthol and 2-naphthol in the presence of sodium hydroxide led to the preparation of 1- and 2-(3,5-dinitrobenzoyloxy)naphthalene, respectively. Next step was reduction of them by hydrazine hydrate/Pd-C to produce 1- and 2-(3,5-diaminobenzoyloxy)naphthalene. All the prepared compounds were characterized by common spectroscopic methods. These ester containing aromatic diamines with pendent naphthalene group were used to prepare soluble polyimide copolymers via two different methods: catalyzed one-step high-temperature polycondensation in m-cresol, and two-step polycondensation in NMP and subsequent chemical dehydration. The obtained poly(ester-imide)s were characterized and their properties were studied. One-step and two-step methods for the preparation of five-membered ring polyimides were compared. Polymers prepared through one-step method showed higher yield and inherent viscosities and therefore better physical properties.     

Rapid Identification of Bibenzyls of Stemona sessilifolia using Hyphenated LC-UV-NMR and LC-MS Methods

IntroductionThe genusStemonacontains about 25 species,among whichS. sessilifolia,S. japonica,andS. tu-berosahave long been prescribed in traditional Chinesemedicine as insecticides and antitussive agents[1—4].The extracts of the roots of these three spec…     

Synthesis, structure, and catalytic oxidation chemistry from the first oxo-imido Schiff base metal complexes

The molybdenum oxo-imido complex, [Mo(O)(NtBu)Cl2(dme)] (1), was obtained from the reaction between [MoO2Cl2(dme)] and [Mo(NtBu)2Cl2(dme)]. Reactions between [Mo(O)(NR)Cl2(dme)] (where R = tBu or 2,6-iPr2C6H3) and the disodium Schiff base compounds Na(2)(3,5-tBu2)2salen, Na(2)(3,5-tBu2)2salpen, and Na(2)(7-Me)2salen afforded the first oxo-imido transition metal Schiff base complexes: [Mo(O)(NtBu)[(3,5-tBu2)2salen]] (2), [Mo(O)(NtBu)[(3,5-tBu2)2salpen]] (3), and [Mo(O)(N-2,6-iPr2C6H3)[(7-Me)2salen]] (4), respectively. The compounds [Mo(NtBu)2[(3,5-tBu2)2salpen]] (5) from [Mo(NtBu)2(NHtBu)2] and [Mo(N-2,6-iPr2C6H3)(2)[(7-Me)2salen]](6) from [Mo(N-2,6-iPr2C6H3)(2)(NHtBu)2] (7) are also reported. Compounds 1-7 were characterized by NMR, IR, and FAB mass spectroscopy while compounds 3, 4, and 5 were additionally characterized by X-ray crystallography. In conjunction with tBuOOH as oxidant, compound 3 is a catalyst for the oxidation of benzyl alcohol to benzaldehyde and cis-cyclooctene and 1-octene to the corresponding epoxides.     

Ferrocenyl Ionic Compounds Based on 5‐Ferrocenyl‐1H‐tetrazole. Synthesis,Characterization, Migration,and Catalytic Effects During Combustion

Ferrocenyl ionic compounds, consisting of the 5‐ferrocenyltetrazolate anion and a guanidinium or a 1‐alkyl‐3‐methylimidazolium cation, were synthesized and characterized by ¹H NMR, ¹³C NMR, and UV/Vis spectroscopy, as well as elementary analysis. The molecular structures of four compounds were additionally confirmed by single‐crystal X‐ray diffraction. Results of the TG and DSC analyses showed that some compounds display high thermal stability. Cyclic voltammetry investigations suggested that the compounds exhibit redox waves for the ferrocenyl groups and are considered as irreversible redox systems. Migration studies revealed that migration trends of the compounds are much lower than that of 2, 2‐bis(ethylferrocenyl)propane (Catocene), extensively used in composite solid propellants. Their catalytic performances for thermal decomposition of ammonium perchlorate (AP), 1, 3,5‐trinitro‐1, 3,5‐triazacyclohexane (RDX), and 1, 2,5, 7‐tetranitro‐1, 3,5, 7‐tetraazacyclooctane (HMX) were evaluated by DSC and/or TG techniques. Most of the compounds exhibit high catalytic efficiency in the thermal degradation of AP and RDX. Those of the guanidine‐containing compounds 1 – 3 are better, implying that nitrogen‐rich moieties are beneficial to enhancing released heats of some energetic materials. These guanidine salts could be used as ferrocene‐based burning rate catalyst candidates in composite solid propellants.