Three-dimensional triazenido layers attained through classical and non-classical hydrogen interactions and its coordination to palladium under prolific occurrence of bifurcated hydrogen bonding

The new ligand 1,3-bis(3-methoxy-4-methylbenzoate) triazene (1, bmmbt), and the already known ligand 1,3-bis(4-acetylphenyl)triazene (bapht), yield the two new palladium(II) complexes [(bmmbt)Pd(PPh₃)₂Cl]·DMSO (2) and [(bapht)Pd(PPh₃)₂Cl] (3) (Ph = phenyl; DMSO = dimethylsulfoxide). Compound 1 shows the existence of more than one interaction promoting the coupling between the triazene chains. Other remarkable types of interactions in 1 are bifurcated hydrogen contacts and non-classical CH···π bonding. Complexes 2 and 3 present a planar geometry, supported also through bifurcated intramolecular Cl···H-C interactions, as well as the occurrence of trifurcated Cl···H-C intermolecular interactions.     

Synthesis and properties of new photosensitive triazene polyacrylates

1‐(Phenyl)‐3‐(2‐acryloyloxyethyl)‐3‐methyl triazene‐1 (M1) and 1‐(p‐nitrophenyl)‐3‐(2‐acryloyloxyethyl)‐3‐methyl triazene‐1 (M2) were synthesized to study the substituent effect of the triazene unit on the copolymerization with methyl methacrylate (MMA). From the ¹H NMR spectra of the resulting copolymers, their compositions were determined to be 1:3.18 M1/MMA and 1:2.45 M2/MMA, respectively. The polymers were examined with respect to their structure, thermal properties, and surface morphology. The influence of the triazene structure on the photosensitive properties of the copolymers exposed to ultraviolet/laser irradiation was also investigated and compared with that of the parent derivatives. The copolymer containing the phenyl triazene chromophore as the photochemically most active group exhibited a low threshold of ablation and a high etching rate for fluences under 400 mJ cm^?2. Scanning electron microscopy images confirm the formation of ablated craters more clearly in the copolymer made with M1, for which the thermal effects of the ablation mechanism were visible only with 2500× magnification. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5271–5282, 2006     

An experimental and theoretical study of dipole moments of N-alkyl-1,3-bis-(p-chlorophenyl)triazenes and 1-(3,4-dimethyl-5-isoxazolyl)-3-aryltriazenes

The dielectric constants, densities, and the refractive indices of dilute benzene solutions have been used to obtain the experimental dipole moments of 1,3-diphenyltriazene (1a), 1,3-diphenyl-3-methyltriazene (Ib), 1,3-bis(p-chlorophenyl)triazene (IIa), its N-alkyi derivatives (IIb-IIg), and 1-(3,4-dimethyl-5-isoxazolyl)-3-phenyltriazene (IIIb) and its N-methyl derivative (IIIc). The results show that the dipole moment of IIa is increased by an increment of about 0.77 D (average value for methyl, ethyl, n-propyl, allyl, and benzyl) on N-alkyl substitution. The increment for the n-butyl group is Δμ = 1.19 D. Some of the experimental values are compared with those from PPP and CNDO/2 calculations.     

Photocatalytic cleavage of hydroxytriazenes: a solid-state synthesis of azo-dyes under sunlight irradiation

Sunlight-induced decomposition of hydroxytriazenes, and green photochemical synthesis of azo-dyes is described. Three substituted hydroxytriazenes, viz: 3-hydroxy-3-(2-methylphenyl)-1-(3-chloro-4-fluorophenyl)triazene (o-CFHT), 3-hydroxy-3-(3-methylphenyl)-1-(3-chloro-4-fluorophenyl)triazene (m-CFHT), and 3-hydroxy-3-(4-methylphenyl)-1-(3-chloro-4-fluorophenyl)triazene (p-CFHT) were co-crystallized with ??-naphthol in equimolar ratio and exposed to sunlight for 9?C10?h. The reaction resulted in formation of azo-dyes which were identified by comparison with the products obtained by the conventional method (standard azo-dye), by use of HPLC. A probable mechanism has been suggested. This is first eco-friendly synthesis of azo-dyes using hydroxytriazenes.     

On the reaction of 5-aminopyrimidine with diazonium salts

The reaction of 5-aminopyrimidine with benzenediazonium chloride, p-methylbenzenediazonium chloride and p-bromobenzenediazonium chloride is described. The reaction leads to a mixture of compounds, i.e. 1-aryl-3-(pyrimidin-5-yl)triazene ( 6 ), 5-amino-4-aryl-6-arylazopyrimidine ( 7 ) and 4-aryl-6-arylazo-5-hydroxypyrimidine ( 8 ). The yields are found to be strongly dependent on the substituent present in the diazonium salt. Attempts to rearrange 1-(p-bromophenyl)-3-(pyrimidin-5-yl)triazene ( 6c ) under basic and acidic conditions into a 1,2,3-triazole derivative failed.     

Cyclization of vicinally substituted heterocyclic analogs of 3,4-bis(indol-1-yl)maleimide under the action of protic acids: a quantum chemical study

B3LYP/6-31G(d) density functional quantum chemical calculations of vicinally substituted bis(indol-1-yl)derivatives of 1,5-dihydropyrrol-2-one, furan-2,5-dione, cyclopent-4-ene-1,3-dione, cyclobut-3-ene-1,2-dione, and pyrrolidine-2,5-dione were carried out to study the effect of modification of the maleimide moiety in 3,4-bis(indol-1-yl)maleimides on the direction of intramolecular cyclization under the action of protic acids. Geometric parameters, charge distributions, energy characteristics, and frontier orbital energies of these compounds and the corresponding indoleninium cations were determined. Alternative protonation routes of 3,4-bis(indol-1-yl)-1,5-dihydropyrrol-2-one have been studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1348–1352, July, 2008.     

The synthesis,X‐ray structure analysis,and photophysical characterization of 4‐[(E)‐2‐(4‐cyanophenyl)diazenyl]‐morpholine

A novel triazene, 4‐[(E)‐2‐(4‐cyanophenyl)diazenyl]‐morpholine ( 1 ) was prepared via a diazonium ion coupling reaction between 4‐aminobenzonitrile and morpholine. The x‐ray structure of 1 was determined and evidenced π delocalization in the triazene subunit. The room temperature absorption spectrum of 1 in acetonitrile was dominated by an intense triazene‐centered π→π* transition at 325 nm. Compound 1 was observed to be luminescent, with an emission maximum at 434 nm in room temperature acetonitrile solution. The emission spectrum of 1 in propionitrile glass at 77K exhibited a narrowed emission band with a maximum at 449 nm. Broad emission from 400–700 nm with poorly resolved vibrational structure was observed from solid 1 at room temperature. J. Heterocyclic Chem., 2011.     

Zur Aktivierung partiell silylierter Kohlenhydrate mittels Triphenylphosphan/Azodicarbonsäureester

On the Activation of Partially Silylated Carbohydrates Using Triphenylphosphane/Diethylazodicarboxylate Reaction of methyl α-D-glucopyranoside ( 1 ) with two equivalents of t-butyldimethylchlorosilane yields methyl 2,6-bis[O-(t-butyldimethylsilyl)]-α-D-glucopyranoside ( 1a ) and methyl 3,6-bis[O(t-butyldimethylsilyl)]-α-D-glucopyranoside ( 1b ) in a ratio of 4:1. The anomeric β-pyranoside 2 affords methyl 2,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside ( 2a ) and methyl 3,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside ( 2b ) in nearly equal amounts. 2b is isomerized to methyl 4,6-bis[O(t-butyldimethylsilyl)]-β;-D-glucopyranoside ( 2c ) (83%) and 2a (10%) with triphenylphosphane/diethylazodicarboxylate. Structures were assigned by NMR.-analysis and CD.-analysis of the corresponding benzoates 1c , 1d and 2d and of the acetates 2e and 2f . 1a is transformed into methyl 4-azido-2, 6-bis[O(t-butyldimethylsilyl)]-4-deoxy-α-D-galactopyranoside ( 3 ) with triphenylphosphane/diethylazodicarboxylate/HN₃. 2a and 2c yield the 3-azido-allosides 5 and 7 respectively under similar conditions. The activation by triphenylphosphane/diethylazodicarboxylate is high enough to introduce also p-nitrobenzoate groups with inversion of configuration at the reaction center. By this way 1a and 2a give methyl 2, 6-bis[O(t-butyldimethylsilyl)]-4-O-p-nitrobenzoyl-α-D-galactopyranoside ( 4 ) and methyl 2, 6-bis[O-(t-butyldimethylsilyl)]-3-O?ptrobenzoyl-β-D-allopyranoside ( 6 ) respectively. For elucidation of structures the acetate derivatives 3a-7a were prepared.     

The oxidative coupling of indole with some phenolic compounds,naphthols and catechols

The oxidative coupling of indole with three naphthols, 2-naphthol, 2,3-dihydroxynaphthalene and 2,7-dihydroxynaphthalene gave 1,1-bis(3′-indolyl)-2(1H)naphthalenone, 1,1-bis(3′-indolyl)-3-hydroxy-2(1H)naphthalenone and 1,1-bis(3′-indolyl)-7-hydroxy-2(1H)naphthalenone, respectively. The coupling of indole with protocatechuic aldehyde gave bis-(3-indolyl)-(3′,4′-di-hydroxyphenyl)methane and that of indole with homocatechol gave 3-(2′-methyl-3′,4′-di-hydroxyphenyl)indole.     

Conformational analysis and electronic structure calculations of S-1,2-bis(2-dibutenoyl)glycerol and S-1,2-bis(2,4-hexadienoyl)glycerol,two analogues of 1,2-bis(2,4-octadecadienoyl)-sn-glycero-3-phosphorylcholine

As a model for 1,2-bis(2,4-octadecadienoyl)-sn-glycero-3-phosphorylcholine, a doubly unsaturated membrane-forming lipid molecule, force-field (MMP2) calculations were performed on S-1,2-bis(2-dibutenoyl)glycerol, and CNDO/S-calculations 2

1 CNDO: Complete neglect of differential overlap, a semi-empirical quantum-mechanical method.

on the derived minimum-energy conformations of S-1,2-bis(2,4-hexadienoyl)glycerol. The energy hypersurface especially with respect to the dihedral angles along the C(1)-C(2) and the two C O ester bonds was explored and the rotational strength as a function of these angles was calculated. The two gauche-forms were found to be most stable, with a slight preference for the g⁻-form. The experimental circular dichroism data obtained for 1,2-bis(2,4-hexadienoyl)-sn-glycero-3-phosphorylcholine, the corresponding phosphorylcholine, indicate a dynamic equilibrium between two forms of opposite chirality possibly involving the g⁺-and the g⁻-forms.     

Triazene proton affinities: A comparison between density functional,Hartree–Fock,and post-Hartree–Fock methods

The consistency of three density functional computational implementations (DMol, DGauss, and deMon) are compared with high-level Hartree–Fock and Møller–Plesset (MP) calculations for triazene (HN?NNH₂) and formyl triazene (HN?NNHCOH). Proton affinities on all electronegative sites are investigated as well as the geometries of the neutral and protonated species. Density functional calculations employing the nonlocal gradient corrections show agreement with MP calculations for both proton affinities and geometries of neutral and protonated triazenes. Local spin density approximation DMol calculations using numerical basis sets must employ an extended basis to agree with other density functional codes using analytic Gaussian basis sets. The lowest energy conformation of triazene was found to be nonplanar; however, the degree of nonplanarity, as well as some bond lengths, is dependent on the basis set, electron correlation treatment, and methods used for the calculation. © 1994 by John Wiley & Sons, Inc.

1 This article is a U.S. Government work and, as such, is in the public domain in the United States of America.

     

Synthesis and properties of some aryl-s-triazines

The synthesis and reactions of several substituted s-triazines were studied in attempts to prepare 4,6-bis(4-chlorophenyl)-s-lriazine-2-carboxylie acid ( 2 ) and 2-aldehyde ( 8 ). The 4,6-bis-(4-chlorophenyl)-s-triazine derivatives were surprisingly inert to a variety of reagents. 4,6-Bis-(4-chlorophenyl)-2-methyl-s-triazine ( 1 ) could not be oxidized with any of a variety of oxidants. On bromination 1 gave 4,6-bis(4-chlorophenyl)-2-dibromomethyl-s-triazine ( 4 ) which was resistant to hydrolysis but on oxidation with selenium dioxide gave 2 . Compound 2 was also prepared by the oxidation of 4,6-bis(4-chlorophenyl)-2-hydroxymethyl-s-triazme ( 7 ) with potassium permanganate. Other reagents did not oxidize 7 to 8 . 4,6-Bis(4-chloroanilino)-2-mcthyl-s-triazine ( 3 ) was also resistant to oxidizing agents. 2-Diazomethy1-4,6-dichloro-s-triazine ( 11 ) on reaction with 4-chloroaniline gave 4,6-bis(4-chloroanilino)-2-chloromethyl-s-triazine ( 12 ). All efforts to prepare 8 were unsuccessful.     

含吡啶基四硫富瓦烯衍生物的合成、 结构和电化学性质

在乙酰乙酸乙酯和氧化亚铜共同催化下, 二-(1,3-二硫环戊烯-2-硫酮-4,5-二硫)合锌酸四乙基铵盐分别与2-碘吡啶(1a)、 3-碘吡啶(1b)和4-碘吡啶(1c)反应, 制得硫酮化合物2,3-二(2-吡啶硫基)-1,3-二硫环戊烯-2-硫酮(2a)、 2,3-二(3-吡啶硫基)-1,3-二硫环戊烯-2-硫酮(2b)和2,3-二(4-吡啶硫基)-1,3-二硫环戊烯-2-硫酮(2c). 在醋酸汞催化下, 硫酮化合物2a, 2b和2c分别被氧化为2,3-二(2-吡啶硫基)-1,3-二硫环戊烯-2-酮(3a)、 2,3-二(3-吡啶硫基)-1,3-二硫环戊烯-2-酮(3b)和2,3-二(4-吡啶硫基)-1,3-二硫环戊烯-2-酮(3c). 以亚磷酸三乙酯为偶联剂, 氧酮化合物3a, 3b和3c分别发生自偶联反应生成2,3,6,7-四(2-吡啶硫基)四硫富瓦烯(4a)、 2,3,6,7-四(3-吡啶硫基)四硫富瓦烯(4b)和2,3,6,7-四(4-吡啶硫基)四硫富瓦烯(4c). 采用核磁共振波谱(NMR)、 傅里叶变换红外光谱(FTIR)和质谱(MS)分析了所合成化合物的结构和组成, 通过X射线衍射分析确认了吡啶基四硫富瓦烯衍生物4b和4c的晶体结构. 循环伏安法研究结果表明, 化合物4a, 4b和4c呈现准可逆的两电子转移过程, 结合量子化学计算, 分析了不同位置取代的吡啶基对四硫富瓦烯电化学电势的影响.     

Protonation of 25,27-bis(1-octyloxy)calix[4]arene-crown-6 in the 1,3-alternate conformation

From extraction experiments in the two-phase water-nitrobenzene system and γ-activity measurements, the stability constant of protonated 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6 in nitrobenzene saturated with water was determined. By using DFT calculations, the most probable structure of the 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6 · H₃O⁺ complex species was derived. Correspondence: Emanuel Makrlík, Faculty of Applied Sciences, University of West Bohemia, Pilsen, Czech Republic.     

Hexacoordinated MIV (M=Ti,Zr, Hf) Tetrachlorido Complexes with Chelating Dithienylethane Based 1,2 Diketone Ligand – π-Conjugation as Decisive Factor for Axial Chirality Mode

1,2-bis(2,5-dimethylthiophen-3-yl)ethane-1,2-dione ( 1 , DTEthane) reacts with MCl₄ metal precursors of group four (M=Ti, Zr, Hf) via coordination of the carbonyl groups. The molecular structure of complex 2–4 were determined in scXRD studies in the solid state and characterized by means of multi-nuclear and multi-dimensional NMR spectroscopy in solution. While the resulting titanium complex [TiCl₄(DTEthane)] 2 shows a monomeric structure, where 1 binds in a bidentate fashion, complexes with a Zr ( 3 ) and Hf ( 4 ) center have dimeric scaffolds in which the ligands adopt a bridging mode. Quantum chemical calculations using density functional theory (G16, B97D3/def2-TZVP) were used to evaluate the general trend of dimer formation (Ti<Zr<Hf). The molecular structures derived from both scXRD and the DFT optimized structures reveal the carbonyl groups in conjugation with the adjacent thiophene substituent. As a result, they are coplanar and rotation about the two C−C axes (C1−C7; C8−C9) is restricted allowing for only one chiral axis along C7−C8. This gains special importance with respect to previously described complexes carrying the closely related 1,2-endiolato ligand (1,2-bis(2,5-dimethylthiophen-3-yl)ethene-1,2-diolate), in which no coplanarity of the thiophene rings to their neighboring metallacycle was observed allowing for two chiral axes. Noteworthy, further DFT calculations addressing the pathway of racemization found transition states, which are characterized by contrary rotations of both thiophene rings and a loss of conjugation rather than a direct rotation around the axis C7−C8.     

Synthesis and reactivity with M(II) (M=Co and Cu) chloride of 1-[(2-carboxyethyl)benzene]-3-[benzothiazole]triazene

Reaction of ethyl anthranilate, sodium nitrite, and 2-aminobenzothiazole produces a new triazenide compound, 1-[(2-carboxyethyl)benzene]-3-[benzothiazole]triazene (HL), which has been characterized by X-ray crystallography and NMR spectrum. In the presence of Et₃N, reaction of HL and CuCl₂?·?2H₂O or CoCl₂?·?6H₂O in THF/methanol affords a tetranuclear copper(II) complex [Cu₄L₄(µ-OMe)₄]?·?4THF (1) and a cobalt(III) complex [CoL′₃] (2) (L′ is 1-[benzothiazole] triazene ion), accompanied by C–N bond cleavage of HL. They are characterized by X-ray crystallography and magnetic susceptibility measurement. Magnetic studies indicate significant antiferromagnetic coupling between the copper(II) centers for 1. The value obtained for the coupling constant J is ?585?cm^?1.     

Chromophore Systeme, 2. Konformation und Lichtabsorption von (2-Alkoxyvinyl)ethandionen

Chromophoric Systems, 2. – Conformation and Absorption of Light in (2-Alkoxyvinyl)ethanediones The unusual color properties of yellow 1,2-bis(4,5-dihydrofuran-3-yl)ethane-1,2-dione ( 1 ) and colorless 1,2-bis(5,6-dihydro-4H-pyran-3-yl)ethane-1,2-dione ( 2 ) in the solid state and in solution are investigated by crystal structure analysis, UV-Vis, PE, and ¹³C-NMR spectroscopy as well as by reparameterized force-field calculations. Dione 1 takes an antiperiplaner CO/CO conformation of its chromophore in the solid state whereas dione 2 is twisted in this respect by 102°. In solution both chromophores are not planar, but 1 is less distorted (ca. 142°) than dione 2 (ca. 126°). The calculated rotational barrier for CO/CO twisting amounts to 0.9 kcal mol⁻¹ for 1 and to 2.2 kcal mol⁻¹ for 2 .     

Synthesis of 2,5-diethyl-3,4-bis(trifluoromethyl)furan and its derivatives

The addition reaction of propionaldehyde to hexafluoro-2-butyne ( 1 ) under γ-ray irradiation gave trans-6,6,6-trifluoro-4-trifluoromethyl-4-hexen-3-one ( 2 ) and 4,5-bis(trifluoromethyl)octa-3,6-dione ( 3 ). The latter compound was treated with sulfuric acid to give 2,5-diethyl-3,4-bis(trifluoromethyl)furan ( 4a ). Several reactions, such as bromination, dehydrobromination and oxidation, were carried out to prepare derivatives of 4a .     

2,3- and 3,4-Bis(diethoxyphosphorylmethyl)-5-tert-butylfurans

Reduction of 2-, 4-acetoxymethyl derivatives of 5-tert-butylfuran-3-carboxylic acid leads to the corresponding bis(hydroxymethyl)furans. Bis(chloromethyl)furans prepared from the latter were involvedin reaction with sodium diethyl phosphite. In the presence of two equivalents of a phosphorus-containing nucleophile, bis(phosphonomethyl)furans are formed. One equivalent of sodium diethyl phosphite reacts with 3,4-bis(chloromethyl)furan to give a mixture of 3-and 4-phosphorylated products in a 4.5:1 ratio in a low yield. The revealed difference in reactivity between the 3- and 4-chloromethyl groups demonstrates the importance of shielding of the chloromethyl group by the neighboring tert-butyl substituent. Examination of the ¹H NMR spectra of 3,4-bis(hydroxymethyl)-, 3,4-bis(chloromethyl)-, 3,4-bis(diethoxyphosphorylmethyl)-5-tert-butylfurans, and also specially prepared 5-tert-butyl-3-(diethoxyphosphorylmethyl)-4-(ethoxymethyl)-2-methylfuran established that the signal of the substituent neighboring to the tert-butyl group is always shifted downfield.     

Spectral,luminescent, and photophysical properties of dipyrrolylbenzenes

Dipyrroles with a phenylene bridge, 1,4-bis(pyrrol-2-yl)benzene, 4-(1-vinylpyrrol-2-yl)-1-(pyrrol-2-yl)benzene, and 1,4-bis(1-vinylpyrrol-2-yl)benzene, show intense room-temperature fluorescence in solutions. Analysis of electronic absorption spectra, fluorescence spectra, and results of B3LYP, TD B3LYP, and CIS quantum chemical calculations showed that the introduction of a bulky substituent in position 1 of the pyrrole ring makes the ground-state structures of dipyrrolylbenzenes less planar. Excited-state geometries of all molecules relax to more planar conformations. An increase in the probability of nonradiative transitions has little effect on the quantum yields of fluorescence (Φ_f) of dipyrrolylbenzenes. Even for 1,4-bis(1-vinylpyrrol-2-yl)benzene, where the pyrrole rings deviate from the benzene ring plane by 44°, the fluorescence efficiency remains high enough (Φ_f = 0.7). Substitution at nitrogen atoms has little effect on positions of fluorescence band maxima. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1433–1438, July, 2008.