نتایج جستجو برای: hammett

تعداد نتایج: 424  

2013
B. Thimme Gowda D. Krishna Bhat H. Fuess

Fifteen methyl-, nitro-, or mixed substituted N-(phenyl)-2-chloroacetamides were investigated by C1 NQR. The temperature dependence of the frequencies of the 3-methylphenyl and 2,6-dimethylphenyl derivatives were studied for the range 77 K<T<300 K. Only one co C-Cl frequency was observed for the compound with the two exceptions. For N-(2-nitro,4-chlorophenyl)-2-chloroacetamide the observed valu...

1998
William A. McHale Andrei G. Kutateladze

Irradiation of dithiane-aldehyde/ketone adducts in the presence of benzophenone leads to C-C bond cleavage regenerating the carbonyl compounds. It is established that the mechanism of this reaction involves photochemically induced single electron transfer from the dithiane moiety to the excited molecule of ET-photosensitizer, accompanied by mesolytic C-C cleavage in the generated cation-radical...

2013
Ibon Alkorta Goar Sánchez-Sanz José Elguero

Four models of halogen bonds were used to quantify this bond using the DFT B97D/6-311+G(d) computational level: para-substituted iodobenzenes, paraand meta-substituted bromobenzenes complexed with three simple Lewis bases (NH3, NCH and CNH), 1-bromo-4-substituted-bicyclo[2.2.2]octanes with NH3 and 3and 4-substituted pyridines complexed with BrCl and BrF. In addition, the combination of the para...

Journal: :Journal of the American Chemical Society 2006
Bryan K Spraul S Suresh Jianyong Jin Dennis W Smith

A series of 19 p-substituted aromatic trifluorovinyl ether compounds were prepared from versatile intermediate p-Br-C(6)H(4)-O-CF=CF(2) and underwent thermal radical mediated cyclodimerization to new difunctional compounds containing the 1,2-disubstituted perfluorocyclobutyl (PFCB) linkage. The synthetic scope demonstrates the functional group transformation tolerance of the fluorovinyl ether, ...

Journal: :The Journal of chemical physics 2013
Tobias Fahleson Patrick Norman Sonia Coriani Antonio Rizzo Geert L J A Rikken

We report on the results of a systematic ab initio study of the Jones birefringence of noble gases, of furan homologues, and of monosubstituted benzenes, in the gas phase, with the aim of analyzing the behavior and the trends within a list of systems of varying size and complexity, and of identifying candidates for a combined experimental/theoretical study of the effect. We resort here to analy...

Journal: :Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 2008
Habibe Tezcan Elif Uzluk M Levent Aksu

In this study, new 1:2 Ni complexes of 1,3-substituted phenyl-5-phenylformazans were synthesized with -Cl, -Br substituents in the o-, m-, p-positions of the 1-phenyl ring and -NO2 group in the m-position of the 3-phenyl ring. Their structures were elucidated and spectral behaviors were investigated with the use of elemental analysis, GC-Mass, 1H NMR, 13C NMR, FTIR, UV-vis spectra. Furthermore ...

1998
Bei Chen Fengting Liang Haipeng Chen Jianbo Wang

Intramolecular C±H insertion by Rh-mediated carbenoids has attracted considerable interest in recent years. In addition to its synthetic applications, there have been extensive investigations into the mechanism of this reaction. We have recently studied the electronic e€ects of this reaction through the measurement of the relative reactivities of Rh-mediated carbenoid insertion into a series of...

Journal: :Journal of the American Chemical Society 2005
Xiaoyin Xiao Larry A Nagahara Adam M Rawlett Nongjian Tao

We have studied electron transport properties of unsubstituted oligo(phenylene ethynylene) (OPE) (1) and nitro-substituted OPE (2) covalently bound to two gold electrodes. The conductance values of single 1 and 2 are approximately 13 and approximately 6 nS, respectively. In addition to a decrease in the conductance, the presence of the nitro moiety leads to asymmetric I-V characteristics and a ...

Journal: :Physical chemistry chemical physics : PCCP 2008
Franco Cozzi Rita Annunziata Maurizio Benaglia Kim K Baldridge Gerardo Aguirre Jesús Estrada Yongsak Sritana-Anant Jay S Siegel

A model for studying polar-pi interactions between arenes spaced at van der Waals distances is developed on the basis of peri-diarylbiphenylenes. A set of 1,8-diarylbiphenylenes is synthesized comprising two Hammett series, one with reference to mesityl ring interactions and the other with reference to pentafluorophenyl ring interactions. X-Ray crystal structures of several derivatives are dete...

Journal: :Journal of the American Chemical Society 2001
W H Lee H Lee J A Kim J H Choi M Cho S J Jeon B R Cho

Two-photon absorption (TPA) cross sections of four representative series of octupolar molecules are theoretically investigated. The general structure--TPA-property relationship is described by using the effective four-state valence-bond three-charge-transfer model. As the charge-transfer character of the ground electronic state increases due to the strong donors or acceptors, (i) the transition...

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