piperidines has been researched along with tetracyanoethylene* in 2 studies
2 other study(ies) available for piperidines and tetracyanoethylene
| Article | Year |
|---|---|
Synthesis, spectroscopic and thermal structural investigations of the charge-transfer complexes formed in the reaction of 1-methylpiperidine with sigma- and pi-acceptors.
The reactions of the electron donor 1-methylpiperidine (1MP) with the pi-acceptors 7,7,8,8-tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil=CHL) and iodine (I(2)) were studied spectrophotometrically in chloroform at room temperature. The electronic and infrared spectra of the formed molecular charge-transfer (CT) complexes were recorded. The obtained results showed that the stoichiometries of the reactions are not fixed and depend on the nature of the acceptor. Based on the obtained data, the formed charge-transfer complexes were formulated as [(1MP)(TCNE)(2)], [(1MP)(DDQ)].H(2)O, [(1MP)(CHL)] and [(1MP)I]I(3), while in the case of 1MP-TCNQ reaction, a short-lived CT complex is formed followed by rapid N-substitution by TCNQ forming the final reaction products 7,7,8-tricyano-8-piperidinylquinodimethane (TCPQDM). The five solids products were isolated and have been characterized by electronic spectra, infrared spectra, elemental analysis and thermal analysis. Topics: Chloranil; Ethylenes; Fungicides, Industrial; Iodine; Molecular Structure; Nitriles; Piperidines; Spectrum Analysis; Thermogravimetry | 2010 |
Determination of the degree of charge-transfer contributions to surface-enhanced Raman spectroscopy.
We explore the application of a previously suggested formula for determining the degree of charge transfer in surface-enhanced Raman scattering (SERS). SERS is often described as a phenomenon which obtains its enhancement from three major sources, namely the surface plasmon resonance, charge-transfer resonances as well as possible molecular resonances. At any chosen excitation wavelength, it is possible to obtain contributions from several sources and this has led to considerable confusion. The formula for the degree of charge transfer enables one to separate these effects, but it requires that spectra be obtained either at two or more different excitation wavelengths or as a function of applied potential. We apply this formula to several examples, which display rather large charge-transfer contributions to the spectrum. These are p-aminothiophenol (PATP), tetracyano-ethylene (TCNE) and piperidine. In PATP we can show that several lines of the same symmetry give the same degree of charge transfer. In TCNE we are able to identify the charge-transfer transition, which contributes to the effect, and are able to independently determine the degree of charge transfer by wavenumber shifts. This enables a comparison of the two techniques of measurement. In piperidine, we present an example of molecule to metal charge transfer and show that our definition of charge transfer is independent of direction. Topics: Chemistry, Physical; Electrons; Ethylenes; Nitriles; Phenols; Piperidines; Spectrum Analysis, Raman; Sulfhydryl Compounds; Surface Plasmon Resonance | 2008 |