Conjugated anisotropy

The anisotropy of the magnetic susceptibility of a cyclic conjugated system, attributable to induced ring currents in its rc-electron network, is one of the important quantities indicative of 7t-electron delocalization. The method used for the calculation of the magnetic susceptibilities of nonalternant hydrocarbons is the London-Hoarau method taken together with the Wheland-Mann SCF technique . The resonance integral is assumed again to be of exponential form but... 

Apart from the tunable color emission covering the full visible range, there are several other aspects supporting the interest in PTs for PLEDs. PTs are examples of classical conjugated polymers with intrinsic one-dimensionality of the polymer chain. Alignment can induce anisotropy in macroscopic properties such as electron transport or optical properties. Polarized... 

Fluorescence anisotropy is generally used to provide information about the dipolar orientational dynamics occurring after excitation of a system. This technique has successfully been used to probe ultrafast dynamics of energy transfer in organic conjugated dendrimers. The detected emission intensities Tar and Ter for parallel and perpendicularly polarized excitation respectively, were used to construct an observable emission anisotropy R(t) in accordance with the equation [121] ... 

Steady-state measurements of the fluorescence anisotropy of fluorescein derivatives form the basis of a sensitive analytical technique also used to detect and quantitate proteins [36], steroids [37-39], therapeutic drugs, and narcotics [40-42], In a different approach, the anisotropy of the fluorescein conjugate is measured as a function of the medium viscosity to determine the segmental mobility of the chains that cover the binding site [43-45],... 

Experimental ring currents[60] are associated with the anisotropy of 1H shifts at protons pointing inside and outside the annulene. The virtually equal shifts of 13.78 and 13.46 ppm in 14 and 18 annulenes clearly support the PPP results in Fig. 5, which also rationalize the decreasing shifts of 10.03 and 6.41 ppm for 22 and 26 annulenes. Moreover, the PPP ring current[47] of the anion [18]—4 is 1.49 times that of neutral [18], while the measured XH shift increases 1.57 times[60]. In general, the identification of ring currents in conjugated molecules requires careful atten-... 

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