Integrated NMR and Computational Study of Push–Pull NLO Probes: Interplay of Solvent and Structural Effects

From Graphene to Carbon Nanotubes: Variation of the Electronic States and Nonlinear Optical Responses

From the same piece of graphene sheet, (3, 3) and (6, 0) carbon nanotube clips were obtained on the basis of the different manners of rolling. The nature of the electronic state varies differently with different manners of rolling and is significantly affected by zigzag edges. The intermediate structures formed during the rolling process were functionalized with fluorine and oxygen atoms to investigate the electronic states and nonlinear optical (NLO) responses. Passivation of the intermediate structures with fluorine neither changes the nature of electronic states and nor improves the NLO responses. In constrast, passivation with oxygen enhances the NLO properties and changes the electronic states of the structures upon passivating at the open zigzag edges.

Orientational order of two fluoro- and isothiocyanate-substituted nematogens by combination of 13C NMR spectroscopy and DFT calculations

Orientational order properties of two nematogens containing a fluoro- and isothiocyanate-substituted biphenyl moiety have been investigated by means of (13)C NMR spectroscopy. (13)C NMR spectra acquired on static samples under high-power (1)H-decoupling allowed both (13)C chemical shift anisotropies and (13)C-(19)F couplings to be measured. These data were used to determine the local principal order parameter and biaxiality for the different rigid fragments of the molecules. To this aim, advanced DFT methods for the calculation of geometrical parameters and chemical shift tensors were used. The orientational order parameters obtained by NMR have been critically compared with those obtained by dielectric spectroscopy. Trends of order parameters with temperature have been analyzed in terms of both mean field theory and the empirical Haller equation.