  The relationship between the molecular structure and the formation of the NTB
phase is still at an early stage of development. This is mainly related to
molecular geometry, while the correlation between the NTB phase and the
electronic structure is ambiguous. To explore the electronic effect on
properties and stabilization of the NTB phase we investigated
2,3-difluoro-4,4-dipentyl-p-terphenyl dimers (DTC5Cn). We used IR polarized
spectroscopy, which can at least in principle, bring information about the
ordering in NTB phase. All dimers show a significant drop of the average value
of the transition dipole moment d{\mu}/dQ for parallel dipoles at the
transition to the NTB phase, and an increase for perpendicular dipoles, despite
its remaining unchanged for the monomer. These results coincide well with DFT
simulations of vibrational dipole derivatives for molecules assembled in
pseudo-layers of the NTB phase. The DFT calculations were used to determine the
geometric and electronic properties of the hydrogen bonded complexes. We have
provided experimental and theoretical evidence of stabilization of the NTB
phase by arrays of multiple hydrogen bonds (XF...HX, X-benzene ring).
