Two-dimensional hetero-spectral correlation fluorescence-Raman spectroscopy for a thermotropic liquid-crystalline oligomer

In this paper, 2D fluorescence and 2D hetero-spectral fluorescence-Raman correlation spectroscopies were performed to better understand the dynamic process of liquid crystalline (LC) oligomer, the esterification product of ethyl 4-[4′-oxy-4-biphenyl-carbonyloxy]-4′-biphenylcarboxylate with poly(ethylene oxide)s (PEO) (DP = 12) (designated as 12-4). We found that 2D fluorescence correlation spectroscopy provided much more detailed information on the mechanism of dynamic development of LC oligomer with temperature variation than conventional 1D fluorescence spectroscopy. Furthermore, we investigated the structural change of 12-4 at the molecular level during the phase transitions by using 2D hetero-spectral fluorescence-Raman correlation spectroscopy.