Mustafa Akdogan

In this study, novel tetra-substituted p-(dodecyloxy)-phenol derivatives of cyclotriphosphazenes (1, 2, and 3) were synthesized to investigate their mesogenic and electrical properties. The molecular structures of the compounds were confirmed by mass spectrometry, FT–IR, 1H, and 31P NMR spectroscopic techniques. Their thermodynamic parameters and structural self-assemblies were comprehensively evaluated using Differential Scanning Calorimetry (DSC), Polarized Optical Microscopy (POM), and X-ray Diffraction (XRD). The results demonstrated that while compound 3 remained non-mesomorphic, compounds 1 and 2 exhibited mesomorphic behavior consistent with a smectic phase during both heating and cooling cycles. XRD analysis revealed well-defined lamellar layer spacings are 27.35 Å and 39.83 Å for 1 and 2, respectively, which closely correlated with the focal-conic fan and broken mosaic textures observed via POM. Temperature-dependent DC electrical conductivity measurements revealed low room-temperature conductivities of 8.98x10-11 S/cm for compound 1 and 4.42x10-12 S/cm for compound 2, highlighting their potential as flexible organic electrically insulating materials. Notably, a pronounced three-order-of-magnitude increase in current (from the pA to the nA regime) was observed near the clearing temperatures (52–57 °C), demonstrating that temperature-dependent electrical conductivity measurements can serve as a sensitive complementary tool for monitoring phase transitions in cyclotriphosphazene-based liquid crystalline materials.