Novel Magneson-I derived λ-shaped tris azo liquid crystalline trimers

One new homologous series of liquid crystalline λ-shaped tris azo trimers containing azobenzene moiety as a rigid core and ether linkages were synthesized by the reaction of various n-butylazobenzene having bromoalkoxy tail with magneson-I dye respectively. Their right structure was confirmed by FT-IR, 1H NMR, 13C NMR spectroscopy, mass spectrometry and elemental analysis. On the polarising optical microscope (POM), their thermotropic properties were examined, and additional studies were conducted using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). All the trimers with an even number of flexible spacers (n = 2 and 4) show excellent liquid crystalline properties as an enantiotropic nematic phase with greater mesophase length and good thermal stability. The introduction of odd-membered methylene disrupts the orderly stacking of layers and results in a change in mesogenic behaviour. Their structure-property relationships, the influence of different flexible spacers, the mesophase ranges and the photo-isomerisation of liquid crystalline trimers were described. A view of their photochromic behaviour was gained by UV–Visible spectroscopy. The 6-31G (d, p) basis set is combined with the B3LYP functional, which is used for computational studies of λ-shaped tris azo trimers. This approach allows for the determination of various quantum mechanical descriptors that can help us comprehend the mesogenic nature of molecules in computational studies. The results of the Gaussian calculation showed that the target compounds have low energy differences between HOMO-LUMO levels and good chemical reactivity. The examination of ESP and optical characteristics also yielded important information about the electronic structure and potential uses of these compounds. [Display omitted] •New series of λ-Shape Tris azo liquid crystalline trimers with azobenzene core were synthesized.•DSC and POM techniques were used to examine liquid crystalline properties.•Trimers with an even number of flexible spacer (n = 2 and 4) show enantiotropic mesophase.•Odd membered trimers (n = 3 and 5) show monotropic mesophase.•DFT calculations were used to conduct theoretical studies on these molecules.