• 1 School of Chemical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia
  • 2 The Department of Chemical Sciences, Faculty of Science, Universiti Tunku Abdul Rahman, Perak, Malaysia
  • 3 Centre for Nano-materials and Displays, BMS College of Engineering, Basavanagudi, Bangalore, 560019, Karnataka, India
Curr Org Synth, 2021;18(4):352-365.
PMID: 33530909 DOI: 10.2174/1570179418666210202123935


INTRODUCTION: This is the first report on chiral polymorphic hydrazine-based asymmetric liquid crystal trimers, 1-[4'-(4''-(5-Cholesteryloxy)carbonyl)butyloxy]-3-[N-benzylideneoxy-N'-(4'''-decyloxybenzylidene) hydrazine] butyloxybenzenes, and 1-[4'-(4''-(10-cholesteryloxy)carbonyl)nonyloxy]-3-[N-benzylideneoxy-N'-(4'''- decyloxybenzylidene)hydrazine]butyloxybenzenes., in which the hydrazine and cholesterol arms were connected via two flexible methylene spacers (n = 3-12 units and m = 4 or 9, respectively) to the central resorcinol core.

MATERIALS AND METHODS: FT-IR, 1D and 2D NMR spectroscopy, and CHN microanalysis were used to elucidate the structures of the trimers. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction were used to study the transitional and phase properties of the trimers, which were length and spacer parity dependent. Trimers with short spacer length in the cholesteryl arm, m = 4 showed an interesting phase sequence of BP/N*-TGBA*-SmA*.

RESULTS AND DISCUSSION: The TGBA* phase was sensitive to spacer length as it was only observed in trimers with short ester linkage. For the long analogues, m = 9, characteristic visible reflection and a much simpler phase sequence with only N* and SmA* phases were observed.

CONCLUSION: The X-ray diffraction measurements revealed that layer periodicities of the SmA* phase were approximately half the estimated all-trans molecular length (d/L ≈ 0.44-0.52), thus suggesting that the molecules are either strongly intercalated or bent.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.