TY  - BOOK
AU  - Mohamed Hamed Ali Mohamed
AU  - Abdelgwad Ali Fahmi , 
AU  - Magdi Mikhail Naoum , 
TI  - Effect of polarity and orientation of substituents on the mesophase behavior of some newly prepared bilaterally substituted liquid crystals / 
PY  - 2017///
CY  - Cairo : 
PB  - Mohamed Hamed Ali Mohamed , 
KW  - Azo/ester compounds
KW  - Di-lateral substitution
KW  - Phenylazo benzoate
N1  - Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Organic Chemistry; Issued also as CD
N2  - Eight homologous series of 2- (or 3-) substituted phenyl 4'-(4"-alkoxy  (2"-, or 3"-substituted phenylazo) benzoates (InXY) were prepared in which  the suffix 2X3 refers to the lateral substituent X attached to the terminal  benzene ring that carries the alkoxy group, and the suffix 2Y3 refers to the  substituent attached to the other terminal phenyl group. Within each  homologous series, the length of the terminal alkoxy group varies between 8,  10, 12, and 16 carbons, while the lateral polar substituents, X and Y,  alternatively varies between CH3 and F. Compounds prepared were  characterized by infrared, 1H-NMR spectroscopy, mass spectroscopy and  elemental analyses, and their mesophase behavior investigated by differential  scanning calorimetry (DSC) and identified by polarized light microscopy  (PLM). The results were discussed in terms of polarity and steric effects of  the two lateral groups. Transition temperatures were first correlated with the  alkoxy-chain length (n) within each homologous series. Comparative  correlations were made to investigate the effect of the second lateral  substituent on the mesophase behavior of the previously investigated mono- laterally substituted analogues. Studies were extended to compare the phase  stability of each pair of compounds that maintain one of the substituents (X or  Y) constant while the other changes.UV-vis spectroscopic study revealed that  the compounds I8XY exhibited two absorption bands: low intense bands at  254-263 and a broad band at 364{u2013}376. These bands are attributed to the s{u2013}s{u2217}  transition of the phenyl rings and the whole mesogenic portion
UR  - http://172.23.153.220/th.pdf
ER  -