000			03003cam a2200337 a 4500
003			EG-GiCUC
005			20250223032455.0
008			191208s2019 ua ho f m 000 0 eng d
040			_aEG-GiCUC _beng _cEG-GiCUC
041	0		_aeng
049			_aDeposite
097			_aM.Sc
099			_aCai01.12.10.M.Sc.2019.Mo.E
100	0		_aMohamed Mahfouz Kaddah Fathi
245	1	0	_aEffect of lateral methyl substitution on the mesophase behaviour of some new four-ring azo-ester-azo compounds / _cMohamed Mahfouz Kaddah Fathi ; Supervised Abelgawad A. Fahmi , Magdi M. Naoum
246	1	5	_aتأثير مجموعة الميثيل الأستبدالية الجانبية على سلوك الطور لبعض مركبات الآزو- استر- أزو الجديدة رباعية الحلقة
260			_aCairo : _bMohamed Mahfouz Kaddah Fathi , _c2019
300			_a112 P. : _bfacsimiles , photographs ; _c25cm
502			_aThesis (M.Sc.) - Cairo University - Faculty of Science - Department of Organic Chemistry
520			_aThe effect of introducing a lateral methyl substitution into the previously investigated laterally neat four-ring analogues, 4-substituted phenylazo phenyl 4ʹ-(4ʺ-alkoxyphenylazo) benzoates (Ina{u2013}e), on their mesophase behaviour was investigated for the newly prepared five homologous series of 4-substituted phenylazo phenyl 4ʹ-(3ʺ-methyl-4ʺ-alkoxyphenylazo) benzoates (IIna-e). Within each homologous series, the alkoxy group varies between 6, 8, 10, 12, 14, and 16 carbons, while the substituent, X, is a polar group that alternatively changes between the electron-donating (CH³O and CH³) and the electron-withdrawing (Br and NO²) groups, including the un-substituted homologues (Hnc). Their mesophase stabilities were determined by differential scanning calorimetry (DSC) and phases identified by polarized light microscopy (PLM). The results showed that, independent of either of the alkoxy-chain length (n) or the polarity of the substituent X, the nematic phase is predominant with relatively high stability and wide temperature ranges. All compounds show a good thermal stability in the mesophases domain, except the nitro and Br substituted derivatives bearing short alkoxy chain length. Comparison of the mesophase behavior was also made between the present series and corresponding three-ring laterally CH³-substituted azo/ester analogues. UV-vis absorption spectra revealed that both derivatives with the electron donating or the electron withdrawing groups exhibited red shifts of the s{u2192}s* transition compared with that of the un-substituted ones
530			_aIssued also as CD
653		4	_aFour-ring azo/ester/azo derivatives
653		4	_aLateral-methyl substitution
653		4	_aMesophase stability
700	0		_aAbdelgawad Ali Fahmi , _eSupervisor
700	0		_aMagdi Mekhael Naoum , _eSupervisor
856			_uhttp://172.23.153.220/th.pdf
905			_aNazla _eRevisor
905			_aSamia _eCataloger
942			_2ddc _cTH
999			_c75709 _d75709