The blue emissions for the polyamide derived from benzidine, attributed to the highly conjugation system, was blue shifted with the introduction of flexible linkages.
The blue emissions at 420 nm and 405 nm for the polyamide derived from benzidine, attributed to the highly conjugation system, was blue-shifted (shifted to a lower frequency) compared with that of polyamides containing flexible linkages.
The blue emissions at 420 nm and 405 nm for the polyamide 18 derived from benzidine, attributed to the highly conjugation system, also blue-shifted (shifted to a lower wavelength) upon introducing flexible linkages such as ether bond in 20 (314 nm), methylene group in 23 (336 nm) or sulfone group in 24 (344 nm) in the polymeric chains.
Their electronic properties are attributed to the σ-conjugation originating from the overlap of Si sp3 orbitals [1].
This downfield shift of the signals can be attributed to the lack of conjugation from the electron-donating bromothiophene group allowing for the electron-withdrawing effect of the nitrobenzene group to dominate and deshield the protons.
The low conductivity values were attributed to the low degree of conjugation in the polymers caused by non-planarity of the polymer chains.
The results also indicated that the effects of physical size on the relative barriers and stabilities of reaction intermediates along the CO desorption channel could be attributed to the disruption of π-conjugation of the graphene ribbon surface.
This effect is attributed to the decrease in π-conjugation of the meso-phenyl substituents (33) and is similar to that observed in case of meso-unsubstituted tetrabenzoporphyrins, which absorb at shorter wavelengths than the meso-phenylsubstituted analogues (47).
The presence of a band at 798 cmay may be attributed to the Si C stretching vibrations, indicating the conjugation of amide groups with the silica framework via the APTES hydrolysis [33].
