Nitro pole

The combined inductive and field effects of these poles do not produce strong discrimination between the m- and /i-positions in nitration m p for. NMe3+, and smaller for the protonated poles). This situation is in marked contrast to that produced by, say, the nitro group ( 9.1.3), and suggests that the —M effect is more discriminating between m- and -positions than is the — I effect. 

It will be noticed that this account makes no allowance for the electrostatic interaction of the positive pole with the electrophile, the nitro-nium ion. This should generally work for deactivation, and its influence at nuclear positions should be in the order ortho > meta > para. This point is resumed below. 

In addition to nitro derivatives, polyphosphazenes with sulfonyl-based chro-mophores (259) and (260) have been prepared according to a post-azo coupling approach with 4-ethylsulfonylbenzenediazonium fluoroborate. Absorptions of these polymers are blue-shifted compared to the absorptions of the nitro analogues. NLO activities of poled films of (259) and (260) have been determined by second harmonic generation measurements. " ... 

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