Knott

Most of the qualitative relationships between color and structure of methine dyes based on the resonance theory were established independently during the 1940 s by Brooker and coworkers (16, 72-74) and by Kiprianov (75-78), and specific application to thiazolo dyes appeared later with the studies of Knott (79) and Rout (80-84). In this approach, the absorptions of dyes belonging to amidinium ionic system are conveyed by a group of contributing structures resulting from the different ways of localization of the 2n rr electrons on the 2n l atoms of the chromophoric cationic chain, rather than by a single formula ... 

Knott s rule concerns the importance of the place of the nitrogen atom replacing a methine carbon in the conjugated chain when the atom is separated from the active auxochromic atoms by an odd number of conjugated atoms, the shift is bathochromic. It is hypsochromic when there is an even number, Tne importance of the shift could establish a measure of M effect of various heterocyclic nuclei (79. 124). Many papers have been published, and examples have been given to verify these rules (79-84). 

Amino-4-aryl-5-acetic acid selenazoles were used by Knott (2l i as intermediates in the preparation of T.2, 4.6-naphthoselenazoles (21. 30, 31). 

J. F. Knott, fundamentals of fracture Mechanics, Butterworths, London, 1979. 

C. T. Russell, ia K. Knott and B. Battdck, eds.. The Scientific Programme During the InternationalMagnetospheric Study, Academic Press, Inc., New York,... 

The direction of the long-wavelength maximum shift caused by the heterosubstitution or the introduction of substituents is deterrnined by the Forster-Dewar-Knott rule (40—42). Spatial hindrances within the symmetrical PMDs cause bathochromic effects (39,43), whereas the introduction of an acetylenic bond is accompanied by the maximum shift to the short-wavelength spectral region (44). 

Knorr Synthesis. Condensation of an a-aminoketone with a carbonyl compound was first reported by Knott (20). This reaction and its modifications are among the most important and widely used methods for the synthesis of pyrroles. 

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