عنوان مقاله [English]
Relationships between the colour and constitution of organic dyes have long been a subject of great interest to both theoretical and organic chemists and as a consequence a vast number of publications on this subject have appeared in the scientific literature since Witt first proposed his theory of chromophores and auxochromic groups more than a century ago. The advent of quantum theory greatly accelerated progress in this field and the eventual development of quantitative methods for spectroscopic predictions has proved to be of considerable practical value in the search for new dyes. Certainly today the colour chemist is in a position to predict the visible absorption spectrum of any conjugated molecule, however complex, if not with high precision, at least with some confidence as to the general appearance of the spectrum relative to some model chromogen. In spite of the obvious importance of colour and constitution studies, general review papers on this topic have been relatively scarce up until a few years ago. This paper will review the history and development of color and constitution issue and introduce various theoretical and practical methods in this area with a focus on organic dyes in discussions.