“…To date, only the -naphthol (1) (Jarvis, 1961;Olivieri et al, 1989;Salmen et al, 1988;Whitaker, 1977Whitaker, , 1978bGrainger & McConnell, 1969;Guggenberger & Teufer, 1975;Diamantis et al, 1992;Alcock et al, 1968), naphthol AS (2) (Kobelt et al, 1972(Kobelt et al, , 1974Whitaker, 1978a) and acetoacetanilide (3) (Paulus et al, 1983;Paulus, 1984;Gridunova et al, 1991;Paulus & Rieper, 1985;Whitaker 1983aWhitaker ,b, 1984aWhitaker ,b, 1985aWhitaker ,b,c, 1986Whitaker & Walker, 1987;Golinski, 1988) classes of pigment have given crystal structures using standard laboratory techniques. The dif®culty in growing good quality crystals is further shown by the poor quality of some of these determinations (e.g.…”