| 摘要 |
Dyes comprising an inner salt of a compound of the formula: Q1=Z-Q2 wherein: Q1 is a 4-(benz¢b!-4H-pyrylium)methylidene, 4-(benz¢b!-4H-thiopyrylium)methylidene or 4-(benz¢b!-4H-selenopyrylium)methylidene grouping; Z is a 1,3-(2-hydroxy-4-oxo-2-cyclobutylidene) hydroxide or 1,3-(2-hydroxy-4,5-dioxo- -2-cyclopentylidene) hydroxide ring; and Q2 is a 4-(benz¢b!-4H-pyran-4-ylidene)methyl, 4-(benz¢b!-4H-thiopyran-4-ylidene)methyl or 4-(benz¢b!- -4H-selenopyran-4-ylidene)methyl grouping; wherein at least one of the groupings Q1 and Q2 carries at its 2-position a substituent in which a non-aromatic carbon atom- is bonded directly to the benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus, subject to the proviso that if this 2-substituent contains an aromatic nucleus, this aromatic nucleus is not conjugated with the benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus to which it is attached, are useful as visible and near infra-red absorbers, having high extinction coefficients and improved solubility in polymeric media.
|
