| 摘要 |
The invention relates to a photographic element comprising at least one light-sensitive silver halide emulsion layer having associated therewith a heterocyclic magenta or cyan dye-forming coupler of formula (I),whereinHET is a heterocyclic coupler comprising at least two fused rings and having at least one bridgehead nitrogen atom;S is bonded to a position of HET capable of releasing the heterocyclylthio moiety from HET upon reaction with oxidized developer;X is a heteroatom selected from nitrogen, oxygen and sulfur, bonded to the carbon atom bearing the exocyclic S and to other ring atoms only; andZ are the atoms necessary to complete an unsubstituted or substituted heterocyclic ring or ring system, which may contain one or more other heteroatoms selected from nitrogen, oxygen and sulfur;provided also that the heterocyclylthio moiety released upon reaction with oxidized developer does not significantly inhibit silver development nor cause a bleach acceleration effect.The couplers have good activity and the heterocyclylthio coupling-off groups can comprise or be linked to photographically useful groups, such as dyes, development accelerators or electron transfer agents, thereby providing a practical way of attaching these groups to fused heterocyclic ring systems.
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