| 摘要 |
A photographic element comprising a support having situated thereon at least one silver halide emulsion layer, the layer containing a photographic coupler represented by the formula <IMAGE> wherein COUP is a coupler moiety having a coupling site to which T1 is attached; T1 is a timing or linking group which releases from COUP during processing and which functions by electron transfer down a conjugated chain, or by nucleophilic displacement reaction, to release from HETERO; HETERO is a heterocyclic group containing at least two heteroatoms independently selected from oxygen, nitrogen, or sulfur, wherein one of the heteroatoms is directly attached to T1; R1 and R2 are independently selected from hydrogen, or an aliphatic, carbocyclic, or heterocyclic group, or may be bonded together to form a 5, 6, or 7 membered ring; and PUG is a photographically useful group.
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