| 摘要 |
Photographic elements are provided which contain a compound having the formula: R1-NH-(Q)m-C(R2)(R3)-(TIME)n-PAM wherein: R1 is an electron withdrawing moiety; Q is a group comprising a conjugated system; m is 0 or 1, and when m=1, -NH-Q-C(R2)(R3)- is a timing or linking group which undergoes electron migration along a conjugated system to cause a cleavage reaction; TIME is a timing or linking group; n is 0, 1, 2 or 3, preferably 0 or 1; PAM is a photographically active moiety; and R2 and R3 are independently hydrogen, susbtituted or unsubstituted alkyl, aryl, heteroaryl, alkenyl, or alkynyl groups, can be combined with R1 to form a ring, or can combine together to form a ring, with the proviso R2 and R3 cannot together form a double bond with another atom and neither R2 nor R3 can be selected from RO-, RS-, R2N-, or RSe- where R represents any substituent. Photographic elements comprising the novel blocked image-modifying compounds of the present invention provide for the opportunity to specifically control the strength and location of image modification. They are also useful when incorporated in oligomeric or other polymeric species. Further, when such compounds unblock to fonn development inhibitors, excellent control of push processing, control of fog development, and control of specific layer developability can be obtained. These three applications can be realized by controlling the release rates. To control push processing, steady release upon extended processing is desirable; for control of fog development, gradual release during keeping is desirable; and for control of specific layer developability, rapid release upon processing is desirable.
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