On-press developable imageable elements

A negative-working, on-press developable imageable element comprising a substrate having thereon an imageable layer comprising:

• a radically polymerizable component,
• an initiator composition capable of generating free radicals sufficient to initiate polymerization of free radically polymerizable groups upon exposure to imaging infrared radiation,
• a polymeric binder, and
• an infrared radiation absorbing compound comprising a chromophore that is represented by the following Structure (CHROMOPHORE):
• wherein one or both of Q1 and Q2 are independently substituted or unsubstituted acyl groups —(C═O)—R3′ and —(C═O)—R4′ respectively, wherein R3′ and R4′ are independently substituted or unsubstituted alkyl or aryl groups, or they are joined together to form a ring structure, or one of Q1 and Q2 is hydrogen and the other is a substituted or unsubstituted acyl group,
• A and A′ are independently —S—, —O—, —NH—, —CH2—, or —CR′R″— groups wherein R′ and R″ are independently substituted or unsubstituted alkyl groups, or R′ and R″ together can form a substituted or unsubstituted cyclic group,
• Z represents the carbon atoms needed to form a 5- to 7-membered carbocyclic ring,
• Z1 and Z2 are independently substituted or unsubstituted benzo or naphtho condensed rings, and
• R1′ and R2′ are independently substituted or unsubstituted alkyl, cycloalkyl, or aryl groups.