Abstract: A thermographic element comprising in a non-aqueous binder medium a silver salt oxidizing agent in reactive association with a compound comprising a plurality of redox color releasing moieties such that oxidation of each redox color releasing moiety causes release from said compound of a thermally diffusible dye.The compounds many of which are new incorporate two or more developer moieties into a single molecule to minimize the diffusibility of the compound. Following oxidation, either directly by the silver salt or by means of a cross-oxidizing agent, each oxidized developer moiety releases a thermally diffusible dye. The compounds are of sufficient size and molecular weight to slow or prevent diffusion in imaging systems and yet possess several active developer moieties per molecule which is advantageous over known ballasted dye releasers which comprise bulky molecules with only a single developer moiety.

Abstract: A photothermographic element comprising a support bearing at least one heat-developable, photosensitive, image-forming photothermographic emulsion layer comprising:(a) a photosensitive silver halide;(b) a non-photosensitive, reducible source of silver;(c) a reducing agent for the non-photosensitive reducible silver source; and(d) a binder;wherein the reducing agent is a hydrazide redox-dye-releasing compound of the general formulae: ##STR1## wherein: D represents the chromophore of a thermally mobile dye; X represents a single bond or a divalent linking group; R.sup.1 and R.sup.2 independently represent an organic group; and n.gtoreq.1.