Using heteroaromatic 1,2-diketones, we previously developed a series of solid-state mechanoresponsive RTP materials, 15 solventfree liquid RTP materials, and photoresponsive RTP crystals. They exhibited RTP under non-rigid molecular environments, such as amorphous solids or solvent-free liquids. Considering that typical metal-free organic compounds rarely show RTP under these conditions, our results were encouraging enough to expect large kps for those diketones; however, their inherent molecular RTP properties have not been fully investigated.