Two types of two-step mechanochromic luminescence (MCL) as well as bicolor MCL have been achieved by changing the R substituent.

2-Acetyl-6-[(benzyloxy)methyl]-9-methoxy-8-methyl-11,11adihydro-2H-pyrazino[1,2-b]isoquinoline-1,4,7,10(3H,6H)-tetraone (11a) was prepared as the CDE ring model of renieramycins, and its novel photo-induced transformation was demonstrated to construct a 1,3-dioxol ring. PCC (2.0 eq.) CH 2 Cl 2 rt, 1.5 h Me HO OMe O OBn 19 MeO Me OBn HN NAc O O 14 (1.0 eq.) 1 M t BuOK/ t BuOH (1.2 eq.) CH 2 Cl 2 , rt, 2.5 h 24 81% H 2 , 10% Pd-C EtOH : DMF (1 : 1) rt, 1.5 h 98% MeO Me OH HN NAc O 25 O 91% 2 steps from 21 H 2 , Pd/C, EtOH, DMF, 94%

Organic emitters capable of changing their luminescence properties in response to mechanical stimuli have recently attracted considerable attention. While mechanoresponsive switching of luminescence color has been widely investigated, there are only a limited examples regarding the on-off luminescence intensity switching by mechanical stimulation. Consequently, rational design guidelines for mechanoresponsive switching of luminescence intensity have not been established. Herein, on-off luminescence switching has been achieved by two-component organic emitters composed of phenanthroimidazolylbenzothiadiazoles, which ex-hibit mechanochromic luminescence (MCL), and non-emissive pigments. In these two-component emitters, the emission color can be tuned by changing the MCL dye, and the apparent color under room light can be modulated by changing the non-emissive pigment. Moreover, we have demonstrated the encryption and decryption of luminescent displays by using the two-component emitter. The present two-component strategy is expected to serve as a useful method for developing advanced mechanoresponsive luminescent materials.