We further investigated the effects of the substituent on photolysis using 1 H NMR spectroscopy. We synthesized several derivatives and found that the proton signals changed significantly due to bond cleavage after photo irradiation. (Figure ). To evaluate the impact of the β-silyl effect on photocleavage efficiency, a methyl-substituted analog (Me-Carb 4) was synthesized and compared with Carb 2 and Si-Carb 3 (Figure ). The photolysis of Me-Carb 4 was slightly faster than that of unmodified Carb 2. This reflects the difference in cation stability between the primary and secondary carbocations in the excited state. We observed a significant improvement in photolysis from Me-Carb 4 to Si-Carb 3. This difference between 4 and 3 can be attributed to the β-cation stabilizing effect of the remote silyl groups. Next, we synthesized vinyl-derivative 5, recently reported as a superior photocleavable coumarin designed using an alternative cation-stabilizing approach, to compare it with our newly developed coumarin. Si-Carb 3 exhibited photolytic activity comparable to that of the previous reported vinyl-derivative 5. In addition, Si-Carb 3 exhibited substantially greater stability against enzymatic hydrolysis than the vinyl-derivative 5, which can be attributed to the three-dimensional bulkiness of the TMS group that more effectively protects carbonyl bonds against carboxylesterase (Supplementary Figure ).