Catalyst-free single-molecule cascade photoreactions for spatiotemporally programmed encryption

The escalating crisis of information leakage necessitates a shift from static identifiers to intelligent, dynamically secure systems. Current approaches, even up-to-date time-dependent ones, remain constrained by non-progressive or multicomponent designs that lack programmable spatiotemporal control, underscoring the need for a minimal, integrated molecular platform. Herein, we report a single-molecule system (4BT-Py-PTC) that achieves time-gated, graded multicolor fluorescence via sequential, catalyst-free photoreactions. This designed pathway involves thiocarbonate hydrolysis, alkene cleavage, and aldehyde photooxidation, progressively transforming the initial yellow emitter into red- (3BT-Py, 5 min), yellow- (2BT-CHO, 20 min), and blue-emissive (5BT-COOH, 80 min) products. This intrinsic programmability enables a higher-order of spatiotemporal command. Leveraging this output, we demonstrate two encryption modes: time-gated 3D codes and organogel matrices for multistage (reveal-conceal-erase) control with temporal keys. This work establishes an approach centered on catalyst-free, single-molecule cascade photoreactions, redefining secure materials through spatiotemporal encryption and benchmarking dynamic anti-counterfeiting and data protection.