邻苯二酚双联罗丹明在弹性体中的力致变色和光致变色

In this work, a novel double-spiro mechaophore ISO-ABPX fused be catechol was designed and synthesized, and its photochromic and mechanochromic behaviors and mechanisms in polyurethane (PU) and double-network elastomer (PMA-PU) were systematically investigated. It was found that under both 365 nm ultraviolet light irradiation and external pressure, ISO-ABPX only underwent the ring-opening reaction of a single spiro group, generating the open-closed state (ISO-ABPXOC), which showed characteristic absorption bands at 520 and 557 nm, accompanied by a significant enhancement of fluorescence at 592 nm. The second spiro ring remained stable under both light and mechanical stimuli and was difficult to open. By constructing a double­network structure (PMA-PU), the photochromic response of the material was significantly suppressed, while the mechanochromic behavior remained prominent, demonstrating its selectivity in response to stimuli. The study also revealed that the ISO-ABPX@PU system reversibly returned to the initial closed-ring state after heating at 40 ℃, indicating good reversibility. Theoretical calculations (CoGEF) further revealed that the force required to break the C―N bond of the spiro group was approximately 4.37 nN, which supports the experimentally observed single spiro ring-opening pathway from an energy perspective. This work not only expands the structural types of bis-spiro force-responsive molecules but also provides new molecular design strategies and experimental evidence for the development of intelligent mechanical sensing materials with reversible and multi-state response properties.