trans12diarylethene

Trans12diarylethene is a member of the diarylethene family, a class of photochromic compounds characterized by two aryl groups linked through a central ethene bridge. In the open, trans form, the aryl groups lie on opposite sides of the C=C bond. This open form is typically colorless and can absorb light in the ultraviolet region.

The hallmark of trans12diarylethenes is reversible photochromism: exposure to ultraviolet light induces a cyclization reaction that closes the ring, extends conjugation, and produces a colored, closed-ring isomer. Irradiation with visible light or, in some derivatives, thermal processes can reverse the reaction, regenerating the colorless open form. The efficiency and wavelength range of switching depend on the substituents on the aryl rings, the presence of heteroatoms, and the overall molecular design. Substituents are often chosen to balance fast switching, high fatigue resistance, and stable two-state performance.

Key properties include the photostationary state under irradiation, switching quantum yields, thermal back-reaction rates, and fatigue resistance over many cycles. The open form tends to be thermally stable for many derivatives, while the closed form offers enhanced absorption in the visible region.

Applications of trans12diarylethene derivatives encompass molecular switches for data storage, smart materials, and optoelectronic devices, where light-controlled changes in absorption, color, or conductivity enable functionality. Synthesis typically involves assembling the diarylethene core through cross-coupling or condensation strategies to place the aryl units on the ethene bridge with the desired trans geometry. See also diarylethene, photochromism, and molecular switch.