Nat. Commun.: you may not believe that the color of light can determine the reaction products

In the existing chemical reactions, it is very meaningful to control the reaction process accurately through various external conditions, which is also the "Holy Grail" that chemists have been pursuing Optical control is a common idea, because light can be highly controllable in time and space, which meets the requirements of precision Therefore, several photoinduced reactions have been used in 3D laser lithography and protein preparation It is important that the process of photoinitiation provides a new way to carry out photochemical reactions in an orthogonal way (so-called λ orthogonal) by activating selected chromophores Each chromophore has a different specific wavelength for the mapping It is interesting to use different colors of light as a switchable door to choose thermal activation or optical activation, which seems to have not been studied in depth So far, only a few light control systems have been designed to induce isomerization by external light stimulation, so as to regulate the reactivity of chromophores, but they are not allowed to completely turn off their thermal reactivity Although it has been reported that the study can switch between two reaction paths, its thermal reactivity can not be stopped at all Therefore, the new idea is that thermal reactivity can be completely replaced by photoreactivity Hannes Houck, Filip Du Prez and Christopher Barner kowollik, scientists from Australia, Germany and Belgium, reported a new type of photochemical reaction They demonstrated the reaction principle of triazolinone These substances are commonly used as coupling agents in biomedical and polymer research They can be used for Diels alder reaction and addition reaction The team reports that ultraviolet light causes a Diels alder reaction with photodiodes On the contrary, if it is kept dark at room temperature, the addition reaction will take place However, under the visible light irradiation, the reactants will be activated, photopolymerization will take place, and all reactions will be stopped If the light is turned off again and kept dark, the photopolymerization products will decompose into monomers and continue the addition reaction The phenomenon of light switching TAD reaction (source: Nat Commun.) can be used to connect small molecules with compounds of interest in biomedicine, and conduct fine control It also provides the possibility of designing super-high resolution photoresist for 3D laser lithography In the past, it is always possible to switch between the opening and closing of the reaction, but it depends on the temperature as the control factor Light not only has more precise control over time, but also can be turned on and off instantaneously It can also be controlled spatially, covering specific areas so that they are always in shadow, while other parts can be exposed to light The response to light of different wavelengths will increase another level of control This will provide more complex feature settings The common goal of photochemists is to react with light It is not easy to cut off the chemical reaction with light, especially it needs to be reversible But if this can be done, there will be surprising new applications For example, sub micron level lithography pattern Paper link: https:// corresponding author: http://