Photo-Responsive Luminescent Lanthanide Complexes

光开关是一种化合物，当光线照射到化合物上时，它可以在两种稳定形式之间切换。一个常见的例子是一类称为偶氮苯的化合物。它们的工作原理类似于墙上的电灯开关，当施加刺激时，就会产生变化。在你家里有开关的情况下，刺激就是你的手，而变化是灯是开还是关。而在光开关的情况下，光是刺激，对于偶氮苯分子来说，输出是化合物长度的变化。光开关在传感器、电子设备以及医疗和生物应用中具有重要作用。例如，药物释放可以受到光的刺激，或者可以进一步了解反应灵敏的生物系统中涉及的机制，如离子通道。在更复杂的系统中使用光开关可以控制光开关的存在形式，从而控制它们与系统中其他化合物的相互作用。镧系元素是一组具有独特性质的元素。与生物物种的发光相比，一种特性是长寿命发光(发光的能力)。研究发现，这种发光可以通过其他化合物(生色团)的存在来控制，这些化合物可以改变发光的强度，也可以完全关闭发光。这种可切换的性质意味着发射可以根据相互作用的生色团的性质和状态而开启或关闭。这使得它们成为令人兴奋的生物成像化合物。它们的光学性质也使它们成为具有吸引力的化合物，用于光电子器件，如屏幕和显示器。该项目的目的是设计一种偶氮苯光开关影响镧系元素发光的系统。要做到这一点，必须在这两个物种之间进行能量转移。能量转移可以通过空间发生，并取决于两个物种彼此之间的距离有多近(Forster Resonance Energy Transfer)，或者直接通过一个键将两个物种连接在一起(Dexter Energy Transfer)。在可切换发光稀土络合物的工程中理解和确定能量转移助剂的机制。此外，需要考虑所选择的偶氮苯和稀土元素的类型。最近，人们发现当可见光照射到偶氮苯上时，开关长度会增加，这是很有希望的候选方案，因为可见光对周围环境的破坏比紫外线小得多。所选择的稀土元素必须具有良好的发光性能，并且为了与偶氮苯很好地工作，它必须能够在与引起偶氮苯开关的光相似的范围内吸收/发射光。将偶氮苯光开关与稀土络合物结合是化学中的一个新领域。这两个独立的系统都得到了很好的研究，但将两者结合在一个系统中的例子寥寥无几。通过合成一种新型的光敏性稀土络合物，其中的发光可以受偶氮苯的长度的影响，导致了许多新的和令人兴奋的发现的可能性。该项目属于ESPRC物理科学研究领域。

Photo-switches are chemical compounds that can switch between two stable forms when light is shone onto the compound. A common example is a class of compounds called azobenzenes. They work similarly to a light switch on the wall, when the stimulus is applied this induces a change. In the case of a switch in your home the stimulus is your hand and the change is whether the light is switched on or off. Whereas with the photo-switch, the light is the stimulus and the output is, in the case of azobenzene molecules, a change in length of the compound. Photo-switches have functions in sensors, electronic devices, and in medical and biological applications. For example drug release could be stimulated by light or the mechanisms involved in responsive biological systems, such as ion channels, can be further understood. Using photo-switches within a more complicated system can lead to control over the forms of photo-switch present and thus their interactions with other compounds in the system.Lanthanides are a group of elements which have unique properties. One property is long- lived luminescent (the ability to emit light), in comparison to the luminescence of biological species. Research has found that this luminescence can be controlled by the presence of other compounds (chromophores) which can either change the intensity of the luminescence or turn off the luminescence completely. This switchable property means that emission can be turned on or off depending on the nature and state of the interacting chromophore. This makes them exciting compounds for bio-imaging. Their optical properties also make them attractive compounds for optic-electronic devices, such as screens and displays.The aim of this project is to engineer a system in which the azobenzene photo-switch influences the luminescence of the lanthanide. For this to work, energy transfer between the two species must occur. Energy transfer can either happen through space and is dependent on how close the two species are relative to each other (Forster Resonance Energy transfer) or directly though a bond attaching the two species together (Dexter Energy transfer). Understanding and determining the mechanism of energy transfer aids in the engineering of a switchable luminescent lanthanide complex. In addition, the type of azobenzene and lanthanide chosen need to be considered. Recently azobenzenes have been discovered that switch length when visible light is shone onto them, these are promising candidates as visible light is much less destructive to surrounding enviroments than UV-light. The lanthanide chosen must have good luminescent properties and in order to work well with the azobenzene it must be able to absorb/emit light in a similar range to the light that induces switching in the azobenzene.Combining azobenzene photo-switches and lanthanide complexes is a new area in chemistry. Both separately are well researched, however there has only been a few examples when the two have been combined in a single system. Through synthesising a new photo-responsive lanthanide complex, in which the luminescence can be influenced by the length of the azobenzene leads to the possibility of many new and exciting discoveries. This project falls within the ESPRC physical sciences research area.