Property-Enhanced Porphyrins

在自然光合作用中，太阳光被直接收集并传递给一对组织精确的卟啉，这对特殊的卟啉进行电荷分离。释放出来的电子随后被转化为化学能，用于生物体的发育。简而言之，光合作用消耗二氧化碳和水来产生富含能量的分子，并作为副产品输送氧气。虽然自然光合作用的效率值得怀疑，但它的分子组成部分是自组装的，由常见的无毒元素制成，其废物和副产品对环境有利。与我们最紧迫的环境挑战和不断增加的能源消耗有关，光合作用因此代表了完美的解决方案。然而，参与光合作用的分子结构的复杂性使得人工繁殖变得困难。然而，模拟光合作用的特定方面是可能的，研究人员已经集中精力开发碳捕获、生物燃料生产、水分解和光伏太阳能电池。这些人工光合作用的方法都包括一个天线系统来收集太阳光。就像在自然光合作用中一样，在这些人工系统中天线的作用可以由卟啉来发挥。在吸收入射太阳光能后的飞秒到皮秒内，卟啉经历了特定的机制。对这个项目特别感兴趣的是，我们将研究以下机制：内部转换，系统间交叉和直接电荷分离。这些弛豫路径中的每一个都决定了整个器件的转换效率。因此，了解能够增强这些特定途径的因素以开发更有效的设备是至关重要的。我们建议使用最新的激光技术来研究这些本质上超快的机制。更准确地说，我们将系统地研究一系列独特的单卟啉的原子取代、环弯曲和环扩展的影响，这些单卟啉彼此之间只有一个组成部分不同。同样，为了研究宿主电负性的影响，我们将研究卟啉嵌入复合物（称为细胞色素），它们因配体的性质和静电环境而彼此不同。该项目的结果是生成一系列物理特性，以增强内部转换、系统间交叉或电荷分离。有了这样的清单，我们就可以为特定的应用设计改进的卟啉。

In natural photosynthesis, the sun light is directly collected and conveyed to a pair of precisely organised porphyrins, the special pair, which undergoes charge separation. The liberated electron is then translated into chemical energy that is used to develop the living organism. In brief, photosynthesis consumes carbon dioxide and water to produce energy-rich molecules and delivers Oxygen as a by-product. While the efficiency of natural photosynthesis is questionable, its molecular building blocks are self-assembled, made from common non-toxic elements and its waste and by-products are environmentally favourable. In relation to our most pressing environmental challenges and ever-increasing energy consumption, photosynthesis thus represents the perfect solution.However, the complexity of the molecular architecture involved in photosynthesis renders it difficult to reproduce artificially. Nevertheless, it is possible to mimic specific aspects of photosynthesis and researchers have concentrated their efforts in the development of carbon capture, bio-fuel production, water splitting and photovoltaic solar cells. Each of these approaches to artificial photosynthesis includes an antenna system to harvest the sun light. Alike in natural photosynthesis, the role of the antenna in these artificial systems can be played by a porphyrin.Within femto- to picoseconds after absorbing the incoming sun light energy, the porphyrin undergoes specific mechanisms. Of particular interest to this project, we will investigate the following mechanisms: internal conversion, inter-system crossing and direct charge separation. Each of these relaxation pathways dictates the overall device's conversion efficiency. It is therefore crucial to understand the factors that can enhance these specific pathways to develop more efficient devices. We propose use the latest laser technology to investigate these mechanisms that are ultrafast by nature. More precisely, we will systematically study the effect of atom substitution, ring bending, and ring expansion in series of unique single-porphyrins that differs from one-another by a single constituent. Similarly, to investigate the effect of host electronegativity, we will investigate porphyrin-embedded complexes (called cytochromes) that differs from one another by the nature of their ligand, and thus electrostatic environment. The outcome of this project is to generate a list of physical characteristics that enhance either internal conversion, inter-system crossing or charge separation. With such list in hand we would then be able to design improved porphyrins for specific applications.