Exploring the modification of a heteroleptic Iron(III) N-heterocyclic carbene complex

Abstract

In recent decades problem of using the finite resource, fossil fuels, as an energy source have caught more and more public attention. The usage of it produces side-products which in long term harms our environment. To combat the usage of such destructive resources, a more sustainable way of creation of energy needs to be implemented, to which scientist have set their eyes on solar cells.
Currently for the third generation of solar cells, DSSC (dye-sensitize solar cells), use ruthenium complexes for its high efficiency. But due to the metal’s scarcity, cost, and toxicity it has very limited usage. To make it more industrial friendly, another metal must replace ruthenium. Iron being ruthenium’s 3d-metal analogue can potentially to replace it, but due to the short living energy state LMCT (ligand to metal charge transfer) poses a problem for iron complexes. To combat it NHC (N-heterocyclic carbene) is being used to extend the lifetime of LMCT.
NHC complexes is quite a new area or chemistry, with very few complexes have been created and explored of their photochemistry. Some iron NHC complex, which was synthesised and explored by Wärnmark and co-workers showed promising photochemistry and applications. My research explores the synthetic pathways of some of those complexes to further advance it towards to potentially be attached to a DSSC.

Popular Abstract

Title: Popular science abstract: Synthesizing each step towards a possible “greener” future

In the modern society there is a drive to not stagnate and always strive towards a brighter future. This drive has made the lives of countless of people better, but without the knowledge of the importance of implementing a sustainable way to work with the resources “given” to us, will lead to major problems in the future. In a society which is growing rapidly, which also brings a rise in resource consumption, there are currently not enough resources available on earth to sustain our over consuming habits. To sustain our current lifestyle and population, we would need the equivalent of 1,75 earths 1. Some most important resources used are finite, such as fossil fuels.
Energy is currently what our society relies heavily on and is the backbone for our society to function. But the current worldwide way to create energy is to use oil (fossil fuels), coal, nuclear energy, and natural gases to create energy, but these methods are not sustainable and are harmful for the environment. The usage of fossil fuels leads to the production of greenhouse (CO2, CH4, N2O, etc.) gases, which in turn keeps the heat longer on earth. The anthropogenic greenhouse gas release gives a rise in temperature and will in the long run create a lot of problems for all communities around the world. The usage of nuclear energy creates a lot of radioactive waste which needs to be disposed safely and currently are just locked up under ground and have the risk of leakage of radioactive materials into our soils and waters.
Seeing how this is currently a big problem, maybe even the biggest problem in this generation. A quote by Paul McCartney sums up what many people have in mind “There must be a better way to make the things we want, a way that doesn’t spoil the sky, or the rain or the land.”.
One huge energy source that can be utilized is the energy emitted from the sun. The sun emits more energy to earth than what the whole human civilization consumes for a whole year. This energy ball is giving out free energy, if one can utilize it. The sun creates energy and is unaffected by whether we harvest its energy and is therefore a sustainable source of energy. Knowing this has led many to try to come up with a way to use its energy. Intrigued by nature’s own solar harvesting system, photosynthesis, the plants that utilize the solar energy, can covert the solar energy, CO2 and water to turn it into glucose, which it can utilize during nighttime for cellular respiration.
There are currently technologies which try to combat the problem such as solar cells, but due to its cost to either maintain or manufacture is too expensive it will act as a barrier to put it into everyday usage. There are some that are not too expensive but will run into the problem of efficiency of said technology. To solve these problems, some component in the solar cells needs to be exchanged into a more inexpensive material, this has led to a possibility of changing out the core component, ruthenium, in the dye in solar cells from a ruthenium complex to iron complex, which is the most earth abundant metal and much cheaper than ruthenium. With a cheaper cost, it may allow for a large-scale application.
Iron NHC (N-heterocyclic carbene) complexes have not only proven to be a possible candidate for solar cells, but have displayed its excellence in catalysis, which had led to hydrogen production 2, 3.
This is where I come in, by testing out different synthetic pathways towards modified ligands, the iron complex may be able to be enhanced and possibly unlocking its potential to bond with other molecules to ultimately be able to be put in solar cells.

• author: Tan, Niklas
• supervisor: Jesper Schwarz
• organization: Department of Chemistry
• course: KEML10 20231
• year: 2023
• type: M2 - Bachelor Degree
• subject: Chemistry
• keywords: Iron carbene, Metal organic chemistry, N-heterocyclic carbene complex, Synthesis
• language: English
• id: 9123452
• date added to LUP: 2023-06-20 11:49:59
• date last changed: 2023-06-20 11:49:59