Violating the Aufbau principle: an efficient way to improve the stability of luminescent radicals

The Aufbau principle,also known as“building-up”principle,is a method of explaining the arrangements of electrons within atoms of different chemical elements.The principle was initially introduced by Danish physicist Niels Bohr and the basic statements include“Electrons will fill orbitals in increasing order of energy,and each orbital can contain a maximum of two electrons,and these must have opposite spins”[1].The principle is not perfect,and there are a few exceptions,but it is a very useful tool for learning about atomic and molecular structure.