Electron spin represents sensitive local probe of its environment and, thus, experiences strong/weak magnetic couplings. These can be thoroughly studied by electron spin resonance spectroscopy (ESR). In this context technical developments regarding pulsed/high magnetic field ESR spectrometers will be exploited in order to achieve new insight into the properties of the material under investigation. Therefore, within this project proposal several open questions are to be addressed: a) how to control the electron spin decoherence in a solid material when nuclear spin bath dynamics is a determining factor. Here, the hyperfine interaction in terms of nuclear spectral diffusion is in the focus of interest. Experimental model systems in which this channel of electron spin phase memory time decay is dominant will be purposely tailored; b) how to describe magnetic interactions in the crystal structure containing transition metal centres (metal-organic frameworks, coordination polymers);c) how to get information about rotational and translational dynamics of paramagnetic molecules in liquid systems by taking fully into account the effects of hyperfine, exchange, and dipolar interactions on their ESR spectra. These three non-trivial experimental tasks to be performed in amorphous, liquid and crystalline materials aim to extend the current limits of the existing theoretical models of electron spin-spin interactions. The expected goal is to extract as much as possible information from the ESR spectral analyses by proper manipulation of the electron spin states in an ESR experiment and possibly paw the way to influence the properties/design of materials.