Experimental challenges in organic synthesis for the evaluation of molecular structures and for the study of non-covalent interactions

In the last decades, the awareness of the importance of organic chemistry has been growing amongst researchers working in the most diverse fields of science. Indeed, much of the current welfare of advanced societies is due to recent huge leaps in the comprehension of the behaviour of matter. In particular, material and life sciences have been undergoing an impressive development, and their academic results keep on having a steady growing impact on our daily routine, albeit most people are not aware of the prompt repercussions of academic research on their own lives. Carbon plays a pivotal role in material and life sciences, hence nowadays both skills and knowledge of organic chemists are fundamental. However, the interpretation of experimental data is often non-trivial, and a theoretical analysis – able to summarize, predict and understand the plethora of experimental data – is important. Hence, computational studies are highly recommended to guide it, since they can (i) anticipate otherwise unpredictable results, (ii) indicate new directions for further investigation, and (iii) readjust misconceptions and false perceptions. The three main aims of this thesis are: i. the exploitation of interdisciplinary approaches involving organic chemistry and state-of-the-art computational methods to gain deeper insights into the studied molecular systems, with special attention to molecular structures; ii. the assessment of the importance of organic chemistry in two apparently unrelated fields, namely astrochemistry and biochemistry; iii. the evaluation of the effects of non-covalent interactions on molecular geometry, whose detailed study is important for both astrochemical and biochemical purposes, but also in the field of catalysis. The presentation of the previous goals will be as unitary as possible, since such aims are intimately interconnected with each other. Finally, some interesting results concerning photocatalysis – a rapidly growing research field of organic chemistry – will be discussed. In the next years, this field is expected to gain unprecedented development with the fruitful interplay between experimental and theoretical chemistry. In particular, the composition of the reaction mixture is known to play a pivotal role in the outcome of the process, due to the reciprocal interactions at the molecular level between the reaction partners. Furthermore, such interactions are also strongly affected by the nature of the solvent. More specifically, three main projects will be discussed. Project 1: Phenylmethanimine The successful endeavour enabling the generation and characterization of an elusive aromatic imine, i.e. phenylmethanimine (PMI), will be described. PMI was chosen because it is expected to be an astrochemically relevant species. Project 2: Fluorothreonine A full account concerning synthesis and characterization of the only fluoro amino acid of natural origin discovered so far, namely 4-fluorothreonine, will be reported. Fluorothreonine was chosen as a test case for the evaluation of the effects of fluorination on molecular properties. Indeed, fluorothreonine is expected to feature interesting conformational behaviours due to peculiar non-covalent interactions involving fluorine. Project 3: Bismuth-mediated photocatalysis A bismuth-mediated photocatalytic reaction in aqueous conditions will be described. Bismuth was chosen as a heavy member of the pnictogens, which are known to be involved in interesting non-covalent interactions.