This project focus on the application of advanced mass spectrometry and laser pumped IR spectroscopy to the study of charged supramolecular adducts and single molecules in the gas phase. The experimental investigation will be supported by theoretical calculations performed at the DFT, QM or MD level of theory depending on system requirements. Main topic is the fundamental question concerning the nature and the strength of the non-covalent interactions responsible of the actual conformation of free charged molecules and of supramolecular organization within ionic clusters. As chemists believe in structure-reactivity relationships, knowing the structure of single molecules and adducts is the first, most important step in the elucidation of their chemical behavior. Investigation of these topics in the gas phase offer an exclusive, ¿intimate¿ view of the non-covalent interactions involved, without any interference by environmental factors, whose role in condensed phase can affect the intrinsic behavior of the system. Because of their ubiquitous nature, the effect of environmental factors is difficult to evaluate in condensed phase, but it clearly emerges from the comparison of gas-phase experiments on the same system.
Studying non-covalent interactions is of paramount importance in view of their involvement in several applied sciences (e.g. biochemistry, catalysis, separation sciences, sensors, chemical logic gates, molecular machines, nanomaterials, drugs design, and many others), as well as in fundamental questions of chemical knowledge (theoretical and computational chemistry).
The present project is aimed to investigate:
1) Protonated 5-Hydroxymethylfurfural (mutagenic derivative of a common food contaminant) and its adducts with selected amino acids.
2) The alkaline metal cation affinity of quercetin, a natural dye potentially useful as Li+ trapper in ecofriendly batteries.
3) The capability of cucurbit[7]uril to analytically discriminate epimers of aminosugars.
Over the last twenty years, most research activity of our group focused on the gas phase investigation of several aspects of intra-and intermolecular interactions occurring in different systems (including chiral ones) that have been selected on the ground of their archetypal importance from the structural standpoint, but even for their crucial importance in several biochemical processes. Ion chemistry is a fundamental field that is expected to be in close contact with other branch of knowledge. As presented in the previous section, the molecular systems proposed in this project are apparently heterogeneous: 5-hydroxymethylfurfural, metal-ion complexes of quercetin, and non covalent complexes of different epimers of aminosugars with the cavity of cucurbit[7]uril. The trait d¿union crossing this proposal is the study of non covalent interactions, providing an unique contribution to the comprehension of molecular recognition processes that cannot be investigated in condensed phase, where environmental factors can affect or even overcome the development of the intimate forces involved.
Indeed, the spectroscopic investigation of non covalent complexes of 5-HMF with selected biomolecules offer the opportunity to point out the factors determining the reactivity of this food contaminant, that has been identified as a carcinogenic molecule.
The affinity of quercetin and other natural dyes towards lithium ion can be fully understood by characterizing the coordination site(s) in the gas phase and comparing the structural features of the Li+-complexes with that of other metal cations. These findings can provide a safe feedback to biomaterial designers, to drive the choice of natural compounds as efficient lithium ion energy storage.
The strong affinity of cucurbit[7]uril towards aminosugars can be exploited to develop a fast and reliable analytical approach to discriminate aminosugar epimers through mass spectrometry. Furthermore the chirality effects on noncovalent interactions involved in the relative stabilization of diastereomeric supramolecular adducts will be analyzed in terms of their relative energy (theoretical approach), as well as their structural and stereoelectronic implications (IRMPD spectroscopy).
It should clearly emerge how the importance of the molecular recognition, from the one end crosses a large number of pratical fields, and on the other end, its fundamental implications are continuously stimulated by the synthesis of new artificial receptors and biomaterials.