Non-covalent interactions taking place in solution are essential in chemical and biological systems. The solvent environment plays an important role in determining the geometry and stability of interactions. This thesis examines aromatic stacking interactions, alkyl-alkyl interactions, edge-to-face aromatic interactions, halogen bonds and hydrogen…hydrogen interactions in solution. Chapter 1 briefly introduces the different classes of non-covalent interactions, in addition to the state-of-the-art models and methods for investigating these weak interactions. The chapter finishes with a focus on dispersion interaction in alkanes and arenes. Chapter 2 investigates dispersion interactions between stacked aromatics in solution using a new class of complexes and thermodynamic double mutant cycles (DMCs). In extended aromatics, dispersion was detected as providing a small but significant contribution to the overall stacking free energies. Chapter 3 concerns the experimental measurement of alkyl-alkyl dispersion interactions in a wide range of solvents using Wilcox torsion balances. The contribution of dispersion interactions to alkyl-alkyl association was shown to be very small, with DMC, QSPR method and Hunter's solvation model. Chapter 4 studies edge-to-face aromatic interactions in series of solvents. In the open system, edge-to-face aromatic interactions were found to be sensitive to the solvent environment. The solvent effects were complicated and cannot be rationalised by a single parameter. Further analysis is needed. Chapter 5 describes a preliminary approach to investigate organic halogen…π interactions in solution using supramolecular complexes and torsion balances. Chapter 6 is a preliminary investigation of the ability of hydrogen atoms to act as H bond acceptors in silane compounds. Computations and 1H NMR demonstrated a weak interaction between silane and perfluoro-tert-butanol.

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Un pont de dihidrogen (dihydrogen bond,DHB) és un tipus de pont d'hidrogen atípic que s'estableix entre un hidrur metàl·lic i un donador de protons com un grup OH o NH. Els ponts de dihidrogen són claus en les característiques geomètriques i altres propietats de compostos que en presenten tan de molècules petites com el dímer de NH3BH3, com d'estructures superiors més complicades com complexes metàl·lics o sòlids. Poden ser útils aplicats a certes molècules o síntesis moleculars per a obtenir nous materials amb propietats o característiques fetes a mida. El treball d'aquesta tesi està orientat a millorar la comprensió dels ponts de dihidrogen, aprofundint en certs aspectes de la seva naturalesa atòmica/molecular utilitzant mètodes teòrics basats en la química física quàntica. / A dihydrogen bond (or DHB) is a kind of unconventional hydrogen bond, established between a metal hydride bond and a proton donor like OH or NH. They are the key to important structure features and properties in compounds which have them. They can be responsible for the specific geometry not only of small molecules like the NH3 BH3 dimer, but also of higher structures like metallic complexes or solids. It is in this fashion that dihydrogen bonds can be profitable, up to a plausible extent, when they can be used in certain molecules or certain syntheses to obtain a new material with particular or even tailored properties or geometries. The work developed in this thesis is aimed to have a deeper understanding of dihydorgen bonds, deepening on certain aspects using theoretical methods.