This thesis delves into the properties of small molecular species in various confined environments in condensed phase using non-linear infrared spectroscopy. Chapter 1 provides an overview of the relevant confined systems and methodologies applied, while Chapters 2 and 3 provide the description of theoretical background and experimental techniques. In Chapter 4, we explore the ultrafast dynamics of water molecules enclosed in small clusters formed by 2,6-lutidine near the lower solution critical temperature (LSCT) using mid-infrared pump-probe spectroscopy. Chapter 5 reports on the vibrational coupling in aqueous acetate and terephthalate ions using two-dimensional infrared spectroscopy (2D-IR). In Chapter 6, we introduce a novel synthetic approach for preparing polycrystalline UiO-66 metal-organic framework membranes superimposed on flat c-sapphire substrates and investigate the vibrational interactions of terephthalate linkers in this material using information from Chapter 5. Finally, in Chapters 7 and 8, we use vibrational sum-frequency generation (VSFG) spectroscopy to investigate the absorption and orientation of carboxylate ions with different substituents at the water-air interface.