Analysis of the MD simulations (validated by comparisons to experimental results, Figure ) provide insight to the structural properties of H 2 O within the zeolite frameworks and its dependence on interactions among H 2 O molecules, (SiOH) x defects, and the siloxane pore walls. Ti-FAU-F, on average, stabilizes ~118 H 2 O molecules per unit cell, while Ti-BEA-F contains an average of ~5 H 2 O molecules per unit cell (Table ). In comparison, Ti-MFI-F and stabilizes only ~ 2 H 2 O molecules per unit cell. Strikingly, H 2 O molecules do not enter the Si-CDO-F structure over throughout the course of our 1 µs MD simulations. These low uptakes are qualitatively consistent with reported H 2 O uptakes into these hydrophobic frameworks. The MD simulations indicate that the numbers of H 2 O molecules stabilized within hydrophilic variants of Ti-FAU, -BEA, and -MFI differ only slightly from values in hydrophobic samples (Table ) but Si-CDO-OH possesses ~2 H 2 O per unit cell. Given the small change in the overall volume per unit cell between hydrophilic and hydrophobic samples of the zeolites, the number of water molecules per unit cell for these variants are expected to be similar. However, the hydrophilic samples preferentially stabilize H 2 O molecules near defects and increase the local density of water. Conversely, the hydrophobic samples containing similar number of water molecules would exhibit higher fluctuations in the water molecule positions in absence of any stabilizing interaction with the pore. Together, these data suggest H 2 O completely fills the supercages of FAU but does not fully occupy the sub-nanometer channels of BEA, MFI, and CDO. Instead, H 2 O molecules coalesce into discrete structures distributed throughout these porous architectures. Speciation of the HBs to H 2 O molecules within the MD simulations reveal that the percentage of HBs that H 2 O forms with surface functions (i.e., SiOH or Si-O-Si linkages) increases as characteristic pore diameters decrease and (SiOH) 4 density increases (Tables and). HBs between H 2 O molecules and SiOH functions account for 1% and 6% of all HB interactions within Ti-FAU-F and Ti-FAU-OH, respectively. In contrast, much larger percentages of HBs involve SiOH groups within Ti-BEA-OH (16%), Ti-MFI-OH (35%), and Si-CDO-OH (60%). Further, these trends and further analysis indicate H 2 O molecules form one-dimensional chains (primarily dimers through tetramers) with multiple points of interactions with (SiOH) x defects within BEA, MFI, and CDO structures. The prevalence and structure of these oligomeric chains agrees with IR spectra that show large fractions of H 2 O exists in DA hydrogenbonding configurations inside Ti-BEA, Ti-MFI, and Si-CDO-OH (Figs. and). In summary, concurrent interpretation of the infrared spectra of ν(O-H), parity between <N HB > IR and <N HB > MD , and simulated distributions of HB configurations strongly suggest that H 2 O forms three-dimensional bulk-like structures within FAU but largely one-dimensional oligomers within BEA, MFI, and CDO, the density of which should vary with the activity of liquid H 2 O and density of silanol groups.