Surface-anchored, oriented, monolithic Metal–Organic framework thin films: Surface and interface phenomena in crystalline MOF architectures

Metal–organic frameworks (MOFs) are crystalline materials renowned for their high porosity, chemical tunability, and modular design. The development of surface-anchored and oriented MOF thin films—particularly those fabricated by layer-by-layer or epitaxial growth—has shifted MOF research from powder studies to investigations of well-defined, surface-confined architectures. This review examines MOF thin films from a surface-science perspective, emphasizing how controlled growth at well-defined interfaces enables quantitative studies of structure–property relationships, interfacial charge and energy transfer, polarization-dependent optical responses, and dynamic guest–host interactions. The long-range crystallographic order achievable in these oriented films gives rise to band-structure effects and anisotropic transport phenomena that cannot be observed in MOF thin films prepared from powder-derived particles. Their monolithic and defect-controlled nature allows detailed characterization by advanced surface-sensitive techniques such as IRRAS, XPS, NEXAFS, UPS, nanoindentation, ellipsometry, and AFM, providing direct links between microscopic structure and macroscopic functionality. Beyond serving as model systems, oriented MOF films represent versatile platforms for adsorption, catalysis, and electronic coupling at hybrid organic–inorganic interfaces. The review also highlights how computational modeling, machine learning, and AI-guided synthesis accelerate the rational design of interface-engineered MOF architectures with tailored properties.