Bhoi, U.Kalyani, M.Ananthram, K.S.Saha, S.Acharya, A.Hassan, N.Raj, M.Tarafder, K.Ballav, N.2026-02-032025Journal of Materials Chemistry A, 2025, 13, 43, pp. 37396-3740220507488https://doi.org/10.1039/d5ta05740jhttps://idr.nitk.ac.in/handle/123456789/19983Azobenzene-based photo-switchable molecules have shown significant potential in stimuli-responsive systems, especially when incorporated into metal–organic frameworks (MOFs). This study reports thin films of lanthanide-based metal–organic frameworks (Ln-MOFs) with 4,4?-azobenzene dicarboxylic acid (H<inf>2</inf>ADA) as the organic linker – Tb-ADA, Eu-ADA, and Gd-ADA – using an electrodeposition method. Upon heating to 400 K, a reversible structural transition was observed via variable temperature grazing-incidence X-ray diffraction (GIXRD) and Raman spectroscopy, not due to trans–cis isomerization but rather a thermally-induced conformational twist of the ADA linker. Density functional theory (DFT) combined with molecular dynamics (MD) simulations supports this interpretation, revealing high-energy atropisomeric states stabilized by MOF confinement. Molecular doping of these films with 7,7,8,8-tetracyanoquinodimethane (TCNQ) significantly enhanced their electrical conductivity, increasing by two orders of magnitude at 400 K. This enhancement is attributed to improved ?–? stacking and charge-transfer interactions facilitated by the conformational twist. Temperature-dependent X-ray photoelectron spectroscopy (XPS) confirmed redox activity in TCNQ@Tb-ADA films, showing reversible conversion between Tb(iii) and Tb(iv), with back electron transfer at 400 K restoring Tb(iii). These findings introduce a new mechanism of thermally-driven conformational switching in MOFs and open avenues for developing responsive electronic materials based on azobenzene linkers. This journal is © The Royal Society of Chemistry, 2025Ada (programming language)AzobenzeneCharge transferConformationsCrystalline materialsDensity functional theoryElectron transitionsMolecular dynamicsOrganometallicsRedox reactionsThin filmsDicarboxylic acidDoping effectsMetalorganic frameworks (MOFs)Molecular dopingOrganicsPhoto-switchableStimuli-responsive systemsTetracyanoquinodimethaneThermally drivenThin-filmsSemiconductor dopingX ray photoelectron spectroscopy