Fluorine doped tin oxide fto substrates

All solvents and commercially supplied chemicals were reagent grade and used as received without further purification. ZrCl₄ (99.99%), tetrabutylammonium hexafluorophosphate (n-Bu₄NPF₆, for electrochemical analysis, ≥99.0%), potassium hexafluorophosphate (KPF₆, ≥99.0%), 4-amino-3-hydroxybenzoic acid (97%), and fluorine-doped tin oxide (FTO) substrates (7 Ω/sq) were purchased from Sigma-Aldrich. Naphthalene-1,4,5,8-tetracarboxylic dianhydride (≥98.0%) was purchased from TCI. Glacial acetic acid, and N,N-dimethylformamide (DMF) (99.9%) were purchased from VWR. ¹H-NMR spectra were measured using a JEOL 400 MHz spectrometer at 293 K. The chemical shifts given in ppm are internally referenced to the residual solvent signal. MOF samples were digested prior to NMR measurement by addition of 25 µL of HF to a suspension of 10 mg of MOF in 0.575 mL of DMSO-d₆. ESI-MS data were collected on a Thermo LCQ XP Max mass spectrometer in negative mode with electrospray ionization. Electronic absorption spectra were measured using a Varian Cary 50 UV-Vis spectrophotometer. ATR-FTIR data were collected on a Bruker ALPHA FTIR Spectrometer from 4000 cm⁻¹ to 450 cm⁻¹ at room temperature.