# Electronic Properties of Electron-Deficient Zn(II) Porphyrins for HBr Splitting
## 2 Experimental
### Syntheses
#### 2.2.11 Porphyrin 2  
In a dry Schlenk tube under N\({}_{2}\) flow, 0.0632 mmol (67.1 mg) of ZnTPPF\({}_{19}\)-click-CHO were dissolved in CHCl\({}_{3}\) (5 mL), then 0.316 mmol (5 eq.) of cyanoacetic acid and piperidine (0.02 mL) were added under stirring. The mixture was refluxed overnight, then the solvent was evaporated in vacuo and the crude residue was washed with a saturated aqueous solution of NaCl (20 mL) and extracted with CH\({}_{2}\)Cl\({}_{2}\) (3 \(\times\) 10 mL). The organic phase was dried over Na\({}_{2}\)SO\({}_{4}\), and the solvent was removed in vacuo. The crude residue was purified by gravimetric chromatography (CH\({}_{2}\)Cl\({}_{2}\):CH\({}_{3}\)OH = 9:1), affording 64.0 mg of porphyrin 2 (80% yield) as a purple powder. \({}^{1}\)H-NMR (400 MHz, THF-d\({}_{8}\), 25 \({}^{\circ}\)C) \(\delta\), ppm: 9.23 (2H, d), 9.18 (1H, s), 9.11 (5H, m), 8.55 (1H, broad s), 8.32 (4H, broad s). \({}^{19}\)F-NMR (400 MHz, THF-d\({}_{8}\), 25 \({}^{\circ}\)C) \(\delta\), ppm: \(-\)138.18 (2F, dd), \(-\)139.48 (6F, dd), \(-\)149.38 (2F, d), \(-\)156.15 (3F, dd), \(-\)165.12 (6F, td). ESI-ITMS: \(m/z\) calculated for C\({}_{56}\)H\({}_{15}\)F\({}_{19}\)N\({}_{8}\)O\({}_{2}\)Zn = 1258.17; found = 1255.82 [M-1]\({}^{-}\). Photoanode Preparation  
Colloidal SnO\({}_{2}\) paste was prepared by following a literature procedure [19]. Fluorine tin oxide glass (FTO TEC 8, Pilkington, St Helens, UK) cleaning was performed by sonicating the slides in an Alconox(r) solution for 10 min and in 2-propanol for a further 10 min. After blow-drying the resulting FTOs, a thin blocking/adhesion layer of SnO\({}_{2}\) was obtained by spin coating a 0.3 M SnCl\({}_{2}\) solution in ethanol, followed by heating at 500 \({}^{\circ}\)C for 15 min in air. After cooling these substrates at room temperature, the SnO\({}_{2}\) paste was blade cast onto them to obtain a wet film, which was fired at 500 \({}^{\circ}\)C for 30 min, leading to a mesoporous network composed of SnO\({}_{2}\). [9] Finally, an overlayer of TiO\({}_{2}\), serving both as a passivation layer and to improve dye adsorption, was formed by immersion of the SnO\({}_{2}\) films in an aqueous 0.4 M Titanium tetrachloride (TiCl\({}_{4}\)) solution for 12 h, followed by rinsing with DI water and heating at 450 \({}^{\circ}\)C for 30 min. Staining of the resulting photoanodes was carried out by immersion in a 2 \(\upmu\)M solution of each porphyrin in a toluene/ethanol 1:1 mixture containing \(2\times 10^{-5}\) M chenedooxycholic acid as an anti-aggregating agent. Preferred adsorption times were 6 h for **1** and 14 h for **2**. Spectroscopic and Electrochemical Measurements in Solution  
Electronic absorption spectra of porphyrins **1** and **2** in solution were recorded at room temperature in toluene, using a Shimadzu UV3600 spectrophotometer and quartz cuvettes with 1 cm optical path length. Photoluminescence experiments were carried out at room temperature, and photoluminescence quantum yields were measured with a C11347 Quantaurus-QY Absolute Photoluminescence Quantum Yield Spectrometer (Hamamatsu Photonics K.K., Shizuoka, Japan), equipped with a 150 W Xenon lamp, an integrating sphere, and a multi-channel detector. Steady state emission and excitation spectra and photoluminescence lifetimes were obtained with a FLS 980 spectrofluorimeter (Edinburgh Instrument Ltd., Livingston, UK). Continuous excitation for the steady state measurements was provided by a 450 W Xenon arc lamp. Photoluminescence lifetime measurements were performed using an Edinburgh Picosecond Pulsed Diode Laser EPL-445 (Edinburgh Instruments Ltd.), with central wavelength of 442.2 nm and repetition rate of 20 MHz, by Time-Correlated Single-Photon Counting method (TCSPC). The voltammetric studies of porphyrins in solution were performed in a 4 cm\({}^{3}\) cell, with \(5\times 10^{-4}\) M solutions in DMF (Aldrich, 99.8%) with 0.1 M tetrabutylammonium perchlorate (TBACIO4, Fluka) as the supporting electrolyte. The solutions were de-aerated by N\({}_{2}\) bubbling.