Transition to a new era with light-based hydrogen production for a carbon-free society: An overview

Dye–catalyst dyads for photoelectrochemical water oxidation based on metal-free sensitizers

“…The desired product was isolated as a white solid (383 mg, 0.65 mmol) with 51% yield. 1 9-(Pyridin-4-ylmethyl)-3,6-bis(5-(4,4,5,5-tetramethyl-1,3-dioxolan-2-yl)thiophen-2-yl)-9H-carbazole (3a). Compound 2 (270 mg, 0.46 mmol) was dissolved in 12 mL of anhydrous THF in a two-necked ask under N 2 atmosphere, then the solution was cooled to 0 C using an ice bath, and NaH 60% (36 mg, 0.92 mmol) was added and the solution was stirred at 0 C for 1 h. Meanwhile in a becher 4-(bromomethyl)pyridine hydrobromide (177 mg, 0.70 mmol) was dissolved in 25 mL of a saturated aqueous solution of K 2 CO 3 and 25 mL of Et 2 O.…”

“…The light yellow precipitated solid (285 mg 0.42 mmol) was ltered and washed with Et 2 O achieving a 91% yield. 1 9-(Pyridin-3-ylmethyl)-3,6-bis(5-(4,4,5,5-tetramethyl-1,3-dioxolan-2-yl)thiophen-2-yl)-10H-carbazole (3b). Compound 2 (383 mg, 0.65 mmol) was dissolved in 10 mL of anhydrous THF in a two-necked ask under N 2 atmosphere, then the solution was cooled to 0 C using an ice bath and NaH 60% (90 mg, 2.21 mmol) was added.…”

“…The desired product was isolated as a light-yellow solid (420 mg 0.61 mmol) with 95% yield. 1 H NMR (400 MHz, CDCl General procedure A for the cleavage of the protective group for the aldehydic functionality (iii). Pinacol ester precursor was dissolved in 10% HCl/THF (1 : 2).…”

“…The desired product was isolated as a yellow solid (91 mg, 0.19 mmol) with 91% yield. 1 5,5 0 -(9-(Pyridin-3-ylmethyl)-9H-carbazole-3,6-diyl) bis(thiophene-2-carbaldehyde) (4b). Product 4b was synthetized according to general procedure A for the cleavage of the protective group using product 3b (420 mg, 0.61 mmol), 27 mL 10% HCl/THF (1 : 2).…”

“…In the search for an alternative to fossil fuels, hydrogen is gaining increasing interest in the scientic community and the automotive-aerospace sector, because its combustion generates only water with a zero-carbon footprint. [1][2][3] Hydrogen is today mainly produced from methane via the steam-reforming reaction. 4 It is, therefore, critical to develop sustainable and clean processes to produce hydrogen.…”