1：Experimental Design and Method Selection:

The study involved synthesizing a nickel salicylaldimine complex with ether arms, characterizing it using various spectroscopic techniques, and testing its photocatalytic activity for H2 evolution under visible light irradiation. Theoretical DFT calculations were used to support mechanistic insights.

2：Sample Selection and Data Sources:

The catalyst was synthesized from commercially available reagents. Photocatalytic experiments used solutions of the catalyst, a photosensitizer (IrIII(ppy)2(dtbbpy)), and triethylamine as a sacrificial electron donor in methanol-water mixtures.

3：List of Experimental Equipment and Materials:

Key instruments included NMR spectrometers (Bruker AVANCE 400 MHz, Bruker AV-300), UV-vis spectrophotometer (Shimadzu UV-3600), elemental analyzer (Elementar vario MICRO cube), mass spectrometer (Q-TOF Premier LC HR), potentiostat (Biologic SP-300), gas chromatograph (Agilent 7890A), transient absorption spectrometer (Edinburgh Instruments LP920), EPR spectrometers (JEOL FA200, Bruker ELEXSYS), and computational software (Gaussian 09). Materials included nickel acetate, 2,3-dihydroxybenzaldehyde, 2-methoxyethoxy ether, 2,3-diamino-5-chloropyridine, solvents (methanol, acetonitrile, tetrahydrofuran), and chemicals from Sigma-Aldrich, Alfa-Aesar, and TCI.

4：9). Materials included nickel acetate, 2,3-dihydroxybenzaldehyde, 2-methoxyethoxy ether, 2,3-diamino-5-chloropyridine, solvents (methanol, acetonitrile, tetrahydrofuran), and chemicals from Sigma-Aldrich, Alfa-Aesar, and TCI. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The catalyst was synthesized in two steps, characterized, and used in photocatalytic H2 evolution experiments. Reactions were conducted in Schlenk tubes under argon, irradiated with a 300 W xenon lamp (λ > 420 nm). H2 production was quantified by GC. Spectroscopic studies (transient absorption, EPR, UV-vis) were performed to probe intermediates and kinetics. DFT calculations optimized geometries and mapped reaction pathways.

5：Data Analysis Methods:

Data were analyzed using software like Origin for kinetic fitting, Gaussian for DFT, and standard techniques for spectroscopic data. Turnover numbers were calculated based on moles of H2 produced per mole of catalyst.