Recent progress on the design and development of diaminotriazine based molecular catalysts for light-driven hydrogen production

[Display omitted] •Recent progress in diaminotriazine based molecular catalysts is discussed.•An explicit comparison has been made for the diaminotriazine based molecular catalysts.•DAT based ligands and their molecular catalysts strategies have been analyzed and discussed.•The mechanism of HER has been clearly explained by providing some evidences.•The role of each component for HER has been described and discussed.•Emerging and perspective trends of molecular catalysts in the next decade is outlined. With the depletion of fossil fuels and an increase in global warming, developing clean and sustainable energy resources is imperative. Among the different possible eco-friendly energy resources, H2 has a bright perspective since it is a clean, environmentally benign, and sustainable energy carrier. Sunlight-triggered H2 evolution reaction (HER) is a compelling solution to harvest the abundant and inexhaustible power of solar energy in chemical bonds in H2 molecules. At present, the primary concern relies upon the design of novel and efficient photocatalysts for the profitable production of H2. The article briefly reviews the recent development of molecular complexes and organic frameworks (e.g., MOFs, COFs, HOFs) as prominent H2 production photocatalysts, including their essential characteristics, mechanism of photocatalytic HER over these materials, and photocatalytic systemsrecently developed. More importantly, studies on the design of diaminotriazine-based molecular complexes – an advanced photocatalyst class for light-driven H2 production are reviewed and discussed in detail. This article encloses the following discussion about diaminotriazine-based ligands, and their complexes: (i) advances in structures and properties, (ii) preparation strategies, and (iii) diaminotriazine based molecular catalysts developed for HER. Our recent works on this photocatalyst class are also highlighted, in which diaminotriazine-based catalysts developed by our group are compared with previous molecular catalysts in terms of structure and catalytic activity. The review is expected to provide a crucial basis and significant ideas contributing to the development of efficient molecular catalysts for H2 production.