A travel though the atrane route, a versatile tool for the materials soft-synthesis: A twenty-five years perspective

The use of triethanolamine in the preparation of materials has been a fertile area of research during the last decades. It is used in sol-gel synthesis because of its ability to regulate pH, act as a structure-directing agent, and form atrane complexes with a wide variety of elements. The atranes harmonize the hydrolysis and condensation processes of inorganic species with their interaction with surfactant molecules or micelles for the obtention of homogeneous materials. This review describes the basic principles of the formation of atrane complexes and their use in material synthesis, followed by a compilation of the main examples found in the bibliography. These materials include pure and doped silicas by using micelles as porogen species (MCM-41, SBA-15, UVM-7, etc.), or without using template agents (TUD-1, UVM-11, etc.), non-silica oxides (Al2O3, TiO2, ZrO2, etc.), mesoporous phosphates and phosphonates, zeotypes (zeolites, aluminophosphates or silicoaluminophosphates, and layered double hydroxides. The atrane route shows a versatile approach for the preparation of these materials with up to three elements simultaneously. The focus of the review centers on the synthesis of the materials and the discussion of their main applications. These examples enrich with a discussion about the future perspective of the topic.