biostudies-literatureNgo ATGeneralitat de CatalunyaMinisterio de Ciencia, Innovación y UniversidadesAgencia Estatal de Investigación"La Caixa" FoundationNational Research Foundation of KoreaHORIZON EUROPE Reforming and enhancing the European Research and Innovation systeme2420492https://www.ebi.ac.uk/biostudies/studies/S-EPMC12447033biostudies-literatureUnknown37(37)Spin-crossover (SCO) molecular-based switches have shown promise across a range of applications since their discovery, including sensing, information storage, actuators, and displays. Yet limited processability remains a barrier to their real-world implementation, as traditional methods for integrating SCO materials into polymer matrices are often complex, expensive, and prone to producing uneven material distributions. Herein, we demonstrate how 3D flow-focusing chemistry enables unprecedented control for the direct fabrication of SCO composite materials, addressing key challenges in processability, scalability, and cost. By using a 3D coaxial flow-focusing microfluidic device, we simultaneously synthesize [Fe(Htrz)₂(trz)](BF₄) and achieve its homogeneous incorporatiAdvanced materials (Deerfield Beach, Fla.)On-the-Fly Synthesis of Freestanding Spin-Crossover Architectures With Tunable Magnetic Properties.PMC12447033PID2020‐116612RB‐C33CEX2021‐001202NRF-2022R1C1C10073382021 SGR 00270LCF/BQ/PI24/12040015101047081CEX2021-001202NRF‐2022R1C1C1007338PID2020-116612RB-C33Diaz-Marcos JJang BNgo ATPons RPalacios-Corella MAromi GPuigmarti-Luis JSevim SPane SMayor TSAguila DVale JPMattera MfalseOn-the-Fly Synthesis of Freestanding Spin-Crossover Architectures With Tunable Magnetic Properties.Spin-crossover (SCO) molecular-based switches have shown promise across a range of applications since their discovery, including sensing, information storage, actuators, and displays. Yet limited processability remains a barrier to their real-world implementation, as traditional methods for integrating SCO materials into polymer matrices are often complex, expensive, and prone to producing uneven material distributions. Herein, we demonstrate how 3D flow-focusing chemistry enables unprecedented control for the direct fabrication of SCO composite materials, addressing key challenges in processability, scalability, and cost. By using a 3D coaxial flow-focusing microfluidic device, we simultaneously synthesize [Fe(Htrz)₂(trz)](BF₄) and achieve its homogeneous incorporati2025-01-01T00:00:00Z2025 Sep2026-06-03T15:29:56.767Z2026-04-29T03:12:41.843ZS-EPMC124470334051170510.1002/adma.202420492