Spin cross over may be induced by external stimuli such as light, heat, pressure, and magnetic fields, and provides an electronic origin responsible for corporative structural, electrical, magnetic, and/or optical alterations, with wide applications such as in memory, display, and sensor technologies. Based on recent experiments at HPCAT, together with electronic transport data, a research group observed a pressure-driven spin-cross-overs in the 2D honeycomb antiferromagnetic materials MnPS3 and MnPSe3 at room temperature. Applying pressure to the confined 2D systems leads to a dramatic magnetic moment collapse of Mn2+ (d5) from S = 5/2 to S = 1/2. Significantly, a number of collective phenomena were observed along with the spin change, including a large lattice collapse (∼20% in volume), and the formation of metallic bonding. Experimental evidence shows that all of these events occur in the honeycomb lattice, indicating a strongly cooperative mechanism that facilitates the occurrence of the abrupt pressure-driven spin transition. This result not only provides a new mechanism for novel switching materials that are applicable for sensor and memory devices, but also offers a platform to study the fundamental relationship between spin, orbital, lattice, and macroscopic functionalities under pressure. More in Y. Wang, et al., JACS, 138, 15751, 2016.