Mechanochemistry, a burgeoning field in green chemistry, has been utilized frequently to synthesize various organic molecules, metal complexes, coordination polymers (CPs) and metal-organic frameworks (MOFs) in the solid state from the reactants with very little or no solvent. These mechanical grinding reactions also resulted in successful isolation of materials that are inaccessible otherwise from solution. On the contrary, single crystal X-ray crystallographic technique is routinely used to study the solid-state structural transformations driven by thermal and photochemical methods. In the absence of single crystals, [2 + 2] photocycloaddition reactions can easily be monitored by NMR spectroscopy along with other suitable physical and analytical techniques. During mechanical grinding, several structural changes have been found to take place with the loss of single crystalline nature. Here from our personal perspective, we reviewed how this [2 + 2] cycloaddition reactions have been used effectively to monitor the structural changes induced by mechanochemical grinding. These structural transformations are caused by the pedal motion of olefin bonds, conformational changes of molecular fragments, movements of molecules, change in the composition by absorbing water from the atmosphere, anisotropic expansion of volume, rotation of helical coordination polymers, dimensionality change, loss of coordinating and lattice solvents and catalytic role of template molecules on the [2 + 2] photocycloaddition reactivity.

机械化学是绿色化学中的一个新兴领域，经常被用来在固态下用很少或没有溶剂的反应物合成各种有机分子、金属配合物、配位聚合物（CP）和金属有机框架（MOF）。这些机械研磨反应还成功地分离了原本无法从溶液中获得的材料。相反，单晶X射线晶体学技术通常用于研究热和光化学方法驱动的固态结构转变。在没有单晶的情况下，[2 + 2]光环加成反应可以通过核磁共振光谱以及其他合适的物理和分析技术。在机械研磨过程中，发现随着单晶性质的丧失，发生了一些结构变化。在此，从我们个人的角度，我们回顾了如何有效地利用[2 + 2]环加成反应来监测机械化学研磨引起的结构变化。这些结构转变是由烯烃键的踏板运动、分子片段的构象变化、分子的运动、从大气中吸收水而引起的组成变化、体积的各向异性膨胀、螺旋配位聚合物的旋转、维度变化、损失而引起的。配位和晶格溶剂以及模板分子的催化作用对[2+2]光环加成反应活性的影响。