Exfoliation of layered porous metal-organic frameworks (MOFs) in a top-down fashion constitutes a successful approach to 2D metal-organic nanosheets (MONs), the analogs of graphene. The planned synthesis of layered MOFs is a challenging crystal-engineering exercise. Development of photochromic MONs that respond to light is a much bigger challenge; indeed, photochromic MONs are heretofore unknown. Here, we demonstrate engineering of layered MOFs and access to photochromic MONs. The strategy entails the use of programmed photochromic organic linkers characterized by a bulged core and metal-mediated self-assembly that occurs only in two dimensions, leading to layered MOFs. MONs exfoliated from such MOFs exhibit brilliant photochromism perceptible to the naked eye. We show that the MONs can be entrapped in an ormosil matrix for the development of polymer composites that display uncomplicated thermal bleaching kinetics. Thus, immobilization of photochromic 2D MONs containing void spaces in a polymer matrix for ophthalmic lens and other applications is compellingly demonstrated.

以自上而下的方式剥离分层的多孔金属有机骨架（MOF）构成了成功的2D金属有机纳米片（MONs）（石墨烯的类似物）的方法。分层MOF的计划合成是一项艰巨的晶体工程设计工作。响应光的光致变色MONs的开发是一个更大的挑战。实际上，迄今为止，光致变色的MON是未知的。在这里，我们演示了分层MOF的工程设计以及对光致变色MON的访问。该策略需要使用程序化的光致变色有机连接基，其特征是核心和金属介导的自组装仅在两个方向上发生，从而导致分层的MOF。从此类MOF剥落的MON表现出肉眼可感知的明亮的光致变色现象。我们表明，MONs可以被困在ormosil基质中，用于开发显示简单的热漂白动力学的聚合物复合材料。因此，令人信服地证明了用于眼科镜片和其他应用的在聚合物基质中包含空隙的光致变色2D MON的固定化。