Metal–organic frameworks (MOFs) are useful synthetic materials that are built by the programmed assembly of metal nodes and organic linkers¹. The success of MOFs results from the isoreticular principle², which allows families of structurally analogous frameworks to be built in a predictable way. This relies on directional coordinate covalent bonding to define the framework geometry. However, isoreticular strategies do not translate to other common crystalline solids, such as organic salts^3,4,5, in which the intermolecular ionic bonding is less directional. Here we show that chemical knowledge can be combined with computational crystal-structure prediction⁶ (CSP) to design porous organic ammonium halide salts that contain no metals. The nodes in these salt frameworks are tightly packed ionic clusters that direct the materials to crystallize in specific ways, as demonstrated by the presence of well-defined spikes of low-energy, low-density isoreticular structures on the predicted lattice energy landscapes^7,8. These energy landscapes allow us to select combinations of cations and anions that will form thermodynamically stable, porous salt frameworks with channel sizes, functionalities and geometries that can be predicted a priori. Some of these porous salts adsorb molecular guests such as iodine in quantities that exceed those of most MOFs, and this could be useful for applications such as radio-iodine capture^9,10,11,12. More generally, the synthesis of these salts is scalable, involving simple acid–base neutralization, and the strategy makes it possible to create a family of non-metal organic frameworks that combine high ionic charge density with permanent porosity.

金属有机框架（MOF）是有用的合成材料，由金属节点和有机连接体 ¹ 的程序组装而成。 MOF 的成功源于等网状原理 ² ，该原理允许以可预测的方式构建结构相似的框架系列。这依赖于方向坐标共价键来定义框架几何形状。然而，等网状策略并不能转化为其他常见的结晶固体，例如有机盐 ^3,4,5 ，其中分子间离子键的方向性较差。在这里，我们展示了化学知识可以与计算晶体结构预测 ⁶ （CSP）相结合来设计不含金属的多孔有机卤化铵盐。这些盐框架中的节点是紧密堆积的离子簇，引导材料以特定方式结晶，正如在预测的晶格能量景观上存在明确的低能量、低密度等网状结构尖峰所证明的那样 ^7,8 。这些能量景观使我们能够选择阳离子和阴离子的组合，形成热力学稳定的多孔盐框架，其通道尺寸、功能和几何形状可以先验预测。其中一些多孔盐吸附分子客体（例如碘）的量超过了大多数 MOF，这对于放射性碘捕获等应用可能很有用 ^9,10,11,12 。更一般地说，这些盐的合成是可扩展的，涉及简单的酸碱中和，并且该策略使得创建一系列将高离子电荷密度与永久孔隙率结合起来的非金属有机框架成为可能。