To prepare new functional covalent architectures that are difficult to synthesize using conventional organic methods, we developed a strategy that employs metal-organic assemblies as precursors, which are then reduced and demetalated. The host-guest chemistry of the larger receptor thus prepared was studied using NMR spectroscopy and fluorescence experiments. This host was observed to strongly bind aromatic polyanions in water, including the fluorescent dye molecule pyranine with nanomolar affinity, thus allowing for the design of an indicator-displacement assay.Subcomponentself-assemblyallowsthesynthesisofincreasingly complex architectures, from helicates [1] to metal-organic capsules, [2] wherein dynamic covalent imine bonds (C = N) [3] and coordinative nitrogen-metal bonds (N!M) are formed during the same self-assembly process. This approach offers several advantages: A large increase in molecular complexity can be achieved in a single reaction step; a structure can be rapidly modified with minimal synthetic effort to optimize a desired property, and the subcomponents employed are often either commercially available or straightforward to synthesize.[2f] This strategy is thus complementary to the use of metal-carbon bonds to generate complex organometallic structures. [4] This work demonstrates the utility of subcomponent selfassembly as a means of preparing new functional covalent architectures that would be difficult to synthesize using conventional organic methods. Herein, metal-organic assemblies are used as precursors for the synthesis of metal-free complex organic structures. The imine linkages could be reduced to secondary amines through treatment with borohydride [5] to obtain purely covalent architectures. These robust new organic structures overcome some of the limitations of their metal-organic analogues, such as insolubility in water, poor stability in acidic or basic media, and lack of flexibility, thus enabling adaptive binding to prospective guest molecules.This method thus builds upon and complements a recently reported strategy wherein dynamic imine structures that do not contain metal ion templates were hydrogenated.[6] The involvement of metal ion templates allows for additional structural complexity to be introduced [7] and provides additional information to guide the self-assembly process. Our method allows the "capture" of this additional structural complexity to achieve new functions: nanomolar affinity for the fluorescent dye molecule pyranine (K d = 1.2 10 À9 m), and the design of an indicator-displacement assay [8] involving the pyranine host complex.The supramolecular chemistry of anions is a topic of continuing interest because of the vital role of anions in many chemical and biological processes.[9] In recent years, there have been many reports on the design and preparation of three-dimensional covalent receptors for anion binding. [9c, 10] However, yield optimization and isolation of macroscopic amounts of products for further studies can be rendered difficul...