Suprametallogels and uses thereof

The disclosure provides nanostructures (e.g., nanospheres and nano-paddlewheels) formed through transition metal-ligand (e.g., Pd(II)-, Ni(II)-, or Fe(II)-ligand of Formula (A)) coordination and junction self-assembly. The disclosure also provides supramolecular complexes that include the nanostructures connected by divalent linkers Y. The provided supramolecular complexes are able to form gels (e.g., hydrogels). The gels are suprametallogels and exhibited excellent mechanical properties without sacrificing self-healing and showed high robustness and storage modulus. The present disclosure further provides compositions (e.g., gels) that include the nanostructures or supramolecular complexes and optionally an agent (e.g., small molecule), where the nanostructures and the nanostructure moieties of the supramolecular complexes may encapsulate and slowly release the agent. The nanostructures, supramolecular complex, and compositions may be useful in delivering an agent to a subject, tissue, or cell, as super-absorbent materials, and in treating a disease (e.g., a genetic diseases, proliferative disease (e.g., cancer or benign neoplasm), hematological disease, neurological disease, gastrointestinal disease (e.g., liver disease), spleen disease, respiratory disease (e.g., lung disease), painful condition, genitourinary disease, musculoskeletal condition, infectious disease, inflammatory disease, autoimmune disease, psychiatric disorder, or metabolic disorder).