C6r6

C6r6 is a hypothetical molecular motif invoked in theoretical chemistry and in science fiction to describe a sixfold-symmetric macrocycle assembled from six carbon-rich rings with six substituent groups R. The name reflects a modular, sixfold framework rather than a single established compound, and its exact realization is intentionally not fixed.

In conceptual models, each ring is connected by flexible linkers at defined positions, yielding a persistent sixfold axis and variable connectivity; depending on linkers, C6r6 may adopt planar or curved geometries, with possible D6h or C6 symmetry. The structure is discussed as a thought experiment to explore how macrocyclic topology influences properties such as conjugation and rigidity.

No experimental realization is reported; proposed synthetic routes involve iterative macrocyclization with protecting-group strategies, followed by post-assembly fusion, but these remain speculative. The lack of a concrete synthesis means that practical reactivity and stability are not established.

Potential properties include a rigid conjugated framework and tunable electronic absorption, which in theory could enable distinctive optical or host-guest behavior. Hypothetical applications span molecular sieves, fluorescence materials, and components of larger supramolecular assemblies, illustrating how modular sixfold systems might contribute to materials design in principle.

The term appears in theoretical discussions and in speculative fiction from the early 21st century onward; as an aid to thinking about symmetry, topology, and modular design. See also macrocycle, polycyclic aromatic hydrocarbon, cycloparaphenylene.