Isomerism for substituted nanothreads with chemical formula ((CH)₅X)_n and regularities in their energetics

Pressure-driven polymerization of solid pyridine to one-dimensional crystalline “nanothreads” has been recently achieved experimentally through non-topochemical reaction. This route might also be feasible for the polymerization of other hetero-substituted or functionalized aromatic molecules to form one-dimensional saturated structures. The atomic structures of these threads have not yet been fully determined due to experimentally challenges in synthesis and characterization. We systematically enumerated the isomeric possibilities for substituted nanothreads with chemical formula ((CH)₅X)_n (X=heteroatom or –CR substituent) under a symmetry-conditioned permutation constraint and limit on unit cell size. Isomerization for these systems encompasses both changes in heteroatom position within a given framework and also changes in the connectivity of the sp³ framework itself. Regularities in their isomerization energetics have been investigated.