Anion recognitions via cocrystallizations with organic pi-acids in the efficient self-assembly of nanoscopic one-dimensional molecular chains (Wires)

The self-assembly of various anions (e.g., thiocyanate, nitrite/nitrate, sulfite/sulfate, tetrahalometallates, etc.) with prototypical pi-acids (consisting of cyano- and nitrosubstituted pyrazine and benzene, as well as tetracyancethylene) occurs rapidly and selectively to yield a series of novel one-dimensional structures. The wire-like molecular chains all consist of parallel stacks of pi-acids and alternate anions of different sizes and shapes that establish the dihedral angles alpha and phi sufficient to define these unique structures. Analogy of such linear arrays to nanoscopic wires is reinforced by the protective sheath of countercations that are completely arrayed around the linear cores. The critical feature of these efficient self-assemblies is shown to derive from anion/pi-recognitions via charge-transfer forces between the electron-rich anions acting as electron donors and the electron-poor pi-acids acting as electron acceptors to spontaneously generate synthons according to Mulliken theory.