Strategies for Control of Lattice Architecture in Low-Dimensional Molecular Metals: Assembly of Partially Oxidized Face-to-Face Linked Arrays of Metallomacrocycles

Abstract

This paper discusses an approach to control molecular stacking interactions in low-dimensional mixed valence materials by locking partially oxidized metallomacrocycles together in a face-to-face orientation. Thus, doping of the cofacially linked oligomers [M(Pc)0]_n (M = Si, Ge, Sn; Pc = phthalocyaninato) with halogen (I₂, Br₂) or quinone (e.g., TCNQ, DDQ) electron acceptors produces robust, electrically conductive polymers with a wide range of stoichiometrics and properties. The new materials have been studied by a variety of physical methods including X-ray diffraction, resonance Raman and infrared spectroscopy, ESR, static magnetic susceptibility, and variable-temperature four-probe electrical conductivity. Evidence is presented that some of the polymers have “metal-like” conductivity in the stacking direction and that transport properties within the series can be readily manipulated by rational variation of lattice architecture (e.g., the identity of the metal, M) and acceptor characteristics. Additional information is presented on doping experiments with electron donors and on employing metallohemiporphyrazines as polymer building blocks.