Magnetic Force Microscopy Images of a Nanometer‐Sized, Purely Organic High‐Spin Polyradical

Magnetic force microscopy (MFM) was applied to study both the molecular image and the magnetic response of π‐conjugated, non‐Kekulé‐, and nondisjoint‐type poly(1,2‐phenylenevinylene) (nondisjoint refers to a molecule in which non‐bonding molecular orbitals share the same region in the molecule and a multiplet ground state is significantly stabilized) networks bearing 4‐substituted di‐ tert ‐butylphenoxyl moities. The polyphenoxyl radicals 1 with molecular weights of 2.6, 9.3, and 32 kDa have a substantial stability even at room temperature and in air, and molecular sizes in the nanometer range of 10, 20, and 35 nm, respectively, with a disk‐like shape. The MFM clearly shows a magnetic gradient response exactly on the position of the polyradical molecule dispersed on a graphite surface. The MFM molecular image of polyradical samples with different molecular weights and spin concentrations was examined as a nanoscale and single‐molecular‐based magnetic dot.