Exploring single molecules by scanning probe microscopy: Porphyrin and phthalocyanine

Utilizing single molecules as the building blocks for electronic devices is one promising pathway for microelectronic miniaturization. Exploring the molecular conformation and controlling the inter- and intramolecular bonding as well as their charge and spin configuration is essential for developing such novel devices. Scanning probe microscopy (SPM) is among the most powerful tools for characterizing and manipulating the single molecules at the atomic level. In this Perspective, a brief review of recent scanning probe microscopic studies of phthalocyanine, an excellent candidate for molecular electronic devices, is given. It is shown how phthalocyanine can be functionalized as a single-molecule switch by the state-of-art STM manipulation. The power of scanning probe techniques is demonstrated via these examples, and future challenges are pointed out.