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An STM can remove a metal atom from an individual phthalocyanine molecule by transferring it to the microscope’s atomically sharp tip. In experiments reported in 2011, researchers used this technique to remove lead from lead-phthalocyanine molecules, while related work demonstrated inserting silver into adsorbed phthalocyanine. These were controlled surface-science experiments—not a commercial technology or a working molecular data-storage system.
What “metallic pick and mix” means
Phthalocyanines are ring-shaped molecules built from alternating carbon and nitrogen atoms. In a metal phthalocyanine, a metal atom sits at the center of the ring. Changing that central atom can change the molecule’s chemical and electronic properties.
The phrase “pick and mix” describes an experimental idea: remove the center metal from one molecule, or insert a different metal, to alter its properties. It does not describe a consumer product or a general-purpose method proven to work with every metal complex.
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How the STM removed a lead atom
In the demetalation experiment, individual lead-phthalocyanine molecules were adsorbed on ultrathin lead islands supported by a silver (Ag(111)) surface. A scanning tunneling microscope (STM) tip interacted with the center of a molecule and transferred its lead atom to the tip. The researchers attributed the transfer to the lead atom being more weakly bound to the molecule’s four nitrogen atoms than to the STM tip.
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An STM uses a metal probe with an atomically sharp tip. A bias between the tip and surface produces a tunneling current. Under carefully controlled conditions, the tip can also manipulate atoms or molecules. Here, withdrawing the tip after the interaction left the molecule without its central lead atom.
The researchers identified starting molecules and products using STM images and spectroscopic fingerprints, rather than treating a change in appearance alone as proof of the reaction. The work was published in the Journal of the American Chemical Society, volume 133, issue 29, pages 11007–11009, in 2011: the primary study on STM-induced demetalation.
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How the related metal-insertion experiment differed
A separate 2011 study reported the complementary operation: metalation, or putting a metal into the molecular center. Using low-temperature STM, researchers converted adsorbed H2Pc molecules into AgPc through stepwise dehydrogenation followed by silver-ion implantation. This study concerned silver insertion, not removal of the lead atom in the JACS experiment.
The metalation paper appeared in Angewandte Chemie International Edition, volume 50, pages 5294–5297, in 2011. Its abstract describes the process and experimental context: the study of controlled metalation on a surface.
| Study | Operation | Molecule and metal | Reported evidence or process |
|---|---|---|---|
| JACS, 2011 | Demetalation: removal | Lead-phthalocyanine; lead transferred to the STM tip | Starting molecules and products distinguished by STM imaging and spectroscopy |
| Angewandte Chemie International Edition, 2011 | Metalation: insertion | Adsorbed H2Pc converted to AgPc | Stepwise dehydrogenation followed by Ag+ implantation under low-temperature STM conditions |
What the experiments did—and did not—establish
The findings demonstrated controlled manipulation of individual molecules in a specialized surface-science setting. The experiments involved molecules adsorbed on surfaces and carefully controlled STM conditions; they do not show that the same procedure works broadly across molecular complexes or outside that setting.
A 2011 Chemistry World report discussed potential uses for phthalocyanines in surface-integrated structures such as sensors and data storage. Those are possible directions, not evidence that the reported manipulation produced a usable sensor, storage system, or commercial device. The report and its original context also quoted supramolecular chemistry researcher Davide Bonifazi describing the work as “one of the first examples of a truly interfaced organised system in which the local molecular properties of each unit can be remotely controlled by an external action,” and researcher Alexander Sperl describing the removal and insertion results as a “tool box” for tuning molecules directly on a surface. These comments reflect the significance researchers saw in the 2011 experiments, not proof of present-day commercial capability.
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