On-Surface Synthesis and Real-Space Visualization of Aromatic P₃ N₃.

Area of Science:

• Surface science
• Inorganic chemistry
• Nanotechnology

Background:

• On-surface synthesis is a powerful technique for creating and studying unstable or unconventional molecules.
• Cyclotriphosphazene (P3N3) is an inorganic aromatic analogue of benzene, but its structural elusiveness has hindered its synthesis and characterization.
• Traditional synthetic methods are often inadequate for producing such fleeting species.

Purpose of the Study:

• To report the precise on-surface synthesis and atomic-level characterization of cyclotriphosphazene (P3N3).
• To demonstrate a novel demasking strategy for generating unstable inorganic aromatic compounds.
• To expand the applicability of this synthesis approach to different precursors and characterization techniques.

Main Methods:

• Utilizing scanning probe microscopy (SPM) for precise molecular manipulation.
• Employing voltage pulse-induced sextuple dechlorination of a hexachlorophosphazene (P3N3Cl6) precursor on Cu(111) and Au(111) surfaces at low temperatures (5.2 K).
• Complementary characterization using matrix isolation infrared and ultraviolet spectroscopy after photolysis of a hexaazide (P3N21) precursor.

Main Results:

• Successful synthesis of the structurally elusive cyclotriphosphazene (P3N3) on metal surfaces.
• Atomic-level imaging revealing the planar D3h-symmetric ring structure of cyclotriphosphazene.
• Demonstration of a versatile demasking strategy applicable to different precursors and stimuli.

Conclusions:

• On-surface synthesis offers a viable route for generating and visualizing unstable inorganic aromatic molecules like cyclotriphosphazene.
• Precise molecular manipulation via SPM is key to achieving controlled synthesis of such species.
• The developed demasking strategy broadens the scope of on-surface synthesis for novel molecular architectures.