High pressure chemistry of Phosphorus allotropes in the presence of simple molecules

Phosphorus is currently attracting a growing attention among chemists, physicists and materials scientists due to the recent synthesis of phosphorene [1], a 2D monoatomic layer of phosphorus atoms, which is structurally related to black phosphorus (P-black) in a similar way as graphene is related to graphite. However, in contrast to the more famous graphene, phosphorene offers the advantage of inherently featuring a natural bandgap, which opens countless possibilities for potential applications [2]. The recent synthesis of Phosphorene by the exfoliation of P-black [3] has stimulated an increasing amount of studies about the properties and chemistry of this allotropic form of the element. Despite extensive structural studies on crystalline P-black, dating back to more than twenty years ago, the high pressure chemistry of Phosphorus in the presence of other molecular systems nowadays remains substantially unexplored. In this experimental study we report about the high pressure chemistry of red and black Phosphorus in the presence of different simple systems. The pressure was generated by membrane diamond anvil cells and the samples were investigated by vibrational spectroscopy (FTIR and Raman) and X-ray diffraction. High Temperature, generated by resistive heating, and electronic photo-excitation, induced by two-photon absorption of a UVML emission of an Ar ion laser, were employed for the activation of the chemical reactivity [4]. Particular emphasis is devoted to the reactive behavior of the red and black allotropes of Phosphorus in the presence of ammonia for the possibility of N-doping and functionalization. The results indicates how the structural properties of the two allotropic forms of Phosphorus are responsible for a different reactive behavior, highlight the stability of the layered structure of P-black towards high pressure chemistry and functionalization under the investigated experimental conditions, and suggest the synthesis of new PN products recoverable at ambient conditions [5,6]. [1] Liu et al., Phosphorene An Unexplored 2D Semiconductor with a High Hole Mobility, ACS Nano, 2014, 8, 4033 [2] H. Wang et al., Black Phosphorus Radio-Frequency Transistors, Nano Lett. 2014, 14, 6424-6429 [Brent_2014] Brent et al., Production of few-layer phosphorene by liquid exfoliation of black phosphorus, Chem. Commun., 2014, 50, 13338 [4] Ceppatelli et al., High-Pressure Chemistry of Red Phosphorus and Water under Near-UV Irradiation Angew. Chem. Int. Ed., 2013, 52, 2313 and Photoinduced Reactivity of Red Phosphorus and Ethanol at High Pressure, J. Phys. Chem. C, 2013, 117, 13129 [5] Raza et al., Novel superconducting skutterudite-type phosphorus nitride at high pressure from first-princple calculations Sci. Rep. 2014, 4, 5889 [6] Baumann et al., Angew. Chem. Int. Ed. Pentacoordinate phosphorus in a High-Pressure polymorph of Phosphorus Nitride Imide P4N6(NH) 2014, 53, 14490 and High-Pressure Polymorph of Phosphorus Nitride Imide HP4N7 Representing a New Framework Topology Inorg. Chem. 2014, 53, 7977