A Highly Emissive Water‐Soluble Phosphorus Corrole

Abstract

The synthesis, spectroscopic, and optical properties of the water-soluble phosphorus complex of a 2-sulfonato-10-(4-sulfonatophenyl)-5,15-dimesitylcorrole have been investigated. The compound was prepared by adopting a novel strategy for the corrole sulfonation, leading to the regioselective isomer in an almost quantitative yield. The phosphorus coordination has a key role in determining the corrole substitution pattern, limiting the formation of poly-substituted species, which affected the reaction of the corrole free base. The resulting complex shows excellent optical properties in terms of emission quantum yield, also in polar protic solvents, including water. P NMR spectroscopy in CD OD indicates that the P sulfonate complex has been isolated in a hexacoordinated geometry with two different ligands (L1=-OH, L2=-OCH ), and it is prone to axial ligand exchange with methanol, with no evidence of intermediate pentacoordinated species. The morphological characterization of thin layers of the P corrole deposited onto an Au(111) surface showed that the addition of an intermediate layer of reduced graphene oxide allows for a better control of corrole aggregation, inducing also transformation of the Au(111) reconstructed surface.

Corroles at the Real Solid–Liquid Interface: In Situ STM Investigation of a Water‐Soluble Corrole Layer Deposited onto Au(111)

“…Despite the increasing efforts towards corrole‐based applications, only sparse reports on the structural arrangement of the corrole layers have appeared in the literature. These works concern the preparation and characterization of corrole assemblies, mostly in ultrahigh vacuum (UHV) or in air conditions . STM investigations at the “solid–liquid interface” have been reported in some articles .…”

“…Upon comparing images recorded after subsequent scans (Figure a,b), clusters of molecules appeared displaced and aggregated, decreasing in number, but growing in lateral size (with a common height of 0.5 nm). A similar and even more evident phenomenon was observed for Au(111) pre‐treated with reduced graphene oxide (RGO) prior to deposition of the same corrole by the drop‐casting method: small molecular aggregates evolved into larger clusters, with a very high mobility on the surface induced by the STM tip.…”

“…Reagents and solvents (Sigma–Aldrich, Fluka, Merck, and Carlo Erba) were of synthetic grade and were used without further purification. Di‐hydroxy phosphorus(V) [10‐(4‐Sulfonatophenyl)‐5,15‐dimesityl‐2‐sulfonatocorrole] was prepared following literature procedures …”

“…We have recently reported the preparation of a water‐soluble 2‐sulfonato‐10‐(4‐sulfonatophenyl)‐5,15‐dimesitylcorrole phosphorus complex (P corrole), which showed brilliant luminescence properties. The deposition of this corrole onto Au(111) surfaces was studied, characterizing the morphology of corrole aggregates by STM in air …”

5,10,15‐Tris(4‐sulfonatophenyl)corrole Synthesis

“…Furthermore, the chlorosulfonation reaction is regioselective only in the case of 4 , while several regioisomers are obtained from the reaction of 5 . During our studies on the possibility to obtain the target water‐soluble corrole, we then tried to orient the substitution reaction towards those specific positions of the macrocycle using an organosilicon method, but even when the reaction was performed on a trimethylsilyl‐substituted corrole, the reaction took place both onto the para ‐phenyl and β‐pyrrolic positions of the macrocycle.…”