High‐Yielding Synthesis of a Hetero‐Pacman Compound and the Characterization of Intermediates and Side‐Products

Abstract

Through an optimized synthetic procedure, metalloligand 5, which features a hetero-Pacman scaffold comprising a porphyrin and a terpyridine moiety, has been assembled by a double Suzuki reaction. In a subsequent step, a rutheniumbipyridine fragment was introduced at the terpyridine coordination site of metalloligand 5 to form complex 6, which was fully characterized and its potential application in water oxidation catalysis tested. A number of side-products were iso-[a] Institute Scheme 1. Synthesis of compound 6 (mes = mesityl). Reagents and conditions: a) i. BuLi, B(OMe) 3 ; ii. H + /H 2 O; b) 2, [Pd(dppf)Cl 2 ], Rb 2 CO 3 , thf; c) CHCl 3 /MeOH; d) 4, [Pd(dppf)Cl 2 ], Rb 2 CO 3 , dioxane/water; e) i. [Ru(CH 3 CN) 2 (bpy)Cl 2 ], acetone; ii. NH 4 PF 6 /H 2 O.

Sensitised LnIII Emission and Excited‐State Dynamics of Cofacial ‘Pacman’ Porphyrin Terpyridine Complexes

“…A total of 21 signals were observed for the free Pacman complex (see Figures S1 and S2 in the Supporting Information), of which 16 appear in the aromatic region from δ =4.8–10.2 ppm (Figure a). This is in accordance with previously reported results recorded in CDCl 3 . For example, the signal at δ =10.1 ppm (1 H, s) was readily assigned to the single proton at the meso position of the porphyrin opposite the substituted xanthene backbone, whereas the resonances due to the terpyridine chelate group were identified at δ =5.3 (2 H, t), 5.7 (2 H, t), 6.1 (2 H, d), 6.7 (2 H, d) and 7.4 ppm (1 H, s).…”

“…The synthesis of the required cofacial Pacman porphyrin terpyridine complex [Zn(PXT)] by a double Suzuki reaction has previously been reported . To confirm formation of the desired 1:1 Pacman complexes with Ln III cations, we titrated the free [Zn(PXT)] complex with diamagnetic Lu(NO 3 ) 3 ⋅ 5H 2 O and monitored the reaction by 1 H NMR spectroscopy.…”

“…The required [Zn(PXT)] complex was prepared by following a previously reported method, and the corresponding Ln III complexes were prepared stoichiometrically. All solvents and high purity (99.9 %) Ln(NO 3 ) 3 ⋅ x H 2 O salts ( x =6 when Ln=Nd III , Gd III or Lu III ; x =5 when Ln=Yb III ) were used as supplied.…”

“…We have previously demonstrated that the appended terpyridine chelate in [Zn(PXT)] can interact with 3d and 4d transition‐metal cations, such as Fe II or Ru II , and rationalised that this unit may also be suitable for binding larger 4f lanthanide metal cations …”

Sensitized Photochemical CO2 Reduction by Hetero‐Pacman Compounds Linking a ReI Tricarbonyl with a Porphyrin Unit

“…The synthesis of TXP‐Zn has been reported previously . Subsequent reaction with Re(CO) 5 Cl in toluene afforded an almost quantitative yield of Re‐TXP‐Zn .…”