Intensely Photoluminescent Diamidophosphines of the Alkaline‐Earth Metals, Aluminum, and Zinc

Abstract

The positively charged and weakly polarizable s-block metals commonly do not usually have phosphine ligands in molecular complexes. Herein, we report mono- and dinuclear small diamidophosphine complexes of the alkaline-earth metals Mg, Ca, and Sr, which were prepared from simple precursors and a phosphine-functionalized diamine ligand N,N-bis(2-(diphenyl-phosphino)phenyl)ethane-1,2-diamine (PNHNHP). The alkaline-earth metal based complexes [(PNNP)Mg] and [(PNNP)M(thf) ] (M=Ca, Sr), exhibit unusual coordination spheres and show bright fluorescence, both in the solid state and in solution. For comparison, the even stronger luminescent Al and Zn complexes [(PNNP)Zn] and [(PNNP)AlCl] were prepared. Emission lifetimes in the nanosecond range and high photoluminescence quantum yields up to 93 % are observed at room temperature.

Photoactive Complexes with Earth-Abundant Metals

“…45 ; g in toluene; 46 h in toluene; 47 i CH2Cl2 under N2; 48 k in CH2Cl2; 49 ; l in cyclohexane; 50 m in CH2Cl2; 51 n in benzene; 52 o in C6D6 or C7D8. 53 (ILCT = intraligand charge transfer; IL = intraligand excitation).…”

Boosting Wide‐Range Tunable Long‐Afterglow in 1D Metal–Organic Halide Micro/Nanocrystals for Space/Time‐Resolved Information Photonics

“…[ 6 ] In principle, complexes of coordinated central metals featuring the weak heavy‐atom effect (Al III , Mg II , and Zn II ) exhibit fluorescence governed by the lowest singlet state (S 1 ). [ 7–9 ] Alternatively, complexes containing noble transition metals (such as Ir III , Pt II , and Ru II ), which strongly exhibit the heavy‐atom effect, experience promoted intersystem crossing (ISC) from S 1 to T 1 , causing phosphorescence from the lowest triplet state (T 1 ) to become the dominant emission. [ 10–12 ] At a sufficiently small energy gap between S 1 and T 1 (Δ E ST ), triplet excitons can be converted back to singlet excitons following the reverse ISC process (T 1 →S 1 ) with the aid of thermal equilibrium, thus generating the TADF emission from the S 1 state, with the representative central metals including Cu I , Ag I , and Au I .…”

Dinuclear ZnII Complexes Exhibiting Thermally Activated Delayed Fluorescence and Luminescence Polymorphism

“…In the literature, multinuclear complexes, in particular the well‐known clusters of coinage metals, have proven to be superior emitters in terms of emission efficiency, thanks to suppressed structural‐distortion‐induced nonradiative decay . Likewise, a few dinuclear Zn II complexes have been recently shown to exhibit enhanced luminescence . The redshift in emission for Zn(PhOPy)‐PXZ with respect to Zn(PhOPy)‐DMAC is in line with the more pronounced electron‐donor nature of PXZ compared with DMAC , which is suggestive of involvement of the donor moieties in the emitting state.…”