Stepwise Increase of Nd^III‐Based Phosphorescence by AIE‐Active Sensitizer: Broadening the AIPE Family from Transition Metals to Discrete Near‐Infrared Lanthanide Complexes**

Abstract

We designed two near-infrared (NIR) lanthanide complexes [(L) 2 -Nd(NO 3 ) 3 ] (L = TPE 2 -BPY for 1, TPE-BPY for 2) by employing aggregation-induced emission (AIE)-active tetraphenylethylene (TPE) derivatives as sensitizers, which possessed matched energy to Nd III , prevented competitive deactivation under aggregation, even shifted the excitation window toward 600 nm by twisted intramolecular charge transfer. Furthermore, benefiting from the 4 f electron shielding effect and antenna effect, the enhanced excitation energies of the AIE-active sensitizers by structural rigid-ification transferred into the inert Nd III excited state through 3 LMCT, affording the first aggregation-induced phosphorescence enhancement (AIPE)-active discrete NIR-emitting lanthanide complexes. As 1 equipped with more AIE-active TPE than 2, L!Nd energy transfer efficiency in the former was higher than that in the latter under the same conditions. Consequently, the crystal of 1 exhibited one of the longest lifetimes (9.69 μs) among Nd III -based complexes containing CÀ H bonds.

Lanthanide‐Functionalized Water‐Soluble Ionic Motors: Synergetically Regulated Rotary Motion by Allostery and Triplet Sensitization

“…With this strategy, many works by chelating Ln( β ‐diketone) 3 ·2H 2 O or Ln(NO 3 ) 3 ·6H 2 O with dipyridyl analogs for functional materials, have been widely developed. [ 22,25 ]…”

“…Also, the rotary speeds of Ln‐complexed L indicated by the thermal half‐life τ 1/2 severely depend on temperatures (Table 2), the higher temperature the faster rotations. Once cooling down the measurement temperature to restrict the rotation of L on decreasing the excited energy exhausting, the sensitized Ln III ‐based luminescence is gradually enhanced, [ 25 ] thus, the temperature‐dependent luminescence performance could be used as luminescent thermometers. [ 26 ] By successively decreasing the measurement temperature from 293 to 140 K in EtOH/MeOH (3:1 v/v) mixed solutions, two luminescent transitions, one at 480 nm from singlet transitions of L, the other at 616 nm from 5 D 0 → 7 F 2 of Eu 3+ , appear (Figure 2d).…”

“…With this strategy, many works by chelating Ln(𝛽-diketone) 3 •2H 2 O or Ln(NO 3 ) 3 •6H 2 O with dipyridyl analogs for functional materials, have been widely developed. [22,25] Among Ln III , Eu 3+ (mainly within 375-394 nm) exhibits more intensive absorption than Er 3+ (≈364-652 nm), and the absorption of Er 3+ is stronger than that of Ho 3+ (≈287-641 nm) in visible region. [15,22] The phosphorescence bands of L differently overlap with the absorption bands of f-f′ transitions, pumping the energy into the lanthanide excited states (Figure 2b).…”

Aggregation‐Induced Emission and Single‐Molecule Magnet Behavior of TPE‐Based Ln(III) Complexes

“…In 2020, the first AIE‐active Tb(III) luminophores was achieved by modulating ligand‐ligand charge transfer bands [24] . Recently, Nd(III)‐based near‐infrared (NIR) complexes were isolated with AIE‐active sensitizers, which displayed one of the longest lifetimes among Nd(III)‐based complexes containing C−H bonds [25] …”

“…[24] Recently, Nd(III)-based nearinfrared (NIR) complexes were isolated with AIE-active sensitizers, which displayed one of the longest lifetimes among Nd(III)-based complexes containing CÀ H bonds. [25] On the other hand, lanthanide complexes provide a unique platform to prepare single-molecule magnets (SMMs). In the last five years or so, Dy(III) SMMs have grown rapidly and made some impressive achievements, especially the high-temperature organometallic molecules based on [Dy(Cp R ) 2 ] + cations [26] and air-stable macrocyclic compounds with general formula [DyL E L A 2 ] + (L E = equatorial macrocyclic ligand; L A = anionic axial ligand).…”