Nonsymmetric [Pt(C^N*N′^C′)] Complexes: Aggregation‐Induced Emission in the Solid State and in Nanoparticles Tuned by Ligand Structure

Abstract

Five square-planar [Pt(C^N*N'^C')] complexes (Pt1-Pt5) with novel nonsymmetric tetradentate ligands (L1-L5) were synthesized and characterized. Varying the structure of the metalating aromatic systems result in substantial changes in photophysical properties and intermolecular interaction mode of the complexes in solution and in solid state. The complexes are strongly emissive in tetrahydrofuran solution, with the band maxima ranging from 560 to 690 nm. Three of these complexes (Pt1, Pt2, Pt4) afford nanospecies upon injection of their solution into water, which show aggrega-tion-induced emission (AIE) with a strong red shift of emission bands. In the solid state, crystalline samples of these complexes demonstrate mechanochromism upon grinding with a bathochromic shift of the emission. DFT and TD-DFT computational analysis of monomeric Pt1-Pt5 in solution and model dimeric emitters formed through intermolecular interaction of Pt1, Pt2, Pt4 molecules allowed assignment of observed AIE to the 3 MMLCT excited states of Pt-Pt bonded aggregates of these complexes.

Platinum complexes with aggregation-induced emission

“…2C). 56 In the same year, Zhang et al reported a rigid oxygen-bridged p -menthane-modified tetradentate cyclometalated platinum( ii ) complex ( Pt12 ). 16 Pt12 exhibited significant aggregation-enhanced emission (AEE) in a DMSO/H 2 O mixture (5 × 10 −5 mol L −1 ) with a high PLQY of 73.2%.…”

Metal carbonyl mediated rearrangement of 5-(2-oxoalkyl)-1,2,4-oxadiazoles: synthesis of fully substituted pyrimidines

“…Compound 8 was prepared following a slightly modified published procedure. 39 To a solution of bromopyrimidine 6 (139 mg, 0.35 mmol) and N-phenylpyridin-2-amine (51 mg, 0.30 mmol) in toluene (8 mL), t-BuOK (45 mg, 0.4 mmol), dppf (11 mg, 20 µmol) and Pd 2 (dba) 3 (9.2 mg, 10 µmol) were added under an Ar atmosphere. The reaction mixture was stirred at for 1 d at 110 °C (oil-bath temperature).…”

On the thermodynamics of aggregation toward phosphorescent metallomesogens: From electronic tuning to supramolecular design

“…The synthesis of asymmetric CˆN*NˆC-coordinated yet non-mesogenic Pt(II) complexes was recently reported by Tunik et al, but without studying the effect of fluorination and chain length on the thermodynamics of aggregation while using orthogonal phenyl moieties at the bridging N-atom. [20] Herein, the photophysics of the six resulting complexes were studied by steady-state and time-resolved photoluminesce spectroscopy. To gain a deeper understanding of the excited-state properties, time-dependent density functional theory (TD-DFT) calculations were performed.…”