Investigation of Suzuki–Miyaura catalyst‐transfer polycondensation of AB‐type fluorene monomer using coordination‐saturated aryl Pd(II) halide complexes as initiators

Abstract

Novel triarylamine-based coordination-saturated aryl Pd(II) halide complexes ligated by PEt 3 , PCy 3 , and P(o-tol) 3 were successfully synthesized by direct oxidative addition of aryl halide to the corresponding Pd(0) precursors. SuzukiMiyaura coupling polymerization of 2-(7-halide-9,9-dioctylfluoren-2-yl)21,3,2-dioxaborinane with these Pd(II) complexes as initiators was investigated for the synthesis of poly(fluorene)s with triarylamine end group. Pd(II) complexes with PCy 3 or P(o-tol) 3 exhibited catalytic activity and realized the catalysttransfer polycondensation at 75 C and room temperature, respectively, while the polymerization using Pd(II) catalyst ligated by PEt 3 did not proceed, which indicated that the bulky phosphine ligands could facilitate the reductive elimination and further promote the polymerization. In addition, the dimeric Pd(II) complex with P(o-tol) 3 can convert into monomeric Pd(II) intermediate with an open coordination site, which had a higher activity. The end groups of the afforded polyfluorene were analyzed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, in which the Ar/H end groups are indicative of the catalyst-transfer polymerization.

Excellent Control of Perylene Diimide End Group in Polyfluorene via Suzuki Catalyst Transfer Polymerization

“…For Pd4–Pd6 , the proton integral ratio of characteristic perylene unit in Ar group to methyl in TXP‐2,4 is 8:18, rather than 8:36, that is, the ratio of Ar group to TXP‐2,4 in Pd4–Pd6 is 1:1. The result illustrates that Pd4–Pd6 should be a bromide‐bridged dimeric structure . All complexes have good thermal stability and can be weighted and transferred in air at room temperature.…”

“…In addition, it is important to note that Ð around 1.60 is rather broad compared with the polymerization carried out at 0 °C . However, the value is reasonable for the polymerization at room temperature, which in the meantime implies that a slow initiation process takes place because the dimeric structure has to be converted into three‐coordinated initiator with a vacant coordination site for these complexes …”

“…The polymerization with Pd1–Pd3 as the initiators can be realized at an elevated temperature (75 °C) for a short reaction time (1 h), which is consistent with our previous work, but results in incomplete end‐functionalization (see following discussion). In addition, all polymerizations were carried out in the aqueous K 3 PO 4 and THF system to afford high yield polymers (isolated yield >80%) with relatively narrow Ð , compared with the base of KF/18‐crown‐6 ether used in our previous work (see Table S in the Supporting Information for detail) . The molecular weights ( M n ) ranging from 1.25 × 10 4 to 2.20 × 10 4 g mol −1 could be obtained and adjusted by variation of the monomer to initiator ratio.…”

Diversifying Cross‐Coupling Strategies, Catalysts and Monomers for the Controlled Synthesis of Conjugated Polymers

“…The first example of sp 2 -sp coupling in CTP was also reported with this catalyst. [70] Several other sterically demanding phosphines, tris(1-adamantyl)phosphine, [154] tricyclohexylphosphine [155] and (o-tolyl)phosphine, [156] have been explored for polyfluorene synthesis. Ar ecent report has appeared from Yokozawa andc o-workers on the use of AmPhos( di-tert-butyl(4-dimethylaminophenyl)phosphine) for 3-alkylthiophene polymerization.…”

Recent Advances in Conjugated TADF Polymer Featuring in Backbone‐Donor/Pendant‐Acceptor Structure: Material and Device Perspectives

“…jointly explored another successful example that demonstrated the promising potential of Type 3 TADF polymer (Figure ). In that work, two alternately conjugated polymers, namely PAPTC and PAPCC (Figure a for polymer geometry and structure) were explored, which were chemically created by modified Suzuki coupling copolymerization using Pd[P(o‐Tol) 3 ] 2 Cl 2 as the catalyst . The backbone was composed of traditional wide band‐gap carbazole and 9,10‐dihydroacridine derivative units that was previously explored as donor for gaining efficient TADF small molecules .…”