Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

Abstract

SummaryHomoleptic zinc(II) complexes of di(phenylacetylene)azadipyrromethene (e.g., Zn(WS3)2) are potential non-fullerene electron acceptors for organic photovoltaics. To tune their properties, fluorination of Zn(WS3)2 at various positions was investigated. Three fluorinated azadipyrromethene-based ligands were synthesized with fluorine at the para-position of the proximal and distal phenyl groups, and at the pyrrolic phenylacetylene moieties. Additionally, a CF3 moiety was added to the pyrrolic phenyl positions to study the effects of a stronger electron withdrawing unit at that position. The four ligands were chelated with zinc(II) and BF2 + and the optical and electrochemical properties were studied. Fluorination had little effect on the optical properties of both the zinc(II) and BF2 + complexes, with λmax in solution around 755 nm and 785 nm, and high molar absorptivities of 100 × 103 M−1cm−1 and 50 × 103 M−1cm−1, respectively. Fluorination of Zn(WS3)2 raised the oxidation potentials by 0.04 V to 0.10 V, and the reduction potentials by 0.01 V to 0.10 V, depending on the position and type of substitution. The largest change was observed for fluorine substitution at the proximal phenyl groups and CF3 substitution at the pyrrolic phenylacetylene moieties. The later complexes are expected to be stronger electron acceptors than Zn(WS3)2, and may enable charge transfer from other conjugated polymer donors that have lower energy levels than poly(3-hexylthiophene) (P3HT).

Chemical strategies to modify amyloidogenic peptides using iridium(iii) complexes: coordination and photo-induced oxidation

“…46 Moreover, uorine atoms were introduced into the ancillary ligand framework affording Ir-F and Ir-F2 to chemically impart the ability to interact with Ab through hydrogen bonding, alter photophysical properties of the complexes, and enhance the molecules' biocompatibility. [49][50][51] Two water (H 2 O) molecules were incorporated as ligands to enable covalent coordination to Ab via replacement with amino acid residues of the peptide, e.g., histidine (His). 20,52,53 The four Ir(III) complexes were synthesized following previously reported procedures with modications (Scheme 1 and Fig.…”

Organic and Organometallic Fluorinated Materials for Electronics and Optoelectronics: A Survey on Recent Research

“…with inverted configuration, using P3HT as the electron donor. Fluorination was found to have little effect on the optical properties of zinc(II) complexes but to be beneficial for their performances in devices, leading to an increase of PCE values, due to an increase of J sc , vs. devices made with the non‐fluorinated analogue …”

Structure–Property Study of Homoleptic Zinc(II) Complexes of Di(arylethynyl) Azadipyrromethene as Nonfullerene Acceptors for Organic Photovoltaics: Effect of the Aryl Group

“…These complexes tend to be amorphous, making it hard to obtain a crystal structure. The first crystal structure of a Zn­(WS3) 2 derivative published was that of the complex with fluorine at the para distal phenyls, which showed intermolecular interactions between the pyrrolic phenyls of two neighboring molecules . This suggested that the aromatic group on the pyrrolic substituent plays an important role in intermolecular π–π interactions and charge transport.…”

“…The first crystal structure of a Zn(WS3) 2 derivative published was that of the complex with fluorine at the para distal phenyls, which showed intermolecular interactions between the pyrrolic phenyls of two neighboring molecules. 16 This suggested that the aromatic group on the pyrrolic substituent plays an important role in intermolecular π−π interactions and charge transport. To test this hypothesis, the phenyl in the pyrrolic phenylethynyl groups was replaced with the larger 1-naphthyl group.…”

“…The zinc(II) complexes were synthesized using our published procedure in good yields. 16 To save resources, we explored purifying the complexes by solvent washing instead of column chromatography. Only Zn(L2) 2 could be purified satisfactorily by washing with solvents.…”