Phosphorescent Pt() complexes bearing cyclometalated difluorophenylpyridinate and diphosphine building blocks

• Published in: New journal of chemistry 2023-01, Vol.47 (3), p.1435-1443
• Main Authors: Shahsavari, Hamid R, Chamyani, Samira, Aghakhanpour, Reza Babadi, Dolatyari, Vahideh, Paziresh, Sareh
• Format: Article
• Language: English
• Subjects: Banded structure; Benzene; Density functional theory; Dichloromethane; Emission analysis; Emission spectra; Ethane; Molecular interactions; Phosphorescence; Room temperature; Solid state
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d2nj05555d

Two distinct categories of cycloplatinated( ii ) complexes [Pt(dfppy)(P^P)]Cl, 2 , and [Pt 2 Cl 2 (dfppy) 2 (μ-P^P)], 3 , where dfppy = 2-(2,4-difluorophenyl)pyridinate, P^P = bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis(diphenylphosphino)benzene (dppbz), were synthesized and characterized. These compounds were photophysically investigated, and their absorption and emission spectra were recorded under different conditions. Bright green and bluish green emissions were observed for the complexes with mostly well-structured emission bands ( 3 ILCT/ 3 MLCT for the mononuclear and 3 ILCT/ 3 MLCT/ 3 XLCT for the binuclear complexes, L = dfppy, X = Cl) in the range of 460-480 nm (solid and CH 2 Cl 2 fluid solution states, 298 and 77 K). Unexpectedly, due to the inter-molecular interactions, the complex [Pt(dfppy)(dppm)]Cl, 2a , shows a very weak emission in the solid state, whereas its ppy (2-phenylpyridinate) derivative has a bright green emission under the same conditions. The complexes [Pt(dfppy)(dppe)]Cl, 2b , and [Pt(dfppy)(dppbz)]Cl, 2c , in their solid form, exhibit strong emissions at room temperature that are significantly higher than those observed for their ppy counterparts. The binuclear complexes of [Pt 2 Cl 2 (dfppy) 2 (μ-dppm)], 3a , and [Pt 2 Cl 2 (dfppy) 2 (μ-dppe)], 3b , show "no emission" and "weak emission" in the solid state at 298 K, respectively. Finally, DFT (density functional theory) and TD-DFT (time-dependent DFT) calculations were used to support the obtained photophysical data. Mononuclear and binuclear cycloplatinated complexes with a variety of biphosphine ligands were investigated for their luminescent characteristics.