Improvement of Solid Photoluminescence of Tridentate Schiff Base Pt(II) Foldamer by Hybridizing Poly (4‐Vinylpyridine)

Abstract

A series of bis(tridentate Schiff base platinum) complex (Pt 2 L 2 ) linked with 2-methylenepropane-1,3-diyl were synthesized, and their photophysical properties were examined to analyze different solid states. X-ray crystallographic analysis indicated that Pt 2 L 2 containing 4-vinylpyridine (Pt 2 L 2 4VP) as a ligand had a helically-folded structure. It caused upfield chemical shifts and a redshift in UV-Vis absorption spectra compared to the analogous mononuclear complex. Pt 2 L 2 containing dimethylsulfoxide (Pt 2 L 2 DMSO) had no such helically-folded structure due to the steric repulsion of DMSO. Pt 2 L 2 4VP did not exhibit solid photoluminescence owing to the crystal packing. The mixture of poly(4-vinylpyridine) (P4VP) and Pt 2 L 2 DMSO (Pt 2 L 2 DMSOÀ P4VP) showed a similar redshift in UV-Vis absorption and excitation spectra to Pt 2 L 2 4VP, implying the helically-folded structure of Pt 2 L 2 with P4VP coordination. The Pt 2 L 2 DMSOÀ P4VP exhibited solid photoluminescence with a longer phosphorescence lifetime (2.4 μs) than the Pt 2 L 2 4VP crystals (0.5 μs), indicating regulated aggregation of the Pt 2 L 2 frames in the P4VP matrix.