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Page 4 of 13 Cheng et al. Chem Synth 2023;3:13 https://dx.doi.org/10.20517/cs.2022.43

From the IR measurements of 3-5 [Supplementary Figures 2-4], the disappearance of the strong absorption
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of the N=N=N stretch of the azide precursor at ca. 2095 cm , the appearance of weak absorption of the C≡C
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stretch at 2110 cm and strong absorption of the triflate counter-ion at ca. 1155 and 1030 cm indicated the
successful incorporation of the platinum(II) complexes onto the polymer via “click” reaction.
RESULTS AND DISCUSSION
The polymers, PF-Br, PFP-Br and PFT-Br, are soluble in dichloromethane and give high-energy absorption
bands with a peak maxima at ca. 375-398 nm [Supplementary Figure 5 and Supplementary Table 1], which
are assigned as the π→π* transitions along the polymer backbone, while these polymers show strong
vibronic-structured emissions with peak maxima at ca. 410-462 nm upon photoexcitation [Supplementary
Figures 6-9 and Supplementary Table 2], which are assigned as the singlet [π→π*] fluorescence of the
conjugated polymer backbone.

For complexes 1-5, they all give pale yellow solutions in acetonitrile. Their corresponding UV-vis
absorption data and spectra in acetonitrile at 298 K are depicted in Table 1 and Figure 1, respectively. All the
complexes exhibit intense absorption bands at ca. 285-341 nm with molar extinction coefficients in the
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order of 10 dm mol cm and less intense low-energy absorption bands at ca. 420-466 nm with molar
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3
extinction coefficients in the order of 10 dm mol cm . The higher-energy bands are ascribed to
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3
3
intraligand (IL) [π→π*] transitions of alkynyl and terpyridine ligands, while the lower-energy bands are
assigned as an admixture of metal-to-ligand charge transfer (MLCT) [dπ(Pt)→π*(tpy)] and ligand-to-ligand
charge transfer (LLCT) [π(alkynyl)→π*(tpy)] transitions. For the platinum(II)-containing conjugated
polymers 3-5, intense absorption bands at ca. 374-409 nm have been observed. With reference to the
previous studies on the conjugated polymers [51-54] and the UV-vis absorption studies of the corresponding
organic polymers [Supplementary Figure 5], these absorptions are tentatively assigned as the IL [π→π*]
transitions of the polymer backbones. Interestingly, the lower-energy bands of 3-5 are extended to longer
wavelengths when compared to the reference complex 2. Since the molecular structures of the platinum(II)
pendants in 3-5 are the same as that in 2, the further red-shifted absorption tails suggest the existence of
metal-metal-to-ligand charge transfer (MMLCT) character. As such, concentration-dependent UV-vis
absorption studies have been performed. Based on the spectra [Supplementary Figures 10-14], the precursor
platinum(II) complexes 1 and 2 and the platinum(II)-containing conjugated polymers 3-5 show good
agreement with Beer’s Law, suggesting that there are no significant intermolecular self-assembly properties
of 1-5 upon increasing the concentration. However, the intramolecular self-assembly mode of having two
platinum(II) pendants in each repeating unit, which are stabilized by the presence of intramolecular Pt···Pt
and π-π interactions, may explain the presence of low-energy MMLCT bands for the platinum(II)-
containing conjugated polymers 3-5. In this regard, temperature-dependent UV-vis absorption experiments
for 3-5 have been carried out. From the spectra [Figures 2-4], the low-energy band at ca. 450 nm shows a
drop in absorbance accompanied by a blue shift of the high-energy band at ca. 400 nm upon increasing
temperature, suggesting the occurrence of deaggregation process of both the platinum(II) terpyridine
moieties and the polymer backbones, which corroborates with the disruption of intramolecular Pt···Pt and
π-π interactions at high temperatures.

Complexes 1 and 2 are found to give phosphorescence in degassed solutions, while dual-emissive behaviors
have been observed for the platinum(II)-containing conjugated polymers 3-5 in degassed solutions upon
excitation. The luminescence data of all complexes have been summarized in Table 2. Upon photoexcitation
at λ > 350 nm, 1 and 2 show Gaussian-shape emission bands centered at 596 nm and 630 nm in degassed
acetonitrile [Supplementary Figure 15]. The large Stokes shifts and the long emission lifetimes in the
microsecond regime indicate that these emissions are originated from a triplet parentage. Together with the