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Page 2 of 13 Cheng et al. Chem Synth 2023;3:13 https://dx.doi.org/10.20517/cs.2022.43

INTRODUCTION
Over the past few decades, conjugated polymers, which have been extensively studied with well-known
[2-4]
[5]
[1]
examples such as poly(p-phenylene vinylene) (PPV) , polypyrrole (PPy) , polythiophene (PT) and so
on, represent important classes of organic macromolecules, and have found widespread applications in
organic photovoltaic devices, light-emitting diodes, sensing materials, and others [6-11] . The prominence of
conjugated polymers can be attributed to their unique properties of high planarity and extended π-electron
delocalization, empowering them with rich photophysical and electrochemical functionalities for specific
applications [6-11] . After the success in designing and synthesizing different kinds of conjugated polymers,
attempts have been made to integrate conjugated polymers with transition metals, namely metallo-
conjugated polymers, with a view to not only improving the physical properties of the parent organic
polymers such as mechanical strength, thermal stability and carrier mobility but also enriching their
photophysical properties such as harvesting energy from the triplet excited state and extending the
absorption spectrum to the red or near-infrared (NIR) region [12-19] . Earlier examples include ruthenium(II)-
containing conjugated polymers with poly(bpy-co-benzobisoxazole)s or poly(bpy-co-benzobisthiazole)s as
the polymer backbones and iridium(III)-containing conjugated polymers with polyfluorene as the
[20]
polymer backbone and carbazole unit as the pendant . Unlike most other commonly studied transition
[21]
metal centers, including ruthenium(II), rhodium(III) and iridium(III), d platinum(II) center favors
8
coordination of a square-planar geometry, and their complexes, especially those bearing conjugated
aromatic ligands capable of exhibiting π-π interactions, are well-known for their ability to self-assemble [22-26] ,
forming aggregates [27-31] and providing remarkable photophysical properties associated with Pt···Pt and π-π
interactions [32-35] . In light of their supramolecular assembly capability, it is envisaged that the introduction of
platinum centers into conjugated polymers may provide an opportunity to further modulate the
photophysical and morphological properties of the resulting metal–organic hybrid materials [36-38] . Although
there were examples of platinum(II)-containing conjugated polymers such as platinum(II) polyynes [39-46] and
cyclometalating bidentate ligand-containing platinum(II)-based conjugated polymers [47-49] , none of these
examples demonstrates supramolecular assembly properties or utilizes the system of tridentate N-donor
ligands. In this work, a series of alkynylplatinum(II) terpyridine complexes (1 and 2) and
alkynylplatinum(II) terpyridine-containing conjugated polymers with different polymer backbones (3-5)
[Scheme 1] has been synthesized and their photophysical properties as well as FRET processes have been
studied. With the aid of various spectroscopic techniques, the photophysical and spectroscopic properties of
the organic polymers, platinum(II) precursor complexes and the newly synthesized platinum(II)-containing
conjugated polymers have been investigated systematically. It was found that the choice of the polymer
backbones would influence the intramolecular FRET efficiencies of the system of platinum(II)-containing
polymers. Through the understanding of different factors affecting the spectroscopic properties and FRET
processes of the platinum(II)-containing polymers, it is envisaged that the present study can provide further
insights into the design and development of metal-containing polymers for the construction of different
functional materials.

EXPERIMENTAL
Syntheses of conjugated polymers and complexes 1-5
The synthetic routes for platinum (II) precursor and reference complex are depicted in Supplementary
Scheme 1. Alkynylplatinum (II) terpyridine precursor 1 for “click” reaction was prepared based on a
modified procedure of copper(I)-catalyzed dehalogenation reaction (pp 9, Supplementary
Materials) . The alkynylplatinum (II) terpyridine reference complex 2 was obtained through copper(I)-
[50]
catalyzed alkyne-azide cycloaddition (“click” reaction) by reacting 1, 1-azidohexane, CuBr, PMDETA and
sodium ascorbate in a saturated solution of ammonium triflate in DMF (pp S10, Supplementary Materials).
1 and 2 were obtained as orange and red solid, respectively. These complexes are found to be highly soluble
in organic solvents such as dichloromethane, chloroform, acetone, methanol, THF, and others.