Sterically Encumbered Bipyridyl-Derivatized Conjugated Polymers and Metallopolymers Incorporating Phenylenevinylene, Phenyleneethynylene, and Fluorenylene Segments

Abstract

This work reports the preparation of a series of 2,2′-bipyridyl (bipy) modified π-conjugated polymers having an average of one or three monomer units (p-arylene ethynylene for PPE1 and PPE3 or 7,7dihexylfluorene for PF1 and PF3) between metal-binding sites. Spectroscopic data demonstrate that strategic placement of sterically encumbered mesityl groups about the metal binding sites enforces a 1:1 metal to bipy binding ratio. This steric coordination control ensures that the metalated polymers remain solution processable rather than forming insoluble networks via coordinative cross-linking. The solution photophysical and electrochemical properties of metal-free and metalated materials are reported and compared with those of related conjugated polymers and conducting metallopolymers.

Conjugated polymers with regularly spacedm-phenylene units and post-polymerization modification to yield stimuli-responsive materials

“…This has been done with success for a wide range of organic polymers, including CPs such as hyperbranched poly( p ‐phenylene ethynylene)s and some poly( p ‐phenylene vinylene)s in which the conjugation is periodically disrupted by m ‐phenylene units. Derivatives of P1‐I (Chart ) in which the iodo substituent is replaced by small‐molecule chromophores have shown low incidence of interchain interactions while enforcing intrachain interactions between the backbone π ‐system and the small‐molecule chromophore, leading to intramolecular charge transfer and Forster resonance energy transfer (FRET) …”

“…Both small molecules (Chart (A)) and polymers (Chart (B)–(D)) have proven useful for fluorescence‐based detection of nitroaromatics . In each of these cases the bulky side chains such as iptycenes (Chart (A) and (B)), cyclophane‐containing ‘canopy’ (Chart (C)) and m ‐terphenyls (Chart (D)) provide free volume around a π ‐conjugated fluorophore for analyte occupancy. Crosslinked conjugated microporous polymer networks likewise provide the free volumes necessary for efficient nitroaromatic entry and detection …”

“…Hybrid organic–inorganic materials such as conjugated metallopolymers resulting from metal ion binding to a ligand‐modified CP can also exhibit a synergistic combination of CP optical properties with the redox properties available to metal complexes to yield improved materials for use in thin films in organic light‐emitting diodes and solar cells . The incorporation of metal‐binding units within a sterically shielded cleft can eliminate undesirable crosslinking/network formation and thus these units are excellent candidates for soluble metal ion detection applications . In light of these findings, it was of interest to explore whether post‐polymerization modification of P1‐I and P2‐I with metal‐ligating pyridyl units could be used to yield similarly soluble conjugated metallopolymers.…”

“…Derivatives of P1-I (Chart 1) in which the iodo substituent is replaced by small-molecule chromophores have shown low incidence of interchain interactions while enforcing intrachain interactions between the backbone -system and the small-molecule chromophore, leading to intramolecular charge transfer and Forster resonance energy transfer (FRET). 28,50,54 Herein, the readily prepared P1-I and P2-I (Chart 1) were chosen as the basis for further investigation because they possess both periodic disruption of -conjugation that will lead to more uniform 732 photophysical characteristics and an iodo substituent for facile post-polymerization modification. Specifically, two sets of polymers containing a crosslinking, a potentially metal ion-responsive or a redox-active unit were targeted for study (Scheme 1).…”

Imine-linked conjugated organic polymer bearing bis(imino)pyridine ligands and its catalytic application in C–C coupling reactions

“…The successful design and synthesis of these polymers linked by B-O [3][4][5], C-C [6,7], C-N [8], and C=N [9][10][11][12] bonds have been reported. Recent studies have shown that conjugated organic polymers (COPs) with extended π-conjugation possess high thermal stability and structure diversity [13][14][15]. However, the synthesis of these COP materials usually requires expensive precursors and intricate techniques.…”