Metal‐chloride‐anion‐containing polymers with expanded π‐conjugation systems derived from through‐space interactions in the piperazinium ring

Abstract

Reactions of N‐(2,4‐dinitrophenyl)pyridinium chloride (salt(Cl)) with H+MCl4−1 (M ≡ Fe and Bi) resulted in an anion exchange between Cl− and MCl4− to yield Zincke salts with metal chloride anions, namely salt(Fe) and salt(Bi), respectively. Reactions of the Zincke salts with piperazine resulted in ring‐opening of the pyridinium ring, yielding ionic polymers with 5‐piperazinium‐2,4‐dienylideneammonium metal chloride units, namely polymer(Fe) and polymer(Bi). The corresponding model compounds were synthesized via reactions using salt(Bi) or salt(Cl) as starting materials. The UV–visible spectra of the polymers had absorption maxima at longer wavelengths than those of the model compounds. This indicated that the π‐conjugation system is expanded along the polymer main chain. Superconducting quantum interference device measurements indicated that polymer(Fe) was paramagnetic. Cyclic voltammetry analysis suggested that the polymers underwent electrochemical oxidation. © 2019 Society of Chemical Industry

Synthesis and chemical properties of polyethyleneimines crosslinked by penta‐2,4‐dienylideneammonium unit

“…The magnetic susceptibility for LPEI‐PDA(FeCl 4 ) was calculated to be 2.82 μ B . This value was lower than that of salt(FeCl 4 ) ( χ = 5.83 μ B ) . It was reported that the magnetic susceptibility of an FeCl 4 − containing polyelectrolyte was smaller than that for an FeCl 4 − containing monomer …”

“…The polymer was insoluble in the solvents. It was reported that salt(FeCl 4 ) reacted with piperazine to yield a paramagnetic polymer with piperazinium rings linked by PDA units . The results and solubilities are summarized in Table .…”

“…Salt(Cl), salt(FeCl 4 ), salt(N(CN) 2 ), and LPEI were prepared according to the literatures. The M n and M w values of LPEI determined by GPC were 20 380 and 25 660, respectively.…”

Conjugated polymers with anionic dyes: Synthesis, properties, and sensing ability for nucleosides, DNA, and BSA

“…The absorptions corresponding to polymer(AV49) backbone before and after the addition of nucleosides, DNA, and BSA are almost the same those corresponding to polymer(A − ) reported previously. 20,22,23,26 The UV-vis spectra of polymer(AR52) and model(AR52) were remained essentially unchanged with the addition of BSA. This is likely due to the assumption that the sulfonium group of AR52 cannot interact with BSA due to steric reasons, as mentioned in Section 2.4.…”

“…We reported the synthesis of cationic π-CPs via ring-opening of the pyridinium unit of the Zincke salt, N-(2,-4-dinitrophenyl)pyridinium chloride (salt(Cl − )), with piperazine or chiral 2-methylpiperazines. [20][21][22][23][24][25][26] These polymers are highly soluble in polar organic solvents and in water. Although the polymers comprise aliphatic piperazinium and 2-methylpyperazinium rings linked by π-conjugated 5-piperazinium-2,4-dienylideneammonium (PDA) chloride units, their π-conjugated system is expanded along the polymer chain due to through-space interactions between the piperazinium ring nitrogen orbitals when it is in the boat form.…”