Using alcohols as alkylation reagents for 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium and their one-dimensional iodoplumbates

Abstract

Solvothermal reactions of PbI₂ with 4-cyanopyridine (4-cypy) or 4,4′-bipyridine (4,4′-bipy) and alcohols (ethanol, propanol, iso-propanol, benzyl alcohol, α,α′-dihydroxy-p-xylene) in the presence of PbI₂, I₂ and a trace amount of water in acetonitrile gave rise to a family of 1D iodoplumbate complexes of 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium including {[EC]₄[(Pb₂I₆)₂]·2MeCN}_n (EC⁺ = N-ethyl-4-cyanopyridium) (1), {[PC][PbI₃]}_n (PC⁺ = N-propyl-4-cyanopyridium) (2), {[iPC]₃[(PbI₃)(Pb₂I₆)]}_n (iPC⁺ = N-isopropyl-4-cyanopyridium) (3), {[BzC][PbI₃]}_n (BzC⁺ = N-benzyl-4-cyanopyridium) (4), {[Cxy]₂[(Pb₂I₆)₂]}_n (Cxy²⁺ = 1,4-bis(4-cyanopyridium)-xylene) (5), {[EV]_1.5[Pb₃I₉]}_n (EV²⁺ = N,N′-diethyl-4,4′-bipyridinium) (6), {[PV]_1.5[Pb₃I₉]}_n (PV²⁺ = N,N′-dipropyl-4,4′-bipyridinium) (7), and {[iPV]₂[Pb₄I₁₂]}_n (iPV²⁺ = N,N′-diisopropyl-4,4′-bipyridinium) (8). The resulting 4-cyanopyridinium and viologen cations were generated in situ via the cleavage of C–O bond of alcohols followed by alkylation of 4-cypy or 4,4′-bipy. X-Ray analysis revealed that compounds 1–8 contain one-dimensional anionic [PbI₃]_nⁿ⁻ (1–5, 8) and [Pb₃I₉]_n³ⁿ⁻ (6 and 7) chains that are enclosed into the different cationic channels formed from the 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium. In addition, the optoelectronic and dielectric properties of 1–8 were also investigated.