Mechanochemical synthesis and characterization of kinetically and thermodynamically stable polymorphs of a lead(II) coordination polymer

• Branch tube method was used for synthesis of kinetically stable polymorph.
• Thermodynamically stable polymorph was obtained by grinding kinetically stable one.
• Mechanochemical reaction is a green procedure for synthesis of polymorphs.

1α polymorph of [Pb(μ-Cl)2(μ-bipy)]∞ (bipy = 4,4′-bipyridine) was synthesized by branch tube method. It was found that one of the ways to synthesize of 1β is grinding of 1α. Mechanochemical reactions of compounds [Pb(NO2)2(4,4′-bipy)]n (2), [Pb(NO3)(SCN)(4,4′-bipy)]n (3), [Pb2(NO3)4(4,4′-bipy)]n (4) and [Pb2(SCN)4(4,4′-bipy)]n (5) with KCl, are other ways to synthesize of 1β by solid-state reactions. Synthesis of compounds 2–5 from 1α and 1β, was not possible but synthesis of [Pb(Br)2(4,4′-bipy)]n (6) and [Pb(I)2(4,4′-bipy)]n (7) from 1α and 1β was done successfully. In addition, the morphology of initial precursor has direct influence on morphology of resulting calcined material.

In addition to grinding 1α, mechanochemical reaction is another way to synthesis 1β. Mechanochemical reaction of [Pb(Br)2(4,4′-bipy)]n and [Pb(I)2(4,4′-bipy)]n with KCl was not resulted in formation of 1 polymorphs.Figure optionsDownload as PowerPoint slide