Photo- and triboluminescent robust 1D polymers made of Mn(ii) halides and meta-carborane based bis(phosphine oxide)

Abstract

A series of 1D coordination polymers (CPs), [MnX₂(L)]_n (X = Cl, Br, I), made of MnX₂ units bridged by 1,7-[Ph₂P(O)]₂-meta-carborane ligands (L) through the O–Mn–O linkages, have been designed. At ambient temperature, these CPs manifest green phosphorescence with quantum yields of up to 60%, which is the highest value for Mn(II) CPs. CP [MnI₂(L)]_n and its structurally different solvate [MnI₂(L)·CH₂Cl₂]_n also exhibit bright triboluminescence. Thermochromic luminescence of the designed CPs appears as reversible shifting of their emission color, when the temperature varies from 350 to 77 K and back. Moreover, [MnI₂(L)·CH₂Cl₂]_n reversibly changes its emission properties during desolvation-solvation processes thus featuring solvatochromic luminescence. According to photophysical and EPR data, the observed phosphorescence originates from the ligand-sensitized ⁴T₁ → ⁶A₁ transition in Mn²⁺ ions. Enhanced robustness of the title CPs is demonstrated by retaining their emission properties after prolonged heating at 210 °C.