An Open-shell, Luminescent, Two-Dimensional Coordination Polymer with a Honeycomb Lattice and Triangular Organic Radical

The use of organic radicals as building blocks is an effective approach to the production of open-shell coordination polymers (CPs). Two-dimensional (2D) CPs with honeycomb spin-lattices have attracted attention because of the unique electronic structures and physical properties afforded by their structural topology. However, radical-based CPs with honeycomb spin-lattices tend to have low chemical stability or poor crystallinity, and thus novel systems with high crystallinity and persistence are in strong demand. In this study, a novel triangular organic radical possessing three pyridyl groups, tris(3,5-dichloro-4-pyridyl)methyl radical (trisPyM) was prepared. It exhibits luminescence, high photostability, and a coordination ability, allowing formation of defined and persistent 2D CPs. Optical measurements confirmed the luminescence of trisPyM both in solution and in the solid state, with emission wavelengths, λ_em, of 665 and 700 nm, respectively. trisPyM exhibits better chemical stability under photoirradiation than other luminescent radicals: the half-life of trisPyM in CH₂Cl₂ was 10 000 times that of the tris(2,4,6-trichlorophenyl)methyl radical (TTM), a conventional luminescent radical. Complexation between trisPyM and Zn^II(hfac)₂ yielded a single crystal of a 2D CP trisZn, possessing a honeycomb lattice with graphene-like spin topology. The coordination structure of trisZn is stable under evacuation at 60 °C. Moreover, trisZn exhibits luminescence at 79 K, with λ_em = 695 nm, and is a rare example of a luminescent material among 2D radical-based CPs. Our results indicate that trisPyM may be a promising building block in the construction of a new class of 2D honeycomb CPs with novel properties, including luminescence.

One-dimensional single-helix coordination polymer self-assembled by a crown-ether appended-N-heteroacene radical anion

A crown-ether appended N-heteroacene 1 was reduced in the presence of NaBPh₄ to the radical anion 2 by accepting one electron transferred from both the cathode and BPh₄^- as a reductant. The obtained radical anion 2 can function as a radical anion ligand to bridge two sodium ions to self-assemble into one-dimensional helical coordination polymers.

Recent progress in the electron paramagnetic resonance study of polymers

This review article provides an overview of the contemporary research based on a tailor-made technique to understand the paramagnetic behavior of different polymer classes.

Synthesis, structures and magnetic properties of two chiral mixed-valence iron(ii,iii) coordination networks

Two rare chiral mixed-valence iron(ii,iii) coordination networks have been synthesized through spontaneous asymmetrical crystallization from achiral units in the assembly process.

Two luminescent metal–organic frameworks with multifunctional properties for nitroaromatic compounds sensing and photocatalysis

Two luminescent MOFs were employed as multifunctional materials for selectively sensing of nitroaromatic compounds and photodegradation of RhB.

Radicals in metal–organic frameworks

We discuss early advances in the incorporation of radicals into the ever evolving class of materials known as metal–organic frameworks.