Solid-State Redox Switching of Magnetic Exchange and Electronic Conductivity in a Benzoquinoid-Bridged Mn^II Chain Compound

Abstract

We demonstrate that incorporation of a redox-active benzoquinoid ligand into a one-dimensional chain compound can give rise to a material that exhibits simultaneous solid-state redox switching of optical, magnetic, and electronic properties. Metalation of the ligand 4,5-bis(pyridine-2-carboxamido)-1,2-catechol ((N,O)LH4) with Mn(III) affords the chain compound Mn((N,O)L)(DMSO). Structural and spectroscopic analysis of this compound show the presence of Mn(II) centers bridged by (N,O)L(2-) ligands, resulting partially from a spontaneous ligand-to-metal electron transfer. Upon soaking in a solution of the reductant Cp2Co, Mn((N,O)L)(DMSO) undergoes a ligand-centered solid-state reduction to [Mn((N,O)L)](-), as revealed by a suite of techniques, including Raman and X-ray absorption spectroscopy. The ligand-based reduction engenders a dramatic modulation of the physical properties of the chain compound. An electrochromic response, evidenced by a color change from dark green to dark purple is accompanied by a nearly 40-fold increase in magnetic coupling strength, from J = -0.38(1) to -15.6(2) cm(-1), and a 10,000-fold increase in electronic conductivity, from σ = 2.33(1) × 10(-12) S/cm (Ea = 0.64(1) eV) to 8.61(1) × 10(-8) S/cm (Ea = 0.39(1) eV). Importantly, the chemical reduction is reversible: treatment of the reduced compound with [Cp2Fe](+) regenerates the oxidized chain. Taken together, these results highlight the ability of benzoquinoid ligands to facilitate solid-state ligand-based redox reactions in nonporous coordination solids, giving rise to reversible switching of optical properties, magnetic exchange interactions, and electronic conductivity.

Carving Out Pores in Redox‐Active One‐Dimensional Coordination Polymers

“…In conclusion, we show an ew method for generating conductive porous coordination polymers by sculpting pores in polymers through templating effects by anions that leave the framework upon reduction. When redox-active ligands are coupled to such polymers,this yields ageneral method for simultaneously increasing both conductivity and porosity in as ingle 1D coordination polymer.W hile the properties of coordination polymer chains have previously been shown to be sensitive to their redox state, [17] the ability to simultaneously convert anonporous insulator to aporous conductor is unusual.…”

“…Owing to their unique combination of properties,m etallopolymers [2][3][4][5][6][7][8][9] have elicited significant interest as materials for sensors, [3][4][5] microelectronics, [6,10,11] energy storage, [7,8] gas separation, [9] and catalysis. [9,12] Although there are many examples of redox-active and electrically conductive metallopolymers, [6,[13][14][15][16][17] few are porous. [12] Whereas porosity in network solids,s uch as three-dimensional metal-organic frameworks,arises from voids in the framework, [1,9,18] porosity in 1D coordination polymers depends on how the polymer chains pack in the solid state.Herein, we report amethod to generate porous conductive coordination polymers by reduction of cationic polymers;e xtrusion of counterions provides ameans of generating and tuning the porosity.…”

Carving Out Pores in Redox‐Active One‐Dimensional Coordination Polymers

“…Owing to their unique combination of properties, metallopolymers have elicited significant interest as materials for sensors, microelectronics, energy storage, gas separation, and catalysis . Although there are many examples of redox‐active and electrically conductive metallopolymers, few are porous . Whereas porosity in network solids, such as three‐dimensional metal–organic frameworks, arises from voids in the framework, porosity in 1D coordination polymers depends on how the polymer chains pack in the solid state.…”

“…When redox‐active ligands are coupled to such polymers, this yields a general method for simultaneously increasing both conductivity and porosity in a single 1D coordination polymer. While the properties of coordination polymer chains have previously been shown to be sensitive to their redox state, the ability to simultaneously convert a nonporous insulator to a porous conductor is unusual.…”

A new two-dimensional CdIIcoordination polymer based on 2-(1H-imidazol-1-ylmethyl)-6-methyl-1H-benzimidazole and benzene-1,2-dicarboxylate: synthesis, crystal structure and characterization

“…The synthesis of coordination polymers has attracted considerable interest owing to their fascinating network topologies and special applications (Jeon et al, 2016;Lee et al, 2015;Srivastava et al, 2016;Wang et al, 2016;Yang et al, 2014), but it is still a challenge to predict the exact structures and compositions of the final products. In the construction of coordination polymers, many factors can influence the formation of the final architectures, such as the nature of the metal centres, the organic ligands, the counter-anions, and so on (Lee et al, 2015;Maity et al, 2016).…”