Exploring the Luminescence, Redox, and Magnetic Properties in a Multivariate Metal-Organic Radical Framework

Gonçalo Valente; Pedro Ferreira; Miguel A Hernández-Rodríguez; Carlos D S Brites; João S Amaral; Pavel Zelenovskii; Filipe A Almeida Paz; Samuel Guieu; João Rocha; Manuel Souto

doi:10.1021/acs.chemmater.3c02460

Exploring the Luminescence, Redox, and Magnetic Properties in a Multivariate Metal-Organic Radical Framework

Chem Mater. 2024 Jan 23;36(3):1333-1341. doi: 10.1021/acs.chemmater.3c02460. eCollection 2024 Feb 13.

Authors

Affiliations

¹ Department of Chemistry, CICECO-Aveiro Institute of Materials, University of Aveiro, Aveiro 3810-393, Portugal.
² Department of Physics, CICECO-Aveiro Institute of Materials, University of Aveiro, Aveiro 3810-393, Portugal.
³ Department of Chemistry, LAQV-REQUIMTE, University of Aveiro, Aveiro 3810-393, Portugal.
⁴ CIQUS, Centro Singular de Investigación en Química Bioloxica e Materiais Moleculares, Departamento de Química-Física, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.

Abstract

Persistent neutral organic radicals are excellent building blocks for the design of functional molecular materials due to their unique electronic, magnetic, and optical properties. Among them, triphenylmethyl radical derivatives have attracted a lot of interest as luminescent doublet emitters. Although neutral organic radicals have been underexplored as linkers for building metal-organic frameworks (MOFs), they hold great potential as organic elements that could introduce additional electronic properties within these frameworks. Herein, we report the synthesis and characterization of a novel multicomponent metal-organic radical framework (PTMTC^R@NR-Zn MORF), which is constructed from the combination of luminescent perchlorotriphenylmethyl tricarboxylic acid radical (PTMTC^R) and nonemissive nonradical (PTMTC^NR) organic linkers and Zn(II) ions. The PTMTC^R@NR-Zn MORF structure is layered with microporous one-dimensional channels embedded within these layers. Kelvin probe force microscopy further confirmed the presence of both organic nonradical and radical linkers in the framework. The luminescence properties of the PTMTC^R ligand (first studied in solution and in the solid state) were maintained in the radical-containing PTMTC^R@NR-Zn MORF at room temperature as fluorescence solid-state quenching is suppressed thanks to the isolation of the luminescent radical linkers. In addition, magnetic and electrochemical properties were introduced to the framework due to the incorporation of the paramagnetic organic radical ligands. This work paves the way for the design of stimuli-responsive hybrid materials with tunable luminescence, electrochemical, and magnetic properties by the proper combination of closed- and open-shell organic linkers within the same framework.