Proton Conductivity in a Metal-Organic Cube-Based Framework and Derived Hydrogel with Tubular Morphology

Sutar, P and Das, TN and Jena, R and Dutta, D and Bhattacharyya, AJ and Maji, TK (2023) Proton Conductivity in a Metal-Organic Cube-Based Framework and Derived Hydrogel with Tubular Morphology. In: Langmuir .

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Abstract

The hydrogels, formed by self-assembly of predesigned, discrete metal-organic cubes (MOCs), have emerged as a new type of functional soft material whose diverse properties are yet to be explored. Here, we explore the proton conductivity of a MOC-based supramolecular porous framework (Me2NH2)12Ga8(ImDC)12·DMF·29H2O (1) (ImDC = 4,5-imidazole dicarboxylate) and derived hydrogel (MOC-G1). The intrinsic charge-assisted H-bonded (between anionic MOC Ga8(ImDC)1212- and dimethylammonium cations) framework 1 exhibits an ambient condition proton conductivity value of 2.3 � 10-5 S cm-1 (@40 RH) which increases with increasing temperature (8.2 � 10-4 S cm-1 at 120 °C and 40 RH) and follows the Grotthuss type of mechanism of proton conduction. Self-assembly of the MOCs in the presence of ammonium cations, as molecular binders, resulted in a hydrogel (MOC-G1) that shows directional H-bonded 1D nanotubular morphology. While guest water molecules are immensely important in deciding the proton conductivity of both 1 and MOC-G1, the presence of additional proton carriers, such as DMA and ammonium cations, resulted in at least 1 order increment in the proton conductivity of the latter (1.8 � 10-2 S cm-1) than the former (1.4 � 10-3 S cm-1) under 25 °C and 98 RH condition. The values of proton conductivity of 1 and MOC-G1 are comparable with those of the best proton conduction reports in the literature. This work may pave the way for the development of proton conductors with unique architecture and conductivity requisite for the state-of-the-art technologies by selecting appropriate MOC and molecular binders. © 2024 American Chemical Society.

Item Type:	Journal Article
Publication:	Langmuir
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society.
Keywords:	Binders; Carboxylation; Hydrogels; Hydrogen bonds; Molecules; Morphology; Positive ions; Proton conductivity, Ammonium cations; Dicarboxylates; Diverse properties; H-bonded; Imidazol; Metalorganics; Molecular binders; Proton conduction; Softer materials; Tubular morphology, Organometallics
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit Division of Interdisciplinary Sciences > Interdisciplinary Centre for Energy Research
Date Deposited:	21 May 2024 04:48
Last Modified:	21 May 2024 04:49
URI:	https://eprints.iisc.ac.in/id/eprint/84515

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