Confinement of Mobile Histamine in Coordination Nanochannels for Fast Proton Transfer

Abstract

Along narrow channels: Mutual integration of a microporous coordination polymer and histamine provides a proton conductivity above 10−3 S cm−1 under anhydrous conditions. Anisotropic alignment of histamine molecules in straight 1D channels creates a specific conduction pathway (see picture).

Hydrogen‐Bonded Organic Frameworks (HOFs): A New Class of Porous Crystalline Proton‐Conducting Materials

“…Theh igh thermal stability and structural insight prompted us to investigate the proton conduction properties of these H-bonded frameworks.E lectrochemical impedance spectroscopy (EIS) technique was employed to pelletized sample with controlled humidity and temperature to analyze the proton conduction behavior of the HOF compounds.Atlow humidity conditions,approximately 60 % (30 8 8C) HOF-GS-10 showed proton conduction of 1.78 10 À4 Scm À1 ,w hereas HOF-GS-11 showed proton conduction of 2.6 10 À4 Scm À1 .P EMs working at low humidity and ambient temperatures are desired because they inhibit cathode flooding and maintain unhindered proton transport required for practical applications in fuel cell industries and/ or renewable energy storage devices.N otably,t his is highest report of proton conduction value at low humidity and at ambient temperature in the domain of porous materials (Table S1). This clearly indicates that water plays as ignificant role in proton conduction pathway.T he disappearance of the typical semi-circle at high RH (Figures S37,S42) is accounted for the decrease in the time constant value which depends on the bulk resistance of the sample as previously explained by Kitagawa et al [12] We also performed H 2 Oadsorption isotherm where HOF-GS-10 being comparatively more hydrophobic due to the presence of naphthalene group showed aw ater uptake of 3.47 mmol g À1 whereas the less hydrophobic HOF-GS-11 showed ar elatively more uptake of 11.6 mmol g À1 (Figures S34,35). The reproducibility of these resulted was consistent up to three experiments.Notably,this reports the highest value of proton conduction exhibited by organic based porous materials and the values are comparable to the porous materials,s uch as MOFs (Table S3).…”

Superprotonic Conductivity of a UiO‐66 Framework Functionalized with Sulfonic Acid Groups by Facile Postsynthetic Oxidation

“…[6] Noteworthy features include the regularity of the void spaces in the structure, the tunability of the pore size, and the adjustability of the pore surface properties. The first approach involves the encapsulation of guest molecules (e.g., triazole, [7] imidazole, [8] histamine, [9] ammonium cations, [10] or hydronium ions [11] ) in the structures. The conductivity of a material is predominantly determined by the proton mobility and concentration.…”

Tuning Proton Conductivity by Interstitial Guest Change in Size‐Adjustable Nanopores of a CuI‐MOF: A Potential Platform for Versatile Proton Carriers

“…Surprisingly, though, only three of them can be regarded as versatile platforms for more than two proton‐carrier guests other than water molecules without affecting the MOF framework. First, Kitagawa and co‐workers investigated the proton conductivity of an aluminium‐based porous MOF (Al‐ndc‐MIL‐53) hybridized with encapsulated imidazole or histamine as proton‐carrier guest; they found anhydrous proton conductivities of 2.2×10 −5 S cm −1 at 120 °C for the former and 1.7×10 −3 S cm −1 at 150 °C for the latter. Such a difference in proton conductivity is a result of differences in the concentration and intrinsic properties of the proton‐carrier guests in the hybridized MOF composites.…”