Phosphonated Hexaphenylbenzene: A Crystalline Proton Conductor

Jiménez‐García, Lucía; Kaltbeitzel, Anke; Pisula, Wojciech; Gutmann, Jochen S.; Klapper, Markus; Müllen, Kläus

doi:10.1002/anie.200902116

Cited by 75 publications

(63 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[23,24] Elemental analysis was performed by using a Foss Heraeus Vario EL instrument. The experimental procedure for the synthesis of HPB can be found elsewhere.…”

Section: Experimental Section General Informationmentioning

confidence: 99%

“…[14][15][16][17][18][19][20][21] They combine a high density of ionic groups as the proton source in the mesopores with the mechanical and structural durability of their inorganic pore scaffolds. [23,24] In the present case, hexakis(p-phosphonatophenyl)benzene (HPB) functionalized with hexaphosphonic acid is complexed with a substoichiometric amount of a trivalent metal cation (Al 3+ ) in such a way that nonligated acidic groups still remain on the linker HPB that are able to build up proton-conducting pathways through the material. It was shown recently, that proton diffusivity and the water sorption process in mesoporous silica can be increased significantly by the introduction of hydrophilic groups such as sulfonic acid into the framework structure.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Proton Conductivity in Doped Aluminum Phosphonate Sponges

et al. 2014

Self Cite

View full text Add to dashboard Cite

Proton-conducting networks (NETs) were prepared successfully by the insertion of phosphonated nanochannels into organic-inorganic hybrid materials that contain Al(3+) as the connector and hexakis(p-phosphonatophenyl)benzene (HPB) as the linker. Noncomplexed phosphonic acid groups remain in the framework, which depends on the ratio of both compounds, to yield a proton conductivity in the region of 10(-3) S cm(-1). This conductivity can be further improved and values as high as Nafion, a benchmark proton-exchange membrane for fuel cell applications, can be obtained by filling the network pores with intrinsic proton conductors. As a result of their sponge-like morphology, aluminum phosphonates adsorb conductive small molecules such as phosphonic acids, which results in a very high proton conductivity of approximately 5 × 10(-2) S cm(-1) at 120 °C and 50 % relative humidity (RH). Contrary to Nafion, the doped networks show a remarkably low temperature dependence of proton conductivity from external humidification. This effect indicates a transport mechanism that is different to the water vehicle mechanism. Furthermore, the materials exhibit an activation energy of 40 kJ mol(-1) at 15 % RH that starts to diminish to 10 kJ mol(-1) at 80 % RH, which is even smaller than the corresponding values obtained for Nafion 117.

show abstract

“…[23,24] Elemental analysis was performed by using a Foss Heraeus Vario EL instrument. The experimental procedure for the synthesis of HPB can be found elsewhere.…”

Section: Experimental Section General Informationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proton Conductivity in Doped Aluminum Phosphonate Sponges

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…Metal organophosphonates are stable in water or aqueous environment [5]. The use of metal phosphonates in catalysis, luminescence [6], ion or proton exchange or conductivity [7,8] and in separation is discussed and investigated [9]. Further, cobalt and iron organophosphonates are investigated for their magnetic properties [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Charge-Assisted Hydrogen-Bonded Networks of NH4+ and [Co(NH3)6]3+ with the New Linker Anion of 4-Phosphono-Biphenyl-4′-Carboxylic Acid

Heering¹,

Nateghi²,

Janiak³

2016

Crystals

View full text Add to dashboard Cite

Abstract:The new linker molecule 4-phosphono-biphenyl-4 1 -carboxylic acid (H 2 O 3 P-(C 6 H 4 ) 2 -COOH, H 3 BPPA) has been structurally elucidated in hydrogen-bonded networks with the ammonium cation NH 4 (H 2 BPPA)(H 3 BPPA) (1) and the hexaamminecobalt(III) cation [Co(NH 3 ) 6 ](BPPA)¨4H 2 O (2). The protic O-H and N-H hydrogen atoms were found and refined in the low-temperature single-crystal X-ray structures. The hydrogen bonds in both structures are so-called charge-assisted; that is, the H-bond donor and/or acceptor carry positive and/or negative ionic charges, respectively.The H-bonded network in 1 consists of one formally mono-deprotonated 4-phosphonato-biphenyl-4 1 -carboxylic acid group; that is, a H 2 BPPA´anion and a neutral H 3 BPPA molecule, which together form a 3D hydrogen-bonded network. However, an almost symmetric resonance-assisted hydrogen bond (RAHB) bond [O¨¨¨H = 1.17 (3) and 1.26 (3) Å, O¨¨¨H¨¨¨O = 180 (3)˝] signals charge delocalization between the formal H 2 BPPA´anion and the formally neutral H 3 BPPA molecule. Hence, the anion in 1 is better formulated as [H 2 BPPA¨¨¨H¨¨¨H 2 BPPA]´. In the H-bonded network of 2 the 4-phosphonato-biphenyl-4 1 -carboxylic acid is triply deprotonated, BPPA 3´. The [Co(NH 3 ) 6 ] 3+ cation is embedded between H-bond acceptor groups, -COO´and -PO 3´a nd H 2 O molecules. The incorporation of sixteen H 2 O molecules per unit cell makes 2 an analogue of the well-studied guanidinium sulfonate frameworks.

show abstract

“…Recently, we proposed a novel approach to achieve proton mobility by the self‐organization of small molecules 33, 34. This new concept was demonstrated by the use of phosphonic acid containing crystalline molecules such as hexakis( p ‐phosphonatophenyl)benzene.…”

Section: Introductionmentioning

confidence: 99%

Organic Proton‐Conducting Molecules as Solid‐State Separator Materials for Fuel Cell Applications

Jiménez‐García

Kaltbeitzel

Enkelmann

et al. 2011

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

Organic proton-conducting molecules are presented as alternative materials to state-of-the-art polymers used as electrolytes in proton-exchanging membrane (PEM) fuel cells. Instead of infl uencing proton conductivity via the mobility offered by polymeric materials, the goal is to create organic molecules that control the proton-transport mechanism through supramolecular order. Therefore, a series of phosphonic acid-containing molecules possessing a carbon-rich hydrophobic core and a hydrophilic periphery was synthesized and characterized. Proton conductivity measurements as well as water uptake and crystallinity studies (powder and single-crystal X-ray analysis) were performed under various conditions. These experiments reveal that proton mobility is closely connected to crystallinity and strongly dependent on the supramolecular ordering of the compound. This study provides insights into the proton-conducting properties of this novel class of materials and the mechanisms responsible for proton transport.

show abstract

Phosphonated Hexaphenylbenzene: A Crystalline Proton Conductor

Cited by 75 publications

References 35 publications

Proton Conductivity in Doped Aluminum Phosphonate Sponges

Proton Conductivity in Doped Aluminum Phosphonate Sponges

Charge-Assisted Hydrogen-Bonded Networks of NH4+ and [Co(NH3)6]3+ with the New Linker Anion of 4-Phosphono-Biphenyl-4′-Carboxylic Acid

Organic Proton‐Conducting Molecules as Solid‐State Separator Materials for Fuel Cell Applications

Contact Info

Product

Resources

About