title: Structural diversity in multinuclear Pd(II) assemblies that show low-humidity proton conduction.
abstract: Systematic investigation on synergetic effects of geometry, length, denticity, and asymmetry of donors was performed through the formation of a series of uncommon Pd(II) aggregates by employing the donor in a multicomponent self-assembly of a cis-blocked 90° Pd(II) acceptor and a tetratopic donor. Some of these assemblies represent the first examples of these types of structures, and their formation is not anticipated by only taking the geometry of the donor and the acceptor building units into account. Analysis of the crystal packing of the X-ray structure revealed several H bonds between the counteranions (NO3 (-) ) and water molecules (OH⋅⋅⋅ON). Moreover, H-bonded 3D-networks of water are present in the molecular pockets, which show water-adsorption properties with some variation in water affinity. Interestingly, these complexes exhibit proton conductivity (1.87×10(-5) -6.52×10(-4)  Scm(-1) ) at 296 K and low relative humidity (ca. 46 %) with activation energies of 0.29-0.46 eV. Moreover, the conductivities further increase with the enhancement of humidity. The ability of these assemblies to exhibit proton-conducting properties under low-humidity conditions makes these materials highly appealing as electrolytes in batteries and in fuel-cell applications.
authors.affiliation: Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India), Fax: (+91) 8023601552.
authors.forename: Dipak
authors.initials: D
authors.lastname: Samanta
authors.forename: Partha Sarathi
authors.initials: PS
authors.lastname: Mukherjee
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006813:Humidity; D006860:Hydrogen Bonding; D007477:Ions / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D011522:Protons
chemical_list: D056831:Coordination Complexes; D007477:Ions; D011522:Protons; D010165:Palladium
keywords: cage compounds; palladium; proton conduction; self-assembly