Spectroscopic and adsorptive studies of a thermally robust pyrazolato-based PCP

Abstract

The pyrazolato-based PCP [Ni₈(μ₄-OH)₄(μ₄-OH₂)₂(μ₄-PBP)₆] (NiPBP, H₂PBP = 4,4′-bis(1H-pyrazol-4-yl)biphenyl), whose 3-D architecture is built upon octametallic hydroxo clusters reciprocally connected by organic spacers, is a very promising candidate for gas adsorption applications, owing to its remarkable thermal stability (up to 400 °C in air) and its high void volume (70%). As such, NiPBP was selected as a proof-of-concept material to demonstrate how an optimized set of solid state techniques can concur to create a comprehensive and coherent picture, relating (average and local) structural features to adsorptive properties. To this aim, the response of NiPBP toward different gases, retrieved by gas adsorption measurements (N₂ at 77 K, in the low pressure region; H₂ at 77 K, in the high pressure region), was explained in terms of local-level details, as emerged by coupling electronic, X-ray (absorption and emission), and variable temperature IR spectroscopy.