Pressure-Induced Spectroscopic Changes in a Californium 1D Material Are Twice as Large as Found in the Holmium Analog

Abstract

In this study, the synthesis, characterization, and pressure response of a 1D californium mellitate (mellitate = 1,2,3,4,5,6-benzenehexacarboxylate) coordination polymer, Cf2(mell)­(H2O)10·4H2O (Cf-1), are reported. The Cf–O lengths within the crystal structure are compared to its gadolinium (Gd-1) and holmium (Ho-1) analogs as well. These data show that the average Cf–O bond distance is slightly longer than the average Gd–O bond, consistent with trends in effective ionic radii. UV–vis-NIR absorption spectra as a function of pressure were collected using diamond-anvil techniques for both Cf-1 and Ho-1. These experiments show that the Cf­(III) f → f transitions have a stronger dependence on pressure than that of the holmium analog. In the former case, the shift is nearly linear with applied pressure and averages 6.6 cm–1/GPa, whereas in the latter, it is <3 cm–1/GPa.

Pronounced Pressure Dependence of Electronic Transitions for Americium Compared to Isomorphous Neodymium and Samarium Mellitates

“…Californium mellitate has a smaller shift than both 1-Am and 1-Cm with 6.6 cm −1 /GPa, 35 which suggests that perhaps the perturbations of f → f transitions decrease as the series traverses, albeit the californium compound has a distinctly different structural environment than 1-Am and 1-Cm. This trend is also seen where the shifts get smaller across the lanthanides 1-Nd > 1-Sm > holmium, 35 although holmium possesses the californium structure. Although 1-Am has greater shifts on average than both 1-Cm and californium mellitate, it pales in comparison to the soft donor dithiocarbamate complex NH 4 [Cm(PyDTC) 4 ]•2MeOH (PyDTC − = pyrrolidinedithiocarbamate), which had shifts greater than 60 cm −1 /GPa.…”

“…29−32 Recently, there have been solid-state studies with trivalent actinide metals including plutonium, 33 curium, 34 and californium. 35 Here we report the structure, UV−vis−near-IR (NIR) spectroscopy, and variable-pressure UV−vis−NIR spectroscopy for americium and compare these data with neodymium and samarium analogues because of their similar ionic radii and clear f → f transitions.…”

“…Upon dissolution of thorium and uranium carbides in nitric acid, it has been shown that mellitic acid [C 6 (COOH) 6 , H 6 mell] can be formed. , This organic acid is also environmentally relevant in soil such as humic acid and minerals like honeystone (aluminum mellitate). , A wide variety of coordination modes are available, with the mellitate ion forming diverse structural variability and dimensionality of coordination polymers. Actinide interactions with this organic linker have had a number of studies over the past several decades. − Recently, there have been solid-state studies with trivalent actinide metals including plutonium, curium, and californium . Here we report the structure, UV–vis–near-IR (NIR) spectroscopy, and variable-pressure UV–vis–NIR spectroscopy for americium and compare these data with neodymium and samarium analogues because of their similar ionic radii and clear f → f transitions.…”

Synthesis, characterization, and high-pressure studies of a 3D berkelium(iii) carboxylate framework material

“…16 Recently, our group has studied a series of trivalent actinide mellitates for plutonium, 17 americium, 18 curium, 19 and californium. 20 The Bk(III) mellitate, Bk 2 [C 6 (CO 2 ) 6 ](H 2 O) 8 Á2H 2 O (Bk1), was obtained by layering a green aqueous solution of BkBr 3 ÁnH 2 O (3.5 mg, 14 mmol 249 Bk 3+ content) and mellitic acid with ethanol. Yellowish-green crystals of Bk1 grew in three hours from this solution (further details are given in the ESI †).…”

“…5). Compared to the americium, 18 curium, 19 and californium 20 mellitate, it appears that the average shift of a transition is hypsochromic (blue shifting) as opposed to bathochromic (red shifting) (Fig. S11, ESI †).…”