Thermochromic Uranyl Isothiocyanates: Influencing Charge Transfer Bands with Supramolecular Structure

Autor(es)

Surbella, III, Robert G. ; Ducati, Lucas C. ^[1] ; Autschbach, Jochen ^[2] ; Deifel, Nicholas P. ^[3] ; Cahill, Christopher L. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Chem, Dept Fundamental Chem, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

^[2] SUNY Buffalo, Dept Chem, 312 Nat Sci Complex, Buffalo, NY 14260 - USA

^[3] Hampden Sydney Coll, Dept Chem, Hampden Sydney, VA 23943 - USA

^[4] Surbella, Robert G., III, George Washington Univ, Dept Chem, 800 22nd St NW, Washington, DC 20052 - USA

• Tipo de documento: Artigo Científico
• Fonte: Inorganic Chemistry; v. 57, n. 5, p. 2455-2471, MAR 5 2018.
• Citações Web of Science: 10

Resumo

The synthesis and structural characterization of seven new {[}UO2(NCS)(5)](3-)- and {[}UO2(NCS)(4)Cl](3-)-containing materials charge balanced by 4-phenylpyridinium or 4,4'-bipyridinium cations are reported. Assembly of these materials occurs via a diverse set of noncovalent interactions, with the most prevalent involving the terminal sulfur atoms, which can both accept hydrogen bonds and/or form S center dot center dot center dot S and S center dot center dot center dot O-yl interactions. The electrostatic potential of the {[}UO2(NCS)(5)](3-) and {[}UO2(NCS)(4)Cl](3-) anions was calculated and mapped on the 0.001 au isodensity surface to rationalize the observed assembly modes and to provide an electrostatic basis to elucidate the role of the S atoms as both donors and acceptors of noncovalent interactions. Compounds 1-7 display a range of colors (red to yellow) as well as pronounced thermochromism. A computational treatment (time-dependent density functional theory, TDDFT) of the absorbance properties supports the temperature dependence on the ratio of inter- to intramolecular ligand to metal charge transfer (LMCT) bands as obtained from UV-vis diffuse reflectance analysis. Finally, the luminescence profiles of these materials feature additional peaks atypical for most uranyl-containing materials, and a combined spectroscopic (Raman, IR, and fluorescence) and computational (harmonic frequency calculations) effort assigns these as originating from vibronic coupling between the nu(1) U=O symmetric stretch and bending modes of the isothiocyanate ligands. (AU)

• Processo FAPESP: 14/21930-9 - Estudo do efeito do solvente na constante de acoplamento 1JPt-Tl em complexos de metais pesados por dinâmica molecular ab initio
• Beneficiário: Lucas Colucci Ducati
• Modalidade de apoio: Bolsas no Exterior - Pesquisa