Highly Thermal‐Stable Supramolecular Assembly of a Hydrogen‐Bonded Mononuclear Nickel(II) Histidine Compound

Abstract

A chiral nickel histidine compound, [Ni(L-his) 2 ]×H 2 O (1, L-his = anion of L-histidine), was synthesized in high yield from the reaction of Ni(OAc) 2 ×4H 2 O and L-histidine in the presence of 4,4¢-bipyridine under mild reaction conditions. A single-crystal X-ray diffraction analysis showed that compound 1 crystallizes in the monoclinic system, space group C2, with a chemical formula of C 12 H 18 N 6 NiO 5 , cell parameters: a = 29.416(2) Å, b = 8.2667(7) Å, c = 6.3137(5) Å, b = 90.066(2)°, V = 1535.3(2) Å 3 and Z = 4. Each nickel(II) ion in 1 is six coordinated, bonded to two oxygen donors and four nitrogen donors from two crystallographically independent L-his -ligands with a tridentate coordination mode to form a monomeric species. Monomeric forms of 1 undergo self-assembly to form a three-dimensional (3D) supramolecular architecture via subtle combinations of N-H×××O type hydrogen bonding interactions among the adjacent L-his -ligands and p-p stacking interactions among the imidazole rings of the L-his -ligands. The supramolecular entity exhibits an unusually high thermal stability, at temperatures of up to 360°C and shows reversible de-/re-hydration properties.

Gas-phase complexes of Ni2+ and Ca2+ with deprotonated histidylhistidine (HisHis): A model case for polyhistidyl-metal binding motifs

“…The [M (HisHis-H)] + complexes of (a) Ni 2+ and (b) Ca 2+ were freshly prepared for this study [20] and characterized by positive ion mode electrospray ionization (+ESI) mass spectrometry (MS). Both complexes were prepared in H 2 O/ethanol and this solution was diluted with methanol to a concentration of about 10 M for (+)ESI-MS. All (+)ESI-MS and MS 2 experiments, as well as accurate mass measurements, were conducted on a ThermoFisher LTQ-Orbitrap XL instrument (ThermoFisher, Bremen Germany, see Supporting Information Table S1).…”

“…Wavelength tunable infrared light from the FELIX free electron laser was used for IRMPD as has been described elsewhere [19]. The singly charged metal-HisHis complexes [M (HisHis-H)] + with M = Ni 2+ and Ca 2+ were synthesized according to a standard protocol [20] and the respective precursor ions were trapped, mass selected and irradiated in the QIT. The extremely low density of ions in any tandem MS precludes measurement of gas-phase IR spectra in transmission and therefore IRMPD spectra are acquired by monitoring the extent of precursor ion depletion and product ion formation as the frequency of the IR radiation used for activation is tuned between 5-.…”

IRMPD Spectroscopic and Theoretical Structural Investigations of Zinc and Cadmium Dications Bound to Histidine Dimers

“…Precursors to the Zn(His-H)(His) + and Cd(His-H)(His) + complexes were formed using a procedure adapted from the literature, and all materials were used as delivered and without further purification. 22 Briefly, an aqueous solution (6 mL) of Lhistidine (0.3 mmol) and pyridine (0.1 mmol) was placed in a tube. Three milliliters of a metal salt solution (0.1 mmol), either zinc or cadmium acetate, in ethanol was carefully layered on top.…”