Assembly of three sulfonylcalix[4]arene-based multinuclear complexes: Tunable structures and guest encapsulation properties

Elucidating the role of the o-methoxy group in the lower rim appended salicylideneamine substituents of calix[4]arene ligands on the molecular and electronic structures of dinuclear Fe(iii)-based diamond-core complexes

“…The 57 Fe Mössbauer spectra were obtained on a standard MS-1104Em spectrometer N 0 40-12 in the continuous acceleration mode using the symmetric sawtooth law of velocity change. The spectra were accumulated separately as the source was moved forward and backward, and their subsequent summation was used to eliminate background line distortion.…”

“…A scintillation counter with a thin NaJ(Tl) crystal was used as the detector. The spectra were obtained with a 57 Co source in the Rh matrix. Calibration was performed using the α-Fe spectrum, and isomer shifts were measured from the center of gravity of this reference spectrum obtained at room temperature (RT).…”

“…In order to reveal the impact of the co-existence of two nonequivalent Fe(III) atoms, which differ by the cis-/transorientation of their N atoms within the coordination sphere, on their spin properties, the 57 Fe Mössbauer spectroscopic study of the prepared powdered samples of complexes 4 2 -Fe 2 exp and 5 2 -Fe 2 exp was performed. 101 The hyperfine parameters were obtained by least-square fitting of the spectra with broadened Lorentzian lineshapes.…”

“…Apart from the homometallic species, heterometallic [Ln III 2 -Fe III 2 ] 52 (Ln = Dy, Gd, or Tb) and [M 4 -Fe III 4 ] 53 (M = Na, or K) clusters, which exhibit a sandwich-like motif, can also be generated, and their magnetic or catalytic properties have been documented. Thiacalix [4]arene (2) and sulfonylcalix [4]arene (3) have also demonstrated particular ability to bind Fe(III) cations, forming di-, 54 tri-55 and tetranuclear 56,57 clusters.…”

“…In both compounds, the flexible spacer composed of three methylene bridges was chosen to connect the coordinating salicylideneamine moieties to the macrocycle platform to minimize the possibility of the macrocyclic backbone cone conformation distorting the Fe(III) coordination sphere. Single-crystal and powder X-ray diffraction analyses, HR-ESI mass spectrometry, B3LYP/DFT calculations, 57 Fe Mossbauer spectroscopy and solid-state voltammetry studies were performed in order to elucidate the role of the ortho methoxy group at the salicylideneamine coordinating sites on the molecular structure of the obtained complexes, as well as the energy of the HOMO-LUMO orbitals of the obtained coordination compounds.…”