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    Research data supporting [Mining 2:2 Complexes from 1:1 Stoichiometry: Formation of Cucurbit[8]urilDiarylviologen Quaternary Complexes Favored by Electron-Donating Substituents]
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    Abstract:
    NMR, ITC, Mass, CCS calculation, and UV-Vis data to support the demonstration of 2:2 binding mode of CB[8]-diarylviologen complexes
    Keywords:
    Stoichiometry
    Abstract A laser spectroscopic study on the structure and dynamics of cold host–guest inclusion complexes of crown ethers (CEs) with various neutral and ionic species in the gas phase is presented. The complexes with neutral guest species are formed by using supersonic free jets, and those with ionic species are generated with electrospray ionization combined with a cold 22‐pole ion trap. For CEs, various sizes of 3 n ‐crown‐ n ethers ( n =4, 5, 6, and 8) and their benzene‐substituted species are used. For the guest species, water, methanol, ammonia, acetylene, and phenol are employed as neutral guest species, and for charged guest species, alkali metal cations are chosen. The electronic and vibrational spectra of the complexes are measured by using various laser spectroscopic methods; electronic spectra for the neutral complexes are measured by laser‐induced fluorescence. Discrimination of different species such as conformers is performed by ultraviolet–ultraviolet hole‐burning spectroscopy. The vibrational spectra of selected species are observed by infrared–ultraviolet double‐resonance (IR–UV DR) spectroscopy. For the ionic complexes, ultraviolet photodissociation and IR–UV DR spectroscopy are applied. The complex structures are determined by comparing the observed spectra with those of possible structures obtained by density functional theory calculations. How the host CEs change their conformation or which conformer prefers to form unique inclusion complexes are discussed. These results reveal the key interactions for forming special complexes leading to molecular recognition.
    Conformational isomerism
    Ultraviolet
    Citations (29)
    Double-helical [M2L2]n+, triple-helical [M2L3]n+, and toroidal [M3L3]n+ (M = Cu, Co, Fe, Ni, La, Eu, Gd, Tb, or Lu) supramolecular complexes have been fully characterized by ion spray mass spectrometry (IS-MS). The IS-MS spectra from pure acetonitrile solutions reflect the nature of the cations present in solution with conservation of the charge state and allow an efficient qualitative speciation of the compounds. The mass spectrometry results can be correlated with other powerful techniques (nuclear magnetic resonance and electronic spectroscopy) for the characterization of supramolecular complexes in solution, Structural information is obtained by collision-induced dissociation, which strongly depends on the metal ions used in the supramolecular complexes and on the various connectivities and topologies of the ligands. When the ligand contains 3,5dimethoxybenzyl groups bound to the benzimidazole rings, the partial fragmentation of the complexes is associated with a decrease of the total charge of the complexes and the appearance of the characteristic fragment at m/z 151 that corresponds to the 3,5-dimethoxybenzyl cation. A detailed analysis of the fragmentation pathways of these supramolecular complexes suggests that the metal-nitrogen coordination bonds are very strong in the gas phase.
    Fragmentation
    Collision-induced dissociation
    Coordination complex