Infrared Hole Burning of Crown Ether 18-c-6 Ammonium Ion Complexes

Endicott, Christopher; Strauss, Herbert L.

doi:10.1021/jp0658795

Cited by 14 publications

(16 citation statements)

References 10 publications

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“…The investigation on the molecular guest encapsulation of crown ethers has been extensively performed in the condensed phase by use of several methods such as x-ray diffraction, IR spectroscopy, and Raman spectroscopy. [12][13][14][15][16][17] However, in the condensed phase it is sometimes difficult to distinguish between the interaction of crown ethers-guest species and that of crown ethers-solvent molecules. As a result, the encapsulation mechanism is not completely understood at the molecular level.…”

Section: Introductionmentioning

confidence: 99%

Water-mediated conformer optimization in benzo-18-crown-6-ether/water system

Kusaka

Inokuchi

Ebata

2009

Phys. Chem. Chem. Phys.

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The conformation of benzo-18-crown-6-ether (B18C6) and its encapsulation of water molecules in a supersonic beam are investigated by laser induced fluorescence (LIF), UV-UV hole-burning, IR-UV double resonance (IR-UV DR), and resonance-enhanced multiphoton ionization (REMPI) spectroscopy with the aid of density functional theory (DFT) calculations at the B3LYP/6-31+G* level. At least four B18C6 conformers and nine B18C6-(H2O)n (n = 1-4) clusters are identified in the supersonic beam. IR-UV DR spectra in the CH stretching region suggest that the four B18C6 conformers have different conformations from each other. In contrast, most of the nine B18C6-(H2O)n clusters have a very similar B18C6 conformation. IR-UV DR spectra in the OH stretching region provide quite clear pictures of the hydration networks formed on B18C6. In all four B18C6-(H2O)1 isomers, the water molecule is H-bonded to the two O atoms adjacent to the benzene ring in "bidentate" and "bifurcated" manners. One of the four B18C6-(H2O)1 isomers exhibits a large population, and further hydration networks are preferentially grown on this specific isomer.

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Section: Introductionmentioning

confidence: 99%

Water-mediated conformer optimization in benzo-18-crown-6-ether/water system

Kusaka

Inokuchi

Ebata

2009

Phys. Chem. Chem. Phys.

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“…3 Spectroscopic studies for host-guest complexes have been carried out mostly at room temperature by absorption, fluorescence, NMR, IR and Raman spectroscopy. [4][5][6][7] Since the energy scale of the non-covalent interaction in the complexes is comparable to the thermal energy, only averaged aspects of the host-guest complexes were examined in these studies. Matsuura et al measured Raman spectra of the 18-crown-6-water system at liquid nitrogen temperature.…”

Section: Introductionmentioning

confidence: 99%

Structure of hydrated clusters of dibenzo-18-crown-6-ether in a supersonic jet—encapsulation of water molecules in the crown cavity

Kusaka

Inokuchi

Ebata

2008

Phys. Chem. Chem. Phys.

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The structure of dibenzo-18-crown-6-ether (DB18C6) and its hydrated clusters has been investigated in a supersonic jet. Two conformers of bare DB18C6 and six hydrated clusters (DB18C6-(H(2)O)(n)) were identified by laser-induced fluorescence, fluorescence-detected UV-UV hole-burning and IR-UV double-resonance spectroscopy. The IR-UV double resonance spectra were compared with the IR spectra obtained by quantum chemical calculations at the B3LYP/6-31+G* level. The two conformers of bare DB18C6 are assigned to "boat" and "chair I" forms, respectively, among which the boat form is dominant. All the six DB18C6-(H(2)O)(n) clusters with n = 1-4 have a boat conformation in the DB18C6 part. The water molecules form a variety of hydration networks in the boat-DB18C6 cavity. In DB18C6-(H(2)O)(1), a water molecule forms the bidentate hydrogen bond with the O atoms adjacent to the benzene rings. In this cluster, the water molecule is preferentially hydrogen bonded from the bottom of boat-DB18C6. In the larger clusters, the hydration networks are developed on the basis of the DB18C6-(H(2)O)(1) cluster.

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“…Recently, gas-phase IR spectroscopy was performed to reveal the conformation of the CE complexes with metal ions. − For benzo-CE complexes, UV spectroscopy under cold gas-phase conditions provided information on the conformation. − These complexes showed sharp vibronic structures in their UV spectra, allowing the application of UV–UV and IR–UV double-resonance spectroscopy to examine the number of conformers and their structures. For molecular ion guests, ammonium ions containing the NH 3 + group also form stable complexes with CEs. ,− For CE complexes with molecular ion guests, IR spectroscopy in the gas phase was performed for ammonium ions and protonated amino acids. ,, Recently, we studied dibenzo-18-crown-6 (DB18C6) complexes with primary alkylammonium ions (RNH 3 + ) by cold UV spectroscopy in the gas phase . The DB18C6 complexes with RNH 3 + ions are formed through three N–H···O hydrogen bonds, which induce the formation of a novel encapsulation structure absent in the metal-ion complexes [e.g., K + (DB18C6)] …”

Section: Introductionmentioning

confidence: 99%

Conformation of Benzo-12-Crown-4 Complexes with Ammonium Ions Investigated by Cold Gas-Phase Spectroscopy

et al. 2021

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In this study, we examined the conformation and intermolecular interactions of benzo-12-crown-4 (B12C4) complexes with NH4 +, CH3NH3 + (MeNH3 +), CH3CH2NH3 + (EtNH3 +), and CH3CH2CH2NH3 + (PrNH3 +) using cold gas-phase spectroscopy. All of the B12C4 complexes showed sharp vibronic features in the UV photodissociation spectra, and the position of the 0-0 band was close to that of the B12C4 complex with an isotropic K+ guest. This result suggests that the conformation of B12C4 is maintained despite oriented interactions with ammonium guests via anisotropic N–H···O interactions. Further, we measured the IR–UV double-resonance spectra of these complexes in the NH stretching region. In the IR–UV spectra of the EtNH3 + and PrNH3 + complexes, two distinct IR fingerprints were observed depending on the UV probe wavelength selected, indicating the existence of another (second) conformer for these complexes. Quantum chemical calculations clarified that the second conformer of the EtNH3 + and PrNH3 + complexes was partially stabilized by the C–H···π hydrogen bond. The conformation of B12C4 complexes with ammonium ions is strongly affected by the interaction between the alkyl chain of the ion guest and the benzene ring of the B12C4 host, although the main intermolecular interaction occurs between the NH3 + group and crown cavity through the N–H···O hydrogen bonds.

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Infrared Hole Burning of Crown Ether 18-c-6 Ammonium Ion Complexes

Cited by 14 publications

References 10 publications

Water-mediated conformer optimization in benzo-18-crown-6-ether/water system

Water-mediated conformer optimization in benzo-18-crown-6-ether/water system

Structure of hydrated clusters of dibenzo-18-crown-6-ether in a supersonic jet—encapsulation of water molecules in the crown cavity

Conformation of Benzo-12-Crown-4 Complexes with Ammonium Ions Investigated by Cold Gas-Phase Spectroscopy

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