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Laser Spectroscopic Study of Cold Host–Guest Complexes of Crown Ethers in the Gas Phase
Author(s) -
Inokuchi Yoshiya,
Kusaka Ryoji,
Ebata Takayuki,
Boyarkin Oleg V.,
Rizzo Thomas R.
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201200746
Subject(s) - chemistry , ionic bonding , photochemistry , spectroscopy , infrared spectroscopy , conformational isomerism , density functional theory , ultraviolet , photodissociation , ion , computational chemistry , molecule , organic chemistry , materials science , physics , quantum mechanics , optoelectronics
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.