Spectroscopic, Structural and DFT Study of the Responses of Carbonylmetal Crown Ether Complexes to Alkali Metal Cations

Abstract

Keywords:Crown compounds / Alkali metal ions / IR spectroscopy / Density functional calculations / Molecular sensors / Carbonyl ligands FTIR spectra of tricarbonyl(η 6 -benzo-15-crown-5)chromium(0) (1) in the presence of lithium, sodium and potassium perchlorate salts in methanol show different responses in the Cr-CO vibrational region of the spectrum. Data from the symmetric (ν sym ) and antisymmetric (ν asym ) Cr-CO vibrational stretching modes have been analysed by principal component analysis (PCA) to generate a factor score plot that provides a visual representation of these differential responses. X-ray crystallographic data for the sodium perchlorate complex 1·Na + and dimensions from DFT-derived structures of 1·Li + , 1·Na + and 1·K + indicate that binding M + in the crown causes electron density and structural changes in the [O(4)-C(9)-C(4)-O(8)]Cr-C(1)=O(1) sections of 1, which vary depending on the nature of the cation. This suggests a mode

Azulene Functionalization by Iron-Mediated Addition to a Cyclohexadiene Scaffold

“…Iron carbonyl complexes are of interest as bioprobes, indicating that the azulenes formed in this study could be useful in their own right. In addition to a strong and distinctive absorption in the IR region from the iron carbonyl moiety, the azulene fragment introduces both a fluorophore and a clearly visible colorimetric indicator, thus potentially allowing multimodal chemical sensing.…”

Vibrational spectroscopy of metal carbonyls for bio-imaging and -sensing

“…The use of a benzo-15-crown-5-Cr(CO)3 complex 28 to sense alkali metal ions was first demonstrated by Creaser and Stephenson (figure 10a). 54,55 Crown ethers have high affinity for alkali cations and hence, coupling them to metal carbonyl sensors allow the CO vibrations to act as readout signals via FT-IR spectroscopy. Complex 28 was found to be sensitive to Na + and K + ions, with concentration-dependent shifts of the symmetric and asymmetric stretches to higher wavenumbers; these are indicative of a reduction in the π-back donation from the metal.…”

“…In an extended study, a principal component analysis (PCA) of the IR spectra for analytes with various compositions of cations (Li + , Na + and K + ), and ClO 4 − as the anion, in the 1890-1880 cm −1 region was carried out to give a qualitative factor score plot. 55 The latter allows the qualitative difference in the spectra to be correlated with the different ratios of cations.…”

Electron Density Distribution in 15-Crown-5 and Its Thioanalogs

“…Одной из актуальнейших задач современной химии является переработка радиоактивных отходов [4]. Создание данной технологии сопряжено с рядом трудностей, одной из которых является сильная токсичность радиоактивных соединений, а другойвысокая растворимость получаемых радионуклеотидных комплексов в воде [ Некоторые физико-химических свойства краун-эфиров и их тиоаналогов указаны в [5,6], их уточнение в [7][8][9][10][11][12][13][14][15]. Распределение электронной плотности, как правило, изучают с использованием компьютерных программ [18,20].…”

“…Ранее исследования краун-эфиров методами квантовой химии проводились в работах [7,[10][11][12][13][14][15]. В [14,15] даны геометрические параметры комплексов краун-эфиров с щелочными металлами [7, 10-12, 14, 15], однако электронное строение исходных молекул в данных работах не приводилось.…”