Solvent effects on the reactivities of organometallic compounds

Gutmann, V.

doi:10.1016/s0010-8545(00)82045-7

Cited by 874 publications

(591 citation statements)

References 95 publications

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“…A larger downfield shift was detected for H-8 in the L2 complex because it is closer to the coordinating (CÀ ÀOÀ ÀC) group [ Figure 6, Table 5 Table 5(e)]. This fact also confirmed from the absorption spectrum result of this complex and reported data, which (DMSO) have a very high Gutmann donor number [33]. These results were agreed to the UV-Vis spectral results, which showed that the solution spectrums of complexes were unaffected and no changes were observed with respect to their ligands.…”

Section: Main Group Chemistry 141supporting

confidence: 72%

“…As shown in Figures 2 and 3, the change in the spectra of the complexes demonstrates a change in the environment of the metal ion, for which a reasonable explanation is that the solvent coordinated with the metal ion causes a change in symmetry of the field and effective geometry. Iftikhar and his coworkers [30][31][32] have reported that DMF is especially effective in coordination, which has a high Gutmann donor number [33], enters the inner coordination sphere of the yttrium (III) complexes without replacing any ligand molecule(s). That DMF is not displacing the ligands is shown Table 2.…”

Section: Uv-vis Spectramentioning

confidence: 99%

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¹H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

Ansari¹

2008

Main Group Chemistry

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The compounds, Y(L1-5) 3 , [where L1-5 ¼ quercetin (L1), morin (L2), naringenin (L3), catechin (L4) and chrysin (L5)] were prepared and characterized by elemental analysis, molar conductance, UV-Vis, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and proton nuclear magnetic resonance ( 1 H NMR) spectroscopic studies. Molar conductance showed that the complexes are non-electrolytic in nature. The complexes were anhydrous as revealed by the TGA analyses. The 1 H NMR spectra in DMSO-d 6 revealed a diamagnetic shift. The small chemical shift of the proton resonances suggested that the complexes are dissociated in DMSO solvent and the solvent is coordinated to the Y atoms.

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Section: Main Group Chemistry 141supporting

confidence: 72%

Section: Uv-vis Spectramentioning

confidence: 99%

¹H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

Ansari¹

2008

Main Group Chemistry

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“…Examples of the spectra in n-pentane and trifluoroethanol are shown in Figure 4 and reveal a marked sensitivity to the polarity. Figure 5 shows that linear correlations are obtained when vczc and are plotted against solvent acceptor number (AN), a measure of the propensity of the sol- vent to accept electron pairs (as defined by the 3'P-NMR shift of a reference base ((C2H5)3P0, Gutman, 1976). This parameter has previously been found to correlate well with amide carbonyl stretching frequencies (Grygon and Spiro, 1989;Wang et al, 1991a).…”

Section: Is the Steroid Protonated?mentioning

confidence: 89%

Substrate polarization by residues in Δ⁵‐3‐ketosteroid isomerase probed by site‐directed mutagenesis and UV resonance Raman spectroscopy

Austin

Kuliopulos

et al. 1992

Protein Science

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A5-3-Ketosteroid isomerase (KSI: EC 5.3.3.1) of Pseudomonas testosteroni catalyzes the isomerization of A5-3-ketosteroids to A4-3-ketosteroids by the stereospecific transfer of the steroid 40-proton to the 60-position, using Tyr-14 as a general acid and Asp-38 as a base. Ultraviolet resonance Raman (UVRR) spectra have been obtained for the catalytically active double mutant Y55F + Y88F, which retains Tyr-14 as the only tyrosine residue (referred to as the Y140 mutant), and the Y14F mutant, which has 50,000-fold lower activity. The UVRR results establish that binding of the product analog and competitive inhibitors 19-nortestosterone or 4-fluoro-19-nortestosterone to the Y140 mutant does not result in the formation of deprotonated Tyr-14. The UVRR spectra of the steroid inhibitors show large decreases in the vinyl and carbonyl stretching frequencies on binding to the Y140 enzyme but not on binding to the Y14F enzyme. These changes cannot be mimicked by protonation of the steroids. For 19-nortestosterone, the vinyl and carbonyl stretching frequencies shift down (with respect to the values in aqueous solution) by 18 and 27 cm", respectively, on binding to Y140 KSI. It is proposed that the changes in the steroid resonance Raman spectrum arise from polarization of the enone moiety via the close proximity of the charged Asp-38 side chain to the vinyl group and the directional hydrogen bond between Tyr-14 and the 3-carbonyl oxygen of the steroid enone. The 230-nm-excited UVRR spectra do not, however, show changes that are characteristic of strong hydrogen bonding from the tyrosine hydrogen. It is proposed that this hydrogen bonding is compensated by a second hydrogen bond to the Tyr-14 oxygen from another protein residue.UVRR spectra of the Y14, enzyme obtained using 200 nm excitation show enhancement of the amide I1 and S Raman bands. The secondary structure of KSI was estimated from the amide I1 and S intensities and was found to be low in a-helical structure. The a-helix content was estimated to be in the range of 0-25% (i.e., 10 15%).

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“…Another indication that the amine group might enhance the solubility of a polymer in CO 2 was associated with the electron donating capacity (donor number) of the compounds [37], which is a qualitative measure of Lewis basicity. Kachi et al observed a linear relationship between electron donating capacity (donor number) of a molecule and the red-shift of the Raman bands of supercritical CO 2 , and suggested that the extent of the shift of the CO 2 band can be used as a measure of CO 2 -philicity of solutes in supercritical CO 2 [38].…”

Section: Introductionmentioning

confidence: 99%

“…Kachi et al observed a linear relationship between electron donating capacity (donor number) of a molecule and the red-shift of the Raman bands of supercritical CO 2 , and suggested that the extent of the shift of the CO 2 band can be used as a measure of CO 2 -philicity of solutes in supercritical CO 2 [38]. According to the tabulated data, triethylamine has a donor number of DN [37,39]. It is important to note that unlike primary and secondary amines, tertamines do not form carbamate salts with CO 2 in the absence of water [40].…”

Section: Introductionmentioning

confidence: 99%

Influence of tert-amine groups on the solubility of polymers in CO2

Kilic

Wang

Johnson

et al. 2009

Polymer

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a b s t r a c tThere is a need to develop new, non-fluorous polymers that are highly soluble in CO 2 . Experimental evidence indicates that tertiary amine and pyridine groups may exhibit favorable Lewis acid-Lewis base type interactions with CO 2 . It is therefore reasonable to assume that incorporation of tertiary amines into the side chain or backbone of non-fluorous polymers may impart a degree of CO 2 -solubility to the polymer. We present experimental results for eight different tert-amine-containing polymers. Of these polymers, only propyl dimethylamine-functionalized poly(dimethylsiloxane) is soluble in CO 2 at temperatures and pressures accessible in our experiments, but even this polymer is less soluble than non-functionalized poly(dimethylsiloxane) at the same chain length. We have performed ab initio calculations on tertiary amine-containing moieties representative of some of the polymers examined experimentally. Our calculations confirm that amine-CO 2 interactions are indeed energetically favorable. However, we also find that the moiety self-interactions are typically more favorable than the CO 2 -moiety interactions. This indicates that the lack of solubility of amine-containing polymers in CO 2 is a direct result of strong polymer-polymer interactions.

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Solvent effects on the reactivities of organometallic compounds

Cited by 874 publications

References 95 publications

¹H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

¹H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

Substrate polarization by residues in Δ⁵‐3‐ketosteroid isomerase probed by site‐directed mutagenesis and UV resonance Raman spectroscopy

Influence of tert-amine groups on the solubility of polymers in CO2

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Solvent effects on the reactivities of organometallic compounds

Cited by 874 publications

References 95 publications

1H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

1H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

Substrate polarization by residues in Δ5‐3‐ketosteroid isomerase probed by site‐directed mutagenesis and UV resonance Raman spectroscopy

Influence of tert-amine groups on the solubility of polymers in CO2

Contact Info

Product

Resources

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¹H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

¹H NMR and spectroscopic studies of biologically active yttrium (III)-flavonoid complexes

Substrate polarization by residues in Δ⁵‐3‐ketosteroid isomerase probed by site‐directed mutagenesis and UV resonance Raman spectroscopy