Dataset Information

Conformational preferences of N,N-dimethylsuccinamate as a function of alkali and alkaline earth metal salts: experimental studies in DMSO and water as determined by 1H NMR spectroscopy.

ABSTRACT: The fraction of gauche conformers of N,N-dimethylsuccinamic acid (1) and its Li(+), Na(+), K(+), Mg(2+), Ca(2+), and N(Bu)4(+) salts were estimated in DMSO and D2O solution by comparing the experimental vicinal proton-proton couplings determined by (1)H NMR spectroscopy with those calculated using the Haasnoot, de Leeuw, and Altona (HLA) equation. In DMSO, the gauche preferences were found to increase with decreasing Ahrens ionic radius of the metal counterion. The same trend was not seen in D2O, where the gauche fraction for all of the metallic salts were estimated to be approximately statistical or less. This highlights the importance of metal chelation on the conformation of organic molecules in polar aprotic media, which has implications for protein folding.

SUBMITTER: Lai HW

PROVIDER: S-EPMC3983401 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Conformational preferences of N,N-dimethylsuccinamate as a function of alkali and alkaline earth metal salts: experimental studies in DMSO and water as determined by 1H NMR spectroscopy.

Lai Holden W H HW Liu Albert Tianxiang AT Emenike Bright U BU Carroll William R WR Roberts John D JD

The journal of physical chemistry. A 20140310 11

The fraction of gauche conformers of N,N-dimethylsuccinamic acid (1) and its Li(+), Na(+), K(+), Mg(2+), Ca(2+), and N(Bu)4(+) salts were estimated in DMSO and D2O solution by comparing the experimental vicinal proton-proton couplings determined by (1)H NMR spectroscopy with those calculated using the Haasnoot, de Leeuw, and Altona (HLA) equation. In DMSO, the gauche preferences were found to increase with decreasing Ahrens ionic radius of the metal counterion. The same trend was not seen in D2O ...[more]

PMID: 24506581

Similar Datasets

Project description:Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38?594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24?487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: ([3])Li(+), ([3])Na(+), ([4])K(+), ([4])Rb(+), ([6])Cs(+), ([3])Be(2+), ([4])Mg(2+), ([6])Ca(2+), ([6])Sr(2+) and ([6])Ba(2+), but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of ([6])Na(+), the ratio Ueq(Na)/Ueq(bonded anions) is partially correlated with ?([6])Na(+)-O(2-)? (R(2) = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li(+) in [4]- and [6]-coordination, Na(+) in [4]- and [6]-coordination. For alkali-metal and alkaline-earth-metal ions, there is a positive correlation between cation coordination number and the grand mean incident bond-valence sum at the central cation, the values varying from 0.84?v.u. for ([5])K(+) to 1.06?v.u. for ([8])Li(+), and from 1.76?v.u. for ([7])Ba(2+) to 2.10?v.u. for ([12])Sr(2+). Bond-valence arguments suggest coordination numbers higher than [12] for K(+), Rb(+), Cs(+) and Ba(2+).

Project description:Alkali and alkaline earth metal adducts of a branched glycan, XXXG, were analyzed with helium charge transfer dissociation (He-CTD) and low-energy collision-induced dissociation (LE-CID) to investigate if metalation would impact the type of fragments generated and the structural characterization of the analyte. The studied adducts included 1+ and 2+ precursors involving one or more of the cations: H+ , Na+ , K+ , Ca2+ , and Mg2+ . Regardless of the metal adduct, He-CTD generated abundant and numerous glycosidic and cross-ring cleavages that were structurally informative and able to identify the 1,4-linkage and 1,6-branching patterns. In contrast, the LE-CID spectra mainly contained glycosidic cleavages, consecutive fragments, and numerous neutral losses, which complicated spectral interpretation. LE-CID of [M + K + H]2+ and [M + Na]+ precursors generated a few cross-ring cleavages, but they were not sufficient to identify the 1,4-linkage and 1,6-branching pattern of the XXXG xyloglucan. He-CTD predominantly generated 1+ fragments from 1+ precursors and 2+ product ions from 2+ precursors, although both LE-CID and He-CTD were able to generate 1+ product ions from 2+ adducts of magnesium and calcium. The singly charged fragments derive from the loss of H+ from the metalated product ions and the formation of a protonated complementary product ion; such observations are similar to previous reports for magnesium and calcium salts undergoing electron capture dissociation (ECD) activation. However, during He-CTD, the [M + Mg]2+ precursor generated more singly charged product ions than [M + Ca]2+ , either because Mg has a higher second ionization potential than Ca or because of conformational differences and the locations of the charging adducts during fragmentation. He-CTD of the [M + 2Na]2+ and the [M + 2 K]2+ precursors generated singly charged product ions from the loss of a sodium ion and potassium ion, respectively. In summary, although the metal ions influence the mass and charge state of the observed product ions, the metal ions had a negligible effect on the types of cross-ring cleavages observed.

Project description:Strategies for designing remarkable nonlinear optical materials using excess electron compounds are well recognized in literature to enhance the applications of these compounds in nonlinear optics. In this study, density functional theory simulations are performed to study alkali and alkaline earth metal-doped benzocryptand using the B3LYP/6-31G+(d, p) level of theory. Vertical ionization energies (VIEs), reactivity parameters, interaction energies, and binding energies exposed the thermodynamic stability of these complexes. FMO analysis revealed that HOMO is located on alkali metals having polarized electrons, which are easy to excite. The doping strategy enhanced the charge transfer with low bandgap energy in the range of 0.68-2.23 eV, which is lower than that of the surface BC (5.50 eV). Also, the lower transition energies and higher oscillator strength indicate that these complexes exhibit excellent electronic and optical properties. Non-covalent interaction analysis suggested the presence of van der Waals interactions between dopants and surface. IR analysis provided information about the frequencies of stretching vibrations present in the complexes due to different bonds. UV-vis analysis revealed that all the newly designed excess electron complexes are transparent in the UV region and possessed maximum absorption in the visible and NIR region, ranging from 753.6 to 2150 nm, which is higher than the surface (244 nm). Thus, these complexes have a potential for high-performance NLO materials in the applications of optics. Natural bond orbital analysis (NBO), transition density matrix (TDM), electron density difference map (EDDM), and density of state (DOS) analyses were also performed to study the charge transfer properties. Moreover, these complexes possessed remarkable optoelectronic properties due to a significant increase in the isotropic linear polarizability (α iso) in the range of 629.59-1423.23 au. Further, these systems demonstrated an extraordinary large total first hyperpolarizability (β tl) in the range of 3695.55-910 706.43 au. The rationalization of hyperpolarizability by the two-level model reflected a noteworthy increase in β tl because of low transition energies (ΔE) and high transition dipole moment (Δμ). Thus, our results showed that alkali and alkaline earth metal-doped BC might be a competitor for efficient nonlinear optical properties with practical applications in the area of optoelectronics.

Dataset Information

Conformational preferences of N,N-dimethylsuccinamate as a function of alkali and alkaline earth metal salts: experimental studies in DMSO and water as determined by 1H NMR spectroscopy.

Publications

Conformational preferences of N,N-dimethylsuccinamate as a function of alkali and alkaline earth metal salts: experimental studies in DMSO and water as determined by 1H NMR spectroscopy.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets