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81.
Dr. Laura M. Grimm Dr. Sebastian Spicher Dr. Boryslav Tkachenko Prof. Dr. Peter R. Schreiner Prof. Dr. Stefan Grimme Dr. Frank Biedermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(38):e202200529
The rationalization of non-covalent binding trends is both of fundamental interest and provides new design concepts for biomimetic molecular systems. Cucurbit[n]urils (CBn) are known for a long time as the strongest synthetic binders for a wide range of (bio)organic compounds in water. However, their host-guest binding mechanism remains ambiguous despite their symmetric and simple macrocyclic structure and the wealth of literature reports. We herein report experimental thermodynamic binding parameters (ΔG, ΔH, TΔS) for CB7 and CB8 with a set of hydroxylated adamantanes, di-, and triamantanes as uncharged, rigid, and spherical/ellipsoidal guests. Binding geometries and binding energy decomposition were obtained from high-level theory computations. This study reveals that neither London dispersion interactions, nor electronic energies or entropic factors are decisive, selectivity-controlling factors for CBn complexes. In contrast, peculiar host-related solvation effects were identified as the major factor for rationalizing the unique behavior and record-affinity characteristics of cucurbit[n]urils. 相似文献
82.
Stefan Grimme Prof. Dr. Christian Mück‐Lichtenfeld Dr. Gerhard Erker Prof. Dr. Gerald Kehr Dr. Huadong Wang Dr. Helmut Beckers Dr. Helge Willner Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(14):2592-2595
Don't rewrite the textbooks! Vibrational spectra of a selectively deuterated derivative of phenanthrene indicate that the C4H???HC5 interaction in its “bay” area should be interpreted as steric (Pauli) repulsion. These findings and the results of theoretical analysis are in conflict with interpretations that describe this interaction as strongly stabilizing.
83.
84.
Michal Pitoňák Dr. Pavel Neogrády Dr. Jiří Černý Dr. Stefan Grimme Prof. Pavel Hobza Prof. 《Chemphyschem》2009,10(1):282-289
Scaled MP3 interaction energies calculated as a sum of MP2/CBS (complete basis set limit) interaction energies and scaled third‐order energy contributions obtained in small or medium size basis sets agree very closely with the estimated CCSD(T)/CBS interaction energies for the 22 H‐bonded, dispersion‐controlled and mixed non‐covalent complexes from the S22 data set. Performance of this so‐called MP2.5 (third‐order scaling factor of 0.5) method has also been tested for 33 nucleic acid base pairs and two stacked conformers of porphine dimer. In all the test cases, performance of the MP2.5 method was shown to be superior to the scaled spin‐component MP2 based methods, e.g. SCS–MP2, SCSN–MP2 and SCS(MI)–MP2. In particular, a very balanced treatment of hydrogen‐bonded compared to stacked complexes is achieved with MP2.5. The main advantage of the approach is that it employs only a single empirical parameter and is thus biased by two rigorously defined, asymptotically correct ab‐initio methods, MP2 and MP3. The method is proposed as an accurate but computationally feasible alternative to CCSD(T) for the computation of the properties of various kinds of non‐covalently bound systems. 相似文献
85.
Grimme S 《The Journal of chemical physics》2006,124(3):034108
86.
Twelve conformations of a chiral donor-acceptor (charge-transfer) dyad and six conformations of its dimer complex were structurally optimized by using the Kohn-Sham density functional theory (BLYP/TZV2P) incorporating a recently developed empirical correction scheme that uses C6/R6 potentials for van der Waals interactions (DFT-D). Subsequent time-dependent DFT calculations with BH-LYP and B3-LYP functionals (with triple-zeta basis set) were performed to obtain theoretical circular dichroism (CD) spectra. The experimental CD spectra obtained independently were properly reproduced by averaging the calculated spectra of individual conformers according to a Boltzmann population derived from single-point SCS-MP2 energies. The optical rotations of the monomer were also calculated by using the same functionals with an aug-cc-pVDZ basis set. Dielectric continuum solvation models (COSMO) applied to correct the relative energies from the isolated molecule calculations resulted in conformer distributions that piled the same or even poorer level of agreement with the experimental CD spectrum. Our results clearly show the advantage of the DFT-D method for the geometry optimization of large systems with donor-acceptor interactions and the TD-DFT/BH-LYP calculations for reproducing the experimental CD spectra. As compared with the calculated optical rotations, the wealthy information embedded in the experimental/calculated CD spectra is requisite for the configurational and/or conformational analyses of relatively large and flexible chiral organic molecules in solution. 相似文献
87.
88.
Rapid Dihydrogen Cleavage by Persistent Nitroxide Radicals under Frustrated Lewis Pair Conditions 下载免费PDF全文
Dr. Xin Tao Dr. Gerald Kehr Dr. Xiaowu Wang Dr. Constantin G. Daniliuc Prof. Stefan Grimme Prof. Gerhard Erker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9504-9507
Persistent radicals undergo hydrogen atom abstraction reactions with a great variety of substrates, but not with dihydrogen. It has now been found that the TEMPO radical splits dihydrogen under mild conditions in the presence of the strong bulky B(C6F5)3 boron Lewis acid. The reaction is thought to proceed by a typical frustrated Lewis pair mechanism with the TEMPO radical acting as the active Lewis base. The reaction was analyzed by DFT, which indicates that no significant spin density on the hydrogen atoms is accumulated along the H2 splitting reaction path. 相似文献
89.
S. Grimme 《Journal of computational chemistry》1994,15(4):424-432
Systematic MRD-CI calculations using the AM1 Hamiltonian have been carried out for two polyenes and eight aromatic hydrocarbons ranging from benzene to ovalene (C32H14). Twenty singlet–singlet excitation energies in these compounds were calculated and compared with experimental data and ab initio STO-3G results. On an absolute scale, the AM1/MRD-CI approach underestimates the excitation energies to states with dominant covalent character by an average of 1.1 eV, whereas the errors for ionic states are between ?1.0 and 1.0 eV. The STO-3G calculated data are much too high by ≈ 1 eV and ≈ 5 eV, respectively. The inclusion of σπ-correlation effects through second-order Epstein–Nesbet perturbation theory combined with the use of localized orbitals leads to a significant improvement of the ab initio calculated state energies. In an analogous AM1 treatment, negligible corrections for the σπ correlations are found, which is attributed to the implicit account in the parameters and approximation of the semiempirical Hamiltonian. The possible error sources of the calculational methods are discussed. © 1994 by John Wiley & Sons, Inc. 相似文献
90.
Full geometry optimizations at the dispersion-corrected DFT-BLYP level of theory were carried out for dimers and trimers of pyridine. The DFT-D interaction energies were checked against results from single-point SCS-MP2/aug-cc-pVTZ calculations. Three stacked structures and a planar H-bonded dimer were found to be very close in energy (interaction energies in the range from -3.4 to -4.0 kcal mol(-1)). Two T-shaped geometries are higher lying, by about 1 kcal mol(-1), which is explained by the more favorable electrostatic interactions in the stacked and H-bonded arrangements. The DFT-D approach has proved to be a reliable and efficient tool to explore the conformational space of aromatic van der Waals complexes and furthermore provides interaction energies with errors of less than 10-20 % of DeltaE. Comparisons with previous results obtained by using only partially optimized model geometries strongly indicate that unconstrained optimizations are mandatory in such weakly bonded low-symmetry systems. 相似文献