There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The relatively small diffuse function-augmented basis set, 3-21+G, is shown to describe anion geometries and proton affinities adequately. The diffuse sp orbital exponents are recommended for general use to augment larger basis sets.

Efficient diffuse function‐augmented basis sets for anion calculations. III. The 3‐21+G basis set for first‐row elements, Li–F

A. Water Exchange 2326 B. Proton Exchange 2327 C. Electronic Relaxation 2327 D. Relaxivity 2331 E. Outerand Second-Sphere Relaxivity 2334 F. Methods of Improving Relaxivity 2336 V. Macromolecular Conjugates 2336 A. Introduction 2336 B. General Conjugation Methods 2336 C. Synthetic Linear Polymers 2336 D. Synthetic Dendrimer-Based Agents 2338 E. Naturally Occurring Polymers (Proteins, Polysaccharides, and Nucleic Acids) 2339

https://mriquestions.com/uploads/3/4/5/7/34572113/lauffer_1999_review.pdf

Gadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and Applications

I. Introduction: Conceptual vs Fundamental andComputational Aspects of DFT1793II. Fundamental and Computational Aspects of DFT 1795A. The Basics of DFT: The Hohenberg−KohnTheorems1795B. DFT as a Tool for Calculating Atomic andMolecular Properties: The Kohn−ShamEquations1796C. Electronic Chemical Potential andElectronegativity: Bridging Computational andConceptual DFT1797III. DFT-Based Concepts and Principles 1798A. General Scheme: Nalewajski’s ChargeSensitivity Analysis1798B. Concepts and Their Calculation 18001. Electronegativity and the ElectronicChemical Potential18002. Global Hardness and Softness 18023. The Electronic Fukui Function, LocalSoftness, and Softness Kernel18074. Local Hardness and Hardness Kernel 18135. The Molecular Shape FunctionsSimilarity 18146. The Nuclear Fukui Function and ItsDerivatives18167. Spin-Polarized Generalizations 18198. Solvent Effects 18209. Time Evolution of Reactivity Indices 1821C. Principles 18221. Sanderson’s Electronegativity EqualizationPrinciple18222. Pearson’s Hard and Soft Acids andBases Principle18253. The Maximum Hardness Principle 1829IV. Applications 1833A. Atoms and Functional Groups 1833B. Molecular Properties 18381. Dipole Moment, Hardness, Softness, andRelated Properties18382. Conformation 18403. Aromaticity 1840C. Reactivity 18421. Introduction 18422. Comparison of Intramolecular ReactivitySequences18443. Comparison of Intermolecular ReactivitySequences18494. Excited States 1857D. Clusters and Catalysis 1858V. Conclusions 1860VI. Glossary of Most Important Symbols andAcronyms1860VII. Acknowledgments 1861VIII. Note Added in Proof 1862IX. References 1865

/pdf/conceptual-density-functional-theory-btz9wwrxv9.pdf

Conceptual density functional theory.

Asymmetric enamine catalysis.

Ab Initio-Based Force Field Modeling of the Transition States And Stereoselectivities of Lewis Acid-Catalyzed Asymmetric Diels-Alder Reactions

The transition states of aldol reactions catalyzed by vicinal diamines are characterized with density functional calculations. It was found that a cyclic transition state involving a nine-membered hydrogen-bonded ring is preferred. The crown (chair–chair) conformations of the transition state account for the observed stereoselectivity of these reactions.

Transition States of Vicinal Diamine-Catalyzed Aldol Reactions

The effects of thiomethoxy and methoxy substituents on the rates and the mechanisms of anionic oxy-Cope rearrangements were investigated with density functional theory (B3LYP/6-31+G*). Thiomethoxy ...

Mechanistic Variations and Rate Effects of Alkoxy and Thioalkoxy Substituents on Anionic Oxy-Cope Rearrangements

Diels−Alder reactions of a range of (R)-4-hydroxy-4-[(p-tolylsulfinyl)methyl]-2,5-cyclohexadienones with cyclopentadiene and 1,3-pentadiene proceed in a total π-facial diastereoselective manner from the C-4 OH side. Ab initio calculations at the RHF/6-31G* theory level provide data on transition-state energies for cycloadditions with cyclopentadiene in full agreement with the experimental results.

π-Facial Diastereoselection in Diels−Alder Reactions of (R)-4-[(p-Tolylsulfinyl)methyl]quinols

We report the genome-guided discovery of sungeidines, a class of microbial secondary metabolites with unique structural features. Despite evolutionary relationships with dynemicin-type enediynes, the sungeidines are produced by a biosynthetic gene cluster (BGC) that exhibits distinct differences from known enediyne BGCs. Our studies suggest that the sungeidines are assembled from two octaketide chains that are processed differently than those of the dynemicin-type enediynes. The biosynthesis also involves a unique activating sulfotransferase that promotes a dehydration reaction. The loss of genes, including a putative epoxidase gene, is likely to be the main cause of the divergence of the sungeidine pathway from other canonical enediyne pathways. The findings disclose the surprising evolvability of enediyne pathways and set the stage for characterizing the intriguing enzymatic steps in sungeidine biosynthesis.

K. N. Houk

Papers

Ab Initio-Based Force Field Modeling of the Transition States And Stereoselectivities of Lewis Acid-Catalyzed Asymmetric Diels-Alder Reactions

Transition States of Vicinal Diamine-Catalyzed Aldol Reactions

Mechanistic Variations and Rate Effects of Alkoxy and Thioalkoxy Substituents on Anionic Oxy-Cope Rearrangements

π-Facial Diastereoselection in Diels−Alder Reactions of (R)-4-[(p-Tolylsulfinyl)methyl]quinols

Sungeidines from a Non-canonical Enediyne Biosynthetic Pathway.