Hydrogen bonding overview

Diheterolevulosans, 209-211, 240 Dihexulose dianhydrides, 207 -266, see also Caramels Di-D-fructose dianhydrides 13C NMR spectra, 245-246 conformation, electronic control, 224-228 conformational rigidity, energetic outcomes, 228 hexulopyranose rings, 226 historical overview, 210-213 H NMR spectra, 248 -249 intramolecular hydrogen-bonds, 227 isomerization, 231 -232 1,2-linked, ero-anomeric effect, 224-225 listing, 240-241 nomenclature, 208-210 optical rotations and melting points, 242-243 protonic activation... 

The hydrogen content Ch greatly influences structure and consequently electronic and optoelectronic properties. An accurate measurement of Ch can be made with several ion-beam-based methods see e.g. Arnold Bik et al. [54]. A much easier accessible method is Fourier-transform infrared transmittance (FTIR) spectroscopy. The absorption of IR radiation is different for different silicon-hydrogen bonding configurations. The observed absorption peaks have been indentified [55-57] (for an overview, see Luft and Tsuo [6]). The hydrogen content can be determined from the absorption peak at 630 cm , which includes... 

The examples in the previous section give a comprehensive overview of application areas where molecular rotors have become important fluorescent reporters. Current work on the further development of molecular rotors can broadly be divided into three areas photophysical description, structural modification, and application development. Although a number of theories exist that describe the interaction between a TICT fluorophore and its environment, the detailed mechanism of interaction that includes effects such as polarity, hydrogen bonding, or size and geometry of a hydrophobic pocket are not fully understood. Molecular simulations have recently added considerable knowledge, particularly with... 

Figure 5.10 Schematic overview of self-assembly process of high-axial-ratio nanostructures using bolaamphiphilic monomers. Arrows indicate hydrogen bond functionalities. Reprinted from Ref. 53 with permission of Wiley-VCH.

Mitraki and colleagues also overview the other distinctive family of /3-fibrous folds, called the triple /3-spirals (Fig. 3D). The /3-spiral folds are more complicated than the solenoidal fold, with long central /3-strands that hold the trimer together through interchain hydrogen bonds, and... 

Recent developments in rotational spectroscopy [19] have provided an accurate study of a number of hydrogen bonded dimers in the gas phase. Experimental information is thus available nowadays on the molecular characteristics of such systems. Due to major advances in the field of computational chemistry, a number of theoretical calculations were performed (for an overview on the subject see references [1,20,21]). 

The purpose of this book is to provide the reader with an overview of how hydrogen bonding can contribute to the advancement of the practice of organic synthesis. 

The small-molecule catalysts are covered in Chapters 5 and 6. In Chapter 5, Joshua Payette and Hisashi Yamamoto discuss the importance of polar Bronsted-acid-type catalysts as well as cooperative effects in hydrogen bonding catalysis. Chapter 6 by Mike Kotke and Peter Schreiner is then devoted to the single most popular small-molecule catalyst types, the thiourea catalysts. Chapter 6, the longest of all chapters, also provides an excellent overview of the history and development of the field of small-molecule hydrogen bond catalysis. 

Figure 13-11 (A) Overview of the active site of spinach rubisco showing bound 2-carboxy-D-arabinitol 1,5-bisphosphate and Mg2+ and residues within hydrogen-bonding distance of these ligands. The hydroxyl groups at C2 and C3 of the inhibitor are in cis conformation. 269 Courtesy of Inger Andersson. (B) Structure of the inhibitor 2-carboxy-D-arabinitol 1,5-bisphosphate. A part of the carbamylated lysine 201 and the essential metal ion are also shown.

Complexes are also formed in certain instances between neutral molecules and macrocyclic receptors. Neutral molecules which form such complexes for the most part contain polar O—H, N—H or C—H bonds, and hydrogen bonding interactions are responsible for the solid state structural characteristics of these complexes. For many of these complexes, stoichiometries range considerably, from 1 1 to 1 6 host guest, and include a variety of odd ratios such as 3 2, 2 7, etc. Structural results for these complexes indicate them not to be of the inclusion type in a majority of cases. Thus, discussion in this subsection will be limited to a general overview. A more complete review of neutral molecule complexation can be obtained elsewhere.21... 

For a recent overview of structure and hydrogen bonding in the organic solid state, see Chem. Materials, Special Issue 1994,6, No. 8. 

Hydrate phase diagrams for water-hydrocarbon systems provide a convenient overview of the calculation types. These diagrams differ substantially from the normal hydrocarbon phase diagrams primarily due to hydrates and the hydrogen bonds inherent in aqueous systems. The phase diagrams of Section 4.1 provide an overview for the calculation methods in this chapter and the next. 

An overview of the structure is located in Figure 3b. The structure is assembled from chains of hydrogen-bonded molecules that stretch along the 6-axis. The unit cell contains two types of non-equivalent molecules, each of which form their own chain structures and are inter-related only by a pseudocentering in the a and b directions. 

Several works give an overview the development of the concept of affinity.155-158 There is an autobiographical narrative by Robert Mulliken (1896-1986), who contributed so decisively to the development of molecular orbital theory.159 There are also studies on a number of more specific bonding-mechanisms160-162 and on the reaction of the chemical community to hydrogen bonding.163... 

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