Three-dimensional spectroscopy applications

Electrodeposition on transparent material such as indium tin oxide (ITO) can be used for electrochromic applications [328]. Pb deposition on indium-tin oxide electrode occurs by three-dimensional nucle-ation with a diffusion-controlled growth step for instantaneous nucleation [329], and the electrode process has also been studied using electrochemical impedance spectroscopy [328]. 

Nuclear magnetic resonance (NMR) spectroscopy is a most effective and significant method for observing the structure and dynamics of polymer chains both in solution and in the solid state [1]. Undoubtedly the widest application of NMR spectroscopy is in the field of structure determination. The identification of certain atoms or groups in a molecule as well as their position relative to each other can be obtained by one-, two-, and three-dimensional NMR. Of importance to polymerization of vinyl monomers is the orientation of each vinyl monomer unit to the growing chain tacticity. The time scale involved in NMR measurements makes it possible to study certain rate processes, including chemical reaction rates. Other applications are isomerism, internal relaxation, conformational analysis, and tautomerism. 

Recent examples of the application of three-dimensional H/13C/Y correlation spectroscopy for the characterisation of polymers included studies of polystyrene samples obtained by diphenylphosphinyl radical initiated polymerisation of styrene (Y = 31P),38,39,86 and the characterisation of Sn-containing polybutadiene that was prepared by anionic polymerisation... 

The laser trapping-spectroscopy-electrochemistry technique is unique in that simultaneous three-dimensional manipulation and spectroscopic/elec-trochemical measurements can be conducted for individual microdroplets in solution. Although the technique is highly useful for studying single microdroplets, its applicability and limitations have not been well documented until now. Therefore, before discussing detailed chemistry of single droplets in solution, we describe briefly the characteristics of the technique. 

Beyond imaging, CARS microscopy offers the possibility for spatially resolved vibrational spectroscopy [16], providing a wealth of chemical and physical structure information of molecular specimens inside a sub-femtoliter probe volume. As such, multiplex CARS microspectroscopy allows the chemical identification of molecules on the basis of their characteristic Raman spectra and the extraction of their physical properties, e.g., their thermodynamic state. In the time domain, time-resolved CARS microscopy allows recording of ultrafast Raman free induction decays (RFIDs). CARS correlation spectroscopy can probe three-dimensional diffusion dynamics with chemical selectivity. We next discuss the basic principles and exemplifying applications of the different CARS microspectroscopies. 

The life and work of one of the greatest carbohydrate scientists of our time, Raymond U. Lemieux, is recalled here in a sensitive account by Bundle (Edmonton). During a remarkably productive career extending over more than half a century, Lemieux pioneered the application of NMR spectroscopy in chemistry, developed rational approaches for glycosidic coupling, made major contributions to our understanding of three-dimensional carbohydrate structures and protein binding, and made important contributions in the biomedical area. His own articles in these Advances include the chemistry of streptomycin in Volume 3, the mechanisms of replacement reactions in Volume 9, and in Volume 50 a consideration of Emil Fischer s lock and key concept of enzyme specificity. 

Many applications have been reported in the field of biomolecular NMR spectroscopy which use RDCs for the refinement of three-dimensional structures. The approach is quite powerful and can also be applied to smaller molecules whenever the conformation of a molecule is important, as for example in the case of rational drug design. Traditionally, NMR in liquid crystals is applied on a multitude of small organic compounds to obtain their fully characterized structure. Most examples are measured on all kinds of aromatic systems as reported in refs. 204—212 other recent examples deal with substituted alkanes, aldehydes216,217 or bridged systems like norbomadiene.218 In general, these very detailed studies can be applied to molecules with up to 12 protons. 

Since the end of the seventies, interest in cyclotriveratrylene has moved towards the use of its cone shaped structure for applications in various fields, including investigations of the electronic transitions of the benzene chromophore via UV and CD spectroscopy, studies in the area of host-guest chemistry, synthesis of new types of liquid crystals, and searches for new three-dimensional organic charge-transfer materials. These works have been made possible because efficient synthetic... 

In 1971, the idea of 2D NMR spectroscopy was proposed by Jeener and later implemented by Aue, Bartholdi and Ernst, who published their work in 1976.47 The first experiments, carried out mostly in the liquid phase, have unambiguously proved that 2D NMR spectra provide more information about a molecule than ID NMR spectroscopy and are especially useful in determining the structure of molecules that are too complicated to work with using ID NMR. With the progress in the methodology and software improvement, three-dimensional (3D) and four-dimensional (4D) NMR experiments were gradually introduced into the laboratory practice. Such strategy, the so-called multi-dimensional (or ND) NMR spectroscopy, has found a number of spectacular applications in the structure analysis of natural products. 

Application of NMR to three-dimensional structure determination is covered in several books, including NMR of Proteins and Nucleic Acids by Kurt Wiithrich,60 NMR of Proteins edited by G. M. Clore and A. M. Gronenborn,131 Biomolecular NMR Spectroscopy by Jeremy Evans,132 and Protein NMR Spectroscopy by John Cavanagh et al,120... 

---