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The influence of geometry variations and solvent environment of N-methylacetamide on its energies and absorption intensities was systematically analyzed with the aid of the time-dependent density functional theory (TD-DFT). A combined DFT/coupled oscillator model providing principal features observed in electronic circular dichroism spectra of standard peptide circular dichroism was demonstrated.

Amino-substituted thio(seleno)acrylamides were synthesized in a study and their (super1)H and (super 13)C NMR spectra assigned. Both the NMR data and the results of theoretical calculations at the ab initio level of theory were used to explain the adopted structures of the compounds in terms of E/Z isomerism, and s-cis/s-trans configuration.

The thermal decomposition of 2-azidoactemide(N3CH2CONH2) is studied with the help of matrix-isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. The mechanism of thermal decomposition by obtaining spectra at different temperatures is investigated to detect the final products of pyrolysis.

The relationship between distorted intramolecular H-bonds and infrared absorption properties of the donor NH group in short helical peptides in solution are presented. The helical backbone in the peptides experiences distortions, the extent of which depends on the chain length, that are reflected in both the energy of the stretching mode and the molar extinction coefficient of the intramolecularity H-bonded N-H groups.

The function of hydrogen bonding in the evolution of the nine typical amide bonds are discussed on the basis of force field calculations on the monomer and multimers (n=6) and solution spectra of N-methylacetamide (NMA). The effects of temperature on the structure and the changes in the strength of the hydrogen bonding within a structure of NMA are presented to explain the shortcomings in the results obtained from vibrational spectroscopy.

A condensed data collection approach that facilitates rapid acquisition of multidimensional magic-angle spinning solid-state nuclear magnetic resonance (SSNMR) spectra of proteins is described. The effective use of the mode of data acquisition toward the structural SSNMR studies of paramagnetic proteins is demonstrated by the rapid site-specific determination of backbone amide [super 15]N longitudinal paramagnetic relaxation enhancements.

The determination of hydroxide-catalyzed exchange rate constants for amides of FK506-binding protein (FKBP12), ubiquitin, and chymotrypsin inhibitor 2 (CI2) that are solvent-accessible in the high-resolution X-ray structures is reported. The predictions of the experimental hydrogen exchange data demonstrated the substantial systematic errors in the predicted electrostatic potential that could arise when dielectric shielding due to electronic polarizability is neglected.

Fourier transform infrared (FTIR) spectroscopy in the amide-A region, complemented by amide-I spectra, was utilized to detect cold, isolated peptide model compounds and their aggregates generated in pulsed supersonic jet expansions. The results from the systematic assessment of thermal, matrix embedding, and methylation effects on the vibrational dynamics might serve as elementary reference data for infrared (IR) spectra obtained by ultraviolet (UV)/IR double-resonance studies on more complex amides.

The density functional theoretical method is used for studying amide I infrared (IR) spectral features for two untypical structures suggested for amyloids. It is shown that the amide I IR band characteristic of the [alpha]-sheet conformation in dry environment is located in a high-frequency region and the amide I vibrations of the closely located peptide and amide groups are coupled through-space with each other.

Density functional theory is used to study the electronic structure, vibrational properties, absorption spectra, and thermodynamic properties of crystalline ammonium perchlorate (AP) and ammonium dinitramide (AND). The thermodynamic property shows that AND is easier to decompose than AP as the temperature increases.

The process of femtosecond photolysis is employed to study the primary photodynamics of aqueous formamide. The majority of the formamide molecules are shown to convert the electronic excitation energy to vibrational excitation.

A series of novel macrocycles with diamide-diester groups are derived from dimethyloxalate and amino alcohols by high dilution technique and the enantiomeric recognition properties of these macrocycles toward primary alkyl ammonium salts are evaluated. The studies have highlighted a general tendency for the host to include the guests with the same absolute configuration.

Amide I vibrations that are widely studied and collective vibrations of the protein backbone showing spectral signatures for various secondary structural motifs are described. The introduction of isotope labels made it possible for amide I 2D IR spectra to probe into site-specific structure with Pico second time resolution.

The article discusses the benefits of using several enamides and enecarbamates as the nucleophiles in the several stereoselective reactions that lead to the formation of C-C and C-N bonds. These compounds are easily available and hence are even being used in the Lewis acid-catalyzed reactions.

Isotope-edited infrared (IR) spectroscopy is used for analyzing a series of singly and doubly [super 13]C[double bond]O-labeled [beta]-hairpin peptides stabilized by an Aib-Gly turn sequence. The sign variation of the vibrational coupling between the cross-strand amides in the small and large H-bonding rings has produced frequency shifts of the [super 13]C-labeled bands that have confirmed the registration of the antiparallel strands in the hairpin.

The NMR spectroscopic study results of the kinetics and equilibria of cis/trans isomerization of the amide bonds of N-acetylated peptoids monomers, dipeptoids, and tripeptoids are presented.

Infrared multiple photon dissociation (IRMPD) spectroscopy is used for investigating the protonation sites and structures of protonated GlyGlyGly and AlaAlaAla. The experimental spectra of GGG[H.sup.+] and AAA[H.sup.+] have shown that two main isomers coexist, where the first is a linear structure and the other is cyclic due to hydrogen bonding.

The time-dependent diagonal peak shape changes in the two-dimensional (2D) infrared (IR) spectra is observed in three separate examples of amide-I' vibrations in [D.sub.2]O and a carbonyl transition. The results have provided new approaches for examining protein-bound water at the residue level.

The time-domain computational method is used to calculate the infrared (IR) and polarized (isotropic and anisotropic) Raman spectra for the amide I band of tetraalanine ([(Ala).sub.4]) in aqueous solution. The calculated band profile showed a large negative noncoincidence effect from two types of conditions, the positive coupling between the amide I vibrations of peptide groups and the angle larger than 90 degree between the transition dipoles of the coupled vibrations.

The Herzfeld-Berger method is applied to highly [super 13]C, [super 15]N-enriched solid proteins by using two-dimensional (2D) heteronuclear correlation in combination with high magnetic fields and pattern labeling of [super 13]C sites. This method can be used for interrogating active sites of enzymes, where hydrogen bonding and hybridization of intermediates states often report directly on mechanistic details.

The syntheses, crystal structures and magnetic properties of four new bimetallic complexes of macrocyclic oxamide are described. Results reveal that the oxamido group is observed to be an efficient mediator of magnetic exchange between paramagnetic centers.

The use of protonated L-prolinethioamide instead of the free base derivative as the organocatalyst for the direct aldol addition has a profound and appreciable effect on both the yield and the stereochemical course of the reaction. The results give insights into details of the enamino-iminium mechanism and lead to the conclusion that salts of L-prolinethioamide are more effective catalysts for the aldol reaction than the L-prolinethioamide itself.

The conformations of model dipeptide, N-acetyl-L-prolinamide (AcProNH2) in deuterated chloroform (CDCL3) were studied using femtosecond two-dimensional infrared (2D IR) spectroscopy. The major trans conformation of (AcProNH2) in (CDCL3) determined by the 2D IR measurements, is found to be an intermediate between the C7 and [P.sub.II] form centered at (phi, psi) is approximately equal to (-80 degrees, 100 degrees).

A catalytic one-pot synthesis of cyclic amidines by virtue of tandem reactions involving intramolecular hydroamination under mild conditions is presented. The synthetic methodology demonstrates, as the proof-of principle, that equilibria tandem sequence can be favorably driven by an irreversible step, thereby enabling a facile one-pot synthetic route to deliver molecular complexity under unprecedented mild conditions.

A series of novel S,N-heterocyclic (thiazolyl) substituted carboximidamides is synthesized in yields up to 82% from specific triazinium salts and primary or secondary amines which additionally bear pyridine or imidazole units and these carboximidamides are used as ligands for the complexation of Cu(II) and An(II). The analysis of Cu(II) complex of Cu-4d reveals that the phenolic OH survives while the NH deprotonation yields the delocalized 1,3,5-triazapentadienyl anion and some of their Zn(II) complexes possess catalytic properties for the copolymerization of CO2 to give polycarbonates.

The collective amide I oscillations and the associated linear and two-dimensional infrared (2DIR) spectra for model antiparrel beta-sheets is numerically calculated and the effect of homogeneity is studied. The 2DIR spectra energy disorder leads to diagonal stretching of the diagonal peaks, while the cross-peaks are typically stretched more horizontal.

The study demonstrates that the (super 13)C coupling across antiparallel beta-sheet strands can be identified in the absorption spectrum. The interaction between labeled amide groups in different strands can be used as an indicator of local beta-structure formation, because coupling between close-lying C=O groups on opposing chains leads to the largest frequency shifts, yet some alternate placements can lead to intensity enhancements.

The lateral transport of four single-strand homooligonucleotides on a microscopically flat silica surface chemically modified with chlorodimethyloctadecylsilane in contact with 0.01 M KC1 is investigated using single-molecule spectroscopy. The results reveal the presence of both diffusing and transiently stationary molecules.

The process of protonation and deprotonation of transition metal amide complexes are explained. The properties of the amide ligands are also discussed.