A series of novel naphthalene attached bis-oxazines were synthesized and characterized. The bis-oxazines were studied by VT-NMR analysis to assess the possibility of conformational twist. The bis-oxazine prepared from (l)-methylvalinate show a helical conformational twist in the single crystal X-ray analysis. Three isomers of bis-oxazines were prepared from chiral α-methylbenzyl amines, the mes...

Two different conformational isomers of propanal, cis and gauche, are investigated by the vacuum-UV mass-analyzed threshold ionization (VUV-MATI) spectroscopy to give accurate adiabatic ionization potentials of 9.9997 +/- 0.0006 eV and 9.9516 +/- 0.0006 eV, respectively. cis-Propanal, which is the more stable conformer in the neutral state, becomes less stable in the cation compared to gauche-p...

We report the infrared (IR) absorption spectra of different conformational isomers of gas phase amino acid molecules in the molecular fingerprint region of 330-1500 cm(-1). The IR absorption spectra for three conformers of the amino acid tryptophan show absorption bands that uniquely identify the conformational structure of the molecule and that are well matched by density functional theory cal...

The potential energy surface of acetylsalicylic acid, aspirin, has been explored at the RHF/6-31G* and B3LYP/6-31G* levels, and single-point calculations were performed at levels up to B3LYP/6-311G**//B3LYP/6-31G*. All conformational isomers have been located, the thermochemical functions have been computed, and relative energies and free enthalpies were determined. The conformational space of ...

Conformational isomers of hydroquinone and their 1:1 clusters with water have been spatially separated using a Stark deflector in a supersonic jet. trans-Hydroquinone (HyQ) conformer with zero dipole moment is little influenced by inhomogeneous electric fields, whereas cis conformer with nonzero dipole moment (2.38 D) is significantly deflected from the molecular beam axis into the direction al...

Conformational isomers of alkanethiols are isolated in the molecular beam, and the conformer-specific ionization dynamics have been investigated using vacuum ultraviolet mass-analyzed threshold ionization (MATI) spectroscopy. Only a single conformer of ethanethiol is observed to give the adiabatic ionization potential (IP) of 9.2922 +/- 0.0007 eV for the gauche conformer. For isopropanethiol, I...

A plausible explanation for the unprecedented formation of two conformational isomers of bisphenyldirhodium(III) caprolactamate is presented. The presence of acetic acid during the coupling process leading to the formation of bisphenyldirhodium(III) caprolactamate is shown to increase the propeller conformer at the expense of the biplanar conformer, Acetic acid is also found to catalyze the dec...

Cyclic tetrapeptides are an important class of biologically active molecules that exhibit interesting conformational dynamics, with slow interconversion of several different structures. We present calculations on their energy landscapes using discrete path sampling. In acyclic peptides and large cyclic peptides, isomers containing cis-peptide groups are much less stable than the all-trans isome...

The affinity of amphiphilic compounds for water is important in various processes, e.g., in conformational transitions of biopolymers, protein folding/unfolding, partitioning of drugs in the living systems, and many others. Herein, we study the conformational transition of two isomer forms of poly(methacrylic acid) (PMA), isotactic (iPMA) and atactic (aPMA), in water. These isomers are chemical...