Determination of the absolute stereochemistry of limonene and alpha-santalol by Raman optical activity spectroscopy.

Determining the absolute stereochemistry of organic compounds in solution remains a challenge. We investigated the use of Raman optical activity (ROA) spectroscopy to address this problem. The absolute configurations of (+)-(R)- and (-)-(S)-limonene were determined by ROA spectroscopy, which can be applied to smaller amounts of sample as compared with vibrational circular dichroism (VCD) spectroscopy. This ROA method was also applied to (+)-(E)-alpha-santalol and shown to be successful in the determination of the absolute configuration of this compound. ROA spectroscopy shows promise as a useful tool for determining the absolute stereochemistry of many natural compounds.

Solvent dependence of absorption intensities and wavenumbers of the fundamental and first overtone of NH stretching vibration of pyrrole studied by near-infrared/infrared spectroscopy and DFT calculations.

Near-infrared (NIR) and IR spectra were measured for pyrrole in CCl(4), CHCl(3), and CH(2)Cl(2) to study solvent dependence of absorption intensities and wavenumbers of the fundamental and first overtone of NH stretching vibration. It was found that the wavenumbers of the NH fundamental and its first overtone decrease in the order of CCl(4), CHCl(3), and CH(2)Cl(2), which is the increasing order for of the dielectric constant of the solvents. Their absorption intensities increase in the same order, and the intensity increase is more significant for the fundamental than the overtone. These results for the solvent dependence of the wavenumbers and absorption intensities of NH stretching bands of pyrrole are quite different from those due to the formation of hydrogen bonds. Quantum chemical calculations of the wavenumbers and absorption intensities of NH stretching bands by using the 1D Schrödinger equation based on the self-consistent reaction field (SCRF)/isodensity surface polarized continuum model (IPCM) suggest that the decreases in the wavenumbers of both the fundamental and the overtone of the NH stretching mode with the increase in the dielectric constant of the solvents arise from the anharmonicity of vibrational potential and their intensity increases come from the gradual increase in the slope of the dipole moment function.

Absolute configuration and conformation analysis of 1-phenylethanol by matrix-isolation infrared and vibrational circular dichroism spectroscopy combined with density functional theory calculation.

The absolute configuration and conformation of 1-phenylethanol (1-PhEtOH) have been determined by matrix-isolation infrared (IR) and vibrational circular dichroism (VCD) spectroscopy combined with quantum chemical calculations. Quantum chemical calculations have identified that there are three conformers, namely, I, II, and III, in which characteristic intramolecular interactions are found. The IR spectrum-conformation correlation for 1-PhEtOH has been developed by the Ar matrix-isolation IR measurement and used for the assignments of the observed IR bands. In a dilute CCl(4) solution, 1-PhEtOH exists predominantly as conformer I along with a trace amount of conformer II. By considering conformations and intermolecular hydrogen-bonding in the spectral simulation for (S)-1-PhEtOH, we have successfully reproduced the VCD spectrum of (-)-1-PhEtOH observed in a dilute CS(2) solution. Thus, (-)-1-PhEtOH is of S-configuration and conformer I in the dilute solution. The same method has been applied to analyze the VCD spectra measured in the liquid state of (-)-1-PhEtOH. The absolute configuration of 1-PhEtOH in the condensed phase is enabled by identifying VCD bands that are insensitive to conformational changes and intermolecular interactions. The present work provides a combinatorial procedure for determination of both the absolute configuration and the conformation of chiral molecules in a dilute solution and condensed phase.

Fliplike motion in the thalidomide dimer: Conformational analysis of (R)-thalidomide using vibrational circular dichroism spectroscopy.

The dynamic fliplike motion in the (R)-thalidomide dimer has been reported for the first time. The vibrational circular dichroism (VCD) spectrum of (R)-thalidomide in DMSO-d6 indicates the characteristic nu(CO) bands with opposite signs and reflects the structural property of the equatorial configuration of the phthalimide ring. On the other hand, the VCD spectrum of (R)-thalidomide in CDCl3 exhibits a different pattern of nu(CO) bands and suggests the fliplike motion in dimer forms. This novel insight for the dimer forms would be helpful for the understanding of the structure-activity relationship for thalidomide.

Analysis of vibrational circular dichroism spectra of (s)-(+)-2-butanol by rotational strengths expressed in local symmetry coordinates.

The vibrational circular dichroism (VCD) spectra of (S)-(+)-2-butanol have been observed in dilute CS(2) solutions. Two strong VCD bands are assigned mainly to the OH bending modes with the aid of quantum chemical calculations. The calculated VCD spectra corresponding to these bands are shown to depend on the conformation of the OH group. To understand this feature, we have calculated the contribution of each local vibrational mode to the rotational strengths and concluded that the coupling of the group vibrations between the in-plane and out-of-plane modes about the locally assumed symmetry planes play a significant role in VCD. This finding has provided a new scope of VCD in relation to molecular vibrations.

Long-term outcome of patients with rheumatoid arthritis treated by multiple arthroplasty.

We conducted a study of 82 patients with rheumatoid arthritis (RA) who had undergone multiple arthroplasty and investigated their clinical findings and clinical courses. We reviewed the significance of multiple arthroplasty in the treatment of RA, its problems, and measures to solve them. All patients initially regained and maintained good walking capacity. However, the walking capacity of many patients again decreased over the long term; in the tenth year, 79% of patients were capable of a practical gait. The causes of decreased walking capacity included complications of artificial joints, cervical lesions, and vertebral compression fractures. Fractures were observed in as many as nine patients, indicating that it is important to prevent and treat their cause, that is, osteoporosis. The survival rate was 71% in 10 years. In RA patients, particularly those who have undergone multiple arthroplasty, the major causes of death are infection and rheumatic disease, suggesting that prevention of such diseases should be considered paramount. Appropriate systemic treatment of RA, patient education, and measures against osteoporosis for prevention of complications may preserve the worth of multiple arthroplasty for RA patients with multiple joint destruction.

Indications of total ankle arthroplasty for rheumatoid arthritis: evaluation at 5 years or more after the operation.

Abstract The postoperative results of total ankle arthroplasty (TAA) were surveyed, and the indications of TAA for rheumatoid arthritis (RA) were examined. We have performed TAA in properly selected patients with indication of ankle joint destruction due to RA. The subjects were 18 RA patients (20 joints) who underwent TAA between April 1988 and April 1996. Type-ND or type-TNK Bioceram was used without cement for possible revision of TAA. No destruction of large joints was found in 8 patients, and TAA was used as part of multiple arthroplasty in 10 patients. After the operation, decrease in or disappearance of joint pain was obtained, and range of motion and improved ability to walk were secured. The clinical results were superior to those obtained for 17 joints of 17 patients who underwent ankle arthrodesis during the same period. However, a radiolucent zone was observed an X-ray examination in every case, after 8 years on average (range 5-12 years) after operation. Under present conditions, ankle arthrodesis should be used for younger patients. When no destruction of the hip or knee joint is found and the patient is 65 years of age or older, we believe TAA is indicated. In cases of multiple arthroplasty or with bilateral ankle joint destruction, TAA appears to be useful if patients are young, considering their better life expectancy and quality of life.

Vibrational circular dichroism spectrum of 1-amino-2-propanol.

Vibrational circular dichroism (VCD) spectra of 1-amino-2-propanol, of neat sample and in dilute solution of CDCl3, were measured in 2000 to 800 cm(-1) region. Two VCD bands, which appear at 1272 and 1412 cm(-1) in dilute solution, were assigned, respectively, to the OH bending mode and the mode that is influenced by the OH bending of the most stable conformer. The assignments were confirmed according to the prediction by a high-level density function theory (DFT) calculation and the isotope shift of deuterated samples. The joint analysis of the spectra obtained by the VCD and ordinary infrared (IR) measurements seems to be a useful way of using vibrational spectroscopy to investigate the hydrogen bonding system in solution.

Synthesis and notable antimalarial activity of acyclic peroxides, L-(alkyldioxy)-L-(methyldioxy)cyclododecanes.

Of several bis(alkyldioxy)alkanes and the related acyclic peroxides prepared in this study, 1,1-bis(methyldioxy)cyclododecane showed the most notable antimalarial activity particularly in vivo (almost a half of that of artemisinin).

High Resolution FTIR Study on NH(2)Cl Molecule: Inversion and Anharmonicity.

The high-resolution FTIR absorption spectra of the NH(2)Cl molecule have been measured in the region 500-3600 cm(-1). The rotational structures of all the fundamental bands and a number of overtone and combination bands have been analyzed. Every rotational line of the observed bands except the NH(2) twisting and stretching fundamental bands splits into two components due to the amino inversion motion. The vibrational anharmonicity and the direction of the transition moments have been studied with the help of B3LYP/6-31++G(**) calculations. The amount of inversion splitting depends on the molecular rotation, and the J,K-dependence of the inversion splitting has been determined. Copyright 2001 Academic Press.