Conformational analysis of two alternating copolymers, poly(ethylene imine-alt-ethylene oxide) (PEIEO) and poly(N-methylethylene imine-alt-ethylene oxide) (PMEIEO), has been carried out by the inversionalrotational isomeric state (IRIS) analysis of ab initio molecular orbital (MO) calculations and 1 H and 13 C NMR experiments for their model compounds. On the basis of the conformational energies derived therefrom and molecular mechanics and MO calculations, higher-order structures, physical properties, and functions of the two copolymers have been predicted as an example of molecular design. These copolymers are expected to form various hydrogen bonds: PEIEO, N-H‚‚‚O (interaction energy, -1.75 kcal mol -1 ), C-H‚‚‚N (-0.68 kcal mol -1 ), and C-H‚‚‚O (-0.21 kcal mol -1 ); PMEIEO, C-H‚‚‚N (-0.66 kcal mol -1 ), and C-H‚‚‚O (-0.41 kcal mol -1 ). In particular, the N-H‚‚‚O hydrogen bond of PEIEO is too strong to be broken even by protic solvents such as methanol and water but replaced by an intermolecular N-H‚‚‚OdS attraction in dimethyl sulfoxide. The C-N and C-O bonds of PEIEO prefer the trans state as found for poly(ethylene imine) (PEI) and poly-(ethylene oxide), whereas the C-C bond does not have its own conformational preference and its conformational equilibrium is determined only by the hydrogen bond strength (HBS). The characteristic ratio of PEIEO largely depends on HBS: 1.5 (HBS ) 100%); 6.5 (0%). In contrast, the weak hydrogen bonds of PMEIEO little affect the characteristic ratio; 5.2 (HBS ) 100%); 5.9 (0%). According to Mattice's analysis (Macromolecules 2004, 37, 4711), PEIEO and PEI tend to form circular paths due to the intramolecular hydrogen bonds. Both molecular mechanics calculations using the Amber force field and density functional MO calculations under the periodic boundary condition have suggested that a double-helical structure may be formed in the PEIEO crystal. The possibility that these copolymers will be utilized as gene carriers and ion conductors is discussed, and the synthetic method is also suggested. In conclusion, these copolymers should be promising and deserve to be synthesized.

Structure−property correlations of the following model compounds for oligomer liquid crystals (LCs) have been investigated:  monomers, C6H5O(CH2) x CH3 (x = 4 and 5); dimers, C6H5O(CH2) x OC6H5 (x = 3, 4, 5, and 6); and tetramers, C6H5O(CH2) x OC6H4O(CH2) x OC6H4O(CH2) x OC6H5 (x = 5 and 6). Deuterium NMR quadrupolar splittings observed from the deuterated model compounds dissolved in a nematic solvent, 4‘-methoxybenzylidene-4-n-butylaniline (MBBA) or p-azoxyanisole (PAA), were analyzed by the rotational isomeric state scheme with the maximum entropy method to yield the orientational order parameters, bond conformations, and molecular dimensions. For the dimers in particular, the solute shapes were estimated from phase diagrams of the dimer/MBBA systems, the crystal structures were determined by X-ray diffraction, and the melting points and enthalpies of fusion were evaluated from DSC measurements. From the dimers, the so-called odd−even effect was clearly observed in not only the orientational order and molecular shape in the nematic solution but also the crystal structure and thermal properties; that is, the dimers of x = 4 and 6 have larger order parameters, more anisotropic shapes, better-arranged crystal structures, higher melting points, and larger enthalpies of fusion than those of x = 3 and 5. In the nematic solution, the model compounds preserve the inherent conformational preferences of the ether chain and enhance the shape anisotropy by increasing the trans fractions. As the orientational correlation is expected to persist only within a short range, conformations of the tetramers may represent those of polymer LCs with the same ethereal spacers. The chainlike molecules adjust their spatial configuration to the LC environment, and consequently, physical properties of the LC system are affected.

There have been many studies on the transport of antibiotics into the bile; however, these studies have not taken the bile duct pressure into consideration. The bile duct pressure of the patient with acute obstructive cholangitis is high, and after drainage of the bile, the pressure is not always decreased to the normal range. We studied the effects of the bile duct pressure on the antibiotic (flomoxef sodium) transfer into the bile using beagles after creating the model of acute obstructive cholangitis. Our results showed that sufficient bile flow after drainage is important for the antibiotic transport, and, moreover, the bile acid concentration which may be related to the bilirubin concentration is also highly considerable.