Conformational forcing

Given the information above, the question remains as to the nature of the monolayer states responsible for the stereo-differentiation of surface properties in racemic and enantiomeric films. Although associations in the crystalline phases are clearly differentiated by stereochemical packing, and therefore reflected in the thermodynamic and physical properties of the crystals, there is no indication that the same differentiations occur in a highly ordered, two-dimensional array of molecules on a water surface. However, it will be seen below (pp. 107-127) that conformational forces that are readily apparent in X-ray and molecular models for several diastereomeric surfactants provide a solid basis for interpreting their monolayer behavior. 

As a consequence of the target epoxide s specific stereochemical formation requirements, the aforementioned anhydrosugar conformation forces the hexose out of the stable C4 conformation into the Hq conformation, which is higher in energy and easily attacked by nucleophiles, thus enabling a variety of applications. This particular property of high chenucal reactivity... 

Prod-D-UF product in the docked conformation-forced unfolding... 

Since the CD spectrum of the one isomer of the [Co(i-sdda)-en]+ (Figure 12) shows a positive dominant CD peak and an overall CD curve similar to that of (+)-s-cis-[Co(edda)( -stien)]+, it might be expected to have the A-configuration. However, the A-s-cis-configuration would require the jt-stilbene-diamine backbone to have the X-conformation, forcing the large... 

Like all cyclohexene derivatives, L-shikimic acid (61) assumes a so-called half-chair conformation. Introduction of a double bond into a cyclohexane derivative in a chair conformation forces four of the carbon atoms (1, 2, 5, and 6 in shikimic acid) into a plane. This causes distortion to a halfchair form, as, for example, in conduritol B (63a), the depiction of which shows the positions of the substituents. The distortion has little effect on the dispositions of the substituents opposite the double bond, namely, those on C-3 and C-4 in shikimic acid and those on C-2 and C-3 in formula... 

Aqueous two-phase systems are characterized by a high water content, which makes them compatible with the biological material. The distribution of biomolecules between the phases is determined mainly by their surface properties and the composition of the phase system, and is denoted by partition coefficient, Kpart, defined as the ratio of its concentration in the top and bottom phase, respectively. The partitioning is independent of the absolute concentration of the substance over a fairly wide range. Any substance prefers a phase where a maximum number of interactions are possible these could be related to electrical, hydrophilic, hydrophobic and conformational forces. Reports in the literature have shown that different characteristics of the system can be manipulated in order to achieve the... 

In order to obtain information on the fluctuations in the DPM moiety, we performed molecular dynamics (MD) computations on DPM and 1,1-diphenylcyclohexane (5, DPC). often used as spacers in supramolecular chemistry, as well as on DPN 6 (Scheme 2). The aryl rings of DPN are disposed in a gable conformation forced by the steric effect of the four exo-norbomylic C-H bonds. In contrast to DPN, DPC adopts a helical conformation like... 

Analysis of the time course of fluorescence decay can yield information about the conformational dynamics of the labeled molecules. Obviously, the motion of labeled chain segments is not a free diffusion, since conformational forces direct the motions towards the equilibrium distance distributions. It has been shown in detail (lO, 16) (and therefore will not be repeated here) that, based on the above consideration, one can derive the differential equation describing the changes in N (r,t) with time ... 

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