Chiral objects

If the tctravalcnt carbon atom has three difFcrcnt substituents, the molecule is chiral and it is not possible to superimpose it onto its mirror image. Our feet are also chiral objects the right foot is a mirror image of the left one and does not ftt into the left shoe. 

In order to calculate S, one has to find the nearest configuration of Pi points that is G-symmetric. In the majority of cases, S is the distance of a chiral object from a reflection mirror. The fblding/unfolding procedure was developed for finding that configuration. 

The difference m odor between (R) and (S) carvone results from their different behavior toward receptor sites m the nose It is believed that volatile molecules occupy only those odor receptors that have the proper shape to accommodate them Because the receptor sites are themselves chiral one enantiomer may fit one kind of receptor while the other enantiomer fits a different kind An analogy that can be drawn is to hands and gloves Your left hand and your right hand are enantiomers You can place your left hand into a left glove but not into a right one The receptor (the glove) can accommodate one enantiomer of a chiral object (your hand) but not the other... 

Figure 9.17 Imagine that a left hand interacts with a chiral object, much as a biological receptor interacts with a chiral molecule, (a) One enantiomer fits into the hand perfectly green thumb, red palm, and gray pinkie finger, with the blue substituent exposed. (b The other enantiomer, however, can t fit into the hand. When the green thumb and gray pinkie finger interact appropriately, the palm holds a blue substituent rather than a red one, with the red substituent exposed.

A chiral object and the opposite object formed by inversion form a pair of enan-tiomorphs. If an enantiomorph is a molecular entity, it is called an enantiomer. An equimolar mixture of enantiomers is a racemate. 

In organic stereochemistry the terms center of chirality or center of asymmetry are often used usually they refer to an asymmetrically substituted C atom. These terms should be avoided since they are contradictions in themselves a chiral object by definition has no center (the only kind of center existing in symmetry is the inversion center). 

Perhaps the simplest form of chiral recognition is that in which one enantiomer, for example, A, of a chiral object displays a stronger interaction with a particular enantiomer of a second chiral object, for example, B, rather than its mirror image,... 

Image projections of a chiral object provide a useful analogy to the above diffraction phenomenon. For example, medical X-ray photographs obtained... 

In general, if a molecule contains a tetrahedral carbon atom that has four different groups attached to it, then it will have an optical isomer. These molecules can be described as chiral. You are already familiar with chiral objects in everyday life, such as hands, feet and so on. 

Circularly polarized light is chiral and therefore rep and lep will interact to differing extent with chiral objects, i.e. a chiral medium will exhibit differing optical properties for rep and lep. CD is the difference in absorbance (A) of rep and lep ... 

The heart is achiral and the moon is chiral. The mirror images of chiral objects do not coincide when snperimposed on each other. 

The simplest chiral objects (stereomodels) are composed of four nonplanar points (atoms). Connection of four points requires at least three lines (bonds) that can be arranged in two ways to form a helical or a tripodal unit ... 

Two equal and similar right hands are homochirally similar. Equal and similar right and left hands are heterochirally similar. .. These are also called enantiomorphs ,. .. Any chiral object and its image in a plane mirror are heterochirally similar". 

Chirality Many objects around us are handed. For example, our left and right hands are mirror images of each other, and caimot be superimposed on each other. Other chiral objects include shoes, gloves and printed pages. Many molecules are also handed, i.e. they cannot be superimposed on their mirror images. Such molecules are called chiral molecules. Many compounds that occur in living organisms, e.g. carbohydrates and proteins, are chiral... 

Give two examples of chiral objects and two examples of achiral objects. 

An important approach to stereochemical problems is to make use of the concept of chirality. Chirality (7), namely, the phenomenon that a chiral object and its mirror image cannot be superimposed, has been classified according to different elements of chirality. Chiral molecules may contain chiral centers, axes, and/or planes (2, 3). 

In Fig. 3.1, we have represented a comparison of chiral objects based on their sizes. If we define an object whose mirror image is nonsuperposable with it as chiral, almost all objects of our life are chiral a perfect macroscopic achiral object does not exist. But usually, we use the term chiral in the sense that its mirror image... 

The preceding discussion is somewhat related to Ernst Ruch s extraordinarily fruitful idea to classify chiral objects in two classes shoes and potatoes (Fig. 3.2) If asked to put our left shoes into one box and our right shoes into a second box we could accomplish the task without mental difficulty, in spite of the fact that the right shoes belonging to different people may be quite different in color, shape, and size, and although, probably, there is not a single pair of shoes which are precise mirror images of each other. If asked to solve the same problem with potatoes, we must capitulate. Of course, it is possible that by chance we find an antipodal pair. It is then clear that we must separate them, but for other potatoes different in shape, we have to make new arbitrary decisions each time. Any classification would be very artificial [1-3]. 

Enantiomorph is one of a pair of chiral objects or models that are nonsuperposable mirror images of each other. The adjective enantiomorphic is also applied to mirror image-related groups within a molecular entity. 

S. Capozziello, A. Lattanzi, Spiral galaxies as chiral objects, astrophys. Space Sci. 301,... 

J.F. LeMarechal, Can a non-chiral object be made of two identical chiral moieties J. Chem. 

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