1.3 Nanoscale Reactions

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To evaluate the strength of the nucleophile or charge, resonance structures have to be

taken into account when applicable; resonance structures distribute charge along sev-

eral atoms, thus lowering the charge on the specific nucleophile. Another factor that

modifies reactivity is steric hindrance, or how crowded a functional group is. A crowded,

sterically-hindered functional group is less reactive simply because it is less likely that

the other reactant is going to find it.

Another important property of organic and biomolecules is their specific 3-dimen-

sional structure or stereochemistry. When the specificity of binding is mentioned, stere-

ochemistry is a big part of that. For example, the body only produces L-amino acids,

D-amino acids are toxic.

There are a variety of stereoisomers (Figure 1.26). Some only change in the rotation

of a bond. That is not a different compound, but in instances of e. g. a substrate binding

Figure 1.26: Different stereoisomers of organic structures. Cells can distinguish between all of them.