What molecular features create the sensation of sweetness?
For humans, the "sweet taste buds" are the T1R2+T1R3 &amp; T1R3+T1R3 G-protein coupled receptors.

Chemicals that are sweet are the ones that can bind to these receptors. We know some structures that tend to do this, namely ketones and aldehydes (carbonyl groups).

However, there are chemicals that are sweet that we do not know the mechanism for, such as Curculin, which is up to ~2000 times sweeter than sucrose by weight.