The longest unbranched chain containing the functional group is the parent molecule, or simply the longest unbranched chain for alkanes. Remember that, the longest chain can go round a bend.

The longest unbranched chain containing the functional group is the parent molecule, or simply the longest unbranched chain for alkanes. Remember that, the longest chain can go round a bend.

n-alkane gas molecule can be captured because of its molecular shape (configuration) for the cavity of pillar[5]arene, whereas branched alkane molecule cannot. Disclaimer: AAAS and EurekAlert!