The positive charge of quinoline on the nitrogen is harder to solvate due to steric repulsion of the nearby ring, whereas in pyridine, the small hydrogen atoms in place do not pose a strong steric hindrance for the solvation of the ion.

Why pyridine is more basic than aniline?

In case of aniline, the lone pair of electrons on nitrogen atom takes part in the resonance with the pi electron of benzene ring. ... Hence ,the lone pair of electron on 'N'-atom is available for donation to the electron deficient element, ion or group. Consequently, pyridine is more basic than aniline.

Why is pyridine more basic than pyrrolidine?

Lone pair on nitrogen of pyridine is involved in resonance. We have to see whether or not nitrogen has lone pairs. In pyrrolidine nitrogen's lone do not involve in resonance therefore that would maintain the electron density on nitrogen making pyrrolidine more basic.