A dynamic nuclear magnetic resonance (NMR) study of the polar liquids pyridine and pentafluoropyridine (PFP) confined to porous silica sol-gel glasses is reported. The C-13 NMR spin-lattice relaxation times, T-1, of ortho (C2), meta (C3), and para (C4) carbons were measured in glasses with pore radii ranging from 30 to 94 Angstrom, over a temperature range of -22 to +20 degrees C. The experimental data were analyzed in terms of the two-state, fast exchange model, and the surface-layer relaxation times, T-1s, were calculated. On the basis of surface enhancement factors, T-1b/T-1s, where T-1b is the relaxation time of the hulk liquid, we conclude that fluorination considerably weakens the interaction of pyridine with the glass surface. This is consistent with pyridine serving as a hydrogen bond acceptor for the surface. By analyzing the relaxation differences in C2, C3, and C4, we find that the reorientation of confined pyridine is highly anisotropic, clue to directional hydrogen bonding between the N atoms of pyridine and the OH groups on the glass surface. In contrast, we see no confinement effect on the rotational anisotropy of PFP.