The second dataset featured two hosts in the GDCC family, TEMOA and TEETOA, commonly referred to as Octa-Acids. GDCCs are low-symmetry hosts, fairly rigid, and have a basket-shaped binding site with eight carboxylate groups appended to the host to enhance solubility . Four carboxylates are located near the cavity protruding out to solvent, and four others are at the bottom of the host at the propionate tails. TEMOA has been used in previous SAMPL host-guest challenges with different sets of guests, and appeared with the name OAMe. TEETOA is a new variant synthesized by the Gibb lab, and differs from TEMOA by four ethyl groups which reduce the size of the cavity entry, may elongate the cavity entry, and introduce flexibility at the entrance (Figure ). The guests selected for both TEMOA and TEETOA are mostly rigid with a hydrophobic moiety and a polar region at opposite ends of the molecules. The hydrophilic region of the guests are composed of carboxylate and/or hydroxyl groups (Figure ), and when the guests are in complex with the host, the polar group is typically exposed to the solvent while the hydrophobic region is buried in the deep hydrophobic binding site.