As the 4-alkyl chain length is increased from shorter homologues such as DOM, DOET and DOPR which are all potent hallucinogens, the 5-HT2 binding affinity increases, rising to a maximum with the 4-(n-hexyl) derivative before falling again with even longer chains, but compounds with chain length longer than n-propyl, or with other bulky groups such as isopropyl, t-butyl or γ-phenylpropyl at the 4- position, fail to substitute for hallucinogens in animals or produce hallucinogenic effects in humans, suggesting these have low efficacy and are thus antagonists or partial agonists at the 5-HT2A receptor.
As the 4-alkyl chain length increases from shorter homologues like DOM, DOET, and DOPR, which are all potent hallucinogens, the 5-HT2 binding affinity rises. It reaches its peak with the 4-(n-hexyl) derivative before declining again for longer chains. Compounds with a chain length exceeding n-propyl or containing bulky groups such as isopropyl, t-butyl, or γ-phenylpropyl at the 4-position do not substitute for hallucinogens in animals or produce hallucinogenic effects in humans, indicating low efficacy and suggesting they are antagonists or partial agonists at the 5-HT2A receptor.