The self-immolative intramolecular cyclization involves the nucleophilic secondary amine attacking the carbonyl group. We rationalized that introducing an additional benzyl group at the carbamate nitrogen atom in compound SIE2 could increase the steric hindrance around the reactive carbonyl group, thereby further discriminating the cyclization reactivity in the presence of CB. The formation of a supramolecular complex between SIE2 and CB in D2O was supported by significant shifts in the NMR signals of SIE2 before and after introducing CB (Figure ), as well as ITC measurements (Figure ). However, ITC results unexpectedly revealed two distinct binding events between CB and SIE2 (Ka1 = 6.3 × 10 6 M -1 and Ka2 = 3.7 × 10 4 M -1 ), each corresponding to the binding of approximately one equivalent of CB. This 2:1 stoichiometry between CB and SIE2 is attributed to the positively charged secondary amine promoting the caging of both benzyl groups in SIE2 by CB. A control molecule SIE3 featuring a single benzylamine substituent at the carbamate nitrogen also demonstrated strong binding affinity with CB (Ka = 5.3 × 10 6 M -1 ), supporting that the secondary amine effectively facilitates CB binding to the benzyl group at the carbamate nitrogen, although they are relatively remote. To highlight the structure of the dual-complex of SIE2, we optimized the geometry of a positively charged model molecule SIE2model with two CB molecules at 𝛚B97x-d/6-31G level of theory (see SI for details). Note that both benzyl binding sites in SIE2model are fully inserted inside the CB cage in the bound complex (Figure ). The CB cages create high steric hindrance around the secondary amine and carbonyl reactive groups, sequestering the reactive centers. The protonated SIE2model molecule is also stabilized by a hydrogen bond interaction with the CB cage (Figure ).