This makes 1 the first reported double A-type trimer with an unusual (2O5,46) IFL. Restricted rotation along the C-4 aryl (sp 3 -sp 2 ) carbon-carbon bond is otherwise only typical for B-type PACs, thereby giving rise to atropisomerism and often severe NMR line broadening at ambient temperature. In contrast, A-type PACs, with two IFLs, generally do not exhibit atropisomerism due to the rigidity of the double linkage. Improving 1 H NMR lineshapes of 1 required acquisition at low temperature (255 K; Figure ). The unexpected dynamic peak broadening of 1 despite its two double linkages indicated that the combination of (2O5,46) and (2O7,48) IFLs poses sufficient steric hindrance for restricted rotation between rings B and H to generate observable atropisomers, thus leading to NMR line-broadening. PAC tetramer 2 exhibited a molecular ion at m/z 1149.2291 M  H  in the ()-HRESIMS, corresponding to a molecular formula C60H44O24, as supported by the 13 C NMR data. Lower temperature (255 K) was applied during the 1D and 2D NMR experiments to overcome line broadening due to atropisomerism (Figure ). Analysis of the 1 H NMR spectrum showed four AMX spin systems, corresponding to four 1,3,4-trisubstituted aromatic rings (B/E/H/K). Three singlets at H 5.90, 5.96, and 6.16, as well as two meta-coupled doublets at H 6.02 and 6.03 (J = 2.3 Hz) showed the presence of aromatic rings J, G, D, and A, and further confirmed the tetrameric nature of 2. Two sequential spin systems (H 3.70 and 4.44, both d, J = 3.5 Hz; and H 5.30, 3.95, and 4.47, each brs) that assigned by the COSY data (Figure ), indicated the presence of one double (A-type) and one single (B-type) IFL of 2. Units II and IV were identified as (ent)-epicatechin and (ent)-catechin, respectively, based on the J2,3 values of ~0 and 6.3 Hz.