Autoassembly of cage structures

X-ray diffraction study of DL-1,4-dimethyl-2,5-dioxabicyclo[2.2.1]heptane-3,6-dione: the sense of twist and folding

“…Thus, the experimental sense of twist of dimethyl-dilactones (1 † , 3 8 ) in crystals is confirmed by ab initio models for 1-4 in a free state. In addition to data on the torsional energy surface of (R,R)-2 16 and (R,R)-4 12 obtained by the MM2(91) method, these results show that the above twist sense for lactone groups in bridged dilactones 1-4 is a common tendency to form a groundstate conformation.…”

“…The analogous twist character for a bicyclo[2.2.2]skeleton was observed for dilactone (±)-3 in a crystal without the retention of C 2 symmetry (t 0 = |4.4| and |4.6|°) 8 and confirmed by DFT (B3LYP/6-31G*) models of homochiral dilactones (R,R)-3 and (R,R)-4 [a single synchro-(+,+,+)-twist form, t 0 = 2.9° (3), 3.1° (4)]. 12 As expected, the planarity of the lactone group [C-C(O)-O-C, t 0 ] and the folding of the dilactone ring [the fold angle between mean planes of lactone groups is f = 109.0° (XRD), † 110.2°( MP2) 6 ] in 1 increased as compared with 3 [f = 124.9° (XRD) 8 ].…”

“…However, its structure was not determined by X-ray diffraction (XRD), MW or GED in contrast to its bridged homologue 3 (XRD). 8 At the same time, the geometry of norbornane 5 and norborna-2,5-diene 6, possessing the parent bicyclo[2.2.1]frame rigid system, was investigated thoroughly by the XRD analysis of their plastic crystals. 9,10 Dilactone 1 also tends to form plastic crystals owing to its globular shape.…”

α,α’-Diamino-α,α’-dicarboxyadipic acid tetraester: synthesis, lactamisation and dilactam structure

“…12 The bicyclic molecule 3 features a synchro(-,-,-)-twist conformation (cf. similar dilactones 19,20 ). The torsion angles C(4)-N(5)-C(6)-C(1), C(4)-C(3)-N(2)-C(1) and C(4)-C(8)-C(7)-C(1) are equal to -3.1°, -3.1° and -5.0°, respectively.…”