1986
DOI: 10.1021/ja00266a006
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Cryptand conformational analysis and its mechanistic implications. Molecular mechanics calculations on cryptands [111] and [222]

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Cited by 35 publications
(19 citation statements)
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“…The "guided dynamics" with Mf give essentially "in-in" forms (92%, 92%, 99%, respectively in sets 2 to 4), and zero ffout-out" form. Similar trends emerges from the SHAS: on the average, within each set, the SHAS decreases from 17.8 Pi2 (set 11, 16.8 A' (set 2) to 8.1 A' (set 3) and 8.3 Hi2 (set 4); its ranges from 7.9 to 27.4 A2 in set 1, from 7.9 to 28.0 A2 in set 2, from 3.9 to 18.8 A2 in set 3 and from 3.9 to 12.9 A2 in set 4. These numbers clearly demonstrate the structuring effect of the cation in the simulation, and the conformational preferences of the 222 receptor.…”
Section: Resultssupporting
confidence: 59%
“…The "guided dynamics" with Mf give essentially "in-in" forms (92%, 92%, 99%, respectively in sets 2 to 4), and zero ffout-out" form. Similar trends emerges from the SHAS: on the average, within each set, the SHAS decreases from 17.8 Pi2 (set 11, 16.8 A' (set 2) to 8.1 A' (set 3) and 8.3 Hi2 (set 4); its ranges from 7.9 to 27.4 A2 in set 1, from 7.9 to 28.0 A2 in set 2, from 3.9 to 18.8 A2 in set 3 and from 3.9 to 12.9 A2 in set 4. These numbers clearly demonstrate the structuring effect of the cation in the simulation, and the conformational preferences of the 222 receptor.…”
Section: Resultssupporting
confidence: 59%
“…4,10,15‐Trioxa‐1,7‐diazabicyclo[5.5.5]heptadecane (crypt‐111), the smallest cryptand and an effective proton sponge, was first reported in 1972 by Cheney and Lehn . The most stable conformation of crypt‐111, which directs the two nitrogen lone pairs inside the cavity ( in – in conformation), is a rather weak base (p K a1 =7.1). Under kinetic control monoprotonation occurs outside the cavity with a fast inversion of configuration at one nitrogen, and the formed in – out + cation can be further protonated, with a second inversion at nitrogen, to give the out + – out + dication (p K a2 ≈1) or can slowly convert ( k =2.3×10 −4 s −1 ) into the more stable conformer bearing the proton inside the cavity ( in – in + or H + ⊂crypt‐111 monocation).…”
Section: Methodsmentioning
confidence: 99%
“…The crystal shows high symmetry that is related to the mirrorp lane through the three oxygen atoms of crypt-111.T he cation adopts an in-in + conformation ( Figure 1) with ar ugby-balls hape (intramolecular NÀNa nd OÀOs eparations are 369.6 and 364.7 pm, Ta ble S.4 in the Supporting Information). In-out + and out-out + conformationsh ave been observed in solution, [17] but the in-in arrangement is the most stable for the free cryptand and the protonated derivatives in the gas, [18] liquid, [17] and solid [22] phases.T he nitrogen atoms adopt ad istorted tetrahedral conformation (]CÀNÀC = 112.908).…”
mentioning
confidence: 99%
“…One of the important factors in the formation of metal cryptates is the cryptand conformation equilibria. For cryptands with N bridgeheads, the principal conformers arise from different orientations of the lone pairs of the electrons on the bridgehead atoms 2. Each lone pair may be oriented into the cavity ( endo ) or away from the cavity ( exo ).…”
Section: Introductionmentioning
confidence: 99%