Calculation Driven Synthesis of an Excellent Dihydropyrene Negative Photochrome and its Photochemical Properties
Calculation Driven Synthesis of an Excellent Dihydropyrene Negative Photochrome and its Photochemical Properties
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DOI：
10.1021/ja1100596
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发表时间：
2011-03-23
影响因子：
15
通讯作者：
Mitchell, Reginald H.
中科院分区：
文献类型：
--
作者：
Ayub, Khurshid;Li, Rui;Mitchell, Reginald H.
通过利用密度泛函理论（DFT）活化能垒计算，二氢芘的光致变色性能已经得到了实质性的改善，这表明二异丁烯基环番二烯15'应该对热异构化为二氢芘（DHP）15具有显著的能垒，其本身应该抵抗涉及内部基团迁移到重排的二氢芘9（X = -CH=C（Me）（2））的异构化。作为这些计算的结果，进行了无色环番二烯（CPD）15'的合成，并且从二腈28分四步以37%总产率%实现。环番二烯15'在100 ° C下热异构化为二氢芘15，其中t（1/2）= 4.5h，得到外推的20 ° C t（1/2）类似于16 y，与DFT计算一致。在加热到130 ℃时没有观察到[1，5]-σ迁移重排成9（X = -CH=C（Me）（2））的证据。在环己烷中测定DHP 15 in到CPD 15'的开环异构化量子产率（phi（开放））为0.12 +/-0.01，其为苯并DHP 1的三倍。15的Friedel-Crafts萘甲酰化得到70%的紫色32，其在甲苯中显示出对于任何已知的二氢芘的最大的光化学开环异构化量子产率（phi（open））为0.66 +/- 0.02，类似于在甲苯中比1大9倍。32 ′到32 ′的热闭合，虽然比15 ′快，但给出了一个有用的外推t（1/2），在20 ℃时类似于2 y。
The photochromic properties of dihydropyrenes have been substantially improved by making use of density functional theory (DFT) activation barrier calculations, which suggested that the di-isobutenylcyclophanediene 15' should have a significant barrier to thermal isomerization to the dihydropyrene (DHP) 15, which itself should resist isomerization involving migration of the internal groups to the rearranged dihydropyrene 9 (X = -CH=C(Me)(2)). As a result of these calculations, the synthesis of the colorless cyclophanediene (CPD) 15' was undertaken and achieved from the dinitrile 28 in four steps in 37% overall yield %. The cyclophanediene 15' thermally isomerized to the dihydropyrene 15 at 100 degrees C with t(1/2) = 4.5 h, giving an extrapolated 20 degrees C t(1/2) of similar to 16 y, consistent with the DFT calculations. No evidence for [1,5]-sigmatropic rearrangement in to 9 (X = -CH=C(Me)(2)) was observed on heating to 130 degrees C. The ring-opening isomerization quantum yields (phi(open)) for DHP 15 in to CPD 15' were determined in cyclohexane to be 0.12 +/- 0.01, which is three times greater than for the benzoDHP 1. Friedel-Crafts naphthoylation of 15 gave 70% of purple 32, which in toluene showed the largest photochemical ring-opening isomerization quantum yields (phi(open)) of 0.66 +/- 0.02 for any known dihydropyrene, similar to nine times greater than 1 in toluene. The thermal closing of 32' to 32, although faster than for 15', gave a useful extrapolated t(1/2) of similar to 2 y at 20 degrees C.