Strong π-stacking causes unusually large anisotropic thermal expansion and thermochromism
Strong π-stacking causes unusually large anisotropic thermal expansion and thermochromism
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DOI：
10.1073/pnas.2106572118
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发表时间：
2021-11-01
影响因子：
11.1
通讯作者：
Omary, Mohammad A.
中科院分区：
文献类型：
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作者：
Dharmarwardana, Madushani;Otten, Brooke M.;Omary, Mohammad A.
N-丁氧基苯二亚胺(BNDI)基态二聚体/三聚体/四聚体(BNDI)的PI堆积强度超过50kcal.mol(-1)，大大超过*(3)[Py](2)准分子(类似于30kcal.mol(-1)；形式键级=1)，与其他弱到中等的经典共价键相似。三斜晶型(BNDI-T)和单斜晶型(BNDI-M)的协同pi堆积分别影响了(452，-16.8，-154,273)×10(-6)·K-1和(70.1，-44.7,163,177)×10(-6)·K-1的异常大的线性热膨胀系数(α(A)，α(B)，α(C)，β)。BNDI-T在300-K范围内表现出高度可逆的热致变色性，表现为从橙色(环境温度)到红色(低温)或黄色(375K)的颜色变化，重复热循环至少持续2年以上。
pi-stacking in ground-state dimers/trimers/tetramers of N-butoxyphenyl(naphthalene)diimide (BNDI) exceeds 50 kcal.mol(-1) in strength, drastically surpassing that for the *(3)[pyrene](2) excimer (similar to 30 kcal.mol(-1); formal bond order = 1) and similar to other weak-to-moderate classical covalent bonds. Cooperative pi-stacking in triclinic (BNDI-T) and monoclinic (BNDI-M) polymorphs effects unusually large linear thermal expansion coefficients (alpha(a), alpha(b), alpha(c), beta) of (452, -16.8, -154, 273) x 10(-6).K-1 and (70.1, -44.7, 163, 177) x 10(-6).K-1, respectively. BNDI-T exhibits highly reversible thermochromism over a 300-K range, manifest by color changes from orange (ambient temperature) toward red (cryogenic temperatures) or yellow (375 K), with repeated thermal cycling sustained for over at least 2 y.