Abstract
Understanding the mechanism of linear acene decomposition and its reactivity is a prerequisite for controlling the stability of acenes and their future applications. Previously, we suggested that long acenes may undergo polymerization since the polymerization product is thermodynamically more stable than the dimerization product. However, due to kinetic considerations, the most thermodynamically stable product, the polymer, might not necessarily be formed. To elucidate the situation, we investigated the mechanisms of acene polymerization computationally, using pentacene, hexacene, and heptacene as representative examples. Similarly to dimerization, acene polymerization follows a stepwise biradical pathway. Structural and steric hindrance of the polymer backbone forces acene polymerization to proceed via the less reactive noncentral benzene rings. Consequently, dimerization is always kinetically more favorable than polymerization, irrespective of acene length. Although, for long acenes starting from hexacene, both polymerization and dimerization are barrierless pathways relative to the reactants, polymerization is thermodynamically preferred for hexacene and heptacene and even more so for longer acenes (since polymerization forms four new C-C bonds while dimerization forms only two). Indeed, reinvestigation of available experimental data suggests that acene-based polymers were probably obtained experimentally previously.
| Original language | English |
|---|---|
| Pages (from-to) | 10058-10068 |
| Number of pages | 11 |
| Journal | Journal of Organic Chemistry |
| Volume | 78 |
| Issue number | 20 |
| DOIs | |
| Publication status | Published - Oct 18 2013 |
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ASJC Scopus subject areas
- Organic Chemistry
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Formation of acene-based polymers : Mechanistic computational study. / Zamoshchik, Natalia; Zade, Sanjio S.; Bendikov, Michael.
In: Journal of Organic Chemistry, Vol. 78, No. 20, 18.10.2013, p. 10058-10068.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Formation of acene-based polymers
T2 - Mechanistic computational study
AU - Zamoshchik, Natalia
AU - Zade, Sanjio S.
AU - Bendikov, Michael
PY - 2013/10/18
Y1 - 2013/10/18
N2 - Understanding the mechanism of linear acene decomposition and its reactivity is a prerequisite for controlling the stability of acenes and their future applications. Previously, we suggested that long acenes may undergo polymerization since the polymerization product is thermodynamically more stable than the dimerization product. However, due to kinetic considerations, the most thermodynamically stable product, the polymer, might not necessarily be formed. To elucidate the situation, we investigated the mechanisms of acene polymerization computationally, using pentacene, hexacene, and heptacene as representative examples. Similarly to dimerization, acene polymerization follows a stepwise biradical pathway. Structural and steric hindrance of the polymer backbone forces acene polymerization to proceed via the less reactive noncentral benzene rings. Consequently, dimerization is always kinetically more favorable than polymerization, irrespective of acene length. Although, for long acenes starting from hexacene, both polymerization and dimerization are barrierless pathways relative to the reactants, polymerization is thermodynamically preferred for hexacene and heptacene and even more so for longer acenes (since polymerization forms four new C-C bonds while dimerization forms only two). Indeed, reinvestigation of available experimental data suggests that acene-based polymers were probably obtained experimentally previously.
AB - Understanding the mechanism of linear acene decomposition and its reactivity is a prerequisite for controlling the stability of acenes and their future applications. Previously, we suggested that long acenes may undergo polymerization since the polymerization product is thermodynamically more stable than the dimerization product. However, due to kinetic considerations, the most thermodynamically stable product, the polymer, might not necessarily be formed. To elucidate the situation, we investigated the mechanisms of acene polymerization computationally, using pentacene, hexacene, and heptacene as representative examples. Similarly to dimerization, acene polymerization follows a stepwise biradical pathway. Structural and steric hindrance of the polymer backbone forces acene polymerization to proceed via the less reactive noncentral benzene rings. Consequently, dimerization is always kinetically more favorable than polymerization, irrespective of acene length. Although, for long acenes starting from hexacene, both polymerization and dimerization are barrierless pathways relative to the reactants, polymerization is thermodynamically preferred for hexacene and heptacene and even more so for longer acenes (since polymerization forms four new C-C bonds while dimerization forms only two). Indeed, reinvestigation of available experimental data suggests that acene-based polymers were probably obtained experimentally previously.
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U2 - 10.1021/jo4006415
DO - 10.1021/jo4006415
M3 - Article
VL - 78
SP - 10058
EP - 10068
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 20
ER -