Abstract
Phenylacetylene scaffolds are known to be an important component in electronic devices, but their thermochemistry has not been studied so far. In this paper, we systematically calculate the strain energies (SE) and the standard enthalpies of formation (ΔfH298°) of sixteen linear polyynes-substituted benzene (PSB) and seven cyclic[n]orthophenyleneacetylenes ([n]COPAs) (n = 2–8). The geometries and vibrational frequencies of PSB were calculated at B3LYP/6–31 + G(d,p), mPW1PW91/6–31 + G(d,p), and M06-2X/6–31 + G(d,p) levels of theory and for [n]COPAs, mPW1PW91/6-31G(d) was used. Isodesmic and homodesmotic reactions approach were used to calculate SE and ΔfH298°. The results show that ΔfH298°of PSB increases steadily with the increasing the numbers of [sbnd]C[tbnd]C[sbnd] linkage, and endothermicΔfH298°of these molecules are indicative of an acetylene substituent strain. The SE per-unit monomer (SE/n), and ΔfH298°per-unit monomer (ΔfH298°/n) of [n]COPAs were calculated and results were compared with its meta and para counterpart. In addition, electronic properties such as HOMO, LUMO and HOMO-LUMO energy gap were calculated.
Original language | British English |
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Pages (from-to) | 146-156 |
Number of pages | 11 |
Journal | Thermochimica Acta |
Volume | 654 |
DOIs | |
State | Published - 10 Aug 2017 |
Keywords
- DFT
- Electronic property
- Homodesmotic reaction
- Phenylacetylene scaffold
- Thermochemistry