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Molecular structure of caffeine as determined by gas electron diffraction aided by theoretical calculations
| Title: | Molecular structure of caffeine as determined by gas electron diffraction aided by theoretical calculations |
| Authors: | Egawa, Toru Browse this author | | Kamiya, Akemi Browse this author | | Takeuchi, Hiroshi Browse this author →KAKEN DB | | Konaka, Shigehiro Browse this author |
| Keywords: | Caffeine | | Molecular structure | | Gas electron diffraction | | MP2 calculations | | DFT calculations |
| Issue Date: | 15-Dec-2006 |
| Publisher: | Elsevier B.V. |
| Journal Title: | Journal of Molecular Structure |
| Volume: | 825 |
| Issue: | 1-3 |
| Start Page: | 151 |
| End Page: | 157 |
| Publisher DOI: | 10.1016/j.molstruc.2006.04.024 |
| Abstract: | The molecular structure of caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) was determined by means of gas electron diffraction. The nozzle temperature was 185 °C. The results of MP2 and B3LYP calculations with the 6-31G** basis set were used as supporting information. These calculations predicted that caffeine has only one conformer and some of the methyl groups perform low frequency internal rotation. The electron diffraction data were analyzed on this basis. The determined structural parameters (rg and ∠α) of caffeine are as follows: <r(N–C)ring> = 1.382(3) Å; r(C=C) = 1.382(←) Å; r(C–C) = 1.446(18) Å; r(C=N) = 1.297(11) Å; <r(N–Cmethyl)> = 1.459(13)Å; <r(C=O)> = 1.206(5) Å; <r(C–H)> = 1.085(11) Å; ∠N1–C2–N3 = 116.5(11)°; ∠N3–C4=C5 = 121.5(13)°; ∠C4=C5–C6 = 122.9(10)°; ∠C4=C5–N7 = 104.7(14)°; ∠N9–C4=C5 = 111.6(10)°; <∠N–C–Hmethyl> = 108.5(28)°. Angle brackets denote average values; parenthesized values are the estimated limits of error (3σ) referring to the last significant digit; left arrow in the parenthesis means that this parameter is bound to the preceding one. |
| Relation: | http://www.sciencedirect.com/science/journal/00222860 |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/17171 |
| Appears in Collections: | 理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 江川 徹
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