Synthesis of a Fluoreno[2,3b]fluorene Derivative to Experimentally Verify Extraordinary Optical Properties of Indenofluorenes Tobe Lab. Masahito Miki 1 Contents • Introduction Singlet biradicals Resonance structures Quinodimethanes • Previous work Comparision of UV-vis-NIR spectra p-conjugation space and absorption wave length New Principle for Low Energy Absorption Nonalternant hydrocarbons Excitation energy of biradical compounds • My work 2 Singlet Biradicals HOMO and LUMO of biradicaloids 閉殻 closed shell LUMO 一重項ビラジカル singlet biradical 開殻 open shell y=1 HOMO 0<y<1 Fabian, J. et al. Angew. Chem. Int. Ed. 1989, 28, 677. y=0 biradical character : y 1 2T 1 T 2 nHOMO nLUMO T 2 nHOMO, nLUMO; occupation numbers of HOMO or LUMO UHF/6-31G*//UB3LYP/6-31G* and Yamaguchi scheme Yamaguchi, K. Chem. Phys. Lett. 1975, 33, 330. 3 Resonance Structures benzene Unimportant contributor Energy loss for breaking pbond (272 kJ / mol) Important contributor Closed shell 閉殻構造 ・All electrons are used to bonds. ・closed-shell Open shell 開殻構造 Aromatic stabilization energy 芳香族安定化エネルギー (about 90 kJ / mol) ・A bond is broken ・open-shell 4 Quinodimethanes (QDM) p-quinodimethane o-quinodimethane 速度論的安定化 Kinetic stabilization Kubo, T. et al. Angew. Chem. Int. Ed. 2005, 44, 6564. Chase, D. T. et al. Angew. Chem. Int. Ed. 2011, 50, 11103. 熱力学的安定化 thermodynamical stabilization Shimizu, A.; Tobe, Y. Angew. Chem. Int. Ed. 2011, 50, 6906. 5 Previous Work 1700nm m-quinodimethane UV-vis-NIR absorption spectra of 1b in CH2Cl2. Tobe, Y. et al. Angew. Chem. Int. Ed. 2013, 52, 6076. DES-T = -17.6 kJ/mol 6 Comparision of UV-vis-NIR Spectra UV-vis-NIR absorption spectra of a below compound in CH2Cl2. UV-vis-NIR absorption spectra of 1b in CH2Cl2. Tobe, Y. et al. Angew. Chem. Int. Ed. 2013, 52, 6076. Tobe, Y. et al. Angew. Chem. Int. Ed. 2011, 50, 6906. 1b A derivertive of Indeno[2,1-a]fluorene 7 p-Conjugation Space and Absorption Wave Length acenes Anthony, J. E. et al. Angew. Chem. Int. Ed. 2008, 47, 452. Larger p-conjugation space Lower absorption energy 8 New Principle for Low Energy Absorption 1. Moderate singlet biradical character 2. Nonalternant hydrocarbon 3. Smaller p-conjugation space Lower absorption energy 1a HOMO−LUMO Energy Gap Singlet Biradical Character Nakano.M (unpublished) 2a : 1a > 2a : 1a < 2a Transition Energy (Prediction) : 1a < 2a 9 Nonalternant Hydrocarbons Alternant hydrocarbon naphthalene Nonalternant hydrocarbon azulene LUMO HOMO Michl, J. et al. Tetrahedron 1976, 32, 205. 10 Excitation Energy of Biradical Compounds 7 6 E f (y) 𝑈 𝑓𝐸 (𝑦 𝑈 𝑓𝐸 (𝑦 5 𝛥𝐸𝑎𝑏 = − 2𝐾:𝑎𝑏𝛥𝐸𝑎𝑏 = − 2𝐾𝑎𝑏 Transition Energy 2 2 4 𝑓𝐸 𝑦 = 1 + 1 y=1− 3 1 2 1− 1−𝑦 2 1 0 0.2 𝑈 1+ 2 𝜀𝐻𝐿 0.4 0.6 0.8 2 1 y U Effective Coulombic Repulsion Energy ↘ • Smaller HOMO-LUMO overlap • Larger Biradical Factor (y) Moderate biradical character fE(y) Function of Biradical Factor (y) ↘ Kab Exchange Integral ↗ • Larger Space Separation between HOMO-LUMO • Smaller pi-System ↗ • Increasing U (larger HOMO-LUMO overlap) • Decreasing ɛHL 11 y Biradical Factor Excitation Energy of Biradical Compounds First Transition Energy : 𝛥𝐸𝑎𝑏 Kab Exchange Integral JHHM, Coulombic Integral JLLM in HOMO or LUMO JHLM Coulombic Integral between HOMO and LUMO ↗ ↗ ↘ 𝑈 𝑓𝐸 (𝑦 = − 2𝐾𝑎𝑏 2 • Nonalternant hydrocarbon • Smaller pi-System • Smaller pi-System • Nonalternant hydrocarbon • Larger Space Separation between HOMO-LUMO 1 Kab = 𝐽𝐻𝐻𝑀 + 𝐽𝐿𝐿𝑀 − 2𝐽𝐻𝐿𝑀 4 JHHM, JLLM : Coulombic Integral in HOMO or LUMO JHLM: Coulombic Integral between HOMO and LUMO 12 Nonalternant Hydrocarbons Alternant hydrocarbon naphthalene Nonalternant hydrocarbon azulene LUMO HOMO Michl, J. et al. Tetrahedron 1976, 32, 205. 13 Excitation Energy of Biradical Compounds First Transition Energy : 𝛥𝐸𝑎𝑏 Kab Exchange Integral JHHM, Coulombic Integral JLLM in HOMO or LUMO JHLM Coulombic Integral between HOMO and LUMO ↗ ↗ ↘ 𝑈 𝑓𝐸 (𝑦 = − 2𝐾𝑎𝑏 2 • Nonalternant hydrocarbon • Smaller pi-System • Smaller pi-System • Nonalternant hydrocarbon • Larger Space Separation between HOMO-LUMO 1 Kab = 𝐽𝐻𝐻𝑀 + 𝐽𝐿𝐿𝑀 − 2𝐽𝐻𝐿𝑀 4 JHHM, JLLM : Coulombic Integral in HOMO or LUMO JHLM: Coulombic Integral between HOMO and LUMO 14 New Principle for Low Energy Absorption 1. Moderate singlet biradical character 2. Nonalternant hydrocarbon 3. Smaller p-conjugation space Lower absorption energy 1a HOMO−LUMO Energy Gap Singlet Biradical Character Nakano.M (unpublished) 2b 2a : 1a > 2a : 1a < 2a Transition Energy (Prediction) : 1a < 2a 15 Synthetic Scheme of 2b † 平野慎太朗、大阪大学基礎工学部化学応用科学科、学士学位論文 (2013). 16 conclusion • Biradicaloids have intermediate nature between the nature of two structure which are a closed-shell and open-shell. • Indeno[2,1-b]fluorene has a extraordinary optical property. • Nonalternant hydrocarbons which have moderate singlet biradical character can have the extraordinary optical property. • Synthesis of fluoreno[2,3-b]fluorene is undergone. 17
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