Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives
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Bowling Green State University / OhioLINK
2008
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1224602780 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-bgsu12246027802021-08-03T05:28:38Z Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives Ying, Hu Chemistry T5H Helicene DCM 1H Z-scan BDT 4-methoxyphenyl <p>Light-emitting fluorophores <b>1-10b</b> have been synthesized. Helical compounds end-capped with different electron-rich and electron-poor aryl moieties are evaluated. Photocyclization of <b>10a</b> was investigated, and the X-ray crystal structure of <b>4</b> obtained. We demonstrate that the optical properties of all of the new compounds, and by extension many conjugated materials, can be tuned over the entire blue range (400-480 nm), below.</p><p>The charge-separated state of <b>8</b> was observed in the absorption and emission spectra. DFT (B3LYP/ 6-31G*) calculations identified the optimum geometry of <b>8</b>. The distance between the electron-donating and electron-withdrawing group in <b>8</b> is 20 angstrom; through the bond. The helical structure of the <b>T5H</b> bridge causes the distance of donor and acceptor to be as short as 7.06 angstrom. Rapid charge separation and slow charge recombination was detected by femtosecond pump-probe absorption measurements. A through bond electron transfer mechanism is preferred, although the distance through space is much shorter than the thru-bond distance.</p> <p>The nonlinear optical properties of <b>BDT</b>, <b>T5H</b>, <b>1</b>, <b>6</b>, <b>7</b>, <b>9</b> and <b>11</b> as well as Rhodamine B have been investigated. Rhodamine B in methanol was used for calibration. π-Centers of <b>BDT</b> and <b>T5H</b> were studied. Compounds <b>1</b>, <b>6</b>, <b>7</b>, <b>9</b> and <b>11</b> possess either donor-π (D-π) or donor-π-acceptor (D-π-A) structures. Two-photon absorption cross-sections related to the third-order nonlinear susceptibility were measured using Z-scan techniques. Molecular structure and nonlinear optical property relationship was formulated. Compound <b>9</b> has a two-photon absorption cross-section of 103 GM when excited at 720nm.</p> 2008-11-05 English text Bowling Green State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1224602780 http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1224602780 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Chemistry T5H Helicene DCM 1H Z-scan BDT 4-methoxyphenyl |
| spellingShingle |
Chemistry T5H Helicene DCM 1H Z-scan BDT 4-methoxyphenyl Ying, Hu Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives |
| author |
Ying, Hu |
| author_facet |
Ying, Hu |
| author_sort |
Ying, Hu |
| title |
Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives |
| title_short |
Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives |
| title_full |
Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives |
| title_fullStr |
Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives |
| title_full_unstemmed |
Synthesis and Photophysical Properties of 3D Substituted Heterohelicenes and their Derivatives |
| title_sort |
synthesis and photophysical properties of 3d substituted heterohelicenes and their derivatives |
| publisher |
Bowling Green State University / OhioLINK |
| publishDate |
2008 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1224602780 |
| work_keys_str_mv |
AT yinghu synthesisandphotophysicalpropertiesof3dsubstitutedheterohelicenesandtheirderivatives |
| _version_ |
1719420647976730624 |