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趙奕姼 Ito Chao

趙奕姼 Ito Chao. Charge-Controlled Hydrogen Bonds in Conjugated Molecules. Rosette Nanotubes as Conduits. H. Fenniri et al , J. Am. Chem. Soc . 2002 , 124 , 11064. Time. Covalent bond + Non-covalent bond synthesis. Covalent bond synthesis. How about control hydrogen bonding via

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趙奕姼 Ito Chao

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  1. 趙奕姼Ito Chao Charge-Controlled Hydrogen Bonds in Conjugated Molecules

  2. Rosette Nanotubes as Conduits H. Fenniri et al, J. Am. Chem. Soc. 2002, 124, 11064 Time Covalent bond + Non-covalent bond synthesis Covalent bond synthesis

  3. How about control hydrogen bonding via a remote center? Hydrogen bonding changes properties of bound molecules – e.g. sensors • UV-visible absorption and luminescence spectra changed upon H-bonding Watanabe, S. et al. J. Am. Chem. Soc. 1998, 120, 229.

  4. Beer, P. D. Polarized amide groups enhance binding strength in hydrogen-bonded metallocene complexes * KFe2+ = 4600 M-1 K Fe3+ = 158000 M-1 KCo2+ = 2800 M-1 KCo3+ = 98000 M-1 * * * * * * * More acidic amide proton based on X-ray and IR results Tucker, J. H. R. et al. Angew. Chem. Int. Ed. 2000, 39, 3296.

  5. Implication of charge control in supramolecular chemistry

  6. Charge delocalization of the protonated system

  7. n C=C(N) C=C(P) N=N(N) N=N(P)1 -6.84 -13.17 -7.39 -15.50 2 -6.73 -12.04 -7.66 -16.45 3 -6.64 -11.18 -7.84 -17.99 4 -6.57 -10.47 -7.95 -19.07 4-i H+ H3N Table 1. Ammonia binding energies (kcal/mol) with three-component and two-component systems (4i) calculated at the HF/6-31G* level 4-i -6.22 -7.27 Signal does not die out! Chao, I.; Hwang, T.-S. Angew. Chem. Int. Ed. 2001, 40, 2703.

  8. (C=C)n 1.5 n=3 n=4 n=1 n=2 1.4 r 1.3 N P 1.2 r s t u v 1.5 (N=N)n 1.4 r 1.3 1.2 r s t u v Bond length variation in pyrrole-(X=X)n-imine systems

  9. n C=C(N) C=C(P) N=N(N) N=N(P)1 -6.84 -13.17 -7.39 -15.50 2 -6.73 -12.04 -7.66 -16.45 3 -6.64 -11.18 -7.84 -17.99 4 -6.57 -10.47 -7.95 -19.07 4-i Q(pyr)a Q(pyr)a (0.27) (0.42) (0.22) (0.47) (0.18) (0.59) (0.15) (0.66) a Difference in Mulliken group charge of pyrrole between protonated and neutral three-component systems. H+ H3N Table 1. Ammonia binding energies (kcal/mol) with three-component and two-component systems (4i) calculated at the HF/6-31G* level 4-i -6.22 -7.27 Signal does not die out! Chao, I.; Hwang, T.-S. Angew. Chem. Int. Ed. 2001, 40, 2703.

  10. Table 2. Ammonia binding energy (kcal/mol) of protonated three-component systems with (N=N)n bridges calculated with ab initio and DFT methods. n = 1 n=2 n=3 n=4 HF/6-31G* -15.50 -16.45 -17.99 -19.07 HF/6-31+G** -13.41 -14.29 -15.77 -16.78 HF/6-31+G(2d,2p) -12.94 -13.90 -15.36 -16.33 B3LYP/6-31G* -19.19 -19.37 -19.57 -19.79 B3LYP/6-31+G** -16.06 -16.26 PW91PW91/6-31G* -21.77 -21.88 PW91P86/6-31G* -22.76 -22.87 MP2/6-31G* -18.72 -19.27 -20.08 -21.43 MP2/6-31G*// -18.73 -19.30 -20.07 -21.10 B3LYP/6-31G* MP4(SDQ)/6-31G* -17.75 -19.04 MP4(SDQ)/6-31G*// B3LYP/6-31G* -17.42 -18.30 CCSD(T)/6-31G*// MP4(SDQ)/6-31G* -20.30a -21.04a a Not corrected for BSSE.

  11. Signal maintenance still possible with more feasible bridges Table 3. Ammonia binding energy (kcal/mol) of the protonated three-component system with different -((CH=CH)n-N=N)x- bridges at the HF/6-31G* level. x = 1 x = 2 -(CH=CH-N=N)x- -14.63 -15.62 -((CH=CH)2-N=N)x- -13.90 -14.49 -((CH=CH)3-N=N)x- -13.19 -13.64 -((CH=CH)4-N=N)x- -12.61 -12.98

  12. H+ Protonated (P) Neutral (N)

  13. Ammonia binding energy of protonated pyrrole-(X=X)n-imine -20 (N=N) n -18 -16 Binding Energy (kcal/mol) -14 (C=N) n -12 (C=C) n -10 (C C) ≡ n (N=C) n -8 1 2 3 4 n

  14. Ammonia binding energy of protonated pyrrole-(X=X-X=X)n-imine -20 (N=C-N=N) n -18 -16 (C=C-N=N) n (N=N-C=N) n (C=N-N=N) n Binding Energy (kcal/mol) (N=N-C=C) -14 n (C=C-N=C) -12 n (C=C-C=N) n (C=N-C=C) n -10 (N=N-N=C) n (N=C-C=C) n -8 1 2 n

  15. Model construction DE d+ QH QH (whole mol.)

  16. Correlation of binding energy and QH QH

  17. QH QH Correlation of QH and energy gap between pyrrole HOMO and two-component LUMO QH(a.u.) • Through-bond intramolecular charge transfer (ICT)

  18. + C H = N H 2 Correlation of binding energy and molecular electrostatic potential (MEP) of the two-component system MEP Q = +1 • Through-space electrostatic effect important when ICT is absent

  19. Model construction (C=C)n-iminium 2 1 Signal reduction 1 2 (N=N)n-iminium Signal maintaining

  20. Bridge effect on two-component LUMO Better bridge: Low-lying p-HOMO and p-LUMO • Confirmed by three-component systems containing CF=CF units

  21. Table 1. Ammonia binding energies (kcal/mol) with three-component systems at the HF/6-31G* level n C=C(N) C=C(P) CF=CF(N) CF=CF(P) 1 -6.84 -13.17 -7.07 -14.002 -6.73 -12.04 -7.27 -13.31 3 -6.64 -11.18 -7.38 -12.82 4 -6.57 -10.47 -7.54 -12.51 • CF=CF superior in terms of signal maintenance and signal sensitivity. Hwang, T.-S. et al. Chem. Eur. J., accepted.

  22. Ammonia binding energy of protonated pyrrole-(X=X)n-imine -20 (N=N) n -18 -16 Binding Energy (kcal/mol) -14 (C=N) n -12 (C=C) n -10 (C C) ≡ n (N=C) n -8 1 2 3 4 n • Introduction of N lowers p/p* orbital energies, but orientation important.

  23. Ammonia binding energy of protonated pyrrole-(X=X-X=X)n-imine -20 (N=C-N=N) n -18 -16 (C=C-N=N) n (N=N-C=N) n (C=N-N=N) n Binding Energy (kcal/mol) (N=N-C=C) -14 n (C=C-N=C) -12 n (C=C-C=N) n (C=N-C=C) n -10 (N=N-N=C) n (N=C-C=C) n -8 1 2 n • Introduction of N lowers p/p* orbital energies, but orientation important.

  24. Recent success in employing a remote charge center to affect hydrogen bonding Ka(F-; DMSO) = 440 M-1 Ka(F-; DMSO) = 12000 M-1 Ka(F-; DMSO) = 54000 M-1 Sessler, J. L. et al. J. Am. Chem. Soc. 2002, 124, 1134.

  25. Conclusion • Coupled with experimental evidences, remote control of hydrogen bonds by charge alteration is feasible. • A model is established to understand the signal reduction/maintaining phenomenon. A bridge with low-lying -HOMO and -LUMO is expected to facilitate the signal amplifying behavior. • Orientation of the bridge is important. • Limited structure units can be used to construct bridges of very different properties.

  26. Acknowledgement ＄＄＄國科會、中央研究院 黃聰松 阮寧 陳信允 陳政仲 駱思融

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